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Posted to commits@helix.apache.org by ka...@apache.org on 2013/12/26 06:44:27 UTC
[1/3] Change to reflow theme, update home, 0.6.1
Updated Branches:
refs/heads/helix-website [created] 92edaabc1
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_spectator.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_spectator.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_spectator.md
index a5b9a0e..ed1bd17 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_spectator.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_spectator.md
@@ -17,46 +17,47 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Spectator
+Helix Tutorial: Spectator
+-------------------------
-Next, we\'ll learn how to implement a SPECTATOR. Typically, a spectator needs to react to changes within the distributed system. Examples: a client that needs to know where to send a request, a topic consumer in a consumer group. The spectator is automatically informed of changes in the _external state_ of the cluster, but it does not have to add any code to keep track of other components in the system.
+Next, we\'ll learn how to implement a __spectator__. Typically, a spectator needs to react to changes within the distributed system. Examples: a client that needs to know where to send a request, a topic consumer in a consumer group. The spectator is automatically informed of changes in the _external state_ of the cluster, but it does not have to add any code to keep track of other components in the system.
-### Start the Helix agent
+### Start a Connection
-Same as for a PARTICIPANT, The Helix agent is the common component that connects each system component with the controller.
+Same as for a participant, The Helix manager is the common component that connects each system component with the cluster.
It requires the following parameters:
* clusterName: A logical name to represent the group of nodes
-* instanceName: A logical name of the process creating the manager instance. Generally this is host:port.
+* instanceName: A logical name of the process creating the manager instance. Generally this is host:port
* instanceType: Type of the process. This can be one of the following types, in this case, use SPECTATOR:
- * CONTROLLER: Process that controls the cluster, any number of controllers can be started but only one will be active at any given time.
- * PARTICIPANT: Process that performs the actual task in the distributed system.
- * SPECTATOR: Process that observes the changes in the cluster.
- * ADMIN: To carry out system admin actions.
-* zkConnectString: Connection string to Zookeeper. This is of the form host1:port1,host2:port2,host3:port3.
+ * CONTROLLER: Process that controls the cluster, any number of controllers can be started but only one will be active at any given time
+ * PARTICIPANT: Process that performs the actual task in the distributed system
+ * SPECTATOR: Process that observes the changes in the cluster
+ * ADMIN: To carry out system admin actions
+* zkConnectString: Connection string to ZooKeeper. This is of the form host1:port1,host2:port2,host3:port3
-After the Helix manager instance is created, only thing that needs to be registered is the listener. When the ExternalView changes, the listener is notified.
-
-### Spectator Code
+After the Helix manager instance is created, the only thing that needs to be registered is the listener. When the ExternalView changes, the listener is notified.
A spectator observes the cluster and is notified when the state of the system changes. Helix consolidates the state of entire cluster in one Znode called ExternalView.
Helix provides a default implementation RoutingTableProvider that caches the cluster state and updates it when there is a change in the cluster.
```
manager = HelixManagerFactory.getZKHelixManager(clusterName,
- instanceName,
- InstanceType.PARTICIPANT,
- zkConnectString);
+ instanceName,
+ InstanceType.PARTICIPANT,
+ zkConnectString);
manager.connect();
RoutingTableProvider routingTableProvider = new RoutingTableProvider();
manager.addExternalViewChangeListener(routingTableProvider);
```
+### Spectator Code
+
In the following code snippet, the application sends the request to a valid instance by interrogating the external view. Suppose the desired resource for this request is in the partition myDB_1.
```
-## instances = routingTableProvider.getInstances(, "PARTITION_NAME", "PARTITION_STATE");
+// instances = routingTableProvider.getInstances(, "PARTITION_NAME", "PARTITION_STATE");
instances = routingTableProvider.getInstances("myDB", "myDB_1", "ONLINE");
////////////////////////////////////////////////////////////////////////////////////////////////
@@ -68,5 +69,5 @@ result = theInstance.sendRequest(yourApplicationRequest, responseObject);
```
-When the external view changes, the application needs to react by sending requests to a different instance.
+When the external view changes, the application needs to react by sending requests to a different instance.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_state.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_state.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_state.md
index cb51be9..7a98c09 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_state.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_state.md
@@ -17,44 +17,49 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: State Machine Configuration
+Helix Tutorial: State Machine Configuration
+-------------------------------------------
In this chapter, we\'ll learn about the state models provided by Helix, and how to create your own custom state model.
-## State Models
+### State Models
-Helix comes with 3 default state models that are commonly used. It is possible to have multiple state models in a cluster.
-Every resource that is added should be configured to use a state model that govern its _ideal state_.
+Helix comes with 3 default state models that are commonly used. It is possible to have multiple state models in a cluster.
+Every resource that is added should be configured to use a single state model that will govern its _ideal state_.
-### MASTER-SLAVE
+#### MASTER-SLAVE
* Has 3 states: OFFLINE, SLAVE, MASTER
* Maximum # of masters: 1
-* Slaves are based on the replication factor. Replication factor can be specified while adding the resource
+* Slaves are based on the replication factor. The replication factor can be specified while adding the resource
+#### ONLINE-OFFLINE
-### ONLINE-OFFLINE
-* Has 2 states: OFFLINE and ONLINE. This simple state model is a good starting point for most applications.
+Has 2 states: OFFLINE and ONLINE. This simple state model is a good starting point for most applications.
-### LEADER-STANDBY
-* 1 Leader and multiple stand-bys. The idea is that exactly one leader accomplishes a designated task, the stand-bys are ready to take over if the leader fails.
+#### LEADER-STANDBY
-## Constraints
+1 Leader and multiple stand-bys. The idea is that exactly one leader accomplishes a designated task, the stand-bys are ready to take over if the leader fails.
+
+### Constraints
In addition to the state machine configuration, one can specify the constraints of states and transitions.
For example, one can say:
+
* MASTER:1
- Maximum number of replicas in MASTER state at any time is 1
-* OFFLINE-SLAVE:5
-Maximum number of OFFLINE-SLAVE transitions that can happen concurrently in the system is 5 in this example.
+to indicate that the maximum number of replicas in MASTER state at any time is 1
+
+* OFFLINE-SLAVE:5
+
+to indicate that the maximum number of OFFLINE-SLAVE transitions that can happen concurrently in the system is 5 in this example.
-### State Priority
+#### State Priority
Helix uses a greedy approach to satisfy the state constraints. For example, if the state machine configuration says it needs 1 MASTER and 2 SLAVES, but only 1 node is active, Helix must promote it to MASTER. This behavior is achieved by providing the state priority list as MASTER,SLAVE.
-### State Transition Priority
+#### State Transition Priority
Helix tries to fire as many transitions as possible in parallel to reach the stable state without violating constraints. By default, Helix simply sorts the transitions alphabetically and fires as many as it can without violating the constraints. You can control this by overriding the priority order.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_throttling.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_throttling.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_throttling.md
index 5002156..0760d74 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_throttling.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_throttling.md
@@ -17,13 +17,14 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Throttling
+Helix Tutorial: Throttling
+--------------------------
-In this chapter, we\'ll learn how to control the parallel execution of cluster tasks. Only a centralized cluster manager with global knowledge is capable of coordinating this decision.
+In this chapter, we\'ll learn how to control the parallel execution of cluster tasks. Only a centralized cluster manager with global knowledge (i.e. Helix) is capable of coordinating this decision.
### Throttling
-Since all state changes in the system are triggered through transitions, Helix can control the number of transitions that can happen in parallel. Some of the transitions may be light weight, but some might involve moving data, which is quite expensive from a network and iops perspective.
+Since all state changes in the system are triggered through transitions, Helix can control the number of transitions that can happen in parallel. Some of the transitions may be lightweight, but some might involve moving data, which is quite expensive from a network and IOPS perspective.
Helix allows applications to set a threshold on transitions. The threshold can be set at multiple scopes:
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/site.xml
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/site.xml b/site-releases/0.6.1-incubating/src/site/site.xml
index 7326162..7d6bd69 100644
--- a/site-releases/0.6.1-incubating/src/site/site.xml
+++ b/site-releases/0.6.1-incubating/src/site/site.xml
@@ -17,21 +17,21 @@
-->
<project name="Apache Helix 0.6.1-incubating">
<bannerLeft>
- <src>images/helix-logo.jpg</src>
- <href>http://helix.incubator.apache.org/site-releases/0.6.1-incubating-site</href>
+ <src>../../images/helix-logo.jpg</src>
+ <href>http://helix.incubator.apache.org/</href>
</bannerLeft>
<bannerRight>
- <src>http://incubator.apache.org/images/egg-logo.png</src>
- <href>http://incubator.apache.org/</href>
+ <src>../../images/feather_small.gif</src>
+ <href>http://www.apache.org/</href>
</bannerRight>
<version position="none"/>
<publishDate position="right"/>
<skin>
- <groupId>org.apache.maven.skins</groupId>
- <artifactId>maven-fluido-skin</artifactId>
- <version>1.3.0</version>
+ <groupId>lt.velykis.maven.skins</groupId>
+ <artifactId>reflow-maven-skin</artifactId>
+ <version>1.0.0</version>
</skin>
<body>
@@ -58,27 +58,28 @@
<item name="Release 0.6.1-incubating" href="http://helix.incubator.apache.org/site-releases/0.6.1-incubating-site/"/>
</breadcrumbs>
- <menu name="Apache Helix">
- <item name="Home" href="../../index.html"/>
+ <links>
+ <item name="Helix 0.6.1-incubating" href="./index.html"/>
+ </links>
+
+ <menu name="Get Helix">
+ <item name="Download" href="./download.html"/>
+ <item name="Building" href="./Building.html"/>
+ <item name="Release Notes" href="./releasenotes/release-0.6.1-incubating.html"/>
</menu>
- <menu name="Helix 0.6.1-incubating">
- <item name="Introduction" href="./index.html"/>
- <item name="Getting Helix" href="./Building.html"/>
- <item name="Core concepts" href="./Concepts.html"/>
- <item name="Architecture" href="./Architecture.html"/>
+ <menu name="Hands-On">
<item name="Quick Start" href="./Quickstart.html"/>
<item name="Tutorial" href="./Tutorial.html"/>
- <item name="Release Notes" href="releasenotes/release-0.6.1-incubating.html"/>
- <item name="Download" href="./download.html"/>
+ <item name="Javadocs" href="http://helix.incubator.apache.org/javadocs/0.6.1-incubating"/>
</menu>
<menu name="Recipes">
<item name="Distributed lock manager" href="./recipes/lock_manager.html"/>
<item name="Rabbit MQ consumer group" href="./recipes/rabbitmq_consumer_group.html"/>
<item name="Rsync replicated file store" href="./recipes/rsync_replicated_file_store.html"/>
- <item name="Service Discovery" href="./recipes/service_discovery.html"/>
- <item name="Distributed task DAG Execution" href="./recipes/task_dag_execution.html"/>
+ <item name="Service discovery" href="./recipes/service_discovery.html"/>
+ <item name="Distributed task DAG execution" href="./recipes/task_dag_execution.html"/>
</menu>
<!--
<menu ref="reports" inherit="bottom"/>
@@ -103,9 +104,29 @@
</body>
<custom>
- <fluidoSkin>
+ <reflowSkin>
+ <theme>bootswatch-cerulean</theme>
+ <highlightJs>false</highlightJs>
+ <brand>
+ <name>Apache Helix</name>
+ <href>http://helix.incubator.apache.org</href>
+ </brand>
+ <slogan>A cluster management framework for partitioned and replicated distributed resources</slogan>
+ <bottomNav>
+ <column>Get Helix</column>
+ <column>Hands-On</column>
+ <column>Recipes</column>
+ </bottomNav>
+ <pages>
+ <index>
+ <sections>
+ <columns>3</columns>
+ </sections>
+ </index>
+ </pages>
+ </reflowSkin>
+ <!--fluidoSkin>
<topBarEnabled>true</topBarEnabled>
- <!-- twitter link work only with sidebar disabled -->
<sideBarEnabled>true</sideBarEnabled>
<googleSearch></googleSearch>
<twitter>
@@ -113,7 +134,7 @@
<showUser>true</showUser>
<showFollowers>false</showFollowers>
</twitter>
- </fluidoSkin>
+ </fluidoSkin-->
</custom>
</project>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/xdoc/download.xml.vm
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/xdoc/download.xml.vm b/site-releases/0.6.1-incubating/src/site/xdoc/download.xml.vm
index dabe9ec..2fc59c3 100644
--- a/site-releases/0.6.1-incubating/src/site/xdoc/download.xml.vm
+++ b/site-releases/0.6.1-incubating/src/site/xdoc/download.xml.vm
@@ -24,7 +24,7 @@ under the License.
xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 http://maven.apache.org/xsd/xdoc-2.0.xsd">
<properties>
- <title>Apache Incubator Helix Downloads</title>
+ <title>Apache Helix Downloads</title>
<author email="dev@helix.incubator.apache.org">Apache Helix Documentation Team</author>
</properties>
@@ -34,11 +34,11 @@ under the License.
<param name="class" value="toc"/>
</macro>
</div>
-
- <section name="Introduction">
+
+ <section name="Apache Helix Downloads">
<p>Apache Helix artifacts are distributed in source and binary form under the terms of the
<a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.
- See the included <tt>LICENSE</tt> and <tt>NOTICE</tt> files included in each artifact for additional license
+ See the included <tt>LICENSE</tt> and <tt>NOTICE</tt> files included in each artifact for additional license
information.
</p>
<p>Use the links below to download a source distribution of Apache Helix.
@@ -48,54 +48,6 @@ under the License.
<section name="Release">
<p>Release date: ${releaseDate} </p>
<p><a href="releasenotes/release-${releaseName}.html">${releaseName} Release notes</a></p>
- <a name="mirror"/>
- <subsection name="Mirror">
-
- <p>
- [if-any logo]
- <a href="[link]">
- <img align="right" src="[logo]" border="0"
- alt="logo"/>
- </a>
- [end]
- The currently selected mirror is
- <b>[preferred]</b>.
- If you encounter a problem with this mirror,
- please select another mirror.
- If all mirrors are failing, there are
- <i>backup</i>
- mirrors
- (at the end of the mirrors list) that should be available.
- </p>
-
- <form action="[location]" method="get" id="SelectMirror" class="form-inline">
- Other mirrors:
- <select name="Preferred" class="input-xlarge">
- [if-any http]
- [for http]
- <option value="[http]">[http]</option>
- [end]
- [end]
- [if-any ftp]
- [for ftp]
- <option value="[ftp]">[ftp]</option>
- [end]
- [end]
- [if-any backup]
- [for backup]
- <option value="[backup]">[backup] (backup)</option>
- [end]
- [end]
- </select>
- <input type="submit" value="Change" class="btn"/>
- </form>
-
- <p>
- You may also consult the
- <a href="http://www.apache.org/mirrors/">complete list of mirrors.</a>
- </p>
-
- </subsection>
<subsection name="${releaseName} Sources">
<table>
<thead>
@@ -107,12 +59,12 @@ under the License.
<tbody>
<tr>
<td>
- <a href="[preferred]incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip">helix-${releaseName}-src.zip</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip">helix-${releaseName}-src.zip</a>
</td>
<td>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip.asc">asc</a>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip.md5">md5</a>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip.sha1">sha1</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip.asc">asc</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip.md5">md5</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/src/helix-${releaseName}-src.zip.sha1">sha1</a>
</td>
</tr>
</tbody>
@@ -129,22 +81,22 @@ under the License.
<tbody>
<tr>
<td>
- <a href="[preferred]incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar">helix-core-${releaseName}-pkg.tar</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar">helix-core-${releaseName}-pkg.tar</a>
</td>
<td>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar.asc">asc</a>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar.md5">md5</a>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar.sha1">sha1</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar.asc">asc</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar.md5">md5</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-core-${releaseName}-pkg.tar.sha1">sha1</a>
</td>
</tr>
<tr>
<td>
- <a href="[preferred]incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar">helix-admin-webapp-${releaseName}-pkg.tar</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar">helix-admin-webapp-${releaseName}-pkg.tar</a>
</td>
<td>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar.asc">asc</a>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar.md5">md5</a>
- <a href="http://www.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar.sha1">sha1</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar.asc">asc</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar.md5">md5</a>
+ <a href="http://archive.apache.org/dist/incubator/helix/${releaseName}/binaries/helix-admin-webapp-${releaseName}-pkg.tar.sha1">sha1</a>
</td>
</tr>
</tbody>
@@ -157,22 +109,22 @@ under the License.
<section name="Verifying Releases">
<p>We strongly recommend you verify the integrity of the downloaded files with both PGP and MD5.</p>
-
- <p>The PGP signatures can be verified using <a href="http://www.pgpi.org/">PGP</a> or
- <a href="http://www.gnupg.org/">GPG</a>.
- First download the <a href="http://www.apache.org/dist/incubator/helix/KEYS">KEYS</a> as well as the
- <tt>*.asc</tt> signature file for the particular distribution. Make sure you get these files from the main
+
+ <p>The PGP signatures can be verified using <a href="http://www.pgpi.org/">PGP</a> or
+ <a href="http://www.gnupg.org/">GPG</a>.
+ First download the <a href="http://archive.apache.org/dist/incubator/helix/KEYS">KEYS</a> as well as the
+ <tt>*.asc</tt> signature file for the particular distribution. Make sure you get these files from the main
distribution directory, rather than from a mirror. Then verify the signatures using one of the following sets of
commands:
<source>$ pgp -ka KEYS
$ pgp helix-*.zip.asc</source>
-
+
<source>$ gpg --import KEYS
$ gpg --verify helix-*.zip.asc</source>
</p>
- <p>Alternatively, you can verify the MD5 signature on the files. A Unix/Linux program called
- <code>md5</code> or
+ <p>Alternatively, you can verify the MD5 signature on the files. A Unix/Linux program called
+ <code>md5</code> or
<code>md5sum</code> is included in most distributions. It is also available as part of
<a href="http://www.gnu.org/software/textutils/textutils.html">GNU Textutils</a>.
Windows users can get binary md5 programs from these (and likely other) places:
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.2-incubating/src/site/site.xml
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diff --git a/site-releases/0.6.2-incubating/src/site/site.xml b/site-releases/0.6.2-incubating/src/site/site.xml
index 68cba65..b1bacd9 100644
--- a/site-releases/0.6.2-incubating/src/site/site.xml
+++ b/site-releases/0.6.2-incubating/src/site/site.xml
@@ -29,9 +29,9 @@
<publishDate position="right"/>
<skin>
- <groupId>org.apache.maven.skins</groupId>
- <artifactId>maven-fluido-skin</artifactId>
- <version>1.3.0</version>
+ <groupId>lt.velykis.maven.skins</groupId>
+ <artifactId>reflow-maven-skin</artifactId>
+ <version>1.0.0</version>
</skin>
<body>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.7.0-incubating/src/site/site.xml
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diff --git a/site-releases/0.7.0-incubating/src/site/site.xml b/site-releases/0.7.0-incubating/src/site/site.xml
index babbe1c..4003197 100644
--- a/site-releases/0.7.0-incubating/src/site/site.xml
+++ b/site-releases/0.7.0-incubating/src/site/site.xml
@@ -29,9 +29,9 @@
<publishDate position="right"/>
<skin>
- <groupId>org.apache.maven.skins</groupId>
- <artifactId>maven-fluido-skin</artifactId>
- <version>1.3.0</version>
+ <groupId>lt.velykis.maven.skins</groupId>
+ <artifactId>reflow-maven-skin</artifactId>
+ <version>1.0.0</version>
</skin>
<body>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/trunk/src/site/site.xml
----------------------------------------------------------------------
diff --git a/site-releases/trunk/src/site/site.xml b/site-releases/trunk/src/site/site.xml
index 52b9f8a..f2851a1 100644
--- a/site-releases/trunk/src/site/site.xml
+++ b/site-releases/trunk/src/site/site.xml
@@ -29,9 +29,9 @@
<publishDate position="right"/>
<skin>
- <groupId>org.apache.maven.skins</groupId>
- <artifactId>maven-fluido-skin</artifactId>
- <version>1.3.0</version>
+ <groupId>lt.velykis.maven.skins</groupId>
+ <artifactId>reflow-maven-skin</artifactId>
+ <version>1.0.0</version>
</skin>
<body>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/apt/releasing.apt
----------------------------------------------------------------------
diff --git a/src/site/apt/releasing.apt b/src/site/apt/releasing.apt
index 62f6bb9..3de33f5 100644
--- a/src/site/apt/releasing.apt
+++ b/src/site/apt/releasing.apt
@@ -25,7 +25,7 @@
~~ NOTE: For help with the syntax of this file, see:
~~ http://maven.apache.org/guides/mini/guide-apt-format.html
-Helix release process
+Helix Release Process
[[1]] Post to dev@helix.incubator.apache.org a few days before you plan to do a Helix release
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/markdown/Architecture.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/Architecture.md b/src/site/markdown/Architecture.md
index 933e917..1d724ad 100644
--- a/src/site/markdown/Architecture.md
+++ b/src/site/markdown/Architecture.md
@@ -21,83 +21,81 @@ under the License.
<title>Architecture</title>
</head>
-Architecture
-----------------------------
+## Architecture
+
Helix aims to provide the following abilities to a distributed system:
-* Automatic management of a cluster hosting partitioned, replicated resources.
-* Soft and hard failure detection and handling.
-* Automatic load balancing via smart placement of resources on servers(nodes) based on server capacity and resource profile (size of partition, access patterns, etc).
-* Centralized config management and self discovery. Eliminates the need to modify config on each node.
-* Fault tolerance and optimized rebalancing during cluster expansion.
-* Manages entire operational lifecycle of a node. Addition, start, stop, enable/disable without downtime.
-* Monitor cluster health and provide alerts on SLA violation.
-* Service discovery mechanism to route requests.
+* Automatic management of a cluster hosting partitioned, replicated resources
+* Soft and hard failure detection and handling
+* Automatic load balancing via smart placement of resources on servers (nodes) based on server capacity and resource profile (size of partitions, access patterns, etc)
+* Centralized config management and self discovery, eliminating the need to modify config on each node
+* Fault tolerance and optimized rebalancing during cluster expansion
+* Management of the entire operational lifecycle of a node. Add, start, stop, enable, and disable without downtime
+* Monitoring of cluster health and alerting on SLA violations
+* A service discovery mechanism to route requests
-To build such a system, we need a mechanism to co-ordinate between different nodes and other components in the system. This mechanism can be achieved with software that reacts to any change in the cluster and comes up with a set of tasks needed to bring the cluster to a stable state. The set of tasks will be assigned to one or more nodes in the cluster. Helix serves this purpose of managing the various components in the cluster.
+To build such a system, we need a mechanism to coordinate between different nodes and other components in the system. This mechanism can be achieved with software that reacts to any change in the cluster and comes up with a set of tasks needed to bring the cluster to a stable state. The set of tasks will be assigned to one or more nodes in the cluster. Helix serves this purpose of managing the various components in the cluster.
-Distributed System Components
+## Distributed System Components
In general any distributed system cluster will have the following components and properties:
-* A set of nodes also referred to as instances.
-* A set of resources which can be databases, lucene indexes or tasks.
-* Each resource is also partitioned into one or more Partitions.
-* Each partition may have one or more copies called replicas.
-* Each replica can have a state associated with it. For example Master, Slave, Leader, Standby, Online, Offline etc
+* A set of nodes also referred to as __instances__
+* A set of __resources__ which can be databases, lucene indexes or tasks
+* Subdivisions of each resource into one or more __partitions__
+* Copies of each resource called __replicas__
+* The __state__ of each replica, e.g. Master, Slave, Leader, Standby, Online, Offline, etc.
-Roles
------
+## Roles
-Not all nodes in a distributed system will perform similar functionalities. For example, a few nodes might be serving requests and a few nodes might be sending requests, and some nodes might be controlling the nodes in the cluster. Thus, Helix categorizes nodes by their specific roles in the system.
+Not all nodes in a distributed system will perform similar functionalities. For example, a few nodes might be serving requests and a few nodes might be sending requests, and some other nodes might be controlling the nodes in the cluster. Thus, Helix categorizes nodes by their specific roles in the system.
-We have divided Helix nodes into 3 logical components based on their responsibilities:
+Helix divides nodes into 3 logical components based on their responsibilities:
-1. Participant: The nodes that actually host the distributed resources.
-2. Spectator: The nodes that simply observe the Participant state and route the request accordingly. Routers, for example, need to know the instance on which a partition is hosted and its state in order to route the request to the appropriate end point.
-3. Controller: The controller observes and controls the Participant nodes. It is responsible for coordinating all transitions in the cluster and ensuring that state constraints are satisfied and cluster stability is maintained.
+1. __Participant__: The nodes that actually host the distributed resources
+2. __Spectator__: The nodes that simply observe the current state of each Participant and routes requests accordingly. Routers, for example, need to know the instance on which a partition is hosted and its state in order to route the request to the appropriate endpoint
+3. __Controller__: The node that observes and controls the Participant nodes. It is responsible for coordinating all transitions in the cluster and ensuring that state constraints are satisfied while maintaining cluster stability
-These are simply logical components and can be deployed as per the system requirements. For example:
+These are simply logical components and can be deployed according to system requirements. For example, the Controller:
-1. The controller can be deployed as a separate service
-2. The controller can be deployed along with a Participant but only one Controller will be active at any given time.
+1. can be deployed as a separate service
+2. can be deployed along with a Participant but only one Controller will be active at any given time.
Both have pros and cons, which will be discussed later and one can chose the mode of deployment as per system needs.
+## Cluster State Metadata Store
-## Cluster state metadata store
-
-We need a distributed store to maintain the state of the cluster and a notification system to notify if there is any change in the cluster state. Helix uses Zookeeper to achieve this functionality.
+We need a distributed store to maintain the state of the cluster and a notification system to notify if there is any change in the cluster state. Helix uses [Apache ZooKeeper](http://zookeeper.apache.org) to achieve this functionality.
Zookeeper provides:
-* A way to represent PERSISTENT state which basically remains until its deleted.
-* A way to represent TRANSIENT/EPHEMERAL state which vanishes when the process that created the state dies.
-* Notification mechanism when there is a change in PERSISTENT and EPHEMERAL state
+* A way to represent PERSISTENT state which remains until its deleted
+* A way to represent TRANSIENT/EPHEMERAL state which vanishes when the process that created the state dies
+* A notification mechanism when there is a change in PERSISTENT and EPHEMERAL state
-The namespace provided by ZooKeeper is much like that of a standard file system. A name is a sequence of path elements separated by a slash (/). Every node[ZNode] in ZooKeeper\'s namespace is identified by a path.
+The namespace provided by ZooKeeper is much like that of a standard file system. A name is a sequence of path elements separated by a slash (/). Every node (ZNode) in ZooKeeper\'s namespace is identified by a path.
-More info on Zookeeper can be found at http://zookeeper.apache.org
+More info on Zookeeper can be found at [http://zookeeper.apache.org](http://zookeeper.apache.org)
-## State machine and constraints
+## State Machine and Constraints
Even though the concepts of Resources, Partitions, and Replicas are common to most distributed systems, one thing that differentiates one distributed system from another is the way each partition is assigned a state and the constraints on each state.
For example:
-1. If a system is serving read-only data then all partition\'s replicas are equal and they can either be ONLINE or OFFLINE.
-2. If a system takes _both_ reads and writes but ensure that writes go through only one partition, the states will be MASTER, SLAVE, and OFFLINE. Writes go through the MASTER and replicate to the SLAVEs. Optionally, reads can go through SLAVES.
+1. If a system is serving read-only data then all of a partition\'s replicas are equivalent and they can either be ONLINE or OFFLINE.
+2. If a system takes _both_ reads and writes but must ensure that writes go through only one partition, the states will be MASTER, SLAVE, and OFFLINE. Writes go through the MASTER and replicate to the SLAVEs. Optionally, reads can go through SLAVEs.
-Apart from defining state for each partition, the transition path to each state can be application specific. For example, in order to become MASTER it might be a requirement to first become a SLAVE. This ensures that if the SLAVE does not have the data as part of OFFLINE-SLAVE transition it can bootstrap data from other nodes in the system.
+Apart from defining the state for each partition, the transition path between states can be application specific. For example, in order to become MASTER it might be a requirement to first become a SLAVE. This ensures that if the SLAVE does not have the data as part of OFFLINE-SLAVE transition it can bootstrap data from other nodes in the system.
-Helix provides a way to configure an application specific state machine along with constraints on each state. Along with constraints on STATE, Helix also provides a way to specify constraints on transitions. (More on this later.)
+Helix provides a way to configure an application-specific state machine along with constraints on each state. Along with constraints on STATE, Helix also provides a way to specify constraints on transitions. (More on this later.)
```
- OFFLINE | SLAVE | MASTER
+ OFFLINE | SLAVE | MASTER
_____________________________
| | | |
OFFLINE | N/A | SLAVE | SLAVE |
@@ -115,40 +113,40 @@ MASTER | SLAVE | SLAVE | N/A |
## Concepts
-The following terminologies are used in Helix to model a state machine.
+The following terminologies are used in Helix to model resources following a state machine.
-* IdealState: The state in which we need the cluster to be in if all nodes are up and running. In other words, all state constraints are satisfied.
-* CurrentState: Represents the actual current state of each node in the cluster
-* ExternalView: Represents the combined view of CurrentState of all nodes.
+* __IdealState__: The state in which we need the cluster to be in if all nodes are up and running. In other words, all state constraints are satisfied.
+* __CurrentState__: The actual current state of each node in the cluster
+* __ExternalView__: The combined view of the CurrentState of all nodes.
-The goal of Helix is always to make the CurrentState of the system same as the IdealState. Some scenarios where this may not be true are:
+The goal of Helix is always to make the CurrentState (and by extension, the ExternalView) of the system same as the IdealState. Some scenarios where this may not be true are:
-* When all nodes are down
-* When one or more nodes fail
+* Some or all nodes are down
+* One or more nodes fail
* New nodes are added and the partitions need to be reassigned
### IdealState
-Helix lets the application define the IdealState on a resource basis which basically consists of:
+Helix lets the application define the IdealState for each resource. It consists of:
-* List of partitions. Example: 64
-* Number of replicas for each partition. Example: 3
-* Node and State for each replica.
+* A list of partitions, e.g. 64
+* Number of replicas for each partition, e.g. 3
+* The assigned node and state for each replica
Example:
-* Partition-1, replica-1, Master, Node-1
-* Partition-1, replica-2, Slave, Node-2
-* Partition-1, replica-3, Slave, Node-3
+* Partition-1, replica-1: Master, Node-1
+* Partition-1, replica-2: Slave, Node-2
+* Partition-1, replica-3: Slave, Node-3
* .....
* .....
-* Partition-p, replica-3, Slave, Node-n
+* Partition-p, replica-r: Slave, Node-n
Helix comes with various algorithms to automatically assign the partitions to nodes. The default algorithm minimizes the number of shuffles that happen when new nodes are added to the system.
### CurrentState
-Every instance in the cluster hosts one or more partitions of a resource. Each of the partitions has a state associated with it.
+Every participant in the cluster hosts one or more partitions of a resource. Each of the partitions has a state associated with it.
Example Node-1
@@ -160,7 +158,7 @@ Example Node-1
### ExternalView
-External clients needs to know the state of each partition in the cluster and the Node hosting that partition. Helix provides one view of the system to Spectators as _ExternalView_. ExternalView is simply an aggregate of all node CurrentStates.
+External clients needs to know the state of each partition in the cluster and the Node hosting that partition. Helix provides one view of the system to Spectators as the ExternalView. The ExternalView is simply an aggregate of all node CurrentStates.
* Partition-1, replica-1, Master, Node-1
* Partition-1, replica-2, Slave, Node-2
@@ -176,49 +174,48 @@ Mode of operation in a cluster
A node process can be one of the following:
* Participant: The process registers itself in the cluster and acts on the messages received in its queue and updates the current state. Example: a storage node in a distributed database
-* Spectator: The process is simply interested in the changes in the Externalview.
-* Controller: This process actively controls the cluster by reacting to changes in cluster state and sending messages to Participants.
-
+* Spectator: The process is simply interested in the changes in the ExternalView.
+* Controller: This process actively controls the cluster by reacting to changes in cluster state and sending state transition messages to Participants.
### Participant Node Process
-* When Node starts up, it registers itself under _LiveInstances_
-* After registering, it waits for new _Messages_ in the message queue
+* When the Participant starts up, it registers itself under __LiveInstances__
+* After registering, it waits for new __messages__ in the message queue
* When it receives a message, it will perform the required task as indicated in the message
* After the task is completed, depending on the task outcome it updates the CurrentState
### Controller Process
* Watches IdealState
-* Notified when a node goes down/comes up or node is added/removed. Watches LiveInstances and CurrentState of each node in the cluster
-* Triggers appropriate state transitions by sending message to Participants
+* Notified when a Participant goes down, comes up, is added, or is removed. Watches the ephemeral LiveInstance ZNode and the CurrentState of each Participant in the cluster
+* Triggers appropriate state transitions by sending messages to Participants
### Spectator Process
* When the process starts, it asks the Helix agent to be notified of changes in ExternalView
-* Whenever it receives a notification, it reads the Externalview and performs required duties.
+* Whenever it receives a notification, it reads the ExternalView and performs required duties
-#### Interaction between controller, participant and spectator
+### Interaction between the Controller, Participant and Spectator
-The following picture shows how controllers, participants and spectators interact with each other.
+The following picture shows how Controllers, Participants and Spectators interact with each other.
-## Core algorithm
+## Core Controller Algorithm
-* Controller gets the IdealState and the CurrentState of active storage nodes from Zookeeper
-* Compute the delta between IdealState and CurrentState for each partition across all participant nodes
-* For each partition compute tasks based on the State Machine Table. It\'s possible to configure priority on the state Transition. For example, in case of Master-Slave:
- * Attempt mastership transfer if possible without violating constraint.
- * Partition Addition
- * Drop Partition
-* Add the tasks in parallel if possible to the respective queue for each storage node (if the tasks added are mutually independent)
-* If a task is dependent on another task being completed, do not add that task
-* After any task is completed by a Participant, Controllers gets notified of the change and the State Transition algorithm is re-run until the CurrentState is same as IdealState.
+* Get the IdealState and the CurrentState of active storage nodes from ZooKeeper
+* Compute the delta between IdealState and CurrentState for each partition replica across all Participant nodes
+* For each partition compute tasks based on the State Machine Table. It\'s possible to configure priority on the state Transition. For example, in case of MasterSlave:
+ * Attempt mastership transfer if possible without violating constraints
+ * Partition addition
+ * Partition drop
+* Add the transition tasks in parallel if possible to the respective queue for each storage node (if the tasks added are mutually independent)
+* If a transition task is dependent on another task being completed, do not add that task
+* After any task is completed by a Participant, Controllers gets notified of the change and the algorithm is re-run until the CurrentState matches the IdealState.
-## Helix ZNode layout
+## Helix ZNode Layout
-Helix organizes znodes under clusterName in multiple levels.
+Helix organizes ZNodes under the cluster name in multiple levels.
The top level (under the cluster name) ZNodes are all Helix-defined and in upper case:
@@ -247,6 +244,6 @@ Under CONFIGS, there are different scopes of configurations:
* CLUSTER: contains cluster scope configurations
* PARTICIPANT: contains participant scope configurations
-The following image shows an example of Helix znodes layout for a cluster named "test-cluster":
+The following image shows an example of the Helix ZNode layout for a cluster named "test-cluster":
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/markdown/ClientLibraries.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/ClientLibraries.md b/src/site/markdown/ClientLibraries.md
index 6cdb56e..bcde42c 100644
--- a/src/site/markdown/ClientLibraries.md
+++ b/src/site/markdown/ClientLibraries.md
@@ -24,9 +24,13 @@ under the License.
Client Libraries
----------------------------
-The following client libraries, in addition to the HelixAgent Java interface, are
+The following client libraries, in addition to the Helix Agent Java interface, are
available for Helix:
-### Python
+### Clojure
+
+* `clj-helix` - https://github.com/Factual/clj-helix
+
+### Python
* `pyhelix` - https://github.com/kanakb/pyhelix
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/markdown/Concepts.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/Concepts.md b/src/site/markdown/Concepts.md
index 5bf42ac..def0d1d 100644
--- a/src/site/markdown/Concepts.md
+++ b/src/site/markdown/Concepts.md
@@ -26,22 +26,22 @@ Concepts
Helix is based on the idea that a given task has the following attributes associated with it:
-* _Location of the task_. For example it runs on Node N1
-* _State_. For example, it is running, stopped etc.
+* __Location__, e.g. it is available on Node N1
+* __State__, e.g. it is running, stopped etc.
-In Helix terminology, a task is referred to as a _resource_.
+In Helix terminology, a task is referred to as a __resource__.
-### IdealState
+### Ideal State
-IdealState simply allows one to map tasks to location and state. A standard way of expressing this in Helix:
+An __IdealState__ allows one to map tasks to location and state. A standard way of expressing this in Helix is as follows:
```
- "TASK_NAME" : {
- "LOCATION" : "STATE"
- }
-
+"TASK_NAME" : {
+ "LOCATION" : "STATE"
+}
```
-Consider a simple case where you want to launch a task \'myTask\' on node \'N1\'. The IdealState for this can be expressed as follows:
+
+Consider a simple case where you want to launch a resource \"myTask\" on node \"N1\". The IdealState for this can be expressed as follows:
```
{
@@ -53,11 +53,12 @@ Consider a simple case where you want to launch a task \'myTask\' on node \'N1\'
}
}
```
+
### Partition
-If this task get too big to fit on one box, you might want to divide it into subtasks. Each subtask is referred to as a _partition_ in Helix. Let\'s say you want to divide the task into 3 subtasks/partitions, the IdealState can be changed as shown below.
+If this task get too big to fit on one box, you might want to divide it into subtasks. Each subtask is referred to as a __partition__ in Helix. Let\'s say you want to divide the task into 3 subtasks/partitions, the IdealState can be changed as shown below.
-\'myTask_0\', \'myTask_1\', \'myTask_2\' are logical names representing the partitions of myTask. Each tasks runs on N1, N2 and N3 respectively.
+\"myTask_0\", \"myTask_1\", \"myTask_2\" are logical names representing the partitions of myTask. Each tasks runs on N1, N2 and N3 respectively.
```
{
@@ -81,9 +82,9 @@ If this task get too big to fit on one box, you might want to divide it into sub
### Replica
-Partitioning allows one to split the data/task into multiple subparts. But let\'s say the request rate for each partition increases. The common solution is to have multiple copies for each partition. Helix refers to the copy of a partition as a _replica_. Adding a replica also increases the availability of the system during failures. One can see this methodology employed often in search systems. The index is divided into shards, and each shard has multiple copies.
+Partitioning allows one to split the data/task into multiple subparts. But let\'s say the request rate for each partition increases. The common solution is to have multiple copies for each partition. Helix refers to the copy of a partition as a __replica__. Adding a replica also increases the availability of the system during failures. One can see this methodology employed often in search systems. The index is divided into shards, and each shard has multiple copies.
-Let\'s say you want to add one additional replica for each task. The IdealState can simply be changed as shown below.
+Let\'s say you want to add one additional replica for each task. The IdealState can simply be changed as shown below.
For increasing the availability of the system, it\'s better to place the replica of a given partition on different nodes.
@@ -111,11 +112,11 @@ For increasing the availability of the system, it\'s better to place the replica
}
```
-### State
+### State
Now let\'s take a slightly more complicated scenario where a task represents a database. Unlike an index which is in general read-only, a database supports both reads and writes. Keeping the data consistent among the replicas is crucial in distributed data stores. One commonly applied technique is to assign one replica as the MASTER and remaining replicas as SLAVEs. All writes go to the MASTER and are then replicated to the SLAVE replicas.
-Helix allows one to assign different states to each replica. Let\'s say you have two MySQL instances N1 and N2, where one will serve as MASTER and another as SLAVE. The IdealState can be changed to:
+Helix allows one to assign different __states__ to each replica. Let\'s say you have two MySQL instances N1 and N2, where one will serve as MASTER and another as SLAVE. The IdealState can be changed to:
```
{
@@ -131,23 +132,22 @@ Helix allows one to assign different states to each replica. Let\'s say you have
}
}
}
-
```
### State Machine and Transitions
-IdealState allows one to exactly specify the desired state of the cluster. Given an IdealState, Helix takes up the responsibility of ensuring that the cluster reaches the IdealState. The Helix _controller_ reads the IdealState and then commands each Participant to take appropriate actions to move from one state to another until it matches the IdealState. These actions are referred to as _transitions_ in Helix.
+The IdealState allows one to exactly specify the desired state of the cluster. Given an IdealState, Helix takes up the responsibility of ensuring that the cluster reaches the IdealState. The Helix __controller__ reads the IdealState and then commands each Participant to take appropriate actions to move from one state to another until it matches the IdealState. These actions are referred to as __transitions__ in Helix.
-The next logical question is: how does the _controller_ compute the transitions required to get to IdealState? This is where the finite state machine concept comes in. Helix allows applications to plug in a finite state machine. A state machine consists of the following:
+The next logical question is: how does the controller compute the transitions required to get to IdealState? This is where the __finite state machine__ concept comes in. Helix allows applications to plug in a finite state machine. A state machine consists of the following:
-* State: Describes the role of a replica
-* Transition: An action that allows a replica to move from one state to another, thus changing its role.
+* __State__: Describes the role of a replica
+* __Transition__: An action that allows a replica to move from one state to another, thus changing its role.
Here is an example of MasterSlave state machine:
```
- OFFLINE | SLAVE | MASTER
+ OFFLINE | SLAVE | MASTER
_____________________________
| | | |
OFFLINE | N/A | SLAVE | SLAVE |
@@ -183,7 +183,7 @@ Helix allows each resource to be associated with one state machine. This means y
### Current State
-CurrentState of a resource simply represents its actual state at a Participant. In the below example:
+The __CurrentState__ of a resource simply represents its actual state at a participating node, a __participant__. In the below example:
* INSTANCE_NAME: Unique name representing the process
* SESSION_ID: ID that is automatically assigned every time a process joins the cluster
@@ -209,11 +209,12 @@ CurrentState of a resource simply represents its actual state at a Participant.
}
}
```
+
Each node in the cluster has its own CurrentState.
### External View
-In order to communicate with the Participants, external clients need to know the current state of each of the Participants. The external clients are referred to as Spectators. In order to make the life of Spectator simple, Helix provides an ExternalView that is an aggregated view of the current state across all nodes. The ExternalView has a similar format as IdealState.
+In order to communicate with the participants, external clients need to know the current state of each of the participants. The external clients are referred to as __spectators__. In order to make the life of spectator simple, Helix provides an ExternalView that is an aggregated view of the current state across all nodes. The ExternalView has a similar format as IdealState.
```
{
@@ -242,7 +243,8 @@ In order to communicate with the Participants, external clients need to know the
The core component of Helix is the Controller which runs the Rebalancer algorithm on every cluster event. Cluster events can be one of the following:
-* Nodes start/stop and soft/hard failures
+* Nodes start and/or stop
+* Nodes experience soft and/or hard failures
* New nodes are added/removed
* Ideal state changes
@@ -250,9 +252,9 @@ There are few more examples such as configuration changes, etc. The key takeawa
When a rebalancer is run it simply does the following:
-* Compares the IdealState and current state
-* Computes the transitions required to reach the IdealState
-* Issues the transitions to each Participant
+* Compares the ideal state and current state
+* Computes the transitions required to reach the ideal state
+* Issues the transitions to each participant
The above steps happen for every change in the system. Once the current state matches the IdealState, the system is considered stable which implies \'IdealState = CurrentState = ExternalView\'
@@ -260,7 +262,13 @@ The above steps happen for every change in the system. Once the current state ma
One of the things that makes Helix powerful is that IdealState can be changed dynamically. This means one can listen to cluster events like node failures and dynamically change the ideal state. Helix will then take care of triggering the respective transitions in the system.
-Helix comes with a few algorithms to automatically compute the IdealState based on the constraints. For example, if you have a resource of 3 partitions and 2 replicas, Helix can automatically compute the IdealState based on the nodes that are currently active. See the [tutorial](./site-releases/0.7.0-incubating-site/tutorial_rebalance.html) to find out more about various execution modes of Helix like FULL_AUTO, SEMI_AUTO and CUSTOMIZED.
+Helix allows various granularities of control for adjusting the ideal state. Whenever a cluster event occurs, Helix can operate in one of three modes:
+
+* __FULL\_AUTO__: Helix will automatically determine the location and state of each replica based on constraints
+* __SEMI\_AUTO__: Helix will take in a \"preference list\" representing the location each replica can live at, and automatically determine the state based on constraints
+* __CUSTOMIZED__: Helix will take in a map of location to state and fire transitions to get the external view to match
+
+Helix comes with a few algorithms to automatically compute the IdealState based on the constraints. For example, if you have a resource of 3 partitions and 2 replicas, Helix can automatically compute the IdealState based on the nodes that are currently active. See the [tutorial](./site-releases/0.6.2-incubating-site/tutorial_rebalance.html) to find out more about various execution modes of Helix like FULL_AUTO, SEMI_AUTO and CUSTOMIZED.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/index.md b/src/site/markdown/index.md
index 49cc12f..6d5154e 100644
--- a/src/site/markdown/index.md
+++ b/src/site/markdown/index.md
@@ -21,79 +21,69 @@ under the License.
<title>Home</title>
</head>
-News
-----
-Apache Helix has two new releases:
-
-* [0.6.2-incubating](./site-releases/0.6.2-incubating-site/index.html) - A release that fixes numerous bugs and improves platform stability. [\[Release Notes\]](./releasenotes/release-0.6.2-incubating.html)
+## Apache Helix
-* [0.7.0-incubating](./site-releases/0.7.0-incubating-site/index.html) - A release that includes high-level APIs to logically interact with Participants, Controllers, Resources, and other Helix constructs. __This release is an alpha and APIs are in the process of being finalized__. Feel free to play with it and provide any feedback you have! [\[Release Notes\]](./releasenotes/release-0.7.0-incubating.html)
+Apache Helix is a generic _cluster management_ framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. __Helix automates reassignment of resources in the face of node failure and recovery, cluster expansion, and reconfiguration.__
-What Is Helix?
---------------
-Helix is a generic _cluster management_ framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes.
+## What Is Cluster Management?
-
-What Is Cluster Management?
----------------------------
-To understand Helix, first you need to understand _cluster management_. A distributed system typically runs on multiple nodes for the following reasons:
+To understand Helix, you first need to understand __cluster management__. A distributed system typically runs on multiple nodes for the following reasons:
* scalability
* fault tolerance
* load balancing
-Each node performs one or more of the primary function of the cluster, such as storing and serving data, producing and consuming data streams, and so on. Once configured for your system, Helix acts as the global brain for the system. It is designed to make decisions that cannot be made in isolation. Examples of such decisions that require global knowledge and coordination:
+Each node performs one or more of the primary functions of the cluster, such as storing and serving data, producing and consuming data streams, and so on. __Once configured for your system, Helix acts as the global brain for the system__. It is designed to make decisions that cannot be made in isolation. Examples of such decisions that require global knowledge and coordination:
* scheduling of maintainence tasks, such as backups, garbage collection, file consolidation, index rebuilds
* repartitioning of data or resources across the cluster
* informing dependent systems of changes so they can react appropriately to cluster changes
* throttling system tasks and changes
-While it is possible to integrate these functions into the distributed system, it complicates the code. Helix has abstracted common cluster management tasks, enabling the system builder to model the desired behavior with a declarative state model, and let Helix manage the coordination. The result is less new code to write, and a robust, highly operable system.
+While it is possible to integrate these functions into the distributed system, it complicates the code. Helix has abstracted common cluster management tasks, enabling the system builder to model the desired behavior with a declarative state model, and let Helix manage the coordination. __The result is less new code to write, and a robust, highly operable system__.
+
+## What does Helix provide?
+* Automatic assignment of resources and partitions to nodes
+* Node failure detection and recovery
+* Dynamic addition of resources
+* Dynamic addition of nodes to the cluster
+* Pluggable distributed state machine to manage the state of a resource via state transitions
+* Automatic load balancing and throttling of transitions
+* Optional pluggable rebalancing for user-defined assignment of resources and partitions
-What does Helix provide?
-------------------------
-1. Automatic assignment of resources and partitions to nodes
-2. Node failure detection and recovery
-3. Dynamic addition of resources
-4. Dynamic addition of nodes to the cluster
-5. Pluggable distributed state machine to manage the state of a resource via state transitions
-6. Automatic load balancing and throttling of transitions
-7. Optional pluggable rebalancing for user-defined assignment of resources and partitions
+## Why Helix?
-Why Helix?
-----------
Modeling a distributed system as a state machine with constraints on states and transitions has the following benefits:
* Separates cluster management from the core functionality of the system.
* Allows a quick transformation from a single node system to an operable, distributed system.
* Increases simplicity: system components do not have to manage a global cluster. This division of labor makes it easier to build, debug, and maintain your system.
+---
-Download
---------
+### News
-[0.6.2-incubating](./site-releases/0.6.2-incubating-site/download.html)
+Apache Helix has two new releases:
-[0.7.0-incubating](./site-releases/0.7.0-incubating-site/download.html) (alpha)
+* [0.6.2-incubating](./site-releases/0.6.2-incubating-site/index.html) - A release that fixes numerous bugs and improves platform stability.
-Build Instructions
-------------------
+ [\[Quick Start\]](./site-releases/0.6.2-incubating-site/Quickstart.html) [\[Release Notes\]](./releasenotes/release-0.6.2-incubating.html)
-Requirements: JDK 1.6+, Maven 2.0.8+
+* [0.7.0-incubating](./site-releases/0.7.0-incubating-site/index.html) - A release that includes high-level APIs to logically interact with Participants, Controllers, Resources, and other Helix constructs. __This release is an alpha and APIs are in the process of being finalized__. Feel free to play with it and provide any feedback you have!
-```
-git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
-cd incubator-helix
-git checkout tags/helix-0.6.2-incubating
-mvn install package -DskipTests
-```
+ [\[Quick Start\]](./site-releases/0.7.0-incubating-site/Quickstart.html) [\[Release Notes\]](./releasenotes/release-0.7.0-incubating.html)
+
+### Download
+
+<a href="./site-releases/0.6.2-incubating-site/download.html" class="btn btn-primary btn-small">0.6.2-incubating</a>
-Maven dependency
+<a href="./site-releases/0.7.0-incubating-site/download.html" class="btn btn-primary btn-small">0.7.0-incubating (alpha)</a>
+
+### Maven Dependency
```
<dependency>
@@ -103,3 +93,19 @@ Maven dependency
</dependency>
```
+### Building
+
+Requirements: JDK 1.6+, Maven 2.0.8+
+
+```
+git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
+cd incubator-helix
+git checkout helix-0.6.2-incubating
+mvn install package -DskipTests
+```
+
+### Get Help
+
+[#apachehelix](./IRC.html)
+
+`user@helix.incubator.apache.org`
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/resources/images/feather_small.gif
----------------------------------------------------------------------
diff --git a/src/site/resources/images/feather_small.gif b/src/site/resources/images/feather_small.gif
new file mode 100644
index 0000000..94f1892
Binary files /dev/null and b/src/site/resources/images/feather_small.gif differ
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/resources/images/helix-logo.jpg
----------------------------------------------------------------------
diff --git a/src/site/resources/images/helix-logo.jpg b/src/site/resources/images/helix-logo.jpg
index d6428f6..6299014 100644
Binary files a/src/site/resources/images/helix-logo.jpg and b/src/site/resources/images/helix-logo.jpg differ
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/site.xml
----------------------------------------------------------------------
diff --git a/src/site/site.xml b/src/site/site.xml
index af9225c..3d98c9d 100644
--- a/src/site/site.xml
+++ b/src/site/site.xml
@@ -21,17 +21,17 @@
<href>http://helix.incubator.apache.org/</href>
</bannerLeft>
<bannerRight>
- <src>http://incubator.apache.org/images/egg-logo.png</src>
- <href>http://incubator.apache.org/</href>
+ <src>images/feather_small.gif</src>
+ <href>http://www.apache.org/</href>
</bannerRight>
<publishDate position="none"/>
<version position="none"/>
<skin>
- <groupId>org.apache.maven.skins</groupId>
- <artifactId>maven-fluido-skin</artifactId>
- <version>1.3.0</version>
+ <groupId>lt.velykis.maven.skins</groupId>
+ <artifactId>reflow-maven-skin</artifactId>
+ <version>1.0.0</version>
</skin>
<body>
@@ -57,15 +57,14 @@
<item name="Apache Helix" href="http://helix.incubator.apache.org/"/>
</breadcrumbs>
- <menu name="Apache Helix">
- <item name="Introduction" href="./index.html"/>
+ <menu name="Learn">
<item name="Core concepts" href="./Concepts.html"/>
<item name="Architecture" href="./Architecture.html"/>
<item name="Publications" href="./Publications.html"/>
<item name="Client Libraries" href="./ClientLibraries.html"/>
</menu>
- <menu name="Releases">
+ <menu name="Documentation">
<item name="0.6.2-incubating (stable)" href="./site-releases/0.6.2-incubating-site/index.html"/>
<item name="0.7.0-incubating (alpha)" href="./site-releases/0.7.0-incubating-site/index.html"/>
<item name="0.6.1-incubating" href="./site-releases/0.6.1-incubating-site/index.html"/>
@@ -73,6 +72,7 @@
</menu>
<menu name="Helix 0.6.2-incubating">
+ <item name="Documentation" href="./site-releases/0.6.2-incubating-site/index.html"/>
<item name="Quick Start" href="./site-releases/0.6.2-incubating-site/Quickstart.html"/>
<item name="Tutorial" href="./site-releases/0.6.2-incubating-site/Tutorial.html"/>
<item name="Download" href="./site-releases/0.6.2-incubating-site/download.html"/>
@@ -110,7 +110,7 @@
</body>
<custom>
- <fluidoSkin>
+ <!--fluidoSkin>
<topBarEnabled>true</topBarEnabled>
<googleSearch></googleSearch>
<twitter>
@@ -118,9 +118,31 @@
<showUser>true</showUser>
<showFollowers>false</showFollowers>
</twitter>
- <!-- twitter link work only with sidebar disabled -->
<sideBarEnabled>true</sideBarEnabled>
- </fluidoSkin>
+ </fluidoSkin-->
+ <reflowSkin>
+ <theme>bootswatch-cerulean</theme>
+ <highlightJs>false</highlightJs>
+ <brand>
+ <name>Apache Helix</name>
+ <href>http://helix.incubator.apache.org</href>
+ </brand>
+ <slogan>A cluster management framework for partitioned and replicated distributed resources</slogan>
+ <bottomNav>
+ <column>Learn</column>
+ <column>Documentation|Helix 0.6.2-incubating</column>
+ <column>Get Involved</column>
+ <column>ASF</column>
+ </bottomNav>
+ <pages>
+ <index>
+ <sections>
+ <body />
+ <sidebar />
+ </sections>
+ </index>
+ </pages>
+ </reflowSkin>
</custom>
</project>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/src/site/xdoc/download.xml.vm
----------------------------------------------------------------------
diff --git a/src/site/xdoc/download.xml.vm b/src/site/xdoc/download.xml.vm
index f075bab..ce4769a 100644
--- a/src/site/xdoc/download.xml.vm
+++ b/src/site/xdoc/download.xml.vm
@@ -22,7 +22,7 @@ under the License.
xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 http://maven.apache.org/xsd/xdoc-2.0.xsd">
<properties>
- <title>Apache Incubator Helix Downloads</title>
+ <title>Apache Helix Downloads</title>
<author email="dev@helix.incubator.apache.org">Apache Helix Documentation Team</author>
</properties>
@@ -33,7 +33,7 @@ under the License.
</macro>
</div>
- <section name="Introduction">
+ <section name="Apache Helix Downloads">
<p>Apache Helix artifacts are distributed in source and binary form under the terms of the
<a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.
See the included <tt>LICENSE</tt> and <tt>NOTICE</tt> files included in each artifact for additional license
[3/3] git commit: Change to reflow theme, update home, 0.6.1
Posted by ka...@apache.org.
Change to reflow theme, update home, 0.6.1
Project: http://git-wip-us.apache.org/repos/asf/incubator-helix/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-helix/commit/92edaabc
Tree: http://git-wip-us.apache.org/repos/asf/incubator-helix/tree/92edaabc
Diff: http://git-wip-us.apache.org/repos/asf/incubator-helix/diff/92edaabc
Branch: refs/heads/helix-website
Commit: 92edaabc18c3a0377e17136294f959e5e61457c0
Parents: 2d78ba8
Author: Kanak Biscuitwala <ka...@hotmail.com>
Authored: Wed Dec 25 21:43:58 2013 -0800
Committer: Kanak Biscuitwala <ka...@hotmail.com>
Committed: Wed Dec 25 21:43:58 2013 -0800
----------------------------------------------------------------------
pom.xml | 10 +
.../releasenotes/release-0.6.1-incubating.apt | 36 +--
.../0.6.1-incubating/src/site/apt/releasing.apt | 107 --------
.../src/site/markdown/Architecture.md | 248 -----------------
.../src/site/markdown/Building.md | 11 +-
.../src/site/markdown/Concepts.md | 268 -------------------
.../src/site/markdown/Quickstart.md | 236 +++++++++-------
.../src/site/markdown/Tutorial.md | 155 ++++++-----
.../0.6.1-incubating/src/site/markdown/index.md | 21 +-
.../src/site/markdown/recipes/lock_manager.md | 119 ++++----
.../markdown/recipes/rabbitmq_consumer_group.md | 200 +++++++-------
.../recipes/rsync_replicated_file_store.md | 119 ++++----
.../site/markdown/recipes/service_discovery.md | 93 +++----
.../site/markdown/recipes/task_dag_execution.md | 53 ++--
.../src/site/markdown/tutorial_admin.md | 65 +++--
.../src/site/markdown/tutorial_controller.md | 59 ++--
.../src/site/markdown/tutorial_health.md | 11 +-
.../src/site/markdown/tutorial_messaging.md | 71 ++---
.../src/site/markdown/tutorial_participant.md | 106 ++++----
.../src/site/markdown/tutorial_propstore.md | 7 +-
.../src/site/markdown/tutorial_rebalance.md | 37 +--
.../src/site/markdown/tutorial_spectator.md | 37 +--
.../src/site/markdown/tutorial_state.md | 37 +--
.../src/site/markdown/tutorial_throttling.md | 7 +-
.../0.6.1-incubating/src/site/site.xml | 63 +++--
.../src/site/xdoc/download.xml.vm | 96 ++-----
.../0.6.2-incubating/src/site/site.xml | 6 +-
.../0.7.0-incubating/src/site/site.xml | 6 +-
site-releases/trunk/src/site/site.xml | 6 +-
src/site/apt/releasing.apt | 2 +-
src/site/markdown/Architecture.md | 159 ++++++-----
src/site/markdown/ClientLibraries.md | 8 +-
src/site/markdown/Concepts.md | 66 +++--
src/site/markdown/index.md | 86 +++---
src/site/resources/images/feather_small.gif | Bin 0 -> 7500 bytes
src/site/resources/images/helix-logo.jpg | Bin 13659 -> 20444 bytes
src/site/site.xml | 44 ++-
src/site/xdoc/download.xml.vm | 4 +-
38 files changed, 1021 insertions(+), 1638 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/pom.xml
----------------------------------------------------------------------
diff --git a/pom.xml b/pom.xml
index 5c17bd1..bce0c4c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -539,6 +539,16 @@ under the License.
<version>3.3</version>
<dependencies>
<dependency>
+ <groupId>lt.velykis.maven.skins</groupId>
+ <artifactId>reflow-velocity-tools</artifactId>
+ <version>1.0.0</version>
+ </dependency>
+ <dependency>
+ <groupId>org.apache.velocity</groupId>
+ <artifactId>velocity</artifactId>
+ <version>1.7</version>
+ </dependency>
+ <dependency>
<groupId>org.apache.maven.doxia</groupId>
<artifactId>doxia-module-markdown</artifactId>
<version>1.3</version>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.1-incubating.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.1-incubating.apt b/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.1-incubating.apt
index 9305214..882bb6e 100644
--- a/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.1-incubating.apt
+++ b/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.1-incubating.apt
@@ -1,28 +1,28 @@
-----
- Release Notes for 0.6.1-incubating Apache Helix
+ Release Notes for Apache Helix 0.6.1-incubating
-----
-~~ Licensed to the Apache Software Foundation (ASF) under one
-~~ or more contributor license agreements. See the NOTICE file
-~~ distributed with this work for additional information
-~~ regarding copyright ownership. The ASF licenses this file
-~~ to you under the Apache License, Version 2.0 (the
-~~ "License"); you may not use this file except in compliance
-~~ with the License. You may obtain a copy of the License at
-~~
-~~ http://www.apache.org/licenses/LICENSE-2.0
-~~
-~~ Unless required by applicable law or agreed to in writing,
-~~ software distributed under the License is distributed on an
-~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-~~ KIND, either express or implied. See the License for the
-~~ specific language governing permissions and limitations
+~~ Licensed to the Apache Software Foundation (ASF) under one
+~~ or more contributor license agreements. See the NOTICE file
+~~ distributed with this work for additional information
+~~ regarding copyright ownership. The ASF licenses this file
+~~ to you under the Apache License, Version 2.0 (the
+~~ "License"); you may not use this file except in compliance
+~~ with the License. You may obtain a copy of the License at
+~~
+~~ http://www.apache.org/licenses/LICENSE-2.0
+~~
+~~ Unless required by applicable law or agreed to in writing,
+~~ software distributed under the License is distributed on an
+~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+~~ KIND, either express or implied. See the License for the
+~~ specific language governing permissions and limitations
~~ under the License.
~~ NOTE: For help with the syntax of this file, see:
~~ http://maven.apache.org/guides/mini/guide-apt-format.html
-Release Notes for 0.6.1-incubating Apache Helix
+Release Notes for Apache Helix 0.6.1-incubating
The Apache Helix would like to announce the release of Apache Helix 0.6.1-incubating
@@ -49,7 +49,7 @@ Release Notes for 0.6.1-incubating Apache Helix
** Bug
* [HELIX-25] - setConfig should check if instance exist or not when setting PARTICIPANT config
-
+
* [HELIX-29] - Not receiving transitions after participant reconnection
* [HELIX-30] - ZkHelixManager.carryOverPreviousCurrentState() should use a special merge logic
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/apt/releasing.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/apt/releasing.apt b/site-releases/0.6.1-incubating/src/site/apt/releasing.apt
deleted file mode 100644
index 11d0cd9..0000000
--- a/site-releases/0.6.1-incubating/src/site/apt/releasing.apt
+++ /dev/null
@@ -1,107 +0,0 @@
- -----
- Helix release process
- -----
- -----
- 2012-12-15
- -----
-
-~~ Licensed to the Apache Software Foundation (ASF) under one
-~~ or more contributor license agreements. See the NOTICE file
-~~ distributed with this work for additional information
-~~ regarding copyright ownership. The ASF licenses this file
-~~ to you under the Apache License, Version 2.0 (the
-~~ "License"); you may not use this file except in compliance
-~~ with the License. You may obtain a copy of the License at
-~~
-~~ http://www.apache.org/licenses/LICENSE-2.0
-~~
-~~ Unless required by applicable law or agreed to in writing,
-~~ software distributed under the License is distributed on an
-~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-~~ KIND, either express or implied. See the License for the
-~~ specific language governing permissions and limitations
-~~ under the License.
-
-~~ NOTE: For help with the syntax of this file, see:
-~~ http://maven.apache.org/guides/mini/guide-apt-format.html
-
-Helix release process
-
- [[1]] Post to the dev list a few days before you plan to do an Helix release
-
- [[2]] Your maven setting must contains the entry to be able to deploy.
-
- ~/.m2/settings.xml
-
-+-------------
- <server>
- <id>apache.releases.https</id>
- <username></username>
- <password></password>
- </server>
-+-------------
-
- [[3]] Apache DAV passwords
-
-+-------------
- Add the following info into your ~/.netrc
- machine git-wip-us.apache.org login <apache username> <password>
-
-+-------------
- [[4]] Release Helix
- You should have a GPG agent running in the session you will run the maven release commands(preferred), and confirm it works by running "gpg -ab" (type some text and press Ctrl-D).
- If you do not have a GPG agent running, make sure that you have the "apache-release" profile set in your settings.xml as shown below.
-
- Run the release
-
-+-------------
-mvn release:prepare release:perform -B
-+-------------
-
- GPG configuration in maven settings xml:
-
-+-------------
-<profile>
- <id>apache-release</id>
- <properties>
- <gpg.passphrase>[GPG_PASSWORD]</gpg.passphrase>
- </properties>
-</profile>
-+-------------
-
- [[4]] go to https://repository.apache.org and close your staged repository. Note the repository url (format https://repository.apache.org/content/repositories/orgapachehelix-019/org/apache/helix/helix/0.6-incubating/)
-
-+-------------
-svn co https://dist.apache.org/repos/dist/dev/incubator/helix helix-dev-release
-cd helix-dev-release
-sh ./release-script-svn.sh version stagingRepoUrl
-then svn add <new directory created with new version as name>
-then svn ci
-+-------------
-
- [[5]] Validating the release
-
-+-------------
- * Download sources, extract, build and run tests - mvn clean package
- * Verify license headers - mvn -Prat -DskipTests
- * Download binaries and .asc files
- * Download release manager's public key - From the KEYS file, get the release manager's public key finger print and run gpg --keyserver pgpkeys.mit.edu --recv-key <key>
- * Validate authenticity of key - run gpg --fingerprint <key>
- * Check signatures of all the binaries using gpg <binary>
-+-------------
-
- [[6]] Call for a vote in the dev list and wait for 72 hrs. for the vote results. 3 binding votes are necessary for the release to be finalized. example
- After the vote has passed, move the files from dist dev to dist release: svn mv https://dist.apache.org/repos/dist/dev/incubator/helix/version to https://dist.apache.org/repos/dist/release/incubator/helix/
-
- [[7]] Prepare release note. Add a page in src/site/apt/releasenotes/ and change value of \<currentRelease> in parent pom.
-
-
- [[8]] Send out an announcement of the release to:
-
- * users@helix.incubator.apache.org
-
- * dev@helix.incubator.apache.org
-
- [[9]] Celebrate !
-
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/Architecture.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/Architecture.md b/site-releases/0.6.1-incubating/src/site/markdown/Architecture.md
deleted file mode 100644
index 7acf590..0000000
--- a/site-releases/0.6.1-incubating/src/site/markdown/Architecture.md
+++ /dev/null
@@ -1,248 +0,0 @@
-<!---
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
- http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
-
-Helix aims to provide the following abilities to a distributed system:
-
-* Automatic management of a cluster hosting partitioned, replicated resources.
-* Soft and hard failure detection and handling.
-* Automatic load balancing via smart placement of resources on servers(nodes) based on server capacity and resource profile (size of partition, access patterns, etc).
-* Centralized config management and self discovery. Eliminates the need to modify config on each node.
-* Fault tolerance and optimized rebalancing during cluster expansion.
-* Manages entire operational lifecycle of a node. Addition, start, stop, enable/disable without downtime.
-* Monitor cluster health and provide alerts on SLA violation.
-* Service discovery mechanism to route requests.
-
-To build such a system, we need a mechanism to co-ordinate between different nodes/components in the system. This mechanism can be achieved with a software that reacts to any change in the cluster and comes up with a set of tasks needed to bring the cluster to a stable state. The set of tasks will be assigned to one or more nodes in the cluster. Helix serves this purpose of managing the various components in the cluster.
-
-
-
-Distributed System Components
-
-In general any distributed system cluster will have the following
-
-* Set of nodes also referred to as an instance.
-* Set of resources which can be a database, lucene index or a task.
-* Each resource is also partitioned into one or more Partitions.
-* Each partition may have one or more copies called replicas.
-* Each replica can have a state associated with it. For example Master, Slave, Leader, Standby, Online, Offline etc
-
-Roles
------
-
-
-
-Not all nodes in a distributed system will perform similar functionality. For e.g, a few nodes might be serving requests, few nodes might be sending the request and some nodes might be controlling the nodes in the cluster. Based on functionality we have grouped them into
-
-We have divided Helix in 3 logical components based on their responsibility
-
-1. PARTICIPANT: The nodes that actually host the distributed resources.
-2. SPECTATOR: The nodes that simply observe the PARTICIPANT State and route the request accordingly. Routers, for example, need to know the Instance on which a partition is hosted and its state in order to route the request to the appropriate end point.
-3. CONTROLLER: The controller observes and controls the PARTICIPANT nodes. It is responsible for coordinating all transitions in the cluster and ensuring that state constraints are satisfied and cluster stability is maintained.
-
-
-These are simply logical components and can be deployed as per the system requirements. For example:
-
-1. Controller can be deployed as a separate service
-2. Controller can be deployed along with a Participant but only one Controller will be active at any given time.
-
-Both have pros and cons, which will be discussed later and one can chose the mode of deployment as per system needs.
-
-
-## Cluster state/metadata store
-
-We need a distributed store to maintain the state of the cluster and a notification system to notify if there is any change in the cluster state. Helix uses Zookeeper to achieve this functionality.
-
-Zookeeper provides:
-
-* A way to represent PERSISTENT state which basically remains until its deleted.
-* A way to represent TRANSIENT/EPHEMERAL state which vanishes when the process that created the STATE dies.
-* Notification mechanism when there is a change in PERSISTENT/EPHEMERAL STATE
-
-The namespace provided by ZooKeeper is much like that of a standard file system. A name is a sequence of path elements separated by a slash (/). Every node[ZNODE] in ZooKeeper\'s namespace is identified by a path.
-
-More info on Zookeeper can be found here http://zookeeper.apache.org
-
-## Statemachine and constraints
-
-Even though the concept of Resource, Partition, Replicas is common to most distributed systems, one thing that differentiates one distributed system from another is the way each partition is assigned a state and the constraints on each state.
-
-For example:
-
-1. If a system is serving READ ONLY data then all partition\'s replicas are equal and they can either be ONLINE or OFFLINE.
-2. If a system takes BOTH READ and WRITES but ensure that WRITES go through only one partition then the states will be MASTER, SLAVE and OFFLINE. Writes go through the MASTER and is replicated to the SLAVES. Optionally, READS can go through SLAVES.
-
-Apart from defining STATE for each partition, the transition path to each STATE can be application specific. For example, in order to become MASTER it might be a requirement to first become a SLAVE. This ensures that if the SLAVE does not have the data as part of OFFLINE-SLAVE transition it can bootstrap data from other nodes in the system.
-
-Helix provides a way to configure an application specific state machine along with constraints on each state. Along with constraints on STATE, Helix also provides a way to specify constraints on transitions. (More on this later.)
-
-```
- OFFLINE | SLAVE | MASTER
- _____________________________
- | | | |
-OFFLINE | N/A | SLAVE | SLAVE |
- |__________|________|_________|
- | | | |
-SLAVE | OFFLINE | N/A | MASTER |
- |__________|________|_________|
- | | | |
-MASTER | SLAVE | SLAVE | N/A |
- |__________|________|_________|
-
-```
-
-
-
-## Concepts
-
-The following terminologies are used in Helix to model a state machine.
-
-* IDEALSTATE: The state in which we need the cluster to be in if all nodes are up and running. In other words, all state constraints are satisfied.
-* CURRENTSTATE: Represents the current state of each node in the cluster
-* EXTERNALVIEW: Represents the combined view of CURRENTSTATE of all nodes.
-
-The goal of Helix is always to make the CURRENTSTATE of the system same as the IDEALSTATE. Some scenarios where this may not be true are:
-
-* When all nodes are down
-* When one or more nodes fail
-* New nodes are added and the partitions need to be reassigned
-
-### IDEALSTATE
-
-Helix lets the application define the IdealState on a resource basis which basically consists of:
-
-* List of partitions. Example: 64
-* Number of replicas for each partition. Example: 3
-* Node and State for each replica.
-
-Example:
-
-* Partition-1, replica-1, Master, Node-1
-* Partition-1, replica-2, Slave, Node-2
-* Partition-1, replica-3, Slave, Node-3
-* .....
-* .....
-* Partition-p, replica-3, Slave, Node-n
-
-Helix comes with various algorithms to automatically assign the partitions to nodes. The default algorithm minimizes the number of shuffles that happen when new nodes are added to the system
-
-### CURRENTSTATE
-
-Every instance in the cluster hosts one or more partitions of a resource. Each of the partitions has a State associated with it.
-
-Example Node-1
-
-* Partition-1, Master
-* Partition-2, Slave
-* ....
-* ....
-* Partition-p, Slave
-
-### EXTERNALVIEW
-
-External clients needs to know the state of each partition in the cluster and the Node hosting that partition. Helix provides one view of the system to SPECTATORS as EXTERNAL VIEW. EXTERNAL VIEW is simply an aggregate of all CURRENTSTATE
-
-* Partition-1, replica-1, Master, Node-1
-* Partition-1, replica-2, Slave, Node-2
-* Partition-1, replica-3, Slave, Node-3
-* .....
-* .....
-* Partition-p, replica-3, Slave, Node-n
-
-## Process Workflow
-
-Mode of operation in a cluster
-
-A node process can be one of the following:
-
-* PARTICIPANT: The process registers itself in the cluster and acts on the messages received in its queue and updates the current state. Example: Storage Node
-* SPECTATOR: The process is simply interested in the changes in the Externalview. The Router is a spectator of the Storage cluster.
-* CONTROLLER: This process actively controls the cluster by reacting to changes in Cluster State and sending messages to PARTICIPANTS.
-
-
-### Participant Node Process
-
-* When Node starts up, it registers itself under LIVEINSTANCES
-* After registering, it waits for new Messages in the message queue
-* When it receives a message, it will perform the required task as indicated in the message
-* After the task is completed, depending on the task outcome it updates the CURRENTSTATE
-
-### Controller Process
-
-* Watches IDEALSTATE
-* Node goes down/comes up or Node is added/removed. Watches LIVEINSTANCES and CURRENTSTATE of each Node in the cluster
-* Triggers appropriate state transition by sending message to PARTICIPANT
-
-### Spectator Process
-
-* When the process starts, it asks cluster manager agent to be notified of changes in ExternalView
-* Whenever it receives a notification, it reads the Externalview and performs required duties. For the Router, it updates its routing table.
-
-#### Interaction between controller, participant and spectator
-
-The following picture shows how controllers, participants and spectators interact with each other.
-
-
-
-## Core algorithm
-
-* Controller gets the IdealState and the CurrentState of active storage nodes from Zookeeper
-* Compute the delta between IdealState and CurrentState for each partition across all participant nodes
-* For each partition compute tasks based on the State Machine Table. It\'s possible to configure priority on the state Transition. For example, in case of Master-Slave:
- * Attempt mastership transfer if possible without violating constraint.
- * Partition Addition
- * Drop Partition
-* Add the tasks in parallel if possible to the respective queue for each storage node (if the tasks added are mutually independent)
-* If a task is dependent on another task being completed, do not add that task
-* After any task is completed by a Participant, Controllers gets notified of the change and the State Transition algorithm is re-run until the CurrentState is same as IdealState.
-
-## Helix znode layout
-
-Helix organizes znodes under clusterName in multiple levels.
-
-The top level (under clusterName) znodes are all Helix defined and in upper case:
-
-* PROPERTYSTORE: application property store
-* STATEMODELDEFES: state model definitions
-* INSTANCES: instance runtime information including current state and messages
-* CONFIGS: configurations
-* IDEALSTATES: ideal states
-* EXTERNALVIEW: external views
-* LIVEINSTANCES: live instances
-* CONTROLLER: cluster controller runtime information
-
-Under INSTANCES, there are runtime znodes for each instance. An instance organizes znodes as follows:
-
-* CURRENTSTATES
- * sessionId
- * resourceName
-* ERRORS
-* STATUSUPDATES
-* MESSAGES
-* HEALTHREPORT
-
-Under CONFIGS, there are different scopes of configurations:
-
-* RESOURCE: contains resource scope configurations
-* CLUSTER: contains cluster scope configurations
-* PARTICIPANT: contains participant scope configurations
-
-The following image shows an example of Helix znodes layout for a cluster named "test-cluster":
-
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/Building.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/Building.md b/site-releases/0.6.1-incubating/src/site/markdown/Building.md
index f79193e..b0890ba 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/Building.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/Building.md
@@ -20,7 +20,9 @@ under the License.
Build Instructions
------------------
-Requirements: Jdk 1.6+, Maven 2.0.8+
+### From Source
+
+Requirements: JDK 1.6+, Maven 2.0.8+
```
git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
@@ -29,7 +31,7 @@ git checkout tags/helix-0.6.1-incubating
mvn install package -DskipTests
```
-Maven dependency
+### Maven Dependency
```
<dependency>
@@ -39,8 +41,3 @@ Maven dependency
</dependency>
```
-Download
---------
-
-[0.6.1-incubating](./download.html)
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/Concepts.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/Concepts.md b/site-releases/0.6.1-incubating/src/site/markdown/Concepts.md
deleted file mode 100644
index 02d7406..0000000
--- a/site-releases/0.6.1-incubating/src/site/markdown/Concepts.md
+++ /dev/null
@@ -1,268 +0,0 @@
-<!---
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
- http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
-Helix is based on the idea that a given task has the following attributes associated with it:
-
-* _Location of the task_. For example it runs on Node N1
-* _State_. For example, it is running, stopped etc.
-
-In Helix terminology, a task is referred to as a _resource_.
-
-### IdealState
-
-IdealState simply allows one to map tasks to location and state. A standard way of expressing this in Helix:
-
-```
- "TASK_NAME" : {
- "LOCATION" : "STATE"
- }
-
-```
-Consider a simple case where you want to launch a task \'myTask\' on node \'N1\'. The IdealState for this can be expressed as follows:
-
-```
-{
- "id" : "MyTask",
- "mapFields" : {
- "myTask" : {
- "N1" : "ONLINE",
- }
- }
-}
-```
-### Partition
-
-If this task get too big to fit on one box, you might want to divide it into subTasks. Each subTask is referred to as a _partition_ in Helix. Let\'s say you want to divide the task into 3 subTasks/partitions, the IdealState can be changed as shown below.
-
-\'myTask_0\', \'myTask_1\', \'myTask_2\' are logical names representing the partitions of myTask. Each tasks runs on N1, N2 and N3 respectively.
-
-```
-{
- "id" : "myTask",
- "simpleFields" : {
- "NUM_PARTITIONS" : "3",
- }
- "mapFields" : {
- "myTask_0" : {
- "N1" : "ONLINE",
- },
- "myTask_1" : {
- "N2" : "ONLINE",
- },
- "myTask_2" : {
- "N3" : "ONLINE",
- }
- }
-}
-```
-
-### Replica
-
-Partitioning allows one to split the data/task into multiple subparts. But let\'s say the request rate each partition increases. The common solution is to have multiple copies for each partition. Helix refers to the copy of a partition as a _replica_. Adding a replica also increases the availability of the system during failures. One can see this methodology employed often in Search systems. The index is divided into shards, and each shard has multiple copies.
-
-Let\'s say you want to add one additional replica for each task. The IdealState can simply be changed as shown below.
-
-For increasing the availability of the system, it\'s better to place the replica of a given partition on different nodes.
-
-```
-{
- "id" : "myIndex",
- "simpleFields" : {
- "NUM_PARTITIONS" : "3",
- "REPLICAS" : "2",
- },
- "mapFields" : {
- "myIndex_0" : {
- "N1" : "ONLINE",
- "N2" : "ONLINE"
- },
- "myIndex_1" : {
- "N2" : "ONLINE",
- "N3" : "ONLINE"
- },
- "myIndex_2" : {
- "N3" : "ONLINE",
- "N1" : "ONLINE"
- }
- }
-}
-```
-
-### State
-
-Now let\'s take a slightly complicated scenario where a task represents a database. Unlike an index which is in general read-only, a database supports both reads and writes. Keeping the data consistent among the replicas is crucial in distributed data stores. One commonly applied technique is to assign one replica as MASTER and remaining replicas as SLAVE. All writes go to the MASTER and are then replicated to the SLAVE replicas.
-
-Helix allows one to assign different states to each replica. Let\'s say you have two MySQL instances N1 and N2, where one will serve as MASTER and another as SLAVE. The IdealState can be changed to:
-
-```
-{
- "id" : "myDB",
- "simpleFields" : {
- "NUM_PARTITIONS" : "1",
- "REPLICAS" : "2",
- },
- "mapFields" : {
- "myDB" : {
- "N1" : "MASTER",
- "N2" : "SLAVE",
- }
- }
-}
-
-```
-
-
-### State Machine and Transitions
-
-IdealState allows one to exactly specify the desired state of the cluster. Given an IdealState, Helix takes up the responsibility of ensuring that the cluster reaches the IdealState. The Helix _controller_ reads the IdealState and then commands the Participant to take appropriate actions to move from one state to another until it matches the IdealState. These actions are referred to as _transitions_ in Helix.
-
-The next logical question is: how does the _controller_ compute the transitions required to get to IdealState? This is where the finite state machine concept comes in. Helix allows applications to plug in a finite state machine. A state machine consists of the following:
-
-* State: Describes the role of a replica
-* Transition: An action that allows a replica to move from one State to another, thus changing its role.
-
-Here is an example of MASTERSLAVE state machine,
-
-```
- OFFLINE | SLAVE | MASTER
- _____________________________
- | | | |
-OFFLINE | N/A | SLAVE | SLAVE |
- |__________|________|_________|
- | | | |
-SLAVE | OFFLINE | N/A | MASTER |
- |__________|________|_________|
- | | | |
-MASTER | SLAVE | SLAVE | N/A |
- |__________|________|_________|
-
-```
-
-Helix allows each resource to be associated with one state machine. This means you can have one resource as an index and another as a database in the same cluster. One can associate each resource with a state machine as follows:
-
-```
-{
- "id" : "myDB",
- "simpleFields" : {
- "NUM_PARTITIONS" : "1",
- "REPLICAS" : "2",
- "STATE_MODEL_DEF_REF" : "MasterSlave",
- },
- "mapFields" : {
- "myDB" : {
- "N1" : "MASTER",
- "N2" : "SLAVE",
- }
- }
-}
-
-```
-
-### Current State
-
-CurrentState of a resource simply represents its actual state at a PARTICIPANT. In the below example:
-
-* INSTANCE_NAME: Unique name representing the process
-* SESSION_ID: ID that is automatically assigned every time a process joins the cluster
-
-```
-{
- "id":"MyResource"
- ,"simpleFields":{
- ,"SESSION_ID":"13d0e34675e0002"
- ,"INSTANCE_NAME":"node1"
- ,"STATE_MODEL_DEF":"MasterSlave"
- }
- ,"mapFields":{
- "MyResource_0":{
- "CURRENT_STATE":"SLAVE"
- }
- ,"MyResource_1":{
- "CURRENT_STATE":"MASTER"
- }
- ,"MyResource_2":{
- "CURRENT_STATE":"MASTER"
- }
- }
-}
-```
-Each node in the cluster has its own CurrentState.
-
-### External View
-
-In order to communicate with the PARTICIPANTs, external clients need to know the current state of each of the PARTICIPANTs. The external clients are referred to as SPECTATORS. In order to make the life of SPECTATOR simple, Helix provides an EXTERNALVIEW that is an aggregated view of the current state across all nodes. The EXTERNALVIEW has a similar format as IDEALSTATE.
-
-```
-{
- "id":"MyResource",
- "mapFields":{
- "MyResource_0":{
- "N1":"SLAVE",
- "N2":"MASTER",
- "N3":"OFFLINE"
- },
- "MyResource_1":{
- "N1":"MASTER",
- "N2":"SLAVE",
- "N3":"ERROR"
- },
- "MyResource_2":{
- "N1":"MASTER",
- "N2":"SLAVE",
- "N3":"SLAVE"
- }
- }
-}
-```
-
-### Rebalancer
-
-The core component of Helix is the CONTROLLER which runs the REBALANCER algorithm on every cluster event. Cluster events can be one of the following:
-
-* Nodes start/stop and soft/hard failures
-* New nodes are added/removed
-* Ideal state changes
-
-There are few more such as config changes, etc. The key takeaway: there are many ways to trigger the rebalancer.
-
-When a rebalancer is run it simply does the following:
-
-* Compares the IdealState and current state
-* Computes the transitions required to reach the IdealState
-* Issues the transitions to each PARTICIPANT
-
-The above steps happen for every change in the system. Once the current state matches the IdealState, the system is considered stable which implies \'IDEALSTATE = CURRENTSTATE = EXTERNALVIEW\'
-
-### Dynamic IdealState
-
-One of the things that makes Helix powerful is that IdealState can be changed dynamically. This means one can listen to cluster events like node failures and dynamically change the ideal state. Helix will then take care of triggering the respective transitions in the system.
-
-Helix comes with a few algorithms to automatically compute the IdealState based on the constraints. For example, if you have a resource of 3 partitions and 2 replicas, Helix can automatically compute the IdealState based on the nodes that are currently active. See the [tutorial](./tutorial_rebalance.html) to find out more about various execution modes of Helix like AUTO_REBALANCE, AUTO and CUSTOM.
-
-
-
-
-
-
-
-
-
-
-
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/Quickstart.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/Quickstart.md b/site-releases/0.6.1-incubating/src/site/markdown/Quickstart.md
index 96c4efb..73d7422 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/Quickstart.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/Quickstart.md
@@ -17,23 +17,26 @@ specific language governing permissions and limitations
under the License.
-->
+Quickstart
+---------
+
Get Helix
---------
-First, let\'s get Helix, either build it, or download.
+First, let\'s get Helix. Either build it, or download it.
### Build
- git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
- cd incubator-helix
- git checkout tags/helix-0.6.1-incubating
- mvn install package -DskipTests
- cd helix-core/target/helix-core-pkg/bin //This folder contains all the scripts used in following sections
- chmod +x *
+git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
+cd incubator-helix
+git checkout tags/helix-0.6.1-incubating
+mvn install package -DskipTests
+cd helix-core/target/helix-core-pkg/bin # This folder contains all the scripts used in following sections
+chmod +x *
### Download
-Download the 0.6.1-incubating release package [here](./download.html)
+Download the 0.6.1-incubating release package [here](./download.html)
Overview
--------
@@ -46,9 +49,9 @@ Let\'s Do It
Helix provides command line interfaces to set up the cluster and view the cluster state. The best way to understand how Helix views a cluster is to build a cluster.
-#### First, get to the tools directory
+### Get to the Tools Directory
-If you built the code
+If you built the code:
```
cd helix/incubator-helix/helix-core/target/helix-core-pkg/bin
@@ -70,66 +73,72 @@ You can observe the components working together in this demo, which does the fol
* Kill the third node (Helix takes care of failover)
* Show the cluster state. Note that the two surviving nodes take over mastership of the partitions from the failed node
-##### Run the demo
+### Run the Demo
```
cd helix/incubator-helix/helix-core/target/helix-core-pkg/bin
./quickstart.sh
```
-##### 2 nodes are set up and the partitions rebalanced
+#### The Initial Setup
+
+2 nodes are set up and the partitions are rebalanced.
The cluster state is as follows:
```
CLUSTER STATE: After starting 2 nodes
- localhost_12000 localhost_12001
- MyResource_0 M S
- MyResource_1 S M
- MyResource_2 M S
- MyResource_3 M S
- MyResource_4 S M
- MyResource_5 S M
+ localhost_12000 localhost_12001
+MyResource_0 M S
+MyResource_1 S M
+MyResource_2 M S
+MyResource_3 M S
+MyResource_4 S M
+MyResource_5 S M
```
Note there is one master and one slave per partition.
-##### A third node is added and the cluster rebalanced
+#### Add a Node
+
+A third node is added and the cluster is rebalanced.
The cluster state changes to:
```
CLUSTER STATE: After adding a third node
- localhost_12000 localhost_12001 localhost_12002
- MyResource_0 S M S
- MyResource_1 S S M
- MyResource_2 M S S
- MyResource_3 S S M
- MyResource_4 M S S
- MyResource_5 S M S
+ localhost_12000 localhost_12001 localhost_12002
+MyResource_0 S M S
+MyResource_1 S S M
+MyResource_2 M S S
+MyResource_3 S S M
+MyResource_4 M S S
+MyResource_5 S M S
```
Note there is one master and _two_ slaves per partition. This is expected because there are three nodes.
-##### Finally, a node is killed to simulate a failure
+#### Kill a Node
+
+Finally, a node is killed to simulate a failure
Helix makes sure each partition has a master. The cluster state changes to:
```
CLUSTER STATE: After the 3rd node stops/crashes
- localhost_12000 localhost_12001 localhost_12002
- MyResource_0 S M -
- MyResource_1 S M -
- MyResource_2 M S -
- MyResource_3 M S -
- MyResource_4 M S -
- MyResource_5 S M -
+ localhost_12000 localhost_12001 localhost_12002
+MyResource_0 S M -
+MyResource_1 S M -
+MyResource_2 M S -
+MyResource_3 M S -
+MyResource_4 M S -
+MyResource_5 S M -
```
Long Version
------------
-Now you can run the same steps by hand. In the detailed version, we\'ll do the following:
+Now you can run the same steps by hand. In this detailed version, we\'ll do the following:
* Define a cluster
* Add two nodes to the cluster
@@ -138,20 +147,22 @@ Now you can run the same steps by hand. In the detailed version, we\'ll do the
* Expand the cluster: add a few nodes and rebalance the partitions
* Failover: stop a node and verify the mastership transfer
-### Install/Start zookeeper
+### Install and Start ZooKeeper
Zookeeper can be started in standalone mode or replicated mode.
-More info is available at
+More information is available at
* http://zookeeper.apache.org/doc/r3.3.3/zookeeperStarted.html
* http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServerSetup
In this example, let\'s start zookeeper in local mode.
-##### start zookeeper locally on port 2199
+#### Start ZooKeeper Locally on Port 2199
- ./start-standalone-zookeeper.sh 2199 &
+```
+./start-standalone-zookeeper.sh 2199 &
+```
### Define the Cluster
@@ -161,62 +172,74 @@ zookeeper_address is of the format host:port e.g localhost:2199 for standalone o
Next, we\'ll set up a cluster MYCLUSTER cluster with these attributes:
-* 3 instances running on localhost at ports 12913,12914,12915
-* One database named myDB with 6 partitions
+* 3 instances running on localhost at ports 12913,12914,12915
+* One database named myDB with 6 partitions
* Each partition will have 3 replicas with 1 master, 2 slaves
-* zookeeper running locally at localhost:2199
+* ZooKeeper running locally at localhost:2199
-##### Create the cluster MYCLUSTER
- ## helix-admin.sh --zkSvr <zk_address> --addCluster <clustername>
- ./helix-admin.sh --zkSvr localhost:2199 --addCluster MYCLUSTER
+#### Create the Cluster MYCLUSTER
+
+```
+# ./helix-admin.sh --zkSvr <zk_address> --addCluster <clustername>
+./helix-admin.sh --zkSvr localhost:2199 --addCluster MYCLUSTER
+```
-##### Add nodes to the cluster
+### Add Nodes to the Cluster
In this case we\'ll add three nodes: localhost:12913, localhost:12914, localhost:12915
- ## helix-admin.sh --zkSvr <zk_address> --addNode <clustername> <host:port>
- ./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12913
- ./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12914
- ./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12915
+```
+# helix-admin.sh --zkSvr <zk_address> --addNode <clustername> <host:port>
+./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12913
+./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12914
+./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12915
+```
-#### Define the resource and partitioning
+### Define the Resource and Partitioning
-In this example, the resource is a database, partitioned 6 ways. (In a production system, it\'s common to over-partition for better load balancing. Helix has been used in production to manage hundreds of databases each with 10s or 100s of partitions running on 10s of physical nodes.)
+In this example, the resource is a database, partitioned 6 ways. Note that in a production system, it\'s common to over-partition for better load balancing. Helix has been used in production to manage hundreds of databases each with 10s or 100s of partitions running on 10s of physical nodes.
-##### Create a database with 6 partitions using the MasterSlave state model.
+#### Create a Database with 6 Partitions using the MasterSlave State Model
Helix ensures there will be exactly one master for each partition.
- ## helix-admin.sh --zkSvr <zk_address> --addResource <clustername> <resourceName> <numPartitions> <StateModelName>
- ./helix-admin.sh --zkSvr localhost:2199 --addResource MYCLUSTER myDB 6 MasterSlave
-
-##### Now we can let Helix assign partitions to nodes.
+```
+# helix-admin.sh --zkSvr <zk_address> --addResource <clustername> <resourceName> <numPartitions> <StateModelName>
+./helix-admin.sh --zkSvr localhost:2199 --addResource MYCLUSTER myDB 6 MasterSlave
+```
-This command will distribute the partitions amongst all the nodes in the cluster. In this example, each partition has 3 replicas.
+#### Let Helix Assign Partitions to Nodes
- ## helix-admin.sh --zkSvr <zk_address> --rebalance <clustername> <resourceName> <replication factor>
- ./helix-admin.sh --zkSvr localhost:2199 --rebalance MYCLUSTER myDB 3
+This command will distribute the partitions amongst all the nodes in the cluster. In this example, each partition has 3 replicas.
-Now the cluster is defined in Zookeeper. The nodes (localhost:12913, localhost:12914, localhost:12915) and resource (myDB, with 6 partitions using the MasterSlave model). And the _ideal state_ has been calculated, assuming a replication factor of 3.
+```
+# helix-admin.sh --zkSvr <zk_address> --rebalance <clustername> <resourceName> <replication factor>
+./helix-admin.sh --zkSvr localhost:2199 --rebalance MYCLUSTER myDB 3
+```
-##### Start the Helix Controller
+Now the cluster is defined in ZooKeeper. The nodes (localhost:12913, localhost:12914, localhost:12915) and resource (myDB, with 6 partitions using the MasterSlave model) are all properly configured. And the _IdealState_ has been calculated, assuming a replication factor of 3.
-Now that the cluster is defined in Zookeeper, the Helix controller can manage the cluster.
+### Start the Helix Controller
- ## Start the cluster manager, which will manage MYCLUSTER
- ./run-helix-controller.sh --zkSvr localhost:2199 --cluster MYCLUSTER 2>&1 > /tmp/controller.log &
+Now that the cluster is defined in ZooKeeper, the Helix controller can manage the cluster.
-##### Start up the cluster to be managed
+```
+# Start the cluster manager, which will manage MYCLUSTER
+./run-helix-controller.sh --zkSvr localhost:2199 --cluster MYCLUSTER 2>&1 > /tmp/controller.log &
+```
-We\'ve started up Zookeeper, defined the cluster, the resources, the partitioning, and started up the Helix controller. Next, we\'ll start up the nodes of the system to be managed. Each node is a Participant, which is an instance of the system component to be managed. Helix assigns work to Participants, keeps track of their roles and health, and takes action when a node fails.
+### Start up the Cluster to be Managed
- # start up each instance. These are mock implementations that are actively managed by Helix
- ./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12913 --stateModelType MasterSlave 2>&1 > /tmp/participant_12913.log
- ./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12914 --stateModelType MasterSlave 2>&1 > /tmp/participant_12914.log
- ./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12915 --stateModelType MasterSlave 2>&1 > /tmp/participant_12915.log
+We\'ve started up ZooKeeper, defined the cluster, the resources, the partitioning, and started up the Helix controller. Next, we\'ll start up the nodes of the system to be managed. Each node is a Participant, which is an instance of the system component to be managed. Helix assigns work to Participants, keeps track of their roles and health, and takes action when a node fails.
+```
+# start up each instance. These are mock implementations that are actively managed by Helix
+./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12913 --stateModelType MasterSlave 2>&1 > /tmp/participant_12913.log
+./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12914 --stateModelType MasterSlave 2>&1 > /tmp/participant_12914.log
+./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12915 --stateModelType MasterSlave 2>&1 > /tmp/participant_12915.log
+```
-#### Inspect the Cluster
+### Inspect the Cluster
Now, let\'s see the Helix view of our cluster. We\'ll work our way down as follows:
@@ -229,17 +252,17 @@ Clusters -> MYCLUSTER -> instances -> instance detail
A single Helix controller can manage multiple clusters, though so far, we\'ve only defined one cluster. Let\'s see:
```
-## List existing clusters
-./helix-admin.sh --zkSvr localhost:2199 --listClusters
+# List existing clusters
+./helix-admin.sh --zkSvr localhost:2199 --listClusters
Existing clusters:
MYCLUSTER
```
-
-Now, let\'s see the Helix view of MYCLUSTER
+
+Now, let\'s see the Helix view of MYCLUSTER:
```
-## helix-admin.sh --zkSvr <zk_address> --listClusterInfo <clusterName>
+# helix-admin.sh --zkSvr <zk_address> --listClusterInfo <clusterName>
./helix-admin.sh --zkSvr localhost:2199 --listClusterInfo MYCLUSTER
Existing resources in cluster MYCLUSTER:
@@ -250,11 +273,10 @@ localhost_12914
localhost_12913
```
-
-Let\'s look at the details of an instance
+Let\'s look at the details of an instance:
```
-## ./helix-admin.sh --zkSvr <zk_address> --listInstanceInfo <clusterName> <InstanceName>
+# ./helix-admin.sh --zkSvr <zk_address> --listInstanceInfo <clusterName> <InstanceName>
./helix-admin.sh --zkSvr localhost:2199 --listInstanceInfo MYCLUSTER localhost_12913
InstanceConfig: {
@@ -271,11 +293,11 @@ InstanceConfig: {
}
```
-
-##### Query info of a resource
+
+#### Query Information about a Resource
```
-## helix-admin.sh --zkSvr <zk_address> --listResourceInfo <clusterName> <resourceName>
+# helix-admin.sh --zkSvr <zk_address> --listResourceInfo <clusterName> <resourceName>
./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo MYCLUSTER myDB
IdealState for myDB:
@@ -375,30 +397,38 @@ ExternalView for myDB:
Now, let\'s look at one of the partitions:
- ## helix-admin.sh --zkSvr <zk_address> --listResourceInfo <clusterName> <partition>
- ./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo mycluster myDB_0
+```
+# helix-admin.sh --zkSvr <zk_address> --listResourceInfo <clusterName> <partition>
+./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo mycluster myDB_0
+```
-#### Expand the Cluster
+### Expand the Cluster
Next, we\'ll show how Helix does the work that you\'d otherwise have to build into your system. When you add capacity to your cluster, you want the work to be evenly distributed. In this example, we started with 3 nodes, with 6 partitions. The partitions were evenly balanced, 2 masters and 4 slaves per node. Let\'s add 3 more nodes: localhost:12916, localhost:12917, localhost:12918
- ./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12916
- ./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12917
- ./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12918
+```
+./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12916
+./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12917
+./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12918
+```
And start up these instances:
- # start up each instance. These are mock implementations that are actively managed by Helix
- ./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12916 --stateModelType MasterSlave 2>&1 > /tmp/participant_12916.log
- ./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12917 --stateModelType MasterSlave 2>&1 > /tmp/participant_12917.log
- ./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12918 --stateModelType MasterSlave 2>&1 > /tmp/participant_12918.log
+```
+# start up each instance. These are mock implementations that are actively managed by Helix
+./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12916 --stateModelType MasterSlave 2>&1 > /tmp/participant_12916.log
+./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12917 --stateModelType MasterSlave 2>&1 > /tmp/participant_12917.log
+./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12918 --stateModelType MasterSlave 2>&1 > /tmp/participant_12918.log
+```
And now, let Helix do the work for you. To shift the work, simply rebalance. After the rebalance, each node will have one master and two slaves.
- ./helix-admin.sh --zkSvr localhost:2199 --rebalance MYCLUSTER myDB 3
+```
+./helix-admin.sh --zkSvr localhost:2199 --rebalance MYCLUSTER myDB 3
+```
-#### View the cluster
+### View the Cluster
OK, let\'s see how it looks:
@@ -503,7 +533,7 @@ ExternalView for myDB:
Mission accomplished. The partitions are nicely balanced.
-#### How about Failover?
+### How about Failover?
Building a fault tolerant system isn\'t trivial, but with Helix, it\'s easy. Helix detects a failed instance, and triggers mastership transfer automatically.
@@ -608,15 +638,17 @@ ExternalView for myDB:
As we\'ve seen in this Quickstart, Helix takes care of partitioning, load balancing, elasticity, failure detection and recovery.
-##### ZOOINSPECTOR
+### ZooInspector
You can view all of the underlying data by going direct to zookeeper. Use ZooInspector that comes with zookeeper to browse the data. This is a java applet (make sure you have X windows)
To start zooinspector run the following command from <zk_install_directory>/contrib/ZooInspector
-
- java -cp zookeeper-3.3.3-ZooInspector.jar:lib/jtoaster-1.0.4.jar:../../lib/log4j-1.2.15.jar:../../zookeeper-3.3.3.jar org.apache.zookeeper.inspector.ZooInspector
-#### Next
+```
+java -cp zookeeper-3.3.3-ZooInspector.jar:lib/jtoaster-1.0.4.jar:../../lib/log4j-1.2.15.jar:../../zookeeper-3.3.3.jar org.apache.zookeeper.inspector.ZooInspector
+```
+
+### Next
-Now that you understand the idea of Helix, read the [tutorial](./tutorial.html) to learn how to choose the right state model and constraints for your system, and how to implement it. In many cases, the built-in features meet your requirements. And best of all, Helix is a customizable framework, so you can plug in your own behavior, while retaining the automation provided by Helix.
+Now that you understand the idea of Helix, read the [tutorial](./Tutorial.html) to learn how to choose the right state model and constraints for your system, and how to implement it. In many cases, the built-in features meet your requirements. And best of all, Helix is a customizable framework, so you can plug in your own behavior, while retaining the automation provided by Helix.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/Tutorial.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/Tutorial.md b/site-releases/0.6.1-incubating/src/site/markdown/Tutorial.md
index 27f9fd9..50dcee9 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/Tutorial.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/Tutorial.md
@@ -38,7 +38,7 @@ Convention: we first cover the _basic_ approach, which is the easiest to impleme
4. [Rebalancing Algorithms](./tutorial_rebalance.html)
5. [State Machines](./tutorial_state.html)
6. [Messaging](./tutorial_messaging.html)
-7. [Customized health check](./tutorial_health.html)
+7. [Customizing Health Checks](./tutorial_health.html)
8. [Throttling](./tutorial_throttling.html)
9. [Application Property Store](./tutorial_propstore.html)
10. [Admin Interface](./tutorial_admin.html)
@@ -47,29 +47,29 @@ Convention: we first cover the _basic_ approach, which is the easiest to impleme
First, we need to set up the system. Let\'s walk through the steps in building a distributed system using Helix.
-### Start Zookeeper
+#### Start ZooKeeper
-This starts a zookeeper in standalone mode. For production deployment, see [Apache Zookeeper](http://zookeeper.apache.org) for instructions.
+This starts a zookeeper in standalone mode. For production deployment, see [Apache ZooKeeper](http://zookeeper.apache.org) for instructions.
```
- ./start-standalone-zookeeper.sh 2199 &
+./start-standalone-zookeeper.sh 2199 &
```
-### Create a cluster
+#### Create a Cluster
-Creating a cluster will define the cluster in appropriate znodes on zookeeper.
+Creating a cluster will define the cluster in appropriate znodes on ZooKeeper.
-Using the java API:
+Using the Java API:
```
- // Create setup tool instance
- // Note: ZK_ADDRESS is the host:port of Zookeeper
- String ZK_ADDRESS = "localhost:2199";
- admin = new ZKHelixAdmin(ZK_ADDRESS);
-
- String CLUSTER_NAME = "helix-demo";
- //Create cluster namespace in zookeeper
- admin.addCluster(CLUSTER_NAME);
+// Create setup tool instance
+// Note: ZK_ADDRESS is the host:port of Zookeeper
+String ZK_ADDRESS = "localhost:2199";
+admin = new ZKHelixAdmin(ZK_ADDRESS);
+
+String CLUSTER_NAME = "helix-demo";
+//Create cluster namespace in zookeeper
+admin.addCluster(CLUSTER_NAME);
```
OR
@@ -77,56 +77,54 @@ OR
Using the command-line interface:
```
- ./helix-admin.sh --zkSvr localhost:2199 --addCluster helix-demo
+./helix-admin.sh --zkSvr localhost:2199 --addCluster helix-demo
```
-### Configure the nodes of the cluster
+#### Configure the Nodes of the Cluster
-First we\'ll add new nodes to the cluster, then configure the nodes in the cluster. Each node in the cluster must be uniquely identifiable.
+First we\'ll add new nodes to the cluster, then configure the nodes in the cluster. Each node in the cluster must be uniquely identifiable.
The most commonly used convention is hostname:port.
```
- String CLUSTER_NAME = "helix-demo";
- int NUM_NODES = 2;
- String hosts[] = new String[]{"localhost","localhost"};
- String ports[] = new String[]{7000,7001};
- for (int i = 0; i < NUM_NODES; i++)
- {
-
- InstanceConfig instanceConfig = new InstanceConfig(hosts[i]+ "_" + ports[i]);
- instanceConfig.setHostName(hosts[i]);
- instanceConfig.setPort(ports[i]);
- instanceConfig.setInstanceEnabled(true);
-
- //Add additional system specific configuration if needed. These can be accessed during the node start up.
- instanceConfig.getRecord().setSimpleField("key", "value");
- admin.addInstance(CLUSTER_NAME, instanceConfig);
-
- }
+String CLUSTER_NAME = "helix-demo";
+int NUM_NODES = 2;
+String hosts[] = new String[]{"localhost","localhost"};
+String ports[] = new String[]{7000,7001};
+for (int i = 0; i < NUM_NODES; i++)
+{
+ InstanceConfig instanceConfig = new InstanceConfig(hosts[i]+ "_" + ports[i]);
+ instanceConfig.setHostName(hosts[i]);
+ instanceConfig.setPort(ports[i]);
+ instanceConfig.setInstanceEnabled(true);
+
+ //Add additional system specific configuration if needed. These can be accessed during the node start up.
+ instanceConfig.getRecord().setSimpleField("key", "value");
+ admin.addInstance(CLUSTER_NAME, instanceConfig);
+}
```
-### Configure the resource
+#### Configure the Resource
-A _resource_ represents the actual task performed by the nodes. It can be a database, index, topic, queue or any other processing entity.
-A _resource_ can be divided into many sub-parts known as _partitions_.
+A __resource__ represents the actual task performed by the nodes. It can be a database, index, topic, queue or any other processing entity.
+A resource can be divided into many sub-parts known as __partitions__.
-#### Define the _state model_ and _constraints_
+##### Define the State Model and Constraints
-For scalability and fault tolerance, each partition can have one or more replicas.
-The _state model_ allows one to declare the system behavior by first enumerating the various STATES, and the TRANSITIONS between them.
+For scalability and fault tolerance, each partition can have one or more replicas.
+The __state model__ allows one to declare the system behavior by first enumerating the various STATES, and the TRANSITIONS between them.
A simple model is ONLINE-OFFLINE where ONLINE means the task is active and OFFLINE means it\'s not active.
-You can also specify how many replicas must be in each state, these are known as _constraints_.
+You can also specify how many replicas must be in each state, these are known as __constraints__.
For example, in a search system, one might need more than one node serving the same index to handle the load.
-The allowed states:
+The allowed states:
* MASTER
* SLAVE
* OFFLINE
-The allowed transitions:
+The allowed transitions:
* OFFLINE to SLAVE
* SLAVE to OFFLINE
@@ -138,62 +136,61 @@ The constraints:
* no more than 1 MASTER per partition
* the rest of the replicas should be slaves
-The following snippet shows how to declare the _state model_ and _constraints_ for the MASTER-SLAVE model.
+The following snippet shows how to declare the state model and constraints for the MASTER-SLAVE model.
```
+StateModelDefinition.Builder builder = new StateModelDefinition.Builder(STATE_MODEL_NAME);
- StateModelDefinition.Builder builder = new StateModelDefinition.Builder(STATE_MODEL_NAME);
+// Add states and their rank to indicate priority. A lower rank corresponds to a higher priority
+builder.addState(MASTER, 1);
+builder.addState(SLAVE, 2);
+builder.addState(OFFLINE);
- // Add states and their rank to indicate priority. A lower rank corresponds to a higher priority
- builder.addState(MASTER, 1);
- builder.addState(SLAVE, 2);
- builder.addState(OFFLINE);
+// Set the initial state when the node starts
+builder.initialState(OFFLINE);
- // Set the initial state when the node starts
- builder.initialState(OFFLINE);
+// Add transitions between the states.
+builder.addTransition(OFFLINE, SLAVE);
+builder.addTransition(SLAVE, OFFLINE);
+builder.addTransition(SLAVE, MASTER);
+builder.addTransition(MASTER, SLAVE);
- // Add transitions between the states.
- builder.addTransition(OFFLINE, SLAVE);
- builder.addTransition(SLAVE, OFFLINE);
- builder.addTransition(SLAVE, MASTER);
- builder.addTransition(MASTER, SLAVE);
+// set constraints on states
- // set constraints on states.
+// static constraint: upper bound of 1 MASTER
+builder.upperBound(MASTER, 1);
- // static constraint: upper bound of 1 MASTER
- builder.upperBound(MASTER, 1);
+// dynamic constraint: R means it should be derived based on the replication factor for the cluster
+// this allows a different replication factor for each resource without
+// having to define a new state model
- // dynamic constraint: R means it should be derived based on the replication factor for the cluster
- // this allows a different replication factor for each resource without
- // having to define a new state model
- //
- builder.dynamicUpperBound(SLAVE, "R");
+builder.dynamicUpperBound(SLAVE, "R");
- StateModelDefinition statemodelDefinition = builder.build();
- admin.addStateModelDef(CLUSTER_NAME, STATE_MODEL_NAME, myStateModel);
+StateModelDefinition statemodelDefinition = builder.build();
+admin.addStateModelDef(CLUSTER_NAME, STATE_MODEL_NAME, myStateModel);
```
-#### Assigning partitions to nodes
+##### Assigning Partitions to Nodes
-The final goal of Helix is to ensure that the constraints on the state model are satisfied.
+The final goal of Helix is to ensure that the constraints on the state model are satisfied.
Helix does this by assigning a STATE to a partition (such as MASTER, SLAVE), and placing it on a particular node.
-There are 3 assignment modes Helix can operate on
+There are 3 assignment modes Helix can operate in:
* AUTO_REBALANCE: Helix decides the placement and state of a partition.
* AUTO: Application decides the placement but Helix decides the state of a partition.
* CUSTOM: Application controls the placement and state of a partition.
-For more info on the assignment modes, see [Rebalancing Algorithms](./tutorial_rebalance.html) of the tutorial.
+For more information on the assignment modes, see the [Rebalancing Algorithms](./tutorial_rebalance.html) section of this tutorial.
```
- String RESOURCE_NAME = "MyDB";
- int NUM_PARTITIONS = 6;
- STATE_MODEL_NAME = "MasterSlave";
- String MODE = "AUTO";
- int NUM_REPLICAS = 2;
-
- admin.addResource(CLUSTER_NAME, RESOURCE_NAME, NUM_PARTITIONS, STATE_MODEL_NAME, MODE);
- admin.rebalance(CLUSTER_NAME, RESOURCE_NAME, NUM_REPLICAS);
+String RESOURCE_NAME = "MyDB";
+int NUM_PARTITIONS = 6;
+STATE_MODEL_NAME = "MasterSlave";
+String MODE = "AUTO";
+int NUM_REPLICAS = 2;
+
+admin.addResource(CLUSTER_NAME, RESOURCE_NAME, NUM_PARTITIONS, STATE_MODEL_NAME, MODE);
+admin.rebalance(CLUSTER_NAME, RESOURCE_NAME, NUM_REPLICAS);
```
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/index.md b/site-releases/0.6.1-incubating/src/site/markdown/index.md
index a358d88..b201c32 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/index.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/index.md
@@ -17,18 +17,19 @@ specific language governing permissions and limitations
under the License.
-->
-Navigating the Documentation
-----------------------------
+<head>
+ <title>Helix 0.6.1-incubating Documentation</title>
+</head>
-### Conceptual Understanding
+### Get Helix
-[Concepts / Terminology](./Concepts.html)
+[Download](./download.html)
-[Architecture](./Architecture.html)
+[Building](./Building.html)
-### Hands-on Helix
+[Release Notes](./releasenotes/release-0.6.1-incubating.html)
-[Getting Helix](./Building.html)
+### Hands-On
[Quickstart](./Quickstart.html)
@@ -46,9 +47,5 @@ Navigating the Documentation
[Service discovery](./recipes/service_discovery.html)
-[Distributed Task DAG Execution](./recipes/task_dag_execution.html)
-
-### Download
-
-[0.6.1-incubating](./download.html)
+[Distributed task DAG execution](./recipes/task_dag_execution.html)
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/recipes/lock_manager.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/recipes/lock_manager.md b/site-releases/0.6.1-incubating/src/site/markdown/recipes/lock_manager.md
index 84420dd..0f3206f 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/recipes/lock_manager.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/recipes/lock_manager.md
@@ -16,21 +16,21 @@ KIND, either express or implied. See the License for the
specific language governing permissions and limitations
under the License.
-->
-Distributed lock manager
+Distributed Lock Manager
------------------------
-Distributed locks are used to synchronize accesses shared resources. Most applications use Zookeeper to model the distributed locks.
+Distributed locks are used to synchronize accesses shared resources. Most applications today use ZooKeeper to model distributed locks.
-The simplest way to model a lock using zookeeper is (See Zookeeper leader recipe for an exact and more advanced solution)
+The simplest way to model a lock using ZooKeeper is (See ZooKeeper leader recipe for an exact and more advanced solution)
-* Each process tries to create an emphemeral node.
-* If can successfully create it then, it acquires the lock
-* Else it will watch on the znode and try to acquire the lock again if the current lock holder disappears
+* Each process tries to create an emphemeral node
+* If the node is successfully created, the process acquires the lock
+* Otherwise, it will watch the ZNode and try to acquire the lock again if the current lock holder disappears
-This is good enough if there is only one lock. But in practice, an application will need many such locks. Distributing and managing the locks among difference process becomes challenging. Extending such a solution to many locks will result in
+This is good enough if there is only one lock. But in practice, an application will need many such locks. Distributing and managing the locks among difference process becomes challenging. Extending such a solution to many locks will result in:
-* Uneven distribution of locks among nodes, the node that starts first will acquire all the lock. Nodes that start later will be idle.
-* When a node fails, how the locks will be distributed among remaining nodes is not predicable.
-* When new nodes are added the current nodes dont relinquish the locks so that new nodes can acquire some locks
+* Uneven distribution of locks among nodes; the node that starts first will acquire all the locks. Nodes that start later will be idle.
+* When a node fails, how the locks will be distributed among remaining nodes is not predicable.
+* When new nodes are added the current nodes don\'t relinquish the locks so that new nodes can acquire some locks
In other words we want a system to satisfy the following requirements.
@@ -38,28 +38,29 @@ In other words we want a system to satisfy the following requirements.
* If a node fails, the locks that were acquired by that node should be evenly distributed among other nodes
* If nodes are added, locks must be evenly re-distributed among nodes.
-Helix provides a simple and elegant solution to this problem. Simply specify the number of locks and Helix will ensure that above constraints are satisfied.
+Helix provides a simple and elegant solution to this problem. Simply specify the number of locks and Helix will ensure that above constraints are satisfied.
-To quickly see this working run the lock-manager-demo script where 12 locks are evenly distributed among three nodes, and when a node fails, the locks get re-distributed among remaining two nodes. Note that Helix does not re-shuffle the locks completely, instead it simply distributes the locks relinquished by dead node among 2 remaining nodes evenly.
+To quickly see this working run the `lock-manager-demo` script where 12 locks are evenly distributed among three nodes, and when a node fails, the locks get re-distributed among remaining two nodes. Note that Helix does not re-shuffle the locks completely, instead it simply distributes the locks relinquished by dead node among 2 remaining nodes evenly.
----------------------------------------------------------------------------------------
-#### Short version
- This version starts multiple threads with in same process to simulate a multi node deployment. Try the long version to get a better idea of how it works.
-
+### Short Version
+This version starts multiple threads within the same process to simulate a multi node deployment. Try the long version to get a better idea of how it works.
+
```
git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
cd incubator-helix
+git checkout tags/helix-0.6.1-incubating
mvn clean install package -DskipTests
cd recipes/distributed-lock-manager/target/distributed-lock-manager-pkg/bin
chmod +x *
./lock-manager-demo
```
-##### Output
+#### Output
```
-./lock-manager-demo
+./lock-manager-demo
STARTING localhost_12000
STARTING localhost_12002
STARTING localhost_12001
@@ -117,83 +118,74 @@ lock-group_9 localhost_12001
----------------------------------------------------------------------------------------
-#### Long version
+### Long version
This provides more details on how to setup the cluster and where to plugin application code.
-##### start zookeeper
+#### Start ZooKeeper
```
./start-standalone-zookeeper 2199
```
-##### Create a cluster
+#### Create a Cluster
```
./helix-admin --zkSvr localhost:2199 --addCluster lock-manager-demo
```
-##### Create a lock group
+#### Create a Lock Group
-Create a lock group and specify the number of locks in the lock group.
+Create a lock group and specify the number of locks in the lock group.
```
./helix-admin --zkSvr localhost:2199 --addResource lock-manager-demo lock-group 6 OnlineOffline AUTO_REBALANCE
```
-##### Start the nodes
+#### Start the Nodes
-Create a Lock class that handles the callbacks.
+Create a Lock class that handles the callbacks.
```
-
-public class Lock extends StateModel
-{
+public class Lock extends StateModel {
private String lockName;
- public Lock(String lockName)
- {
+ public Lock(String lockName) {
this.lockName = lockName;
}
- public void lock(Message m, NotificationContext context)
- {
+ public void lock(Message m, NotificationContext context) {
System.out.println(" acquired lock:"+ lockName );
}
- public void release(Message m, NotificationContext context)
- {
+ public void release(Message m, NotificationContext context) {
System.out.println(" releasing lock:"+ lockName );
}
}
-
```
-LockFactory that creates the lock
-
+and a LockFactory that creates Locks
+
```
-public class LockFactory extends StateModelFactory<Lock>{
-
- /* Instantiates the lock handler, one per lockName*/
- public Lock create(String lockName)
- {
+public class LockFactory extends StateModelFactory<Lock> {
+ /* Instantiates the lock handler, one per lockName */
+ public Lock create(String lockName) {
return new Lock(lockName);
- }
+ }
}
```
-At node start up, simply join the cluster and helix will invoke the appropriate callbacks on Lock instance. One can start any number of nodes and Helix detects that a new node has joined the cluster and re-distributes the locks automatically.
+At node start up, simply join the cluster and Helix will invoke the appropriate callbacks on the appropriate Lock instance. One can start any number of nodes and Helix detects that a new node has joined the cluster and re-distributes the locks automatically.
```
-public class LockProcess{
-
- public static void main(String args){
+public class LockProcess {
+ public static void main(String args) {
String zkAddress= "localhost:2199";
String clusterName = "lock-manager-demo";
//Give a unique id to each process, most commonly used format hostname_port
String instanceName ="localhost_12000";
ZKHelixAdmin helixAdmin = new ZKHelixAdmin(zkAddress);
- //configure the instance and provide some metadata
+ //configure the instance and provide some metadata
InstanceConfig config = new InstanceConfig(instanceName);
config.setHostName("localhost");
config.setPort("12000");
@@ -207,47 +199,38 @@ public class LockProcess{
manager.getStateMachineEngine().registerStateModelFactory("OnlineOffline", modelFactory);
manager.connect();
Thread.currentThread.join();
- }
-
+ }
}
```
-##### Start the controller
+#### Start the Controller
-Controller can be started either as a separate process or can be embedded within each node process
+The controller can be started either as a separate process or can be embedded within each node process
-###### Separate process
-This is recommended when number of nodes in the cluster >100. For fault tolerance, you can run multiple controllers on different boxes.
+##### Separate Process
+This is recommended when number of nodes in the cluster \> 100. For fault tolerance, you can run multiple controllers on different boxes.
```
./run-helix-controller --zkSvr localhost:2199 --cluster lock-manager-demo 2>&1 > /tmp/controller.log &
```
-###### Embedded within the node process
+##### Embedded Within the Node Process
This is recommended when the number of nodes in the cluster is less than 100. To start a controller from each process, simply add the following lines to MyClass
```
-public class LockProcess{
-
- public static void main(String args){
+public class LockProcess {
+ public static void main(String args) {
String zkAddress= "localhost:2199";
String clusterName = "lock-manager-demo";
- .
- .
+ // .
+ // .
manager.connect();
HelixManager controller;
- controller = HelixControllerMain.startHelixController(zkAddress,
+ controller = HelixControllerMain.startHelixController(zkAddress,
clusterName,
- "controller",
+ "controller",
HelixControllerMain.STANDALONE);
Thread.currentThread.join();
}
}
```
-
-----------------------------------------------------------------------------------------
-
-
-
-
-
[2/3] Change to reflow theme, update home, 0.6.1
Posted by ka...@apache.org.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/recipes/rabbitmq_consumer_group.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/recipes/rabbitmq_consumer_group.md b/site-releases/0.6.1-incubating/src/site/markdown/recipes/rabbitmq_consumer_group.md
index ec3053a..a78f92e 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/recipes/rabbitmq_consumer_group.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/recipes/rabbitmq_consumer_group.md
@@ -19,40 +19,40 @@ under the License.
RabbitMQ Consumer Group
-=======================
+-----------------------
-[RabbitMQ](http://www.rabbitmq.com/) is a well known Open source software the provides robust messaging for applications.
+[RabbitMQ](http://www.rabbitmq.com/) is well-known open source software the provides robust messaging for applications.
-One of the commonly implemented recipes using this software is a work queue. http://www.rabbitmq.com/tutorials/tutorial-four-java.html describes the use case where
+One of the commonly implemented recipes using this software is a work queue. [http://www.rabbitmq.com/tutorials/tutorial-four-java.html](http://www.rabbitmq.com/tutorials/tutorial-four-java.html) describes the use case where
-* A producer sends a message with a routing key.
-* The message is routed to the queue whose binding key exactly matches the routing key of the message.
+* A producer sends a message with a routing key
+* The message is routed to the queue whose binding key exactly matches the routing key of the message
* There are multiple consumers and each consumer is interested in processing only a subset of the messages by binding to the interested keys
The example provided [here](http://www.rabbitmq.com/tutorials/tutorial-four-java.html) describes how multiple consumers can be started to process all the messages.
-While this works, in production systems one needs the following
+While this works, in production systems one needs the following:
-* Ability to handle failures: when a consumers fails another consumer must be started or the other consumers must start processing these messages that should have been processed by the failed consumer.
-* When the existing consumers cannot keep up with the task generation rate, new consumers will be added. The tasks must be redistributed among all the consumers.
+* Ability to handle failures: when a consumer fails, another consumer must be started or the other consumers must start processing these messages that should have been processed by the failed consumer
+* When the existing consumers cannot keep up with the task generation rate, new consumers will be added. The tasks must be redistributed among all the consumers
In this recipe, we demonstrate handling of consumer failures and new consumer additions using Helix.
-Mapping this usecase to Helix is pretty easy as the binding key/routing key is equivalent to a partition.
+Mapping this usecase to Helix is pretty easy as the binding key/routing key is equivalent to a partition.
-Let's take an example. Lets say the queue has 6 partitions, and we have 2 consumers to process all the queues.
-What we want is all 6 queues to be evenly divided among 2 consumers.
+Let's take an example. Lets say the queue has 6 partitions, and we have 2 consumers to process all the queues.
+What we want is all 6 queues to be evenly divided among 2 consumers.
Eventually when the system scales, we add more consumers to keep up. This will make each consumer process tasks from 2 queues.
-Now let's say that a consumer failed which reduces the number of active consumers to 2. This means each consumer must process 3 queues.
+Now let's say that a consumer failed, reducing the number of active consumers to 2. This means each consumer must process 3 queues.
-We showcase how such a dynamic App can be developed using Helix. Even though we use rabbitmq as the pub/sub system one can extend this solution to other pub/sub systems.
+We showcase how such a dynamic application can be developed using Helix. Even though we use RabbitMQ as the pub/sub system one can extend this solution to other pub/sub systems.
-Try it
-======
+### Try It
```
git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
cd incubator-helix
+git checkout tags/helix-0.6.1-incubating
mvn clean install package -DskipTests
cd recipes/rabbitmq-consumer-group/bin
chmod +x *
@@ -62,63 +62,60 @@ chmod +x $HELIX_PKG_ROOT/bin/*
chmod +x $HELIX_RABBITMQ_ROOT/bin/*
```
-
-Install Rabbit MQ
-----------------
+#### Install RabbitMQ
Setting up RabbitMQ on a local box is straightforward. You can find the instructions here
http://www.rabbitmq.com/download.html
-Start ZK
---------
-Start zookeeper at port 2199
+#### Start ZK
+
+Start ZooKeeper at port 2199
```
$HELIX_PKG_ROOT/bin/start-standalone-zookeeper 2199
```
-Setup the consumer group cluster
---------------------------------
-This will setup the cluster by creating a "rabbitmq-consumer-group" cluster and adds a "topic" with "6" queues.
+#### Setup the Consumer Group Cluster
+
+This will setup the cluster by creating a "rabbitmq-consumer-group" cluster and adds a "topic" with "6" queues.
```
-$HELIX_RABBITMQ_ROOT/bin/setup-cluster.sh localhost:2199
+$HELIX_RABBITMQ_ROOT/bin/setup-cluster.sh localhost:2199
```
-Add consumers
--------------
-Start 2 consumers in 2 different terminals. Each consumer is given a unique id.
+#### Add Consumers
+
+Start 2 consumers in 2 different terminals. Each consumer is given a unique ID.
```
//start-consumer.sh zookeeperAddress (e.g. localhost:2181) consumerId , rabbitmqServer (e.g. localhost)
-$HELIX_RABBITMQ_ROOT/bin/start-consumer.sh localhost:2199 0 localhost
-$HELIX_RABBITMQ_ROOT/bin/start-consumer.sh localhost:2199 1 localhost
+$HELIX_RABBITMQ_ROOT/bin/start-consumer.sh localhost:2199 0 localhost
+$HELIX_RABBITMQ_ROOT/bin/start-consumer.sh localhost:2199 1 localhost
```
-Start HelixController
---------------------
+#### Start the Helix Controller
+
Now start a Helix controller that starts managing the "rabbitmq-consumer-group" cluster.
```
$HELIX_RABBITMQ_ROOT/bin/start-cluster-manager.sh localhost:2199
```
-Send messages to the Topic
---------------------------
+#### Send Messages to the Topic
-Start sending messages to the topic. This script randomly selects a routing key (1-6) and sends the message to topic.
+Start sending messages to the topic. This script randomly selects a routing key (1-6) and sends the message to topic.
Based on the key, messages gets routed to the appropriate queue.
```
$HELIX_RABBITMQ_ROOT/bin/send-message.sh localhost 20
```
-After running this, you should see all 20 messages being processed by 2 consumers.
+After running this, you should see all 20 messages being processed by 2 consumers.
-Add another consumer
---------------------
-Once a new consumer is started, helix detects it. In order to balance the load between 3 consumers, it deallocates 1 partition from the existing consumers and allocates it to the new consumer. We see that
+#### Add Another Consumer
+
+Once a new consumer is started, Helix detects it. In order to balance the load between 3 consumers, it deallocates 1 partition from the existing consumers and allocates it to the new consumer. We see that
each consumer is now processing only 2 queues.
Helix makes sure that old nodes are asked to stop consuming before the new consumer is asked to start consuming for a given partition. But the transitions for each partition can happen in parallel.
@@ -126,7 +123,7 @@ Helix makes sure that old nodes are asked to stop consuming before the new consu
$HELIX_RABBITMQ_ROOT/bin/start-consumer.sh localhost:2199 2 localhost
```
-Send messages again to the topic.
+Send messages again to the topic
```
$HELIX_RABBITMQ_ROOT/bin/send-message.sh localhost 100
@@ -134,94 +131,83 @@ $HELIX_RABBITMQ_ROOT/bin/send-message.sh localhost 100
You should see that messages are now received by all 3 consumers.
-Stop a consumer
----------------
+#### Stop a Consumer
+
In any terminal press CTRL^C and notice that Helix detects the consumer failure and distributes the 2 partitions that were processed by failed consumer to the remaining 2 active consumers.
-How does it work
-================
+### How does this work?
+
+Find the entire code [here](https://git-wip-us.apache.org/repos/asf?p=incubator-helix.git;a=tree;f=recipes/rabbitmq-consumer-group/src/main/java/org/apache/helix/recipes/rabbitmq).
+
+#### Cluster Setup
-Find the entire code [here](https://git-wip-us.apache.org/repos/asf?p=incubator-helix.git;a=tree;f=recipes/rabbitmq-consumer-group/src/main/java/org/apache/helix/recipes/rabbitmq).
-
-Cluster setup
--------------
-This step creates znode on zookeeper for the cluster and adds the state model. We use online offline state model since there is no need for other states. The consumer is either processing a queue or it is not.
+This step creates ZNode on ZooKeeper for the cluster and adds the state model. We use online offline state model since there is no need for other states. The consumer is either processing a queue or it is not.
It creates a resource called "rabbitmq-consumer-group" with 6 partitions. The execution mode is set to AUTO_REBALANCE. This means that the Helix controls the assignment of partition to consumers and automatically distributes the partitions evenly among the active consumers. When a consumer is added or removed, it ensures that a minimum number of partitions are shuffled.
```
- zkclient = new ZkClient(zkAddr, ZkClient.DEFAULT_SESSION_TIMEOUT,
- ZkClient.DEFAULT_CONNECTION_TIMEOUT, new ZNRecordSerializer());
- ZKHelixAdmin admin = new ZKHelixAdmin(zkclient);
-
- // add cluster
- admin.addCluster(clusterName, true);
+zkclient = new ZkClient(zkAddr, ZkClient.DEFAULT_SESSION_TIMEOUT,
+ ZkClient.DEFAULT_CONNECTION_TIMEOUT, new ZNRecordSerializer());
+ZKHelixAdmin admin = new ZKHelixAdmin(zkclient);
- // add state model definition
- StateModelConfigGenerator generator = new StateModelConfigGenerator();
- admin.addStateModelDef(clusterName, "OnlineOffline",
- new StateModelDefinition(generator.generateConfigForOnlineOffline()));
+// add cluster
+admin.addCluster(clusterName, true);
- // add resource "topic" which has 6 partitions
- String resourceName = "rabbitmq-consumer-group";
- admin.addResource(clusterName, resourceName, 6, "OnlineOffline", "AUTO_REBALANCE");
+// add state model definition
+StateModelConfigGenerator generator = new StateModelConfigGenerator();
+admin.addStateModelDef(clusterName, "OnlineOffline",
+ new StateModelDefinition(generator.generateConfigForOnlineOffline()));
+
+// add resource "topic" which has 6 partitions
+String resourceName = "rabbitmq-consumer-group";
+admin.addResource(clusterName, resourceName, 6, "OnlineOffline", "AUTO_REBALANCE");
```
-Starting the consumers
-----------------------
-The only thing consumers need to know is the zkaddress, cluster name and consumer id. It does not need to know anything else.
+### Starting the Consumers
-```
- _manager =
- HelixManagerFactory.getZKHelixManager(_clusterName,
- _consumerId,
- InstanceType.PARTICIPANT,
- _zkAddr);
+The only thing consumers need to know is the ZooKeeper address, cluster name and consumer ID. It does not need to know anything else.
- StateMachineEngine stateMach = _manager.getStateMachineEngine();
- ConsumerStateModelFactory modelFactory =
- new ConsumerStateModelFactory(_consumerId, _mqServer);
- stateMach.registerStateModelFactory("OnlineOffline", modelFactory);
+```
+_manager = HelixManagerFactory.getZKHelixManager(_clusterName,
+ _consumerId,
+ InstanceType.PARTICIPANT,
+ _zkAddr);
- _manager.connect();
+StateMachineEngine stateMach = _manager.getStateMachineEngine();
+ConsumerStateModelFactory modelFactory =
+ new ConsumerStateModelFactory(_consumerId, _mqServer);
+stateMach.registerStateModelFactory("OnlineOffline", modelFactory);
+_manager.connect();
```
-Once the consumer has registered the statemodel and the controller is started, the consumer starts getting callbacks (onBecomeOnlineFromOffline) for the partition it needs to host. All it needs to do as part of the callback is to start consuming messages from the appropriate queue. Similarly, when the controller deallocates a partitions from a consumer, it fires onBecomeOfflineFromOnline for the same partition.
+Once the consumer has registered the state model and the controller is started, the consumer starts getting callbacks (onBecomeOnlineFromOffline) for the partition it needs to host. All it needs to do as part of the callback is to start consuming messages from the appropriate queue. Similarly, when the controller deallocates a partitions from a consumer, it fires onBecomeOfflineFromOnline for the same partition.
As a part of this transition, the consumer will stop consuming from a that queue.
```
- @Transition(to = "ONLINE", from = "OFFLINE")
- public void onBecomeOnlineFromOffline(Message message, NotificationContext context)
- {
- LOG.debug(_consumerId + " becomes ONLINE from OFFLINE for " + _partition);
+@Transition(to = "ONLINE", from = "OFFLINE")
+public void onBecomeOnlineFromOffline(Message message, NotificationContext context) {
+ LOG.debug(_consumerId + " becomes ONLINE from OFFLINE for " + _partition);
+ if (_thread == null) {
+ LOG.debug("Starting ConsumerThread for " + _partition + "...");
+ _thread = new ConsumerThread(_partition, _mqServer, _consumerId);
+ _thread.start();
+ LOG.debug("Starting ConsumerThread for " + _partition + " done");
- if (_thread == null)
- {
- LOG.debug("Starting ConsumerThread for " + _partition + "...");
- _thread = new ConsumerThread(_partition, _mqServer, _consumerId);
- _thread.start();
- LOG.debug("Starting ConsumerThread for " + _partition + " done");
-
- }
}
-
- @Transition(to = "OFFLINE", from = "ONLINE")
- public void onBecomeOfflineFromOnline(Message message, NotificationContext context)
- throws InterruptedException
- {
- LOG.debug(_consumerId + " becomes OFFLINE from ONLINE for " + _partition);
-
- if (_thread != null)
- {
- LOG.debug("Stopping " + _consumerId + " for " + _partition + "...");
-
- _thread.interrupt();
- _thread.join(2000);
- _thread = null;
- LOG.debug("Stopping " + _consumerId + " for " + _partition + " done");
-
- }
+}
+
+@Transition(to = "OFFLINE", from = "ONLINE")
+public void onBecomeOfflineFromOnline(Message message, NotificationContext context)
+ throws InterruptedException {
+ LOG.debug(_consumerId + " becomes OFFLINE from ONLINE for " + _partition);
+ if (_thread != null) {
+ LOG.debug("Stopping " + _consumerId + " for " + _partition + "...");
+ _thread.interrupt();
+ _thread.join(2000);
+ _thread = null;
+ LOG.debug("Stopping " + _consumerId + " for " + _partition + " done");
}
-```
\ No newline at end of file
+}
+```
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/recipes/rsync_replicated_file_store.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/recipes/rsync_replicated_file_store.md b/site-releases/0.6.1-incubating/src/site/markdown/recipes/rsync_replicated_file_store.md
index f8a74a0..3060493 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/recipes/rsync_replicated_file_store.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/recipes/rsync_replicated_file_store.md
@@ -17,25 +17,26 @@ specific language governing permissions and limitations
under the License.
-->
-Near real time rsync replicated file system
-===========================================
+Near-Realtime Rsync Replicated File System
+------------------------------------------
-Quickdemo
----------
+### Quick Demo
* This demo starts 3 instances with id's as ```localhost_12001, localhost_12002, localhost_12003```
* Each instance stores its files under ```/tmp/<id>/filestore```
-* ``` localhost_12001 ``` is designated as the master and ``` localhost_12002 and localhost_12003``` are the slaves.
-* Files written to master are replicated to the slaves automatically. In this demo, a.txt and b.txt are written to ```/tmp/localhost_12001/filestore``` and it gets replicated to other folders.
-* When the master is stopped, ```localhost_12002``` is promoted to master.
+* ```localhost_12001``` is designated as the master, and ```localhost_12002``` and ```localhost_12003``` are the slaves
+* Files written to the master are replicated to the slaves automatically. In this demo, a.txt and b.txt are written to ```/tmp/localhost_12001/filestore``` and they get replicated to other folders.
+* When the master is stopped, ```localhost_12002``` is promoted to master.
* The other slave ```localhost_12003``` stops replicating from ```localhost_12001``` and starts replicating from new master ```localhost_12002```
* Files written to new master ```localhost_12002``` are replicated to ```localhost_12003```
-* In the end state of this quick demo, ```localhost_12002``` is the master and ```localhost_12003``` is the slave. Manually create files under ```/tmp/localhost_12002/filestore``` and see that appears in ```/tmp/localhost_12003/filestore```
-* Ignore the interrupted exceptions on the console :-).
+* In the end state of this quick demo, ```localhost_12002``` is the master and ```localhost_12003``` is the slave. Manually create files under ```/tmp/localhost_12002/filestore``` and see that appear in ```/tmp/localhost_12003/filestore```
+* Ignore the interrupted exceptions on the console :-)
```
git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
+cd incubator-helix
+git checkout tags/helix-0.6.1-incubating
cd recipes/rsync-replicated-file-system/
mvn clean install package -DskipTests
cd target/rsync-replicated-file-system-pkg/bin
@@ -44,103 +45,99 @@ chmod +x *
```
-Overview
---------
+### Overview
-There are many applications that require storage for storing large number of relatively small data files. Examples include media stores to store small videos, images, mail attachments etc. Each of these objects is typically kilobytes, often no larger than a few megabytes. An additional distinguishing feature of these usecases is also that files are typically only added or deleted, rarely updated. When there are updates, they are rare and do not have any concurrency requirements.
+There are many applications that require storage for storing large number of relatively small data files. Examples include media stores to store small videos, images, mail attachments etc. Each of these objects is typically kilobytes, often no larger than a few megabytes. An additional distinguishing feature of these use cases is that files are typically only added or deleted, rarely updated. When there are updates, they do not have any concurrency requirements.
+
+These are much simpler requirements than what general purpose distributed file system have to satisfy; these would include concurrent access to files, random access for reads and updates, posix compliance, and others. To satisfy those requirements, general DFSs are also pretty complex that are expensive to build and maintain.
-These are much simpler requirements than what general purpose distributed file system have to satisfy including concurrent access to files, random access for reads and updates, posix compliance etc. To satisfy those requirements, general DFSs are also pretty complex that are expensive to build and maintain.
-
A different implementation of a distributed file system includes HDFS which is inspired by Google's GFS. This is one of the most widely used distributed file system that forms the main data storage platform for Hadoop. HDFS is primary aimed at processing very large data sets and distributes files across a cluster of commodity servers by splitting up files in fixed size chunks. HDFS is not particularly well suited for storing a very large number of relatively tiny files.
### File Store
It's possible to build a vastly simpler system for the class of applications that have simpler requirements as we have pointed out.
-* Large number of files but each file is relatively small.
-* Access is limited to create, delete and get entire files.
-* No updates to files that are already created (or it's feasible to delete the old file and create a new one).
-
+* Large number of files but each file is relatively small
+* Access is limited to create, delete and get entire files
+* No updates to files that are already created (or it's feasible to delete the old file and create a new one)
+
We call this system a Partitioned File Store (PFS) to distinguish it from other distributed file systems. This system needs to provide the following features:
* CRD access to large number of small files
-* Scalability: Files should be distributed across a large number of commodity servers based on the storage requirement.
-* Fault-tolerance: Each file should be replicated on multiple servers so that individual server failures do not reduce availability.
-* Elasticity: It should be possible to add capacity to the cluster easily.
-
+* Scalability: Files should be distributed across a large number of commodity servers based on the storage requirement
+* Fault-tolerance: Each file should be replicated on multiple servers so that individual server failures do not reduce availability
+* Elasticity: It should be possible to add capacity to the cluster easily
-Apache Helix is a generic cluster management framework that makes it very easy to provide the scalability, fault-tolerance and elasticity features.
-Rsync can be easily used as a replication channel between servers so that each file gets replicated on multiple servers.
-Design
-------
+Apache Helix is a generic cluster management framework that makes it very easy to provide scalability, fault-tolerance and elasticity features.
+rsync can be easily used as a replication channel between servers so that each file gets replicated on multiple servers.
-High level
+### Design
-* Partition the file system based on the file name.
-* At any time a single writer can write, we call this a master.
-* For redundancy, we need to have additional replicas called slave. Slaves can optionally serve reads.
-* Slave replicates data from the master.
-* When a master fails, slave gets promoted to master.
+#### High Level
-### Transaction log
+* Partition the file system based on the file name
+* At any time a single writer can write, we call this a master
+* For redundancy, we need to have additional replicas called slave. Slaves can optionally serve reads
+* Slave replicates data from the master
+* When a master fails, a slave gets promoted to master
-Every write on the master will result in creation/deletion of one or more files. In order to maintain timeline consistency slaves need to apply the changes in the same order.
-To facilitate this, the master logs each transaction in a file and each transaction is associated with an 64 bit id in which the 32 LSB represents a sequence number and MSB represents the generation number.
-Sequence gets incremented on every transaction and and generation is increment when a new master is elected.
+#### Transaction Log
-### Replication
+Every write on the master will result in creation/deletion of one or more files. In order to maintain timeline consistency slaves need to apply the changes in the same order
+To facilitate this, the master logs each transaction in a file and each transaction is associated with an 64 bit ID in which the 32 LSB represents a sequence number and MSB represents the generation number
+The sequence number gets incremented on every transaction and the generation is incremented when a new master is elected
-Replication is required to slave to keep up with the changes on the master. Every time the slave applies a change it checkpoints the last applied transaction id.
-During restarts, this allows the slave to pull changes from the last checkpointed id. Similar to master, the slave logs each transaction to the transaction logs but instead of generating new transaction id, it uses the same id generated by the master.
+#### Replication
+Replication is required for slaves to keep up with changes on the master. Every time the slave applies a change it checkpoints the last applied transaction ID.
+During restarts, this allows the slave to pull changes from the last checkpointed ID. Similar to master, the slave logs each transaction to the transaction logs but instead of generating new transaction ID, it uses the same ID generated by the master.
-### Fail over
-When a master fails, a new slave will be promoted to master. If the prev master node is reachable, then the new master will flush all the
-changes from previous master before taking up mastership. The new master will record the end transaction id of the current generation and then starts new generation
-with sequence starting from 1. After this the master will begin accepting writes.
+#### Failover
+When a master fails, a new slave will be promoted to master. If the previous master node is reachable, then the new master will flush all the
+changes from previous the master before taking up mastership. The new master will record the end transaction ID of the current generation and then start a new generation
+with sequence starting from 1. After this the master will begin accepting writes.
-Rsync based solution
--------------------
+### Rsync-based Solution
-This application demonstrate a file store that uses rsync as the replication mechanism. One can envision a similar system where instead of using rsync,
+This application demonstrates a file store that uses rsync as the replication mechanism. One can envision a similar system where instead of using rsync, one
can implement a custom solution to notify the slave of the changes and also provide an api to pull the change files.
-#### Concept
-* file_store_dir: Root directory for the actual data files
-* change_log_dir: The transaction logs are generated under this folder.
-* check_point_dir: The slave stores the check points ( last processed transaction) here.
+
+#### Concepts
+* file_store_dir: Root directory for the actual data files
+* change_log_dir: The transaction logs are generated under this folder
+* check_point_dir: The slave stores the check points ( last processed transaction) here
#### Master
-* File server: This component support file uploads and downloads and writes the files to ```file_store_dir```. This is not included in this application. Idea is that most applications have different ways of implementing this component and has some business logic associated with it. It is not hard to come up with such a component if needed.
-* File store watcher: This component watches the ```file_store_dir``` directory on the local file system for any changes and notifies the registered listeners of the changes.
-* Change Log Generator: This registers as a listener of File System Watcher and on each notification logs the changes into a file under ```change_log_dir```.
+* File server: This component supports file uploads and downloads and writes the files to ```file_store_dir```. This is not included in this application. The idea is that most applications have different ways of implementing this component and have some associated business logic. It is not hard to come up with such a component if needed.
+* File store watcher: This component watches the ```file_store_dir``` directory on the local file system for any changes and notifies the registered listeners of the changes
+* Change log generator: This registers as a listener of the file store watcher and on each notification logs the changes into a file under ```change_log_dir```
-####Slave
-* File server: This component on the slave will only support reads.
-* Cluster state observer: Slave observes the cluster state and is able to know who is the current master.
+#### Slave
+* File server: This component on the slave will only support reads
+* Cluster state observer: Slave observes the cluster state and is able to know who is the current master
* Replicator: This has two subcomponents
- Periodic rsync of change log: This is a background process that periodically rsyncs the ```change_log_dir``` of the master to its local directory
- Change Log Watcher: This watches the ```change_log_dir``` for changes and notifies the registered listeners of the change
- - On demand rsync invoker: This is registered as a listener to change log watcher and on every change invokes rsync to sync only the changed file.
-
+ - On demand rsync invoker: This is registered as a listener to change log watcher and on every change invokes rsync to sync only the changed file
#### Coordination
The coordination between nodes is done by Helix. Helix does the partition management and assigns the partition to multiple nodes based on the replication factor. It elects one the nodes as master and designates others as slaves.
-It provides notifications to each node in the form of state transitions ( Offline to Slave, Slave to Master). It also provides notification when there is change is cluster state.
-This allows the slave to stop replicating from current master and start replicating from new master.
+It provides notifications to each node in the form of state transitions (Offline to Slave, Slave to Master). It also provides notifications when there is change is cluster state.
+This allows the slave to stop replicating from current master and start replicating from new master.
-In this application, we have only one partition but its very easy to extend it to support multiple partitions. By partitioning the file store, one can add new nodes and Helix will automatically
+In this application, we have only one partition but its very easy to extend it to support multiple partitions. By partitioning the file store, one can add new nodes and Helix will automatically
re-distribute partitions among the nodes. To summarize, Helix provides partition management, fault tolerance and facilitates automated cluster expansion.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/recipes/service_discovery.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/recipes/service_discovery.md b/site-releases/0.6.1-incubating/src/site/markdown/recipes/service_discovery.md
index 8e06ead..6ece922 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/recipes/service_discovery.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/recipes/service_discovery.md
@@ -19,95 +19,90 @@ under the License.
Service Discovery
-----------------
-One of the common usage of zookeeper is enable service discovery.
-The basic idea is that when a server starts up it advertises its configuration/metadata such as host name port etc on zookeeper.
-This allows clients to dynamically discover the servers that are currently active. One can think of this like a service registry to which a server registers when it starts and
-is automatically deregistered when it shutdowns or crashes. In many cases it serves as an alternative to vips.
+One of the common usage of ZooKeeper is to enable service discovery.
+The basic idea is that when a server starts up it advertises its configuration/metadata such as its hostname and port on ZooKeeper.
+This allows clients to dynamically discover the servers that are currently active. One can think of this like a service registry to which a server registers when it starts and
+is automatically deregistered when it shutdowns or crashes. In many cases it serves as an alternative to VIPs.
-The core idea behind this is to use zookeeper ephemeral nodes. The ephemeral nodes are created when the server registers and all its metadata is put into a znode.
-When the server shutdowns, zookeeper automatically removes this znode.
+The core idea behind this is to use ZooKeeper ephemeral nodes. The ephemeral nodes are created when the server registers and all its metadata is put into a ZNode.
+When the server shutdowns, ZooKeeper automatically removes this ZNode.
-There are two ways the clients can dynamically discover the active servers
+There are two ways the clients can dynamically discover the active servers:
-#### ZOOKEEPER WATCH
+### ZooKeeper Watch
-Clients can set a child watch under specific path on zookeeper.
-When a new service is registered/deregistered, zookeeper notifies the client via watchevent and the client can read the list of services. Even though this looks trivial,
-there are lot of things one needs to keep in mind like ensuring that you first set the watch back on zookeeper before reading data from zookeeper.
+Clients can set a child watch under specific path on ZooKeeper.
+When a new service is registered/deregistered, ZooKeeper notifies the client via a watch event and the client can read the list of services. Even though this looks trivial,
+there are lot of things one needs to keep in mind like ensuring that you first set the watch back on ZooKeeper before reading data.
-#### POLL
+### Poll
-Another approach is for the client to periodically read the zookeeper path and get the list of services.
+Another approach is for the client to periodically read the ZooKeeper path and get the list of services.
+Both approaches have pros and cons, for example setting a watch might trigger herd effect if there are large number of clients. This is problematic, especially when servers are starting up.
+But the advantage to setting watches is that clients are immediately notified of a change which is not true in case of polling.
+In some cases, having both watches and polls makes sense; watch allows one to get notifications as soon as possible while poll provides a safety net if a watch event is missed because of code bug or ZooKeeper fails to notify.
-Both approaches have pros and cons, for example setting a watch might trigger herd effect if there are large number of clients. This is worst especially when servers are starting up.
-But good thing about setting watch is that clients are immediately notified of a change which is not true in case of polling.
-In some cases, having both WATCH and POLL makes sense, WATCH allows one to get notifications as soon as possible while POLL provides a safety net if a watch event is missed because of code bug or zookeeper fails to notify.
+### Other Developer Considerations
+* What happens when the ZooKeeper session expires? All the watches and ephemeral nodes previously added or created by this server are lost. One needs to add the watches again, recreate the ephemeral nodes, and so on.
+* Due to network issues or Java GC pauses session expiry might happen again and again; this phenomenon is known as flapping. It\'s important for the server to detect this and deregister itself.
-##### Other important scenarios to take care of
-* What happens when zookeeper session expires. All the watches/ephemeral nodes previously added/created by this server are lost.
-One needs to add the watches again , recreate the ephemeral nodes etc.
-* Due to network issues or java GC pauses session expiry might happen again and again also known as flapping. Its important for the server to detect this and deregister itself.
+### Other Operational Considerations
+* What if the node is behaving badly? One might kill the server, but it will lose the ability to debug. It would be nice to have the ability to mark a server as disabled and clients know that a node is disabled and will not contact that node.
-##### Other operational things to consider
-* What if the node is behaving badly, one might kill the server but will lose the ability to debug.
-It would be nice to have the ability to mark a server as disabled and clients know that a node is disabled and will not contact that node.
-
-#### Configuration ownership
+### Configuration Ownership
-This is an important aspect that is often ignored in the initial stages of your development. In common, service discovery pattern means that servers start up with some configuration and then simply puts its configuration/metadata in zookeeper. While this works well in the beginning,
-configuration management becomes very difficult since the servers themselves are statically configured. Any change in server configuration implies restarting of the server. Ideally, it will be nice to have the ability to change configuration dynamically without having to restart a server.
+This is an important aspect that is often ignored in the initial stages of your development. Typically, the service discovery pattern means that servers start up with some configuration which it simply puts into ZooKeeper. While this works well in the beginning, configuration management becomes very difficult since the servers themselves are statically configured. Any change in server configuration implies restarting the server. Ideally, it will be nice to have the ability to change configuration dynamically without having to restart a server.
-Ideally you want a hybrid solution, a node starts with minimal configuration and gets the rest of configuration from zookeeper.
+Ideally you want a hybrid solution, a node starts with minimal configuration and gets the rest of configuration from ZooKeeper.
-h3. How to use Helix to achieve this
+### Using Helix for Service Discovery
-Even though Helix has higher level abstraction in terms of statemachine, constraints and objectives,
-service discovery is one of things that existed since we started.
-The controller uses the exact mechanism we described above to discover when new servers join the cluster.
-We create these znodes under /CLUSTERNAME/LIVEINSTANCES.
-Since at any time there is only one controller, we use ZK watch to track the liveness of a server.
+Even though Helix has a higher-level abstraction in terms of state machines, constraints and objectives, service discovery is one of things has been a prevalent use case from the start.
+The controller uses the exact mechanism we described above to discover when new servers join the cluster. We create these ZNodes under /CLUSTERNAME/LIVEINSTANCES.
+Since at any time there is only one controller, we use a ZK watch to track the liveness of a server.
-This recipe, simply demonstrate how one can re-use that part for implementing service discovery. This demonstrates multiple MODE's of service discovery
+This recipe simply demonstrates how one can re-use that part for implementing service discovery. This demonstrates multiple modes of service discovery:
* POLL: The client reads from zookeeper at regular intervals 30 seconds. Use this if you have 100's of clients
-* WATCH: The client sets up watcher and gets notified of the changes. Use this if you have 10's of clients.
-* NONE: This does neither of the above, but reads directly from zookeeper when ever needed.
+* WATCH: The client sets up watcher and gets notified of the changes. Use this if you have 10's of clients
+* NONE: This does neither of the above, but reads directly from zookeeper when ever needed
-Helix provides these additional features compared to other implementations available else where
+Helix provides these additional features compared to other implementations available elsewhere:
-* It has the concept of disabling a node which means that a badly behaving node, can be disabled using helix admin api.
-* It automatically detects if a node connects/disconnects from zookeeper repeatedly and disables the node.
-* Configuration management
- * Allows one to set configuration via admin api at various granulaties like cluster, instance, resource, partition
- * Configuration can be dynamically changed.
- * Notifies the server when configuration changes.
+* It has the concept of disabling a node which means that a badly behaving node can be disabled using the Helix admin API
+* It automatically detects if a node connects/disconnects from zookeeper repeatedly and disables the node
+* Configuration management
+ * Allows one to set configuration via the admin API at various granulaties like cluster, instance, resource, partition
+ * Configurations can be dynamically changed
+ * The server is notified when configurations change
-##### checkout and build
+### Checkout and Build
```
git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
cd incubator-helix
+git checkout tags/helix-0.6.1-incubating
mvn clean install package -DskipTests
cd recipes/service-discovery/target/service-discovery-pkg/bin
chmod +x *
```
-##### start zookeeper
+### Start ZooKeeper
```
./start-standalone-zookeeper 2199
```
-#### Run the demo
+### Run the Demo
```
./service-discovery-demo.sh
```
-#### Output
+### Output
```
START:Service discovery demo mode:WATCH
@@ -186,6 +181,4 @@ START:Service discovery demo mode:NONE
Registering service:host.x.y.z_12000
END:Service discovery demo mode:NONE
=============================================
-
```
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/recipes/task_dag_execution.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/recipes/task_dag_execution.md b/site-releases/0.6.1-incubating/src/site/markdown/recipes/task_dag_execution.md
index f0474e4..4a38028 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/recipes/task_dag_execution.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/recipes/task_dag_execution.md
@@ -17,20 +17,18 @@ specific language governing permissions and limitations
under the License.
-->
-# Distributed task execution
+Distributed Task Execution
+--------------------------
-
-This recipe is intended to demonstrate how task dependencies can be modeled using primitives provided by Helix. A given task can be run with desired parallelism and will start only when up-stream dependencies are met. The demo executes the task DAG described below using 10 workers. Although the demo starts the workers as threads, there is no requirement that all the workers need to run in the same process. In reality, these workers run on many different boxes on a cluster. When worker fails, Helix takes care of
-re-assigning a failed task partition to a new worker.
+This recipe is intended to demonstrate how task dependencies can be modeled using primitives provided by Helix. A given task can be run with the desired amount of parallelism and will start only when upstream dependencies are met. The demo executes the task DAG described below using 10 workers. Although the demo starts the workers as threads, there is no requirement that all the workers need to run in the same process. In reality, these workers run on many different boxes on a cluster. When worker fails, Helix takes care of re-assigning a failed task partition to a new worker.
Redis is used as a result store. Any other suitable implementation for TaskResultStore can be plugged in.
-### Workflow
-
+### Workflow
-#### Input
+#### Input
-10000 impression events and around 100 click events are pre-populated in task result store (redis).
+10000 impression events and around 100 click events are pre-populated in task result store (redis).
* **ImpEvent**: format: id,isFraudulent,country,gender
@@ -55,45 +53,45 @@ Redis is used as a result store. Any other suitable implementation for TaskResul
+ **report**: Reads from all aggregates generated by previous stages and prints them. Depends on: **impCountsByGender, impCountsByCountry, clickCountsByGender,clickCountsByGender**
-### Creating DAG
+### Creating a DAG
-Each stage is represented as a Node along with the upstream dependency and desired parallelism. Each stage is modelled as a resource in Helix using OnlineOffline state model. As part of Offline to Online transition, we watch the external view of upstream resources and wait for them to transition to online state. See Task.java for additional info.
+Each stage is represented as a Node along with the upstream dependency and desired parallelism. Each stage is modeled as a resource in Helix using OnlineOffline state model. As part of an Offline to Online transition, we watch the external view of upstream resources and wait for them to transition to the online state. See Task.java for additional info.
```
-
- Dag dag = new Dag();
- dag.addNode(new Node("filterImps", 10, ""));
- dag.addNode(new Node("filterClicks", 5, ""));
- dag.addNode(new Node("impClickJoin", 10, "filterImps,filterClicks"));
- dag.addNode(new Node("impCountsByGender", 10, "filterImps"));
- dag.addNode(new Node("impCountsByCountry", 10, "filterImps"));
- dag.addNode(new Node("clickCountsByGender", 5, "impClickJoin"));
- dag.addNode(new Node("clickCountsByCountry", 5, "impClickJoin"));
- dag.addNode(new Node("report",1,"impCountsByGender,impCountsByCountry,clickCountsByGender,clickCountsByCountry"));
-
-
+Dag dag = new Dag();
+dag.addNode(new Node("filterImps", 10, ""));
+dag.addNode(new Node("filterClicks", 5, ""));
+dag.addNode(new Node("impClickJoin", 10, "filterImps,filterClicks"));
+dag.addNode(new Node("impCountsByGender", 10, "filterImps"));
+dag.addNode(new Node("impCountsByCountry", 10, "filterImps"));
+dag.addNode(new Node("clickCountsByGender", 5, "impClickJoin"));
+dag.addNode(new Node("clickCountsByCountry", 5, "impClickJoin"));
+dag.addNode(new Node("report",1,"impCountsByGender,impCountsByCountry,clickCountsByGender,clickCountsByCountry"));
```
-### DEMO
+### Demo
In order to run the demo, use the following steps
See http://redis.io/topics/quickstart on how to install redis server
```
-
Start redis e.g:
./redis-server --port 6379
git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
+cd incubator-helix
+git checkout helix-0.6.1-incubating
cd recipes/task-execution
mvn clean install package -DskipTests
cd target/task-execution-pkg/bin
chmod +x task-execution-demo.sh
-./task-execution-demo.sh 2181 localhost 6379
+./task-execution-demo.sh 2181 localhost 6379
```
+Here\'s a visual representation of the DAG.
+
```
@@ -130,7 +128,7 @@ chmod +x task-execution-demo.sh
(credit for above ascii art: http://www.asciiflow.com)
-### OUTPUT
+#### Output
```
Done populating dummy data
@@ -198,7 +196,4 @@ Impression counts per gender
{F=3325, UNKNOWN=3259, M=3296}
Click counts per gender
{F=33, UNKNOWN=32, M=35}
-
-
```
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_admin.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_admin.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_admin.md
index 57f34fc..a06b868 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_admin.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_admin.md
@@ -17,11 +17,12 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Admin Operations
+Helix Tutorial: Admin Operations
+--------------------------------
Helix provides interfaces for the operator to administer the cluster. For convenience, there is a command line interface as well as a REST interface.
-### Helix Admin operations
+### Helix Admin Operations
First, make sure you get to the command-line tool, or include it in your shell PATH.
@@ -41,127 +42,125 @@ All other commands have this form:
./helix-admin.sh --zkSvr <ZookeeperServerAddress (Required)> <command> <parameters>
```
-Now, here are the admin commands:
+### Commands
Add a new cluster
```
- --addCluster <clusterName>
+--addCluster <clusterName>
```
Add a new Instance to a cluster
```
- --addNode <clusterName> <InstanceAddress (host:port)>
+--addNode <clusterName> <InstanceAddress (host:port)>
```
Add a State model to a cluster
-_WE NEED A SPEC FOR A VALID STATE MODEL_
```
- --addStateModelDef <clusterName> <filename>>
+--addStateModelDef <clusterName> <filename>
```
Add a resource to a cluster
```
- --addResource <clusterName> <resourceName> <partitionNum> <stateModelRef> <mode (AUTO_REBALANCE|AUTO|CUSTOM)>
+--addResource <clusterName> <resourceName> <partitionNum> <stateModelRef> <mode (AUTO_REBALANCE|AUTO|CUSTOMIZED)>
```
Upload an IdealState (Partition to Node Mapping)
-_WE NEED A SPEC FOR A VALID IDEAL STATE_
```
- --addIdealState <clusterName> <resourceName> <filename>
+--addIdealState <clusterName> <resourceName> <filename>
```
Delete a cluster
```
- --dropCluster <clusterName>
+--dropCluster <clusterName>
```
Delete a resource (drop an existing resource from a cluster)
```
- --dropResource <clusterName> <resourceName>
+--dropResource <clusterName> <resourceName>
```
Drop an existing instance from a cluster
```
- --dropNode <clusterName> <InstanceAddress (host:port)>
+--dropNode <clusterName> <InstanceAddress (host:port)>
```
-Enable/disable the entire cluster. This will pause the controller, which means no transitions will be trigger, but the existing nodes in the cluster continue to function, but without any management by the controller.
+Enable/disable the entire cluster. This will pause the controller, which means no transitions will be triggered, but the existing nodes in the cluster continue to function without any management by the controller.
```
- --enableCluster <clusterName> <true/false>
+--enableCluster <clusterName> <true/false>
```
-Enable/disable an instance. Useful to take a node out of the cluster for maintenance/upgrade.
+Enable/disable an instance. This is useful to take a node out of the cluster for maintenance/upgrade.
```
- --enableInstance <clusterName> <InstanceName> <true/false>
+--enableInstance <clusterName> <InstanceName> <true/false>
```
Enable/disable a partition
```
- --enablePartition <clusterName> <instanceName> <resourceName> <partitionName> <true/false>
+--enablePartition <clusterName> <instanceName> <resourceName> <partitionName> <true/false>
```
-Query info of a cluster
+Query information about a cluster
```
- --listClusterInfo <clusterName>
+--listClusterInfo <clusterName>
```
List existing clusters (remember, Helix can manage multiple clusters)
```
- --listClusters
+--listClusters
```
-Query info of a single Instance in a cluster
+Query info of a single instance in a cluster
```
- --listInstanceInfo <clusterName> <InstanceName>
+--listInstanceInfo <clusterName> <InstanceName>
```
List instances in a cluster
```
- --listInstances <clusterName>
+--listInstances <clusterName>
```
-Query info of a partition
+Query information about a partition
```
- --listPartitionInfo <clusterName> <resourceName> <partitionName>
+--listPartitionInfo <clusterName> <resourceName> <partitionName>
```
-Query info of a resource
+Query information about a resource
```
- --listResourceInfo <clusterName> <resourceName>
+--listResourceInfo <clusterName> <resourceName>
```
List resources hosted in a cluster
```
- --listResources <clusterName>
+--listResources <clusterName>
```
-Query info of a state model in a cluster
+Query information about a state model in a cluster
```
- --listStateModel <clusterName> <stateModelName>
+--listStateModel <clusterName> <stateModelName>
```
-Query info of state models in a cluster
+Query information about state models in a cluster
```
- --listStateModels <clusterName>
+--listStateModels <clusterName>
```
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_controller.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_controller.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_controller.md
index 17cd532..012d99a 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_controller.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_controller.md
@@ -17,29 +17,29 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Controller
+Helix Tutorial: Controller
+--------------------------
Next, let\'s implement the controller. This is the brain of the cluster. Helix makes sure there is exactly one active controller running the cluster.
-### Start the Helix agent
+### Start a Connection
+The Helix manager requires the following parameters:
-It requires the following parameters:
-
* clusterName: A logical name to represent the group of nodes
-* instanceName: A logical name of the process creating the manager instance. Generally this is host:port.
+* instanceName: A logical name of the process creating the manager instance. Generally this is host:port
* instanceType: Type of the process. This can be one of the following types, in this case use CONTROLLER:
- * CONTROLLER: Process that controls the cluster, any number of controllers can be started but only one will be active at any given time.
- * PARTICIPANT: Process that performs the actual task in the distributed system.
- * SPECTATOR: Process that observes the changes in the cluster.
- * ADMIN: To carry out system admin actions.
-* zkConnectString: Connection string to Zookeeper. This is of the form host1:port1,host2:port2,host3:port3.
+ * CONTROLLER: Process that controls the cluster, any number of controllers can be started but only one will be active at any given time
+ * PARTICIPANT: Process that performs the actual task in the distributed system
+ * SPECTATOR: Process that observes the changes in the cluster
+ * ADMIN: To carry out system admin actions
+* zkConnectString: Connection string to ZooKeeper. This is of the form host1:port1,host2:port2,host3:port3
```
- manager = HelixManagerFactory.getZKHelixManager(clusterName,
- instanceName,
- instanceType,
- zkConnectString);
+manager = HelixManagerFactory.getZKHelixManager(clusterName,
+ instanceName,
+ instanceType,
+ zkConnectString);
```
### Controller Code
@@ -48,26 +48,26 @@ The Controller needs to know about all changes in the cluster. Helix takes care
If you need additional functionality, see GenericHelixController on how to configure the pipeline.
```
- manager = HelixManagerFactory.getZKHelixManager(clusterName,
- instanceName,
- InstanceType.CONTROLLER,
- zkConnectString);
- manager.connect();
- GenericHelixController controller = new GenericHelixController();
- manager.addConfigChangeListener(controller);
- manager.addLiveInstanceChangeListener(controller);
- manager.addIdealStateChangeListener(controller);
- manager.addExternalViewChangeListener(controller);
- manager.addControllerListener(controller);
+manager = HelixManagerFactory.getZKHelixManager(clusterName,
+ instanceName,
+ InstanceType.CONTROLLER,
+ zkConnectString);
+manager.connect();
+GenericHelixController controller = new GenericHelixController();
+manager.addConfigChangeListener(controller);
+manager.addLiveInstanceChangeListener(controller);
+manager.addIdealStateChangeListener(controller);
+manager.addExternalViewChangeListener(controller);
+manager.addControllerListener(controller);
```
The snippet above shows how the controller is started. You can also start the controller using command line interface.
-
+
```
cd helix/helix-core/target/helix-core-pkg/bin
./run-helix-controller.sh --zkSvr <Zookeeper ServerAddress (Required)> --cluster <Cluster name (Required)>
```
-### Controller deployment modes
+### Controller Deployment Modes
Helix provides multiple options to deploy the controller.
@@ -75,7 +75,7 @@ Helix provides multiple options to deploy the controller.
The Controller can be started as a separate process to manage a cluster. This is the recommended approach. However, since one controller can be a single point of failure, multiple controller processes are required for reliability. Even if multiple controllers are running, only one will be actively managing the cluster at any time and is decided by a leader-election process. If the leader fails, another leader will take over managing the cluster.
-Even though we recommend this method of deployment, it has the drawback of having to manage an additional service for each cluster. See Controller As a Service option.
+Even though we recommend this method of deployment, it has the drawback of having to manage an additional service for each cluster. See the Controller as a Service option.
#### EMBEDDED
@@ -83,8 +83,7 @@ If setting up a separate controller process is not viable, then it is possible t
#### CONTROLLER AS A SERVICE
-One of the cool feature we added in Helix was to use a set of controllers to manage a large number of clusters.
+One of the cool features we added in Helix was to use a set of controllers to manage a large number of clusters.
For example if you have X clusters to be managed, instead of deploying X*3 (3 controllers for fault tolerance) controllers for each cluster, one can deploy just 3 controllers. Each controller can manage X/3 clusters. If any controller fails, the remaining two will manage X/2 clusters.
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_health.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_health.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_health.md
index ae29436..96a7726 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_health.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_health.md
@@ -17,15 +17,16 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Customizing Health Checks
+Helix Tutorial: Customizing Health Checks
+-----------------------------------------
-In this chapter, we\'ll learn how to customize the health check, based on metrics of your distributed system.
+In this chapter, we\'ll learn how to customize the health check, based on metrics of your distributed system.
### Health Checks
-Note: _this in currently in development mode, not yet ready for production._
+Note: _this in currently in development mode, not yet ready for production_
-Helix provides the ability for each node in the system to report health metrics on a periodic basis.
+Helix provides the ability for each node in the system to report health metrics on a periodic basis.
Helix supports multiple ways to aggregate these metrics:
@@ -36,7 +37,7 @@ Helix supports multiple ways to aggregate these metrics:
Helix persists the aggregated value only.
-Applications can define a threshold on the aggregate values according to the SLAs, and when the SLA is violated Helix will fire an alert.
+Applications can define a threshold on the aggregate values according to the SLAs, and when the SLA is violated Helix will fire an alert.
Currently Helix only fires an alert, but in a future release we plan to use these metrics to either mark the node dead or load balance the partitions.
This feature will be valuable for distributed systems that support multi-tenancy and have a large variation in work load patterns. In addition, this can be used to detect skewed partitions (hotspots) and rebalance the cluster.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
index 4b46671..589f321 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
@@ -17,51 +17,52 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Messaging
+Helix Tutorial: Messaging
+-------------------------
-In this chapter, we\'ll learn about messaging, a convenient feature in Helix for sending messages between nodes of a cluster. This is an interesting feature which is quite useful in practice. It is common that nodes in a distributed system require a mechanism to interact with each other.
+In this chapter, we\'ll learn about messaging, a convenient feature in Helix for sending messages between nodes of a cluster. This is an interesting feature that is quite useful in practice. It is common that nodes in a distributed system require a mechanism to interact with each other.
### Example: Bootstrapping a Replica
Consider a search system where the index replica starts up and it does not have an index. A typical solution is to get the index from a common location, or to copy the index from another replica.
-Helix provides a messaging api for intra-cluster communication between nodes in the system. Helix provides a mechanism to specify the message recipient in terms of resource, partition, and state rather than specifying hostnames. Helix ensures that the message is delivered to all of the required recipients. In this particular use case, the instance can specify the recipient criteria as all replicas of the desired partition to bootstrap.
-Since Helix is aware of the global state of the system, it can send the message to appropriate nodes. Once the nodes respond, Helix provides the bootstrapping replica with all the responses.
+Helix provides a messaging API for intra-cluster communication between nodes in the system. This API provides a mechanism to specify the message recipient in terms of resource, partition, and state rather than specifying hostnames. Helix ensures that the message is delivered to all of the required recipients. In this particular use case, the instance can specify the recipient criteria as all replicas of the desired partition to bootstrap.
+Since Helix is aware of the global state of the system, it can send the message to the appropriate nodes. Once the nodes respond, Helix provides the bootstrapping replica with all the responses.
-This is a very generic api and can also be used to schedule various periodic tasks in the cluster, such as data backups, log cleanup, etc.
+This is a very generic API and can also be used to schedule various periodic tasks in the cluster, such as data backups, log cleanup, etc.
System Admins can also perform ad-hoc tasks, such as on-demand backups or a system command (such as rm -rf ;) across all nodes of the cluster
```
- ClusterMessagingService messagingService = manager.getMessagingService();
-
- // Construct the Message
- Message requestBackupUriRequest = new Message(
- MessageType.USER_DEFINE_MSG, UUID.randomUUID().toString());
- requestBackupUriRequest
- .setMsgSubType(BootstrapProcess.REQUEST_BOOTSTRAP_URL);
- requestBackupUriRequest.setMsgState(MessageState.NEW);
-
- // Set the Recipient criteria: all nodes that satisfy the criteria will receive the message
- Criteria recipientCriteria = new Criteria();
- recipientCriteria.setInstanceName("%");
- recipientCriteria.setRecipientInstanceType(InstanceType.PARTICIPANT);
- recipientCriteria.setResource("MyDB");
- recipientCriteria.setPartition("");
-
- // Should be processed only by process(es) that are active at the time of sending the message
- // This means if the recipient is restarted after message is sent, it will not be processe.
- recipientCriteria.setSessionSpecific(true);
-
- // wait for 30 seconds
- int timeout = 30000;
-
- // the handler that will be invoked when any recipient responds to the message.
- BootstrapReplyHandler responseHandler = new BootstrapReplyHandler();
-
- // this will return only after all recipients respond or after timeout
- int sentMessageCount = messagingService.sendAndWait(recipientCriteria,
- requestBackupUriRequest, responseHandler, timeout);
+ClusterMessagingService messagingService = manager.getMessagingService();
+
+// Construct the Message
+Message requestBackupUriRequest = new Message(
+ MessageType.USER_DEFINE_MSG, UUID.randomUUID().toString());
+requestBackupUriRequest
+ .setMsgSubType(BootstrapProcess.REQUEST_BOOTSTRAP_URL);
+requestBackupUriRequest.setMsgState(MessageState.NEW);
+
+// Set the Recipient criteria: all nodes that satisfy the criteria will receive the message
+Criteria recipientCriteria = new Criteria();
+recipientCriteria.setInstanceName("%");
+recipientCriteria.setRecipientInstanceType(InstanceType.PARTICIPANT);
+recipientCriteria.setResource("MyDB");
+recipientCriteria.setPartition("");
+
+// Should be processed only by process(es) that are active at the time of sending the message
+// This means if the recipient is restarted after message is sent, it will not be processe.
+recipientCriteria.setSessionSpecific(true);
+
+// wait for 30 seconds
+int timeout = 30000;
+
+// the handler that will be invoked when any recipient responds to the message.
+BootstrapReplyHandler responseHandler = new BootstrapReplyHandler();
+
+// this will return only after all recipients respond or after timeout
+int sentMessageCount = messagingService.sendAndWait(recipientCriteria,
+ requestBackupUriRequest, responseHandler, timeout);
```
-See HelixManager.DefaultMessagingService in [Javadocs](http://helix.incubator.apache.org/javadocs/0.6.1-incubating/reference/org/apache/helix/messaging/DefaultMessagingService.html) for more info.
+See HelixManager.DefaultMessagingService in the [Javadocs](http://helix.incubator.apache.org/javadocs/0.6.1-incubating/reference/org/apache/helix/messaging/DefaultMessagingService.html) for more information.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_participant.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_participant.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_participant.md
index 19e6f98..384dfda 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_participant.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_participant.md
@@ -17,28 +17,29 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Participant
+Helix Tutorial: Participant
+---------------------------
-In this chapter, we\'ll learn how to implement a PARTICIPANT, which is a primary functional component of a distributed system.
+In this chapter, we\'ll learn how to implement a __Participant__, which is a primary functional component of a distributed system.
-### Start the Helix agent
+### Start a Connection
-The Helix agent is a common component that connects each system component with the controller.
+The Helix manager is a common component that connects each system component with the controller.
It requires the following parameters:
-
+
* clusterName: A logical name to represent the group of nodes
-* instanceName: A logical name of the process creating the manager instance. Generally this is host:port.
+* instanceName: A logical name of the process creating the manager instance. Generally this is host:port
* instanceType: Type of the process. This can be one of the following types, in this case, use PARTICIPANT
- * CONTROLLER: Process that controls the cluster, any number of controllers can be started but only one will be active at any given time.
- * PARTICIPANT: Process that performs the actual task in the distributed system.
- * SPECTATOR: Process that observes the changes in the cluster.
- * ADMIN: To carry out system admin actions.
-* zkConnectString: Connection string to Zookeeper. This is of the form host1:port1,host2:port2,host3:port3.
+ * CONTROLLER: Process that controls the cluster, any number of controllers can be started but only one will be active at any given time
+ * PARTICIPANT: Process that performs the actual task in the distributed system
+ * SPECTATOR: Process that observes the changes in the cluster
+ * ADMIN: To carry out system admin actions
+* zkConnectString: Connection string to ZooKeeper. This is of the form host1:port1,host2:port2,host3:port3
-After the Helix manager instance is created, only thing that needs to be registered is the state model factory.
-The methods of the State Model will be called when controller sends transitions to the Participant. In this example, we'll use the OnlineOffline factory. Other options include:
+After the Helix manager instance is created, the only thing that needs to be registered is the state model factory.
+The methods of the state model will be called when controller sends transitions to the participant. In this example, we'll use the OnlineOffline factory. Other options include:
* MasterSlaveStateModelFactory
* LeaderStandbyStateModelFactory
@@ -46,55 +47,54 @@ The methods of the State Model will be called when controller sends transitions
```
- manager = HelixManagerFactory.getZKHelixManager(clusterName,
- instanceName,
- InstanceType.PARTICIPANT,
- zkConnectString);
- StateMachineEngine stateMach = manager.getStateMachineEngine();
-
- //create a stateModelFactory that returns a statemodel object for each partition.
- stateModelFactory = new OnlineOfflineStateModelFactory();
- stateMach.registerStateModelFactory(stateModelType, stateModelFactory);
- manager.connect();
+manager = HelixManagerFactory.getZKHelixManager(clusterName,
+ instanceName,
+ InstanceType.PARTICIPANT,
+ zkConnectString);
+StateMachineEngine stateMach = manager.getStateMachineEngine();
+
+//create a stateModelFactory that returns a statemodel object for each partition.
+stateModelFactory = new OnlineOfflineStateModelFactory();
+stateMach.registerStateModelFactory(stateModelType, stateModelFactory);
+manager.connect();
```
-Helix doesn\'t know what it means to change from OFFLIN\-\-\>ONLINE or ONLINE\-\-\>OFFLINE. The following code snippet shows where you insert your system logic for these two state transitions.
+### Example State Model Factory
+
+Helix doesn\'t know what it means to change from OFFLINE\-\-\>ONLINE or ONLINE\-\-\>OFFLINE. The following code snippet shows where you insert your system logic for these two state transitions.
```
public class OnlineOfflineStateModelFactory extends
- StateModelFactory<StateModel> {
- @Override
- public StateModel createNewStateModel(String stateUnitKey) {
- OnlineOfflineStateModel stateModel = new OnlineOfflineStateModel();
- return stateModel;
+ StateModelFactory<StateModel> {
+ @Override
+ public StateModel createNewStateModel(String stateUnitKey) {
+ OnlineOfflineStateModel stateModel = new OnlineOfflineStateModel();
+ return stateModel;
+ }
+ @StateModelInfo(states = "{'OFFLINE','ONLINE'}", initialState = "OFFINE")
+ public static class OnlineOfflineStateModel extends StateModel {
+ @Transition(from = "OFFLINE", to = "ONLINE")
+ public void onBecomeOnlineFromOffline(Message message,
+ NotificationContext context) {
+ System.out.println("OnlineOfflineStateModel.onBecomeOnlineFromOffline()");
+
+ ////////////////////////////////////////////////////////////////////////////////////////////////
+ // Application logic to handle transition //
+ // For example, you might start a service, run initialization, etc //
+ ////////////////////////////////////////////////////////////////////////////////////////////////
}
- @StateModelInfo(states = "{'OFFLINE','ONLINE'}", initialState = "OFFINE")
- public static class OnlineOfflineStateModel extends StateModel {
-
- @Transition(from = "OFFLINE", to = "ONLINE")
- public void onBecomeOnlineFromOffline(Message message,
- NotificationContext context) {
-
- System.out.println("OnlineOfflineStateModel.onBecomeOnlineFromOffline()");
-
- ////////////////////////////////////////////////////////////////////////////////////////////////
- // Application logic to handle transition //
- // For example, you might start a service, run initialization, etc //
- ////////////////////////////////////////////////////////////////////////////////////////////////
- }
-
- @Transition(from = "ONLINE", to = "OFFLINE")
- public void onBecomeOfflineFromOnline(Message message,
- NotificationContext context) {
- System.out.println("OnlineOfflineStateModel.onBecomeOfflineFromOnline()");
+ @Transition(from = "ONLINE", to = "OFFLINE")
+ public void onBecomeOfflineFromOnline(Message message,
+ NotificationContext context) {
+ System.out.println("OnlineOfflineStateModel.onBecomeOfflineFromOnline()");
- ////////////////////////////////////////////////////////////////////////////////////////////////
- // Application logic to handle transition //
- // For example, you might shutdown a service, log this event, or change monitoring settings //
- ////////////////////////////////////////////////////////////////////////////////////////////////
- }
+ ////////////////////////////////////////////////////////////////////////////////////////////////
+ // Application logic to handle transition //
+ // For example, you might shutdown a service, log this event, or change monitoring settings //
+ ////////////////////////////////////////////////////////////////////////////////////////////////
}
+ }
}
```
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
index 4ee9299..50f4fab 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
@@ -17,14 +17,15 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Application Property Store
+Helix Tutorial: Application Property Store
+------------------------------------------
In this chapter, we\'ll learn how to use the application property store.
### Property Store
-It is common that an application needs support for distributed, shared data structures. Helix uses Zookeeper to store the application data and hence provides notifications when the data changes.
+It is common that an application needs support for distributed, shared data structures. Helix uses ZooKeeper to store the application data and hence provides notifications when the data changes.
-While you could use Zookeeper directly, Helix supports caching the data and a write-through cache. This is far more efficient than reading from Zookeeper for every access.
+While you could use ZooKeeper directly, Helix supports caching the data with a write-through cache. This is far more efficient than reading from ZooKeeper for every access.
See [HelixManager.getHelixPropertyStore](http://helix.incubator.apache.org/javadocs/0.6.1-incubating/reference/org/apache/helix/store/package-summary.html) for details.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/92edaabc/site-releases/0.6.1-incubating/src/site/markdown/tutorial_rebalance.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_rebalance.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_rebalance.md
index 1f5930d..0f2da4d 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_rebalance.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_rebalance.md
@@ -17,7 +17,8 @@ specific language governing permissions and limitations
under the License.
-->
-# Helix Tutorial: Rebalancing Algorithms
+Helix Tutorial: Rebalancing Algorithms
+--------------------------------------
The placement of partitions in a distributed system is essential for the reliability and scalability of the system. For example, when a node fails, it is important that the partitions hosted on that node are reallocated evenly among the remaining nodes. Consistent hashing is one such algorithm that can satisfy this guarantee. Helix provides a variant of consistent hashing based on the RUSH algorithm.
@@ -36,21 +37,21 @@ Helix has three options for rebalancing, in increasing order of customization by
* AUTO_REBALANCE
* AUTO
-* CUSTOM
+* CUSTOMIZED
```
- |AUTO REBALANCE| AUTO | CUSTOM |
- -----------------------------------------
- LOCATION | HELIX | APP | APP |
- -----------------------------------------
- STATE | HELIX | HELIX | APP |
- -----------------------------------------
+ |AUTO REBALANCE| AUTO | CUSTOMIZED |
+ ---------------------------------------------
+ LOCATION | HELIX | APP | APP |
+ ---------------------------------------------
+ STATE | HELIX | HELIX | APP |
+ ---------------------------------------------
```
### AUTO_REBALANCE
-When the idealstate mode is set to AUTO_REBALANCE, Helix controls both the location of the replica along with the state. This option is useful for applications where creation of a replica is not expensive.
+When the ideal state mode is set to AUTO_REBALANCE, Helix controls both the location of the replica along with the state. This option is useful for applications where creation of a replica is not expensive.
For example, consider this system that uses a MasterSlave state model, with 3 partitions and 2 replicas in the ideal state.
@@ -100,12 +101,12 @@ If there are 3 nodes in the cluster, then Helix will balance the masters and sla
}
```
-Another typical example is evenly distributing a group of tasks among the currently healthy processes. For example, if there are 60 tasks and 4 nodes, Helix assigns 15 tasks to each node.
-When one node fails, Helix redistributes its 15 tasks to the remaining 3 nodes, resulting in a balanced 20 tasks per node. Similarly, if a node is added, Helix re-allocates 3 tasks from each of the 4 nodes to the 5th node, resulting in a balanced distribution of 12 tasks per node..
+Another typical example is evenly distributing a group of tasks among the currently healthy processes. For example, if there are 60 tasks and 4 nodes, Helix assigns 15 tasks to each node.
+When one node fails, Helix redistributes its 15 tasks to the remaining 3 nodes, resulting in a balanced 20 tasks per node. Similarly, if a node is added, Helix re-allocates 3 tasks from each of the 4 nodes to the 5th node, resulting in a balanced distribution of 12 tasks per node.
-#### AUTO
+### AUTO
-When the application needs to control the placement of the replicas, use the AUTO idealstate mode.
+When the application needs to control the placement of the replicas, use the AUTO ideal state mode.
Example: In the ideal state below, the partition \'MyResource_0\' is constrained to be placed only on node1 or node2. The choice of _state_ is still controlled by Helix. That means MyResource_0.MASTER could be on node1 and MyResource_0.SLAVE on node2, or vice-versa but neither would be placed on node3.
@@ -130,12 +131,12 @@ Example: In the ideal state below, the partition \'MyResource_0\' is constrained
The MasterSlave state model requires that a partition has exactly one MASTER at all times, and the other replicas should be SLAVEs. In this simple example with 2 replicas per partition, there would be one MASTER and one SLAVE. Upon failover, a SLAVE has to assume mastership, and a new SLAVE will be generated.
-In this mode when node1 fails, unlike in AUTO-REBALANCE mode the partition is _not_ moved from node1 to node3. Instead, Helix will decide to change the state of MyResource_0 on node2 from SLAVE to MASTER, based on the system constraints.
+In this mode when node1 fails, unlike in AUTO_REBALANCE mode, the partition is _not_ moved from node1 to node3. Instead, Helix will decide to change the state of MyResource_0 on node2 from SLAVE to MASTER, based on the system constraints.
-#### CUSTOM
+### CUSTOMIZED
-Finally, Helix offers a third mode called CUSTOM, in which the application controls the placement _and_ state of each replica. The application needs to implement a callback interface that Helix invokes when the cluster state changes.
-Within this callback, the application can recompute the idealstate. Helix will then issue appropriate transitions such that _Idealstate_ and _Currentstate_ converges.
+Finally, Helix offers a third mode called CUSTOMIZED, in which the application controls the placement _and_ state of each replica. The application needs to implement a callback interface that Helix invokes when the cluster state changes.
+Within this callback, the application can recompute the ideal state. Helix will then issue appropriate transitions such that the _IdealState_ and _CurrentState_ converge.
Here\'s an example, again with 3 partitions, 2 replicas per partition, and the MasterSlave state model:
@@ -165,4 +166,4 @@ Here\'s an example, again with 3 partitions, 2 replicas per partition, and the M
}
```
-Suppose the current state of the system is 'MyResource_0' -> {N1:MASTER, N2:SLAVE} and the application changes the ideal state to 'MyResource_0' -> {N1:SLAVE,N2:MASTER}. While the application decides which node is MASTER and which is SLAVE, Helix will not blindly issue MASTER-->SLAVE to N1 and SLAVE-->MASTER to N2 in parallel, since that might result in a transient state where both N1 and N2 are masters, which violates the MasterSlave constraint that there is exactly one MASTER at a time. Helix will first issue MASTER-->SLAVE to N1 and after it is completed, it will issue SLAVE-->MASTER to N2.
+Suppose the current state of the system is 'MyResource_0' \-\> {N1:MASTER, N2:SLAVE} and the application changes the ideal state to 'MyResource_0' \-\> {N1:SLAVE,N2:MASTER}. While the application decides which node is MASTER and which is SLAVE, Helix will not blindly issue MASTER \-\-\> SLAVE to N1 and SLAVE \-\-\> MASTER to N2 in parallel, since that might result in a transient state where both N1 and N2 are masters, which violates the MasterSlave constraint that there is exactly one MASTER at a time. Helix will first issue MASTER \-\-\> SLAVE to N1 and after it is completed, it will issue SLAVE \-\-\> MASTER to N2.