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Posted to commits@helix.apache.org by ka...@apache.org on 2014/01/02 01:14:06 UTC
[06/31] Redesign documentation for 0.6.2, 0.7.0, and trunk
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_propstore.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_propstore.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_propstore.md
index 8e7e5b5..a681f92 100644
--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_propstore.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_propstore.md
@@ -21,14 +21,14 @@ under the License.
<title>Tutorial - Application Property Store</title>
</head>
-# [Helix Tutorial](./Tutorial.html): Application Property Store
+## [Helix Tutorial](./Tutorial.html): 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/0.6.2-incubating/reference/org/apache/helix/store/package-summary.html) for details.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_rebalance.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_rebalance.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_rebalance.md
index 8f42a5a..2e1a79b 100644
--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_rebalance.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_rebalance.md
@@ -21,7 +21,7 @@ under the License.
<title>Tutorial - Rebalancing Algorithms</title>
</head>
-# [Helix Tutorial](./Tutorial.html): Rebalancing Algorithms
+## [Helix Tutorial](./Tutorial.html): 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, among others.
@@ -55,7 +55,7 @@ Helix has four options for rebalancing, in increasing order of customization by
### FULL_AUTO
-When the rebalance mode is set to FULL_AUTO, 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 rebalance mode is set to FULL_AUTO, 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.
@@ -105,10 +105,10 @@ 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..
-#### SEMI_AUTO
+### SEMI_AUTO
When the application needs to control the placement of the replicas, use the SEMI_AUTO rebalance mode.
@@ -135,11 +135,11 @@ 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 FULL_AUTO 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 FULL_AUTO 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.
-#### CUSTOMIZED
+### CUSTOMIZED
-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.
+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 idealstate. Helix will then issue appropriate transitions such that _Idealstate_ and _Currentstate_ converges.
Here\'s an example, again with 3 partitions, 2 replicas per partition, and the MasterSlave state model:
@@ -170,12 +170,12 @@ 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.
-#### USER_DEFINED
+### USER_DEFINED
For maximum flexibility, Helix exposes an interface that can allow applications to plug in custom rebalancing logic. By providing the name of a class that implements the Rebalancer interface, Helix will automatically call the contained method whenever there is a change to the live participants in the cluster. For more, see [User-Defined Rebalancer](./tutorial_user_def_rebalancer.html).
-#### Backwards Compatibility
+### Backwards Compatibility
In previous versions, FULL_AUTO was called AUTO_REBALANCE and SEMI_AUTO was called AUTO. Furthermore, they were presented as the IDEAL_STATE_MODE. Helix supports both IDEAL_STATE_MODE and REBALANCE_MODE, but IDEAL_STATE_MODE is now deprecated and may be phased out in future versions.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_spectator.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_spectator.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_spectator.md
index 24c1cf4..e43cd6b 100644
--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_spectator.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_spectator.md
@@ -21,46 +21,46 @@ under the License.
<title>Tutorial - Spectator</title>
</head>
-# [Helix Tutorial](./Tutorial.html): Spectator
+## [Helix Tutorial](./Tutorial.html): 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.SPECTATOR,
+ 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");
////////////////////////////////////////////////////////////////////////////////////////////////
@@ -72,5 +72,4 @@ 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/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_state.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_state.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_state.md
index 4f7b1b5..856b8b3 100644
--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_state.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_state.md
@@ -21,31 +21,31 @@ under the License.
<title>Tutorial - State Machine Configuration</title>
</head>
-# [Helix Tutorial](./Tutorial.html): State Machine Configuration
+## [Helix Tutorial](./Tutorial.html): 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.
+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_.
-### MASTER-SLAVE
+#### MASTER-SLAVE
* 3 states: OFFLINE, SLAVE, MASTER
* Maximum number of masters: 1
* 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.
-### LEADER-STANDBY
+#### 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.
-## Constraints
+### Constraints
In addition to the state machine configuration, one can specify the constraints of states and transitions.
@@ -54,38 +54,40 @@ For example, one can say:
* MASTER:1
<br/>Maximum number of replicas in MASTER state at any time is 1
-* OFFLINE-SLAVE:5
+* OFFLINE-SLAVE:5
<br/>Maximum number of OFFLINE-SLAVE transitions that can happen concurrently in the system is 5 in this example.
-### Dynamic State Constraints
+#### Dynamic State Constraints
We also support two dynamic upper bounds for the number of replicas in each state:
* N: The number of replicas in the state is at most the number of live participants in the cluster
* R: The number of replicas in the state is at most the specified replica count for the partition
-### 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.
-## Special States
+### Special States
-### DROPPED
+There are a few Helix-defined states that are important to be aware of.
+
+#### DROPPED
The DROPPED state is used to signify a replica that was served by a given participant, but is no longer served. This allows Helix and its participants to effectively clean up. There are two requirements that every new state model should follow with respect to the DROPPED state:
* The DROPPED state must be defined
* There must be a path to DROPPED for every state in the model
-### ERROR
+#### ERROR
The ERROR state is used whenever the participant serving a partition encountered an error and cannot continue to serve the partition. HelixAdmin has \"reset\" functionality to allow for participants to recover from the ERROR state.
-## Annotated Example
+### Annotated Example
Below is a complete definition of a Master-Slave state model. Notice the fields marked REQUIRED; these are essential for any state model definition.
@@ -127,5 +129,3 @@ StateModelDefinition stateModel = new StateModelDefinition.Builder("MasterSlave"
// Use the isValid() function to make sure the StateModelDefinition will work without issues
Assert.assertTrue(stateModel.isValid());
```
-
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_throttling.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_throttling.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_throttling.md
index 2317cf1..16a6f81 100644
--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_throttling.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_throttling.md
@@ -21,13 +21,13 @@ under the License.
<title>Tutorial - Throttling</title>
</head>
-# [Helix Tutorial](./Tutorial.html): Throttling
+## [Helix Tutorial](./Tutorial.html): 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:
@@ -36,3 +36,4 @@ Helix allows applications to set a threshold on transitions. The threshold can b
* Resource e.g database
* Node i.e per-node maximum transitions in parallel
+
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_user_def_rebalancer.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_user_def_rebalancer.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_user_def_rebalancer.md
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--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_user_def_rebalancer.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_user_def_rebalancer.md
@@ -21,7 +21,7 @@ under the License.
<title>Tutorial - User-Defined Rebalancing</title>
</head>
-# [Helix Tutorial](./Tutorial.html): User-Defined Rebalancing
+## [Helix Tutorial](./Tutorial.html): User-Defined Rebalancing
Even though Helix can compute both the location and the state of replicas internally using a default fully-automatic rebalancer, specific applications may require rebalancing strategies that optimize for different requirements. Thus, Helix allows applications to plug in arbitrary rebalancer algorithms that implement a provided interface. One of the main design goals of Helix is to provide maximum flexibility to any distributed application. Thus, it allows applications to fully implement the rebalancer, which is the core constraint solver in the system, if the application developer so chooses.
@@ -53,7 +53,7 @@ There are two key fields to set to specify that a pluggable rebalancer should be
### Example
-In the next release (0.7.0), we will provide a full example of a user-defined rebalancer in action.
+In the next release (0.7.0), we will provide a full recipe of a user-defined rebalancer in action.
Consider the case where partitions are locks in a lock manager and 6 locks are to be distributed evenly to a set of participants, and only one participant can hold each lock. We can define a rebalancing algorithm that simply takes the modulus of the lock number and the number of participants to evenly distribute the locks across participants. Helix allows capping the number of partitions a participant can accept, but since locks are lightweight, we do not need to define a restriction in this case. The following is a succinct implementation of this algorithm.
@@ -169,4 +169,4 @@ The rebalancer was invoked once again and the resulting IdealState preference li
### Caveats
- The rebalancer class must be available at runtime, or else Helix will not attempt to rebalance at all
- The Helix controller will only take into account the preference lists in the new IdealState for this release. In 0.7.0, Helix rebalancers will be able to compute the full resource assignment, including the states.
-- Helix does not currently persist the new IdealState computed by the user-defined rebalancer. However, the Helix property store is available for saving any computed state. In 0.7.0, Helix will persist the result of running the rebalancer.
\ No newline at end of file
+- Helix does not currently persist the new IdealState computed by the user-defined rebalancer. However, the Helix property store is available for saving any computed state. In 0.7.0, Helix will persist the result of running the rebalancer.
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/markdown/tutorial_yaml.md
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diff --git a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_yaml.md b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_yaml.md
index 0f8e0cc..4660afa 100644
--- a/site-releases/0.6.2-incubating/src/site/markdown/tutorial_yaml.md
+++ b/site-releases/0.6.2-incubating/src/site/markdown/tutorial_yaml.md
@@ -21,7 +21,7 @@ under the License.
<title>Tutorial - YAML Cluster Setup</title>
</head>
-# [Helix Tutorial](./Tutorial.html): YAML Cluster Setup
+## [Helix Tutorial](./Tutorial.html): YAML Cluster Setup
As an alternative to using Helix Admin to set up the cluster, its resources, constraints, and the state model, Helix supports bootstrapping a cluster configuration based on a YAML file. Below is an annotated example of such a file for a simple distributed lock manager where a lock can only be LOCKED or RELEASED, and each lock only allows a single participant to hold it in the LOCKED state.
@@ -99,4 +99,4 @@ Some notes:
- A rebalancer class is only required for the USER_DEFINED mode. It is ignored otherwise.
-- Built-in state models, like OnlineOffline, LeaderStandby, and MasterSlave, or state models that have already been added only require a name for stateModel. If partition and/or replica counts are not provided, a value of 1 is assumed.
\ No newline at end of file
+- Built-in state models, like OnlineOffline, LeaderStandby, and MasterSlave, or state models that have already been added only require a name for stateModel. If partition and/or replica counts are not provided, a value of 1 is assumed.
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http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/resources/images/system.png
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/src/site/resources/images/system.png b/site-releases/0.6.2-incubating/src/site/resources/images/system.png
deleted file mode 100644
index f8a05c8..0000000
Binary files a/site-releases/0.6.2-incubating/src/site/resources/images/system.png and /dev/null differ
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.6.2-incubating/src/site/site.xml
----------------------------------------------------------------------
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 b1bacd9..5151dff 100644
--- a/site-releases/0.6.2-incubating/src/site/site.xml
+++ b/site-releases/0.6.2-incubating/src/site/site.xml
@@ -17,12 +17,12 @@
-->
<project name="Apache Helix">
<bannerLeft>
- <src>images/helix-logo.jpg</src>
- <href>http://helix.incubator.apache.org/site-releases/0.6.2-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"/>
@@ -58,27 +58,28 @@
<item name="Release 0.6.2-incubating" href="http://helix.incubator.apache.org/site-releases/0.6.2-incubating-site/"/>
</breadcrumbs>
- <menu name="Apache Helix">
- <item name="Home" href="../../index.html"/>
+ <links>
+ <item name="Helix 0.6.2-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-0.6.2-incubating.html"/>
</menu>
- <menu name="Helix 0.6.2-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-0.6.2-incubating.html"/>
- <item name="Download" href="./download.html"/>
+ <item name="Javadocs" href="http://helix.incubator.apache.org/javadocs/0.6.2-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/4a4510d1/site-releases/0.6.2-incubating/src/site/xdoc/download.xml.vm
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/src/site/xdoc/download.xml.vm b/site-releases/0.6.2-incubating/src/site/xdoc/download.xml.vm
index 97e8727..dbc7513 100644
--- a/site-releases/0.6.2-incubating/src/site/xdoc/download.xml.vm
+++ b/site-releases/0.6.2-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>
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.7.0-incubating/src/site/apt/releasing.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.7.0-incubating/src/site/apt/releasing.apt b/site-releases/0.7.0-incubating/src/site/apt/releasing.apt
deleted file mode 100644
index 11d0cd9..0000000
--- a/site-releases/0.7.0-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/4a4510d1/site-releases/0.7.0-incubating/src/site/markdown/Architecture.md
----------------------------------------------------------------------
diff --git a/site-releases/0.7.0-incubating/src/site/markdown/Architecture.md b/site-releases/0.7.0-incubating/src/site/markdown/Architecture.md
deleted file mode 100644
index 933e917..0000000
--- a/site-releases/0.7.0-incubating/src/site/markdown/Architecture.md
+++ /dev/null
@@ -1,252 +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.
--->
-
-<head>
- <title>Architecture</title>
-</head>
-
-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.
-
-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.
-
-
-
-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
-
-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.
-
-We have divided Helix 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.
-
-These are simply logical components and can be deployed as per the system requirements. For example:
-
-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.
-
-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 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.
-
-More info on Zookeeper can be found at http://zookeeper.apache.org
-
-## 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.
-
-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 actual 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 _ExternalView_. ExternalView is simply an aggregate of all node CurrentStates.
-
-* 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: 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.
-
-
-### 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
-* 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
-
-### 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.
-
-#### 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 the cluster name) 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/4a4510d1/site-releases/0.7.0-incubating/src/site/markdown/Building.md
----------------------------------------------------------------------
diff --git a/site-releases/0.7.0-incubating/src/site/markdown/Building.md b/site-releases/0.7.0-incubating/src/site/markdown/Building.md
index 06046d5..48cf597 100644
--- a/site-releases/0.7.0-incubating/src/site/markdown/Building.md
+++ b/site-releases/0.7.0-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-0.7.0-incubating
mvn install package -DskipTests
```
-Maven dependency
+### Maven Dependency
```
<dependency>
@@ -38,9 +40,3 @@ Maven dependency
<version>0.7.0-incubating</version>
</dependency>
```
-
-Download
---------
-
-[0.7.0-incubating](./download.html)
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.7.0-incubating/src/site/markdown/Concepts.md
----------------------------------------------------------------------
diff --git a/site-releases/0.7.0-incubating/src/site/markdown/Concepts.md b/site-releases/0.7.0-incubating/src/site/markdown/Concepts.md
deleted file mode 100644
index fa5d0ba..0000000
--- a/site-releases/0.7.0-incubating/src/site/markdown/Concepts.md
+++ /dev/null
@@ -1,275 +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.
--->
-
-<head>
- <title>Concepts</title>
-</head>
-
-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.
-
-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 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.
-
-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 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:
-
-```
-{
- "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 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:
-
-* 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 examples such as configuration 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 FULL_AUTO, SEMI_AUTO and CUSTOMIZED.
-
-
-
-
-
-
-
-
-
-
-
-
http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/4a4510d1/site-releases/0.7.0-incubating/src/site/markdown/Quickstart.md
----------------------------------------------------------------------
diff --git a/site-releases/0.7.0-incubating/src/site/markdown/Quickstart.md b/site-releases/0.7.0-incubating/src/site/markdown/Quickstart.md
index b4f095b..5381a2b 100644
--- a/site-releases/0.7.0-incubating/src/site/markdown/Quickstart.md
+++ b/site-releases/0.7.0-incubating/src/site/markdown/Quickstart.md
@@ -21,23 +21,31 @@ under the License.
<title>Quickstart</title>
</head>
+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-0.7.0-incubating
- ./build
- 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-0.7.0-incubating
+mvn install package -DskipTests
+# This folder contains quickstart.sh and start-helix-participant.sh
+cd helix-examples/target/helix-examples-pkg/bin
+chmod +x *
+# This folder contains helix-admin.sh, start-standalone-zookeeper.sh, and run-helix-controller.sh
+cd ../../../../helix-core/target/helix-core-pkg/bin
+```
### Download
-Download the 0.7.0-incubating release package [here](./download.html)
+Download the 0.7.0-incubating release package [here](./download.html)
Overview
--------
@@ -50,12 +58,12 @@ 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 incubator-helix/helix-core/target/helix-core-pkg/bin
+cd helix/incubator-helix/helix-examples/target/helix-examples-pkg/bin
```
If you downloaded the release package, extract it.
@@ -74,66 +82,72 @@ 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 incubator-helix/helix-core/target/helix-core-pkg/bin
+cd helix/incubator-helix/helix-examples/target/helix-examples-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
@@ -142,20 +156,22 @@ 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 and 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
@@ -165,62 +181,74 @@ 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
-##### Add nodes to the cluster
+```
+# ./helix-admin.sh --zkSvr <zk_address> --addCluster <clustername>
+./helix-admin.sh --zkSvr localhost:2199 --addCluster MYCLUSTER
+```
+
+### 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:
@@ -233,17 +261,17 @@ 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:
@@ -254,11 +282,10 @@ 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: {
@@ -275,11 +302,11 @@ 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:
@@ -326,6 +353,7 @@ IdealState for myDB:
"myDB_5" : [ "localhost_12914", "localhost_12915", "localhost_12913" ]
},
"simpleFields" : {
+ "IDEAL_STATE_MODE" : "AUTO",
"REBALANCE_MODE" : "SEMI_AUTO",
"NUM_PARTITIONS" : "6",
"REPLICAS" : "3",
@@ -379,30 +407,38 @@ ExternalView for myDB:
Now, let\'s look at one of the partitions:
- ## helix-admin.sh --zkSvr <zk_address> --listPartitionInfo <clusterName> <resource> <partition>
- ./helix-admin.sh --zkSvr localhost:2199 --listPartitionInfo MYCLUSTER myDB 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:
@@ -454,6 +490,7 @@ IdealState for myDB:
"myDB_5" : [ "localhost_12914", "localhost_12915", "localhost_12913" ]
},
"simpleFields" : {
+ "IDEAL_STATE_MODE" : "AUTO",
"REBALANCE_MODE" : "SEMI_AUTO",
"NUM_PARTITIONS" : "6",
"REPLICAS" : "3",
@@ -507,7 +544,7 @@ 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.
@@ -563,6 +600,7 @@ IdealState for myDB:
"myDB_5" : [ "localhost_12914", "localhost_12915", "localhost_12913" ]
},
"simpleFields" : {
+ "IDEAL_STATE_MODE" : "AUTO",
"REBALANCE_MODE" : "SEMI_AUTO",
"NUM_PARTITIONS" : "6",
"REPLICAS" : "3",
@@ -612,15 +650,17 @@ 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/4a4510d1/site-releases/0.7.0-incubating/src/site/markdown/Tutorial.md
----------------------------------------------------------------------
diff --git a/site-releases/0.7.0-incubating/src/site/markdown/Tutorial.md b/site-releases/0.7.0-incubating/src/site/markdown/Tutorial.md
index 081bc7a..b8c5e7e 100644
--- a/site-releases/0.7.0-incubating/src/site/markdown/Tutorial.md
+++ b/site-releases/0.7.0-incubating/src/site/markdown/Tutorial.md
@@ -30,7 +30,7 @@ Convention: we first cover the _basic_ approach, which is the easiest to impleme
### Prerequisites
-1. Read [Concepts/Terminology](./Concepts.html) and [Architecture](./Architecture.html)
+1. Read [Concepts/Terminology](../../Concepts.html) and [Architecture](../../Architecture.html)
2. Read the [Quickstart guide](./Quickstart.html) to learn how Helix models and manages a cluster
3. Install Helix source. See: [Quickstart](./Quickstart.html) for the steps.
@@ -54,17 +54,17 @@ 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. We will show how to do this using both the Java admin interface, as well as the [cluster accessor](./tutorial_accessors.html) interface. You can choose either interface depending on which most closely matches your needs.
-### 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 &
```
-### 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 accessor API:
@@ -103,7 +103,7 @@ Using the command-line interface:
```
-### 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.
The most commonly used convention is hostname_port.
@@ -149,18 +149,18 @@ for (int i = 0; i < NUM_NODES; i++)
}
```
-### 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_.
-#### 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.
+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:
@@ -225,10 +225,10 @@ OR
admin.addStateModelDef(CLUSTER_NAME, STATE_MODEL_NAME, stateModelDefinition);
```
-#### 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.
-Helix does this by assigning a STATE to a partition (such as MASTER, SLAVE), and placing it on a particular node.
+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