You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@zookeeper.apache.org by bu...@apache.org on 2012/03/21 07:15:16 UTC
svn commit: r809385 [27/37] - in /websites/staging/zookeeper/trunk/content:
./ doc/r3.3.5/ doc/r3.3.5/api/ doc/r3.3.5/api/org/
doc/r3.3.5/api/org/apache/ doc/r3.3.5/api/org/apache/zookeeper/
doc/r3.3.5/api/org/apache/zookeeper/class-use/ doc/r3.3.5/api...
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperOverview.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperOverview.html (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperOverview.html Wed Mar 21 06:15:08 2012
@@ -0,0 +1,694 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
+<meta content="Apache Forrest" name="Generator">
+<meta name="Forrest-version" content="0.9">
+<meta name="Forrest-skin-name" content="pelt">
+<title>BookKeeper overview</title>
+<link type="text/css" href="skin/basic.css" rel="stylesheet">
+<link media="screen" type="text/css" href="skin/screen.css" rel="stylesheet">
+<link media="print" type="text/css" href="skin/print.css" rel="stylesheet">
+<link type="text/css" href="skin/profile.css" rel="stylesheet">
+<script src="skin/getBlank.js" language="javascript" type="text/javascript"></script><script src="skin/getMenu.js" language="javascript" type="text/javascript"></script><script src="skin/fontsize.js" language="javascript" type="text/javascript"></script>
+<link rel="shortcut icon" href="images/favicon.ico">
+</head>
+<body onload="init()">
+<script type="text/javascript">ndeSetTextSize();</script>
+<div id="top">
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+<a href="http://www.apache.org/">Apache</a> > <a href="http://hadoop.apache.org/">Hadoop</a> > <a href="http://hadoop.apache.org/zookeeper/">ZooKeeper</a><script src="skin/breadcrumbs.js" language="JavaScript" type="text/javascript"></script>
+</div>
+<!--+
+ |header
+ +-->
+<div class="header">
+<!--+
+ |start group logo
+ +-->
+<div class="grouplogo">
+<a href="http://hadoop.apache.org/"><img class="logoImage" alt="Hadoop" src="images/hadoop-logo.jpg" title="Apache Hadoop"></a>
+</div>
+<!--+
+ |end group logo
+ +-->
+<!--+
+ |start Project Logo
+ +-->
+<div class="projectlogo">
+<a href="http://hadoop.apache.org/zookeeper/"><img class="logoImage" alt="ZooKeeper" src="images/zookeeper_small.gif" title="ZooKeeper: distributed coordination"></a>
+</div>
+<!--+
+ |end Project Logo
+ +-->
+<!--+
+ |start Search
+ +-->
+<div class="searchbox">
+<form action="http://www.google.com/search" method="get" class="roundtopsmall">
+<input value="hadoop.apache.org" name="sitesearch" type="hidden"><input onFocus="getBlank (this, 'Search the site with google');" size="25" name="q" id="query" type="text" value="Search the site with google">
+ <input name="Search" value="Search" type="submit">
+</form>
+</div>
+<!--+
+ |end search
+ +-->
+<!--+
+ |start Tabs
+ +-->
+<ul id="tabs">
+<li>
+<a class="unselected" href="http://hadoop.apache.org/zookeeper/">Project</a>
+</li>
+<li>
+<a class="unselected" href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</li>
+<li class="current">
+<a class="selected" href="index.html">ZooKeeper 3.3 Documentation</a>
+</li>
+</ul>
+<!--+
+ |end Tabs
+ +-->
+</div>
+</div>
+<div id="main">
+<div id="publishedStrip">
+<!--+
+ |start Subtabs
+ +-->
+<div id="level2tabs"></div>
+<!--+
+ |end Endtabs
+ +-->
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+
+
+ </div>
+<!--+
+ |start Menu, mainarea
+ +-->
+<!--+
+ |start Menu
+ +-->
+<div id="menu">
+<div onclick="SwitchMenu('menu_1.1', 'skin/')" id="menu_1.1Title" class="menutitle">Overview</div>
+<div id="menu_1.1" class="menuitemgroup">
+<div class="menuitem">
+<a href="index.html">Welcome</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperOver.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperStarted.html">Getting Started</a>
+</div>
+<div class="menuitem">
+<a href="releasenotes.html">Release Notes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.2', 'skin/')" id="menu_1.2Title" class="menutitle">Developer</div>
+<div id="menu_1.2" class="menuitemgroup">
+<div class="menuitem">
+<a href="api/index.html">API Docs</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperProgrammers.html">Programmer's Guide</a>
+</div>
+<div class="menuitem">
+<a href="javaExample.html">Java Example</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperTutorial.html">Barrier and Queue Tutorial</a>
+</div>
+<div class="menuitem">
+<a href="recipes.html">Recipes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_selected_1.3', 'skin/')" id="menu_selected_1.3Title" class="menutitle" style="background-image: url('skin/images/chapter_open.gif');">BookKeeper</div>
+<div id="menu_selected_1.3" class="selectedmenuitemgroup" style="display: block;">
+<div class="menuitem">
+<a href="bookkeeperStarted.html">Getting started</a>
+</div>
+<div class="menupage">
+<div class="menupagetitle">Overview</div>
+</div>
+<div class="menuitem">
+<a href="bookkeeperConfig.html">Setup guide</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperProgrammer.html">Programmer's guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.4', 'skin/')" id="menu_1.4Title" class="menutitle">Admin & Ops</div>
+<div id="menu_1.4" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperAdmin.html">Administrator's Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperQuotas.html">Quota Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperJMX.html">JMX</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperObservers.html">Observers Guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.5', 'skin/')" id="menu_1.5Title" class="menutitle">Contributor</div>
+<div id="menu_1.5" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperInternals.html">ZooKeeper Internals</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.6', 'skin/')" id="menu_1.6Title" class="menutitle">Miscellaneous</div>
+<div id="menu_1.6" class="menuitemgroup">
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</div>
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper/FAQ">FAQ</a>
+</div>
+<div class="menuitem">
+<a href="http://hadoop.apache.org/zookeeper/mailing_lists.html">Mailing Lists</a>
+</div>
+</div>
+<div id="credit"></div>
+<div id="roundbottom">
+<img style="display: none" class="corner" height="15" width="15" alt="" src="skin/images/rc-b-l-15-1body-2menu-3menu.png"></div>
+<!--+
+ |alternative credits
+ +-->
+<div id="credit2"></div>
+</div>
+<!--+
+ |end Menu
+ +-->
+<!--+
+ |start content
+ +-->
+<div id="content">
+<div title="Portable Document Format" class="pdflink">
+<a class="dida" href="bookkeeperOverview.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br>
+ PDF</a>
+</div>
+<h1>BookKeeper overview</h1>
+<div id="front-matter">
+<div id="minitoc-area">
+<ul class="minitoc">
+<li>
+<a href="#bk_Overview">BookKeeper overview</a>
+<ul class="minitoc">
+<li>
+<a href="#bk_Intro">BookKeeper introduction</a>
+</li>
+<li>
+<a href="#bk_moreDetail">In slightly more detail...</a>
+</li>
+<li>
+<a href="#bk_basicComponents">Bookkeeper elements and concepts</a>
+</li>
+<li>
+<a href="#bk_initialDesign">Bookkeeper initial design</a>
+</li>
+<li>
+<a href="#bk_metadata">Bookkeeper metadata management</a>
+</li>
+<li>
+<a href="#bk_closingOut">Closing out ledgers</a>
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+
+
+
+
+<a name="bk_Overview"></a>
+<h2 class="h3">BookKeeper overview</h2>
+<div class="section">
+<a name="bk_Intro"></a>
+<h3 class="h4">BookKeeper introduction</h3>
+<p>
+ BookKeeper is a replicated service to reliably log streams of records. In BookKeeper,
+ servers are "bookies", log streams are "ledgers", and each unit of a log (aka record) is a
+ "ledger entry". BookKeeper is designed to be reliable; bookies, the servers that store
+ ledgers, can crash, corrupt data, discard data, but as long as there are enough bookies
+ behaving correctly the service as a whole behaves correctly.
+ </p>
+<p>
+ The initial motivation for BookKeeper comes from the namenode of HDFS. Namenodes have to
+ log operations in a reliable fashion so that recovery is possible in the case of crashes.
+ We have found the applications for BookKeeper extend far beyond HDFS, however. Essentially,
+ any application that requires an append storage can replace their implementations with
+ BookKeeper. BookKeeper has the advantage of scaling throughput with the number of servers.
+ </p>
+<p>
+ At a high level, a bookkeeper client receives entries from a client application and stores it to
+ sets of bookies, and there are a few advantages in having such a service:
+ </p>
+<ul>
+
+<li>
+
+<p>
+ We can use hardware that is optimized for such a service. We currently believe that such a
+ system has to be optimized only for disk I/O;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ We can have a pool of servers implementing such a log system, and shared among a number of servers;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ We can have a higher degree of replication with such a pool, which makes sense if the hardware necessary for it is cheaper compared to the one the application uses.
+ </p>
+
+</li>
+
+</ul>
+<a name="bk_moreDetail"></a>
+<h3 class="h4">In slightly more detail...</h3>
+<p> BookKeeper implements highly available logs, and it has been designed with write-ahead logging in mind. Besides high availability
+ due to the replicated nature of the service, it provides high throughput due to striping. As we write entries in a subset of bookies of an
+ ensemble and rotate writes across available quorums, we are able to increase throughput with the number of servers for both reads and writes.
+ Scalability is a property that is possible to achieve in this case due to the use of quorums. Other replication techniques, such as
+ state-machine replication, do not enable such a property.
+ </p>
+<p> An application first creates a ledger before writing to bookies through a local BookKeeper client instance.
+ Upon creating a ledger, a BookKeeper client writes metadata about the ledger to ZooKeeper. Each ledger currently
+ has a single writer. This writer has to execute a close ledger operation before any other client can read from it.
+ If the writer of a ledger does not close a ledger properly because, for example, it has crashed before having the
+ opportunity of closing the ledger, then the next client that tries to open a ledger executes a procedure to recover
+ it. As closing a ledger consists essentially of writing the last entry written to a ledger to ZooKeeper, the recovery
+ procedure simply finds the last entry written correctly and writes it to ZooKeeper.
+ </p>
+<p>
+ Note that currently this recovery procedure is executed automatically upon trying to open a ledger and no explicit action is necessary.
+ Although two clients may try to recover a ledger concurrently, only one will succeed, the first one that is able to create the close znode
+ for the ledger.
+ </p>
+<a name="bk_basicComponents"></a>
+<h3 class="h4">Bookkeeper elements and concepts</h3>
+<p>
+ BookKeeper uses four basic elements:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<strong>Ledger</strong>: A ledger is a sequence of entries, and each entry is a sequence of bytes. Entries are
+ written sequentially to a ledger and at most once. Consequently, ledgers have an append-only semantics;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<strong>BookKeeper client</strong>: A client runs along with a BookKeeper application, and it enables applications
+ to execute operations on ledgers, such as creating a ledger and writing to it;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<strong>Bookie</strong>: A bookie is a BookKeeper storage server. Bookies store the content of ledgers. For any given
+ ledger L, we call an <em>ensemble</em> the group of bookies storing the content of L. For performance, we store on
+ each bookie of an ensemble only a fragment of a ledger. That is, we stripe when writing entries to a ledger such that
+ each entry is written to sub-group of bookies of the ensemble.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<strong>Metadata storage service</strong>: BookKeeper requires a metadata storage service to store information related
+ to ledgers and available bookies. We currently use ZooKeeper for such a task.
+ </p>
+
+</li>
+
+</ul>
+<a name="bk_initialDesign"></a>
+<h3 class="h4">Bookkeeper initial design</h3>
+<p>
+ A set of bookies implements BookKeeper, and we use a quorum-based protocol to replicate data across the bookies.
+ There are basically two operations to an existing ledger: read and append. Here is the complete API list
+ (mode detail <a href="bookkeeperProgrammer.html">
+ here</a>):
+ </p>
+<ul>
+
+<li>
+
+<p>
+ Create ledger: creates a new empty ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Open ledger: opens an existing ledger for reading;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Add entry: adds a record to a ledger either synchronously or asynchronously;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Read entries: reads a sequence of entries from a ledger either synchronously or asynchronously
+ </p>
+
+</li>
+
+</ul>
+<p>
+ There is only a single client that can write to a ledger. Once that ledger is closed or the client fails,
+ no more entries can be added. (We take advantage of this behavior to provide our strong guarantees.)
+ There will not be gaps in the ledger. Fingers get broken, people get roughed up or end up in prison when
+ books are manipulated, so there is no deleting or changing of entries.
+ </p>
+<table class="ForrestTable" cellspacing="1" cellpadding="4">
+<tr>
+<td>BookKeeper Overview</td>
+</tr>
+<tr>
+<td>
+
+ <img alt="" src="images/bk-overview.jpg">
+
+ </td>
+</tr>
+</table>
+<p>
+ A simple use of BooKeeper is to implement a write-ahead transaction log. A server maintains an in-memory data structure
+ (with periodic snapshots for example) and logs changes to that structure before it applies the change. The application
+ server creates a ledger at startup and store the ledger id and password in a well known place (ZooKeeper maybe). When
+ it needs to make a change, the server adds an entry with the change information to a ledger and apply the change when
+ BookKeeper adds the entry successfully. The server can even use asyncAddEntry to queue up many changes for high change
+ throughput. BooKeeper meticulously logs the changes in order and call the completion functions in order.
+ </p>
+<p>
+ When the application server dies, a backup server will come online, get the last snapshot and then it will open the
+ ledger of the old server and read all the entries from the time the snapshot was taken. (Since it doesn't know the
+ last entry number it will use MAX_INTEGER). Once all the entries have been processed, it will close the ledger and
+ start a new one for its use.
+ </p>
+<p>
+ A client library takes care of communicating with bookies and managing entry numbers. An entry has the following fields:
+ </p>
+<table class="ForrestTable" cellspacing="1" cellpadding="4">
+<caption>Entry fields</caption>
+<title>Entry fields</title>
+
+
+<tr>
+
+<th>Field</th>
+ <th>Type</th>
+ <th>Description</th>
+
+</tr>
+
+
+<tr>
+
+<td>Ledger number</td>
+ <td>long</td>
+ <td>The id of the ledger of this entry</td>
+
+</tr>
+
+<tr>
+
+<td>Entry number</td>
+ <td>long</td>
+ <td>The id of this entry</td>
+
+</tr>
+
+
+<tr>
+
+<td>last confirmed (<em>LC</em>)</td>
+ <td>long</td>
+ <td>id of the last recorded entry</td>
+
+</tr>
+
+<tr>
+
+<td>data</td>
+ <td>byte[]</td>
+ <td>the entry data (supplied by application)</td>
+
+</tr>
+
+<tr>
+
+<td>authentication code</td>
+ <td>byte[]</td>
+ <td>Message authentication code that includes all other fields of the entry</td>
+
+</tr>
+
+
+
+</table>
+<p>
+ The client library generates a ledger entry. None of the fields are modified by the bookies and only the first three
+ fields are interpreted by the bookies.
+ </p>
+<p>
+ To add to a ledger, the client generates the entry above using the ledger number. The entry number will be one more
+ than the last entry generated. The <em>LC</em> field contains the last entry that has been successfully recorded by BookKeeper.
+ If the client writes entries one at a time, <em>LC</em> is the last entry id. But, if the client is using asyncAddEntry, there
+ may be many entries in flight. An entry is considered recorded when both of the following conditions are met:
+ </p>
+<ul>
+
+<li>
+
+<p>
+ the entry has been accepted by a quorum of bookies
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ all entries with a lower entry id have been accepted by a quorum of bookies
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<em>LC</em> seems mysterious right now, but it is too early to explain how we use it; just smile and move on.
+ </p>
+<p>
+ Once all the other fields have been field in, the client generates an authentication code with all of the previous fields.
+ The entry is then sent to a quorum of bookies to be recorded. Any failures will result in the entry being sent to a new
+ quorum of bookies.
+ </p>
+<p>
+ To read, the client library initially contacts a bookie and starts requesting entries. If an entry is missing or
+ invalid (a bad MAC for example), the client will make a request to a different bookie. By using quorum writes,
+ as long as enough bookies are up we are guaranteed to eventually be able to read an entry.
+ </p>
+<a name="bk_metadata"></a>
+<h3 class="h4">Bookkeeper metadata management</h3>
+<p>
+ There are some meta data that needs to be made available to BookKeeper clients:
+ </p>
+<ul>
+
+<li>
+
+<p>
+ The available bookies;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ The list of ledgers;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ The list of bookies that have been used for a given ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ The last entry of a ledger;
+ </p>
+
+</li>
+
+</ul>
+<p>
+ We maintain this information in ZooKeeper. Bookies use ephemeral nodes to indicate their availability. Clients
+ use znodes to track ledger creation and deletion and also to know the end of the ledger and the bookies that
+ were used to store the ledger. Bookies also watch the ledger list so that they can cleanup ledgers that get deleted.
+ </p>
+<a name="bk_closingOut"></a>
+<h3 class="h4">Closing out ledgers</h3>
+<p>
+ The process of closing out the ledger and finding the last ledger is difficult due to the durability guarantees of BookKeeper:
+ </p>
+<ul>
+
+<li>
+
+<p>
+ If an entry has been successfully recorded, it must be readable.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ If an entry is read once, it must always be available to be read.
+ </p>
+
+</li>
+
+</ul>
+<p>
+ If the ledger was closed gracefully, ZooKeeper will have the last entry and everything will work well. But, if the
+ BookKeeper client that was writing the ledger dies, there is some recovery that needs to take place.
+ </p>
+<p>
+ The problematic entries are the ones at the end of the ledger. There can be entries in flight when a BookKeeper client
+ dies. If the entry only gets to one bookie, the entry should not be readable since the entry will disappear if that bookie
+ fails. If the entry is only on one bookie, that doesn't mean that the entry has not been recorded successfully; the other
+ bookies that recorded the entry might have failed.
+ </p>
+<p>
+ The trick to making everything work is to have a correct idea of a last entry. We do it in roughly three steps:
+ </p>
+<ol>
+
+<li>
+
+<p>
+ Find the entry with the highest last recorded entry, <em>LC</em>;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Find the highest consecutively recorded entry, <em>LR</em>;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Make sure that all entries between <em>LC</em> and <em>LR</em> are on a quorum of bookies;
+ </p>
+
+</li>
+
+
+</ol>
+</div>
+
+<p align="right">
+<font size="-2"></font>
+</p>
+</div>
+<!--+
+ |end content
+ +-->
+<div class="clearboth"> </div>
+</div>
+<div id="footer">
+<!--+
+ |start bottomstrip
+ +-->
+<div class="lastmodified">
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<div class="copyright">
+ Copyright ©
+ 2008 <a href="http://www.apache.org/licenses/">The Apache Software Foundation.</a>
+</div>
+<!--+
+ |end bottomstrip
+ +-->
+</div>
+</body>
+</html>
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperOverview.pdf
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperOverview.pdf
------------------------------------------------------------------------------
svn:mime-type = application/pdf
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperProgrammer.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperProgrammer.html (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperProgrammer.html Wed Mar 21 06:15:08 2012
@@ -0,0 +1,990 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
+<meta content="Apache Forrest" name="Generator">
+<meta name="Forrest-version" content="0.9">
+<meta name="Forrest-skin-name" content="pelt">
+<title>BookKeeper Getting Started Guide</title>
+<link type="text/css" href="skin/basic.css" rel="stylesheet">
+<link media="screen" type="text/css" href="skin/screen.css" rel="stylesheet">
+<link media="print" type="text/css" href="skin/print.css" rel="stylesheet">
+<link type="text/css" href="skin/profile.css" rel="stylesheet">
+<script src="skin/getBlank.js" language="javascript" type="text/javascript"></script><script src="skin/getMenu.js" language="javascript" type="text/javascript"></script><script src="skin/fontsize.js" language="javascript" type="text/javascript"></script>
+<link rel="shortcut icon" href="images/favicon.ico">
+</head>
+<body onload="init()">
+<script type="text/javascript">ndeSetTextSize();</script>
+<div id="top">
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+<a href="http://www.apache.org/">Apache</a> > <a href="http://hadoop.apache.org/">Hadoop</a> > <a href="http://hadoop.apache.org/zookeeper/">ZooKeeper</a><script src="skin/breadcrumbs.js" language="JavaScript" type="text/javascript"></script>
+</div>
+<!--+
+ |header
+ +-->
+<div class="header">
+<!--+
+ |start group logo
+ +-->
+<div class="grouplogo">
+<a href="http://hadoop.apache.org/"><img class="logoImage" alt="Hadoop" src="images/hadoop-logo.jpg" title="Apache Hadoop"></a>
+</div>
+<!--+
+ |end group logo
+ +-->
+<!--+
+ |start Project Logo
+ +-->
+<div class="projectlogo">
+<a href="http://hadoop.apache.org/zookeeper/"><img class="logoImage" alt="ZooKeeper" src="images/zookeeper_small.gif" title="ZooKeeper: distributed coordination"></a>
+</div>
+<!--+
+ |end Project Logo
+ +-->
+<!--+
+ |start Search
+ +-->
+<div class="searchbox">
+<form action="http://www.google.com/search" method="get" class="roundtopsmall">
+<input value="hadoop.apache.org" name="sitesearch" type="hidden"><input onFocus="getBlank (this, 'Search the site with google');" size="25" name="q" id="query" type="text" value="Search the site with google">
+ <input name="Search" value="Search" type="submit">
+</form>
+</div>
+<!--+
+ |end search
+ +-->
+<!--+
+ |start Tabs
+ +-->
+<ul id="tabs">
+<li>
+<a class="unselected" href="http://hadoop.apache.org/zookeeper/">Project</a>
+</li>
+<li>
+<a class="unselected" href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</li>
+<li class="current">
+<a class="selected" href="index.html">ZooKeeper 3.3 Documentation</a>
+</li>
+</ul>
+<!--+
+ |end Tabs
+ +-->
+</div>
+</div>
+<div id="main">
+<div id="publishedStrip">
+<!--+
+ |start Subtabs
+ +-->
+<div id="level2tabs"></div>
+<!--+
+ |end Endtabs
+ +-->
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+
+
+ </div>
+<!--+
+ |start Menu, mainarea
+ +-->
+<!--+
+ |start Menu
+ +-->
+<div id="menu">
+<div onclick="SwitchMenu('menu_1.1', 'skin/')" id="menu_1.1Title" class="menutitle">Overview</div>
+<div id="menu_1.1" class="menuitemgroup">
+<div class="menuitem">
+<a href="index.html">Welcome</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperOver.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperStarted.html">Getting Started</a>
+</div>
+<div class="menuitem">
+<a href="releasenotes.html">Release Notes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.2', 'skin/')" id="menu_1.2Title" class="menutitle">Developer</div>
+<div id="menu_1.2" class="menuitemgroup">
+<div class="menuitem">
+<a href="api/index.html">API Docs</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperProgrammers.html">Programmer's Guide</a>
+</div>
+<div class="menuitem">
+<a href="javaExample.html">Java Example</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperTutorial.html">Barrier and Queue Tutorial</a>
+</div>
+<div class="menuitem">
+<a href="recipes.html">Recipes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_selected_1.3', 'skin/')" id="menu_selected_1.3Title" class="menutitle" style="background-image: url('skin/images/chapter_open.gif');">BookKeeper</div>
+<div id="menu_selected_1.3" class="selectedmenuitemgroup" style="display: block;">
+<div class="menuitem">
+<a href="bookkeeperStarted.html">Getting started</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperOverview.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperConfig.html">Setup guide</a>
+</div>
+<div class="menupage">
+<div class="menupagetitle">Programmer's guide</div>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.4', 'skin/')" id="menu_1.4Title" class="menutitle">Admin & Ops</div>
+<div id="menu_1.4" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperAdmin.html">Administrator's Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperQuotas.html">Quota Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperJMX.html">JMX</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperObservers.html">Observers Guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.5', 'skin/')" id="menu_1.5Title" class="menutitle">Contributor</div>
+<div id="menu_1.5" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperInternals.html">ZooKeeper Internals</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.6', 'skin/')" id="menu_1.6Title" class="menutitle">Miscellaneous</div>
+<div id="menu_1.6" class="menuitemgroup">
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</div>
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper/FAQ">FAQ</a>
+</div>
+<div class="menuitem">
+<a href="http://hadoop.apache.org/zookeeper/mailing_lists.html">Mailing Lists</a>
+</div>
+</div>
+<div id="credit"></div>
+<div id="roundbottom">
+<img style="display: none" class="corner" height="15" width="15" alt="" src="skin/images/rc-b-l-15-1body-2menu-3menu.png"></div>
+<!--+
+ |alternative credits
+ +-->
+<div id="credit2"></div>
+</div>
+<!--+
+ |end Menu
+ +-->
+<!--+
+ |start content
+ +-->
+<div id="content">
+<div title="Portable Document Format" class="pdflink">
+<a class="dida" href="bookkeeperProgrammer.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br>
+ PDF</a>
+</div>
+<h1>BookKeeper Getting Started Guide</h1>
+<div id="front-matter">
+<div id="minitoc-area">
+<ul class="minitoc">
+<li>
+<a href="#bk_GettingStarted">Programming with BookKeeper</a>
+<ul class="minitoc">
+<li>
+<a href="#bk_instance"> Instantiating BookKeeper.</a>
+</li>
+<li>
+<a href="#bk_createLedger"> Creating a ledger. </a>
+</li>
+<li>
+<a href="#bk_writeLedger"> Adding entries to a ledger. </a>
+</li>
+<li>
+<a href="#bk_closeLedger"> Closing a ledger. </a>
+</li>
+<li>
+<a href="#bk_openLedger"> Opening a ledger. </a>
+</li>
+<li>
+<a href="#bk_readLedger"> Reading from ledger </a>
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+
+
+
+
+<a name="bk_GettingStarted"></a>
+<h2 class="h3">Programming with BookKeeper</h2>
+<div class="section">
+<ul>
+
+<li>
+
+<p>
+<a href="#bk_instance"> Instantiating BookKeeper.</a>
+</p>
+
+</li>
+
+
+<li>
+
+<p>
+<a href="#bk_createLedger"> Creating a ledger. </a>
+</p>
+
+</li>
+
+
+<li>
+
+<p>
+<a href="#bk_writeLedger"> Adding entries to a ledger. </a>
+</p>
+
+</li>
+
+
+<li>
+
+<p>
+<a href="#bk_closeLedger"> Closing a ledger. </a>
+</p>
+
+</li>
+
+
+<li>
+
+<p>
+<a href="#bk_openLedger"> Opening a ledger. </a>
+</p>
+
+</li>
+
+
+<li>
+
+<p>
+<a href="#bk_readLedger"> Reading from ledger </a>
+</p>
+
+</li>
+
+
+</ul>
+<a name="bk_instance"></a>
+<h3 class="h4"> Instantiating BookKeeper.</h3>
+<p>
+ The first step to use BookKeeper is to instantiate a BookKeeper object:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ org.apache.bookkeeper.BookKeeper
+ </span>
+
+</p>
+<p>
+ There are three BookKeeper constructors:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public BookKeeper(String servers)
+ throws KeeperException, IOException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">servers</span> is a comma-separated list of ZooKeeper servers.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public BookKeeper(ZooKeeper zk)
+ throws InterruptedException, KeeperException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">zk</span> is a ZooKeeper object. This constructor is useful when
+ the application also using ZooKeeper and wants to have a single instance of ZooKeeper.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public BookKeeper(ZooKeeper zk, ClientSocketChannelFactory channelFactory)
+ throws InterruptedException, KeeperException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">zk</span> is a ZooKeeper object. This constructor is useful when
+ the application also using ZooKeeper and wants to have a single instance of ZooKeeper.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">channelFactory</span> is a netty channel object
+ (<span class="codefrag computeroutput">org.jboss.netty.channel.socket</span>).
+ </p>
+
+</li>
+
+</ul>
+<a name="bk_createLedger"></a>
+<h3 class="h4"> Creating a ledger. </h3>
+<p> Before writing entries to BookKeeper, it is necessary to create a ledger.
+ With the current BookKeeper API, it is possible to create a ledger both synchronously
+ or asynchronously. The following methods belong
+ to <span class="codefrag computeroutput">org.apache.bookkeeper.client.BookKeeper</span>.
+ </p>
+<p>
+
+<strong>Synchronous call:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerHandle createLedger(int ensSize, int qSize, DigestType type, byte passwd[])
+ throws KeeperException, InterruptedException,
+ IOException, BKException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ensSize</span> is the number of bookies (ensemble size);
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">qSize</span> is the write quorum size;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">type</span> is the type of digest used with entries: either MAC or CRC32.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">passwd</span> is a password that authorizes the client to write to the
+ ledger being created.
+ </p>
+
+</li>
+
+</ul>
+<p>
+ All further operations on a ledger are invoked through the <span class="codefrag computeroutput">LedgerHandle</span>
+ object returned.
+ </p>
+<p>
+ As a convenience, we provide a <span class="codefrag computeroutput">createLedger</span> with default parameters (3,2,VERIFIABLE),
+ and the only two input parameters it requires are a digest type and a password.
+ </p>
+<p>
+
+<strong>Asynchronous call:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void asyncCreateLedger(int ensSize,
+ int qSize,
+ DigestType type,
+ byte passwd[],
+ CreateCallback cb,
+ Object ctx
+ )
+ </span>
+
+</p>
+<p>
+ The parameters are the same of the synchronous version, with the
+ exception of <span class="codefrag computeroutput">cb</span> and <span class="codefrag computeroutput">ctx</span>. <span class="codefrag computeroutput">CreateCallback</span>
+ is an interface in <span class="codefrag computeroutput">org.apache.bookkeeper.client.AsyncCallback</span>, and
+ a class implementing it has to implement a method called <span class="codefrag computeroutput">createComplete</span>
+ that has the following signature:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ void createComplete(int rc, LedgerHandle lh, Object ctx);
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">rc</span> is a return code (please refer to <span class="codefrag computeroutput">org.apache.bookeeper.client.BKException</span> for a list);
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a <span class="codefrag computeroutput">LedgerHandle</span> object to manipulate a ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ctx</span> is a control object for accountability purposes. It can be essentially any object the application is happy with.
+ </p>
+
+</li>
+
+</ul>
+<p>
+ The <span class="codefrag computeroutput">ctx</span> object passed as a parameter to the call to create a ledger
+ is the one same returned in the callback.
+ </p>
+<a name="bk_writeLedger"></a>
+<h3 class="h4"> Adding entries to a ledger. </h3>
+<p>
+ Once we have a ledger handle <span class="codefrag computeroutput">lh</span> obtained through a call to create a ledger, we
+ can start writing entries. As with creating ledgers, we can write both synchronously and
+ asynchronously. The following methods belong
+ to <span class="codefrag computeroutput">org.apache.bookkeeper.client.LedgerHandle</span>.
+ </p>
+<p>
+
+<strong>Synchronous call:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public long addEntry(byte[] data)
+ throws InterruptedException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">data</span> is a byte array;
+ </p>
+
+</li>
+
+</ul>
+<p>
+ A call to <span class="codefrag computeroutput">addEntry</span> returns the status of the operation (please refer to <span class="codefrag computeroutput">org.apache.bookeeper.client.BKDefs</span> for a list);
+ </p>
+<p>
+
+<strong>Asynchronous call:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void asyncAddEntry(byte[] data, AddCallback cb, Object ctx)
+ </span>
+
+</p>
+<p>
+ It also takes a byte array as the sequence of bytes to be stored as an entry. Additionaly, it takes
+ a callback object <span class="codefrag computeroutput">cb</span> and a control object <span class="codefrag computeroutput">ctx</span>. The callback object must implement
+ the <span class="codefrag computeroutput">AddCallback</span> interface in <span class="codefrag computeroutput">org.apache.bookkeeper.client.AsyncCallback</span>, and
+ a class implementing it has to implement a method called <span class="codefrag computeroutput">addComplete</span>
+ that has the following signature:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ void addComplete(int rc, LedgerHandle lh, long entryId, Object ctx);
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">rc</span> is a return code (please refer to <span class="codefrag computeroutput">org.apache.bookeeper.client.BKDefs</span> for a list);
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a <span class="codefrag computeroutput">LedgerHandle</span> object to manipulate a ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">entryId</span> is the identifier of entry associated with this request;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ctx</span> is control object used for accountability purposes. It can be any object the application is happy with.
+ </p>
+
+</li>
+
+</ul>
+<a name="bk_closeLedger"></a>
+<h3 class="h4"> Closing a ledger. </h3>
+<p>
+ Once a client is done writing, it closes the ledger. The following methods belong
+ to <span class="codefrag computeroutput">org.apache.bookkeeper.client.LedgerHandle</span>.
+ </p>
+<p>
+
+<strong>Synchronous close:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void close()
+ throws InterruptedException
+ </span>
+
+</p>
+<p>
+ It takes no input parameters.
+ </p>
+<p>
+
+<strong>Asynchronous close:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void asyncClose(CloseCallback cb, Object ctx)
+ throws InterruptedException
+ </span>
+
+</p>
+<p>
+ It takes a callback object <span class="codefrag computeroutput">cb</span> and a control object <span class="codefrag computeroutput">ctx</span>. The callback object must implement
+ the <span class="codefrag computeroutput">CloseCallback</span> interface in <span class="codefrag computeroutput">org.apache.bookkeeper.client.AsyncCallback</span>, and
+ a class implementing it has to implement a method called <span class="codefrag computeroutput">closeComplete</span>
+ that has the following signature:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ void closeComplete(int rc, LedgerHandle lh, Object ctx)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">rc</span> is a return code (please refer to <span class="codefrag computeroutput">org.apache.bookeeper.client.BKDefs</span> for a list);
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a <span class="codefrag computeroutput">LedgerHandle</span> object to manipulate a ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ctx</span> is control object used for accountability purposes.
+ </p>
+
+</li>
+
+</ul>
+<a name="bk_openLedger"></a>
+<h3 class="h4"> Opening a ledger. </h3>
+<p>
+ To read from a ledger, a client must open it first. The following methods belong
+ to <span class="codefrag computeroutput">org.apache.bookkeeper.client.BookKeeper</span>.
+ </p>
+<p>
+
+<strong>Synchronous open:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerHandle openLedger(long lId, DigestType type, byte passwd[])
+ throws InterruptedException, BKException
+ </span>
+
+</p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ledgerId</span> is the ledger identifier;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">type</span> is the type of digest used with entries: either MAC or CRC32.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">passwd</span> is a password to access the ledger (used only in the case of <span class="codefrag computeroutput">VERIFIABLE</span> ledgers);
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<strong>Asynchronous open:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void asyncOpenLedger(long lId, DigestType type, byte passwd[], OpenCallback cb, Object ctx)
+ </span>
+
+</p>
+<p>
+ It also takes a a ledger identifier and a password. Additionaly, it takes a callback object
+ <span class="codefrag computeroutput">cb</span> and a control object <span class="codefrag computeroutput">ctx</span>. The callback object must implement
+ the <span class="codefrag computeroutput">OpenCallback</span> interface in <span class="codefrag computeroutput">org.apache.bookkeeper.client.AsyncCallback</span>, and
+ a class implementing it has to implement a method called <span class="codefrag computeroutput">openComplete</span>
+ that has the following signature:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void openComplete(int rc, LedgerHandle lh, Object ctx)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">rc</span> is a return code (please refer to <span class="codefrag computeroutput">org.apache.bookeeper.client.BKDefs</span> for a list);
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a <span class="codefrag computeroutput">LedgerHandle</span> object to manipulate a ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ctx</span> is control object used for accountability purposes.
+ </p>
+
+</li>
+
+</ul>
+<a name="bk_readLedger"></a>
+<h3 class="h4"> Reading from ledger </h3>
+<p>
+ Read calls may request one or more consecutive entries. The following methods belong
+ to <span class="codefrag computeroutput">org.apache.bookkeeper.client.LedgerHandle</span>.
+ </p>
+<p>
+
+<strong>Synchronous read:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerSequence readEntries(long firstEntry, long lastEntry)
+ throws InterruptedException, BKException
+ </span>
+
+</p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">firstEntry</span> is the identifier of the first entry in the sequence of entries to read;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lastEntry</span> is the identifier of the last entry in the sequence of entries to read.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<strong>Asynchronous read:</strong>
+
+</p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void asyncReadEntries(long firstEntry,
+ long lastEntry, ReadCallback cb, Object ctx)
+ throws BKException, InterruptedException
+ </span>
+
+</p>
+<p>
+ It also takes a first and a last entry identifiers. Additionaly, it takes a callback object
+ <span class="codefrag computeroutput">cb</span> and a control object <span class="codefrag computeroutput">ctx</span>. The callback object must implement
+ the <span class="codefrag computeroutput">ReadCallback</span> interface in <span class="codefrag computeroutput">org.apache.bookkeeper.client.AsyncCallback</span>, and
+ a class implementing it has to implement a method called <span class="codefrag computeroutput">readComplete</span>
+ that has the following signature:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ void readComplete(int rc, LedgerHandle lh, Enumeration<LedgerEntry> seq, Object ctx)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">rc</span> is a return code (please refer to <span class="codefrag computeroutput">org.apache.bookeeper.client.BKDefs</span> for a list);
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a <span class="codefrag computeroutput">LedgerHandle</span> object to manipulate a ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">seq</span> is a <span class="codefrag computeroutput">Enumeration<LedgerEntry> </span> object to containing the list of entries requested;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">ctx</span> is control object used for accountability purposes.
+ </p>
+
+</li>
+
+</ul>
+</div>
+
+<p align="right">
+<font size="-2"></font>
+</p>
+</div>
+<!--+
+ |end content
+ +-->
+<div class="clearboth"> </div>
+</div>
+<div id="footer">
+<!--+
+ |start bottomstrip
+ +-->
+<div class="lastmodified">
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<div class="copyright">
+ Copyright ©
+ 2008 <a href="http://www.apache.org/licenses/">The Apache Software Foundation.</a>
+</div>
+<!--+
+ |end bottomstrip
+ +-->
+</div>
+</body>
+</html>
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperProgrammer.pdf
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperProgrammer.pdf
------------------------------------------------------------------------------
svn:mime-type = application/pdf
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStarted.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStarted.html (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStarted.html Wed Mar 21 06:15:08 2012
@@ -0,0 +1,444 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
+<meta content="Apache Forrest" name="Generator">
+<meta name="Forrest-version" content="0.9">
+<meta name="Forrest-skin-name" content="pelt">
+<title>BookKeeper Getting Started Guide</title>
+<link type="text/css" href="skin/basic.css" rel="stylesheet">
+<link media="screen" type="text/css" href="skin/screen.css" rel="stylesheet">
+<link media="print" type="text/css" href="skin/print.css" rel="stylesheet">
+<link type="text/css" href="skin/profile.css" rel="stylesheet">
+<script src="skin/getBlank.js" language="javascript" type="text/javascript"></script><script src="skin/getMenu.js" language="javascript" type="text/javascript"></script><script src="skin/fontsize.js" language="javascript" type="text/javascript"></script>
+<link rel="shortcut icon" href="images/favicon.ico">
+</head>
+<body onload="init()">
+<script type="text/javascript">ndeSetTextSize();</script>
+<div id="top">
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+<a href="http://www.apache.org/">Apache</a> > <a href="http://hadoop.apache.org/">Hadoop</a> > <a href="http://hadoop.apache.org/zookeeper/">ZooKeeper</a><script src="skin/breadcrumbs.js" language="JavaScript" type="text/javascript"></script>
+</div>
+<!--+
+ |header
+ +-->
+<div class="header">
+<!--+
+ |start group logo
+ +-->
+<div class="grouplogo">
+<a href="http://hadoop.apache.org/"><img class="logoImage" alt="Hadoop" src="images/hadoop-logo.jpg" title="Apache Hadoop"></a>
+</div>
+<!--+
+ |end group logo
+ +-->
+<!--+
+ |start Project Logo
+ +-->
+<div class="projectlogo">
+<a href="http://hadoop.apache.org/zookeeper/"><img class="logoImage" alt="ZooKeeper" src="images/zookeeper_small.gif" title="ZooKeeper: distributed coordination"></a>
+</div>
+<!--+
+ |end Project Logo
+ +-->
+<!--+
+ |start Search
+ +-->
+<div class="searchbox">
+<form action="http://www.google.com/search" method="get" class="roundtopsmall">
+<input value="hadoop.apache.org" name="sitesearch" type="hidden"><input onFocus="getBlank (this, 'Search the site with google');" size="25" name="q" id="query" type="text" value="Search the site with google">
+ <input name="Search" value="Search" type="submit">
+</form>
+</div>
+<!--+
+ |end search
+ +-->
+<!--+
+ |start Tabs
+ +-->
+<ul id="tabs">
+<li>
+<a class="unselected" href="http://hadoop.apache.org/zookeeper/">Project</a>
+</li>
+<li>
+<a class="unselected" href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</li>
+<li class="current">
+<a class="selected" href="index.html">ZooKeeper 3.3 Documentation</a>
+</li>
+</ul>
+<!--+
+ |end Tabs
+ +-->
+</div>
+</div>
+<div id="main">
+<div id="publishedStrip">
+<!--+
+ |start Subtabs
+ +-->
+<div id="level2tabs"></div>
+<!--+
+ |end Endtabs
+ +-->
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+
+
+ </div>
+<!--+
+ |start Menu, mainarea
+ +-->
+<!--+
+ |start Menu
+ +-->
+<div id="menu">
+<div onclick="SwitchMenu('menu_1.1', 'skin/')" id="menu_1.1Title" class="menutitle">Overview</div>
+<div id="menu_1.1" class="menuitemgroup">
+<div class="menuitem">
+<a href="index.html">Welcome</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperOver.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperStarted.html">Getting Started</a>
+</div>
+<div class="menuitem">
+<a href="releasenotes.html">Release Notes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.2', 'skin/')" id="menu_1.2Title" class="menutitle">Developer</div>
+<div id="menu_1.2" class="menuitemgroup">
+<div class="menuitem">
+<a href="api/index.html">API Docs</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperProgrammers.html">Programmer's Guide</a>
+</div>
+<div class="menuitem">
+<a href="javaExample.html">Java Example</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperTutorial.html">Barrier and Queue Tutorial</a>
+</div>
+<div class="menuitem">
+<a href="recipes.html">Recipes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_selected_1.3', 'skin/')" id="menu_selected_1.3Title" class="menutitle" style="background-image: url('skin/images/chapter_open.gif');">BookKeeper</div>
+<div id="menu_selected_1.3" class="selectedmenuitemgroup" style="display: block;">
+<div class="menupage">
+<div class="menupagetitle">Getting started</div>
+</div>
+<div class="menuitem">
+<a href="bookkeeperOverview.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperConfig.html">Setup guide</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperProgrammer.html">Programmer's guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.4', 'skin/')" id="menu_1.4Title" class="menutitle">Admin & Ops</div>
+<div id="menu_1.4" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperAdmin.html">Administrator's Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperQuotas.html">Quota Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperJMX.html">JMX</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperObservers.html">Observers Guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.5', 'skin/')" id="menu_1.5Title" class="menutitle">Contributor</div>
+<div id="menu_1.5" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperInternals.html">ZooKeeper Internals</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.6', 'skin/')" id="menu_1.6Title" class="menutitle">Miscellaneous</div>
+<div id="menu_1.6" class="menuitemgroup">
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</div>
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper/FAQ">FAQ</a>
+</div>
+<div class="menuitem">
+<a href="http://hadoop.apache.org/zookeeper/mailing_lists.html">Mailing Lists</a>
+</div>
+</div>
+<div id="credit"></div>
+<div id="roundbottom">
+<img style="display: none" class="corner" height="15" width="15" alt="" src="skin/images/rc-b-l-15-1body-2menu-3menu.png"></div>
+<!--+
+ |alternative credits
+ +-->
+<div id="credit2"></div>
+</div>
+<!--+
+ |end Menu
+ +-->
+<!--+
+ |start content
+ +-->
+<div id="content">
+<div title="Portable Document Format" class="pdflink">
+<a class="dida" href="bookkeeperStarted.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br>
+ PDF</a>
+</div>
+<h1>BookKeeper Getting Started Guide</h1>
+<div id="front-matter">
+<div id="minitoc-area">
+<ul class="minitoc">
+<li>
+<a href="#bk_GettingStarted">Getting Started: Setting up BookKeeper to write logs.</a>
+<ul class="minitoc">
+<li>
+<a href="#bk_Prerequisites">Pre-requisites</a>
+</li>
+<li>
+<a href="#bk_Download">Download</a>
+</li>
+<li>
+<a href="#bk_localBK">LocalBookKeeper</a>
+</li>
+<li>
+<a href="#bk_setupBookies">Setting up bookies</a>
+</li>
+<li>
+<a href="#bk_setupZK">Setting up ZooKeeper</a>
+</li>
+<li>
+<a href="#bk_example">Example</a>
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+
+
+
+
+<a name="bk_GettingStarted"></a>
+<h2 class="h3">Getting Started: Setting up BookKeeper to write logs.</h2>
+<div class="section">
+<p>This document contains information to get you started quickly with
+ BookKeeper. It is aimed primarily at developers willing to try it out, and
+ contains simple installation instructions for a simple BookKeeper installation
+ and a simple programming example. For further programming detail, please refer to
+ <a href="bookkeeperProgrammer.html">BookKeeper Programmer's Guide</a>.
+ </p>
+<a name="bk_Prerequisites"></a>
+<h3 class="h4">Pre-requisites</h3>
+<p>See <a href="bookkeeperConfig.html#bk_sysReq">
+ System Requirements</a> in the Admin guide.</p>
+<a name="bk_Download"></a>
+<h3 class="h4">Download</h3>
+<p> BookKeeper is distributed along with ZooKeeper. To get a ZooKeeper distribution,
+ download a recent
+ <a href="http://hadoop.apache.org/zookeeper/releases.html">
+ stable</a> release from one of the Apache Download
+ Mirrors.</p>
+<a name="bk_localBK"></a>
+<h3 class="h4">LocalBookKeeper</h3>
+<p> Under org.apache.bookkeeper.util, you'll find a java program
+ called LocalBookKeeper.java that sets you up to run BookKeeper on a
+ single machine. This is far from ideal from a performance perspective,
+ but the program is useful for both test and educational purposes.
+ </p>
+<a name="bk_setupBookies"></a>
+<h3 class="h4">Setting up bookies</h3>
+<p> If you're bold and you want more than just running things locally, then
+ you'll need to run bookies in different servers. You'll need at least three bookies
+ to start with.
+ </p>
+<p>
+ For each bookie, we need to execute a command like the following:
+ </p>
+<p>
+<span class="codefrag computeroutput">
+ java -cp .:./zookeeper-<version>-bookkeeper.jar:./zookeeper-<version>.jar:../log4j/apache-log4j-1.2.15/log4j-1.2.15.jar\
+ -Dlog4j.configuration=log4j.properties org.apache.bookkeeper.proto.BookieServer 3181 /path_to_log_device/\
+ /path_to_ledger_device/
+ </span>
+</p>
+<p> "/path_to_log_device/" and "/path_to_ledger_device/" are different paths. Also, port 3181
+ is the port that a bookie listens on for connection requests from clients.
+ </p>
+<a name="bk_setupZK"></a>
+<h3 class="h4">Setting up ZooKeeper</h3>
+<p> ZooKeeper stores metadata on behalf of BookKeeper clients and bookies. To get a minimal
+ ZooKeeper installation to work with BookKeeper, we can set up one server running in
+ standalone mode. Once we have the server running, we need to create a few znodes:
+ </p>
+<ol>
+
+<li>
+
+<p>
+<span class="codefrag computeroutput">
+ /ledgers
+ </span>
+</p>
+
+</li>
+
+
+<li>
+
+<p>
+<span class="codefrag computeroutput">
+ /ledgers/available
+ </span>
+</p>
+
+</li>
+
+
+<li>
+
+<p> For each bookie, we add one znode such that the name of the znode is the
+ concatenation of the machine name and the port number that the bookie is
+ listening on. For example, if a bookie is running on bookie.foo.com an is listening
+ on port 3181, we add a znode
+ <span class="codefrag computeroutput">/ledgers/available/bookie.foo.com:3181</span>.
+ </p>
+
+</li>
+
+</ol>
+<a name="bk_example"></a>
+<h3 class="h4">Example</h3>
+<p>
+ In the following excerpt of code, we:
+ </p>
+<ol>
+
+<li>
+
+<p>
+ Create a ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Write to the ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Close the ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Open the same ledger for reading;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Read from the ledger;
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+ Close the ledger again;
+ </p>
+
+</li>
+
+</ol>
+<pre class="code">
+LedgerHandle lh = bkc.createLedger(ledgerPassword);
+ledgerId = lh.getId();
+ByteBuffer entry = ByteBuffer.allocate(4);
+
+for(int i = 0; i < 10; i++){
+ entry.putInt(i);
+ entry.position(0);
+ entries.add(entry.array());
+ lh.addEntry(entry.array());
+}
+lh.close();
+lh = bkc.openLedger(ledgerId, ledgerPassword);
+
+LedgerSequence ls = lh.readEntries(0, 9);
+int i = 0;
+while(ls.hasMoreElements()){
+ ByteBuffer origbb = ByteBuffer.wrap(
+ entries.get(i++));
+ Integer origEntry = origbb.getInt();
+ ByteBuffer result = ByteBuffer.wrap(
+ ls.nextElement().getEntry());
+
+ Integer retrEntry = result.getInt();
+}
+lh.close();
+ </pre>
+</div>
+
+<p align="right">
+<font size="-2"></font>
+</p>
+</div>
+<!--+
+ |end content
+ +-->
+<div class="clearboth"> </div>
+</div>
+<div id="footer">
+<!--+
+ |start bottomstrip
+ +-->
+<div class="lastmodified">
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<div class="copyright">
+ Copyright ©
+ 2008 <a href="http://www.apache.org/licenses/">The Apache Software Foundation.</a>
+</div>
+<!--+
+ |end bottomstrip
+ +-->
+</div>
+</body>
+</html>
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStarted.pdf
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStarted.pdf
------------------------------------------------------------------------------
svn:mime-type = application/pdf
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStream.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStream.html (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStream.html Wed Mar 21 06:15:08 2012
@@ -0,0 +1,612 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
+<meta content="Apache Forrest" name="Generator">
+<meta name="Forrest-version" content="0.9">
+<meta name="Forrest-skin-name" content="pelt">
+<title>Streaming with BookKeeper</title>
+<link type="text/css" href="skin/basic.css" rel="stylesheet">
+<link media="screen" type="text/css" href="skin/screen.css" rel="stylesheet">
+<link media="print" type="text/css" href="skin/print.css" rel="stylesheet">
+<link type="text/css" href="skin/profile.css" rel="stylesheet">
+<script src="skin/getBlank.js" language="javascript" type="text/javascript"></script><script src="skin/getMenu.js" language="javascript" type="text/javascript"></script><script src="skin/fontsize.js" language="javascript" type="text/javascript"></script>
+<link rel="shortcut icon" href="images/favicon.ico">
+</head>
+<body onload="init()">
+<script type="text/javascript">ndeSetTextSize();</script>
+<div id="top">
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+<a href="http://www.apache.org/">Apache</a> > <a href="http://hadoop.apache.org/">Hadoop</a> > <a href="http://hadoop.apache.org/zookeeper/">ZooKeeper</a><script src="skin/breadcrumbs.js" language="JavaScript" type="text/javascript"></script>
+</div>
+<!--+
+ |header
+ +-->
+<div class="header">
+<!--+
+ |start group logo
+ +-->
+<div class="grouplogo">
+<a href="http://hadoop.apache.org/"><img class="logoImage" alt="Hadoop" src="images/hadoop-logo.jpg" title="Apache Hadoop"></a>
+</div>
+<!--+
+ |end group logo
+ +-->
+<!--+
+ |start Project Logo
+ +-->
+<div class="projectlogo">
+<a href="http://hadoop.apache.org/zookeeper/"><img class="logoImage" alt="ZooKeeper" src="images/zookeeper_small.gif" title="ZooKeeper: distributed coordination"></a>
+</div>
+<!--+
+ |end Project Logo
+ +-->
+<!--+
+ |start Search
+ +-->
+<div class="searchbox">
+<form action="http://www.google.com/search" method="get" class="roundtopsmall">
+<input value="hadoop.apache.org" name="sitesearch" type="hidden"><input onFocus="getBlank (this, 'Search the site with google');" size="25" name="q" id="query" type="text" value="Search the site with google">
+ <input name="Search" value="Search" type="submit">
+</form>
+</div>
+<!--+
+ |end search
+ +-->
+<!--+
+ |start Tabs
+ +-->
+<ul id="tabs">
+<li>
+<a class="unselected" href="http://hadoop.apache.org/zookeeper/">Project</a>
+</li>
+<li>
+<a class="unselected" href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</li>
+<li class="current">
+<a class="selected" href="index.html">ZooKeeper 3.3 Documentation</a>
+</li>
+</ul>
+<!--+
+ |end Tabs
+ +-->
+</div>
+</div>
+<div id="main">
+<div id="publishedStrip">
+<!--+
+ |start Subtabs
+ +-->
+<div id="level2tabs"></div>
+<!--+
+ |end Endtabs
+ +-->
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<!--+
+ |breadtrail
+ +-->
+<div class="breadtrail">
+
+
+ </div>
+<!--+
+ |start Menu, mainarea
+ +-->
+<!--+
+ |start Menu
+ +-->
+<div id="menu">
+<div onclick="SwitchMenu('menu_1.1', 'skin/')" id="menu_1.1Title" class="menutitle">Overview</div>
+<div id="menu_1.1" class="menuitemgroup">
+<div class="menuitem">
+<a href="index.html">Welcome</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperOver.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperStarted.html">Getting Started</a>
+</div>
+<div class="menuitem">
+<a href="releasenotes.html">Release Notes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.2', 'skin/')" id="menu_1.2Title" class="menutitle">Developer</div>
+<div id="menu_1.2" class="menuitemgroup">
+<div class="menuitem">
+<a href="api/index.html">API Docs</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperProgrammers.html">Programmer's Guide</a>
+</div>
+<div class="menuitem">
+<a href="javaExample.html">Java Example</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperTutorial.html">Barrier and Queue Tutorial</a>
+</div>
+<div class="menuitem">
+<a href="recipes.html">Recipes</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.3', 'skin/')" id="menu_1.3Title" class="menutitle">BookKeeper</div>
+<div id="menu_1.3" class="menuitemgroup">
+<div class="menuitem">
+<a href="bookkeeperStarted.html">Getting started</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperOverview.html">Overview</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperConfig.html">Setup guide</a>
+</div>
+<div class="menuitem">
+<a href="bookkeeperProgrammer.html">Programmer's guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.4', 'skin/')" id="menu_1.4Title" class="menutitle">Admin & Ops</div>
+<div id="menu_1.4" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperAdmin.html">Administrator's Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperQuotas.html">Quota Guide</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperJMX.html">JMX</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperObservers.html">Observers Guide</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.5', 'skin/')" id="menu_1.5Title" class="menutitle">Contributor</div>
+<div id="menu_1.5" class="menuitemgroup">
+<div class="menuitem">
+<a href="zookeeperInternals.html">ZooKeeper Internals</a>
+</div>
+</div>
+<div onclick="SwitchMenu('menu_1.6', 'skin/')" id="menu_1.6Title" class="menutitle">Miscellaneous</div>
+<div id="menu_1.6" class="menuitemgroup">
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper">Wiki</a>
+</div>
+<div class="menuitem">
+<a href="http://wiki.apache.org/hadoop/ZooKeeper/FAQ">FAQ</a>
+</div>
+<div class="menuitem">
+<a href="http://hadoop.apache.org/zookeeper/mailing_lists.html">Mailing Lists</a>
+</div>
+</div>
+<div id="credit"></div>
+<div id="roundbottom">
+<img style="display: none" class="corner" height="15" width="15" alt="" src="skin/images/rc-b-l-15-1body-2menu-3menu.png"></div>
+<!--+
+ |alternative credits
+ +-->
+<div id="credit2"></div>
+</div>
+<!--+
+ |end Menu
+ +-->
+<!--+
+ |start content
+ +-->
+<div id="content">
+<div title="Portable Document Format" class="pdflink">
+<a class="dida" href="bookkeeperStream.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br>
+ PDF</a>
+</div>
+<h1>Streaming with BookKeeper</h1>
+<div id="front-matter">
+<div id="minitoc-area">
+<ul class="minitoc">
+<li>
+<a href="#bk_StreamSummary">Summary</a>
+</li>
+<li>
+<a href="#bk_LedgerOutputStream">Writing a stream of bytes</a>
+</li>
+<li>
+<a href="#bk_LedgerInputStream">Reading a stream of bytes</a>
+</li>
+</ul>
+</div>
+</div>
+
+
+
+
+<a name="bk_StreamSummary"></a>
+<h2 class="h3">Summary</h2>
+<div class="section">
+<p>
+ When using the BookKeeper API, an application has to split the data to write into entries, each
+ entry being a byte array. This is natural for many applications. For example, when using BookKeeper
+ for write-ahead logging, an application typically wants to write the modifications corresponding
+ to a command or a transaction. Some other applications, however, might not have a natural boundary
+ for entries, and may prefer to write and read streams of bytes. This is exactly the purpose of the
+ stream API we have implemented on top of BookKeeper.
+ </p>
+<p>
+ The stream API is implemented in the package <span class="codefrag computeroutput">Streaming</span>, and it contains two main classes: <span class="codefrag computeroutput">LedgerOutputStream</span> and
+ <span class="codefrag computeroutput">LedgerInputStream</span>. The class names are indicative of what they do.
+ </p>
+</div>
+
+
+<a name="bk_LedgerOutputStream"></a>
+<h2 class="h3">Writing a stream of bytes</h2>
+<div class="section">
+<p>
+ Class <span class="codefrag computeroutput">LedgerOutputStream</span> implements two constructors and five public methods:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerOutputStream(LedgerHandle lh)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a ledger handle for a previously created and open ledger.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerOutputStream(LedgerHandle lh, int size)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a ledger handle for a previously created and open ledger.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">size</span> is the size of the byte buffer to store written bytes before flushing.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<strong>Closing a stream.</strong> This call closes the stream by flushing the write buffer.
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void close()
+ </span>
+
+</p>
+<p>
+ which has no parameters.
+ </p>
+<p>
+
+<strong>Flushing a stream.</strong> This call essentially flushes the write buffer.
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized void flush()
+ </span>
+
+</p>
+<p>
+ which has no parameters.
+ </p>
+<p>
+
+<strong>Writing bytes.</strong> There are three calls for writing bytes to a stream.
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized void write(byte[] b)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">b</span> is an array of bytes to write.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized void write(byte[] b, int off, int len)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">b</span> is an array of bytes to write.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">off</span> is a buffer offset.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">len</span> is the length to write.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized void write(int b)
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">b</span> contains a byte to write. The method writes the least significant byte of the integer four bytes.
+ </p>
+
+</li>
+
+</ul>
+</div>
+
+
+<a name="bk_LedgerInputStream"></a>
+<h2 class="h3">Reading a stream of bytes</h2>
+<div class="section">
+<p>
+ Class <span class="codefrag computeroutput">LedgerOutputStream</span> implements two constructors and four public methods:
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerInputStream(LedgerHandle lh)
+ throws BKException, InterruptedException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a ledger handle for a previously created and open ledger.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public LedgerInputStream(LedgerHandle lh, int size)
+ throws BKException, InterruptedException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">lh</span> is a ledger handle for a previously created and open ledger.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">size</span> is the size of the byte buffer to store bytes that the application
+ will eventually read.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<strong>Closing.</strong> There is one call to close an input stream, but the call
+ is currently empty and the application is responsible for closing the ledger handle.
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public void close()
+ </span>
+
+</p>
+<p>
+ which has no parameters.
+ </p>
+<p>
+
+<strong>Reading.</strong> There are three calls to read from the stream.
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized int read()
+ throws IOException
+ </span>
+
+</p>
+<p>
+ which has no parameters.
+ </p>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized int read(byte[] b)
+ throws IOException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">b</span> is a byte array to write to.
+ </p>
+
+</li>
+
+</ul>
+<p>
+
+<span class="codefrag computeroutput">
+ public synchronized int read(byte[] b, int off, int len)
+ throws IOException
+ </span>
+
+</p>
+<p>
+ where:
+ </p>
+<ul>
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">b</span> is a byte array to write to.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">off</span> is an offset for byte array <span class="codefrag computeroutput">b</span>.
+ </p>
+
+</li>
+
+
+<li>
+
+<p>
+
+<span class="codefrag computeroutput">len</span> is the length in bytes to write to <span class="codefrag computeroutput">b</span>.
+ </p>
+
+</li>
+
+</ul>
+</div>
+
+<p align="right">
+<font size="-2"></font>
+</p>
+</div>
+<!--+
+ |end content
+ +-->
+<div class="clearboth"> </div>
+</div>
+<div id="footer">
+<!--+
+ |start bottomstrip
+ +-->
+<div class="lastmodified">
+<script type="text/javascript"><!--
+document.write("Last Published: " + document.lastModified);
+// --></script>
+</div>
+<div class="copyright">
+ Copyright ©
+ 2008 <a href="http://www.apache.org/licenses/">The Apache Software Foundation.</a>
+</div>
+<!--+
+ |end bottomstrip
+ +-->
+</div>
+</body>
+</html>
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStream.pdf
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/bookkeeperStream.pdf
------------------------------------------------------------------------------
svn:mime-type = application/pdf
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/broken-links.xml
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.3.5/broken-links.xml (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.3.5/broken-links.xml Wed Mar 21 06:15:08 2012
@@ -0,0 +1,2 @@
+<broken-links>
+</broken-links>
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/2pc.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/2pc.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/bk-overview.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/bk-overview.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/built-with-forrest-button.png
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/built-with-forrest-button.png
------------------------------------------------------------------------------
svn:mime-type = image/png
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/favicon.ico
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/favicon.ico
------------------------------------------------------------------------------
svn:mime-type = image/x-ico
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/hadoop-logo.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/hadoop-logo.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/instruction_arrow.png
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/instruction_arrow.png
------------------------------------------------------------------------------
svn:mime-type = image/png
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/state_dia.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/state_dia.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkcomponents.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkcomponents.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zknamespace.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zknamespace.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkperfRW-3.2.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkperfRW-3.2.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkperfRW.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkperfRW.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkperfreliability.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkperfreliability.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkservice.jpg
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zkservice.jpg
------------------------------------------------------------------------------
svn:mime-type = image/jpeg
Added: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zookeeper_small.gif
==============================================================================
Binary file - no diff available.
Propchange: websites/staging/zookeeper/trunk/content/doc/r3.3.5/images/zookeeper_small.gif
------------------------------------------------------------------------------
svn:mime-type = image/gif