zookeeper-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From build...@apache.org
Subject svn commit: r800374 [41/41] - in /websites/staging/zookeeper/trunk/content: ./ doc/r3.4.1/ doc/r3.4.1/api/ doc/r3.4.1/api/org/ doc/r3.4.1/api/org/apache/ doc/r3.4.1/api/org/apache/zookeeper/ doc/r3.4.1/api/org/apache/zookeeper/class-use/ doc/r3.4.1/api...
Date Fri, 16 Dec 2011 23:33:41 GMT
Added: websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperStarted.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperStarted.html (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperStarted.html Fri Dec 16 23:33:33 2011
@@ -0,0 +1,645 @@
+<!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>ZooKeeper 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> &gt; <a href="http://hadoop.apache.org/">Hadoop</a> &gt; <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">&nbsp; 
+                    <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 3.4 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">
+
+             &nbsp;
+           </div>
+<!--+
+    |start Menu, mainarea
+    +-->
+<!--+
+    |start Menu
+    +-->
+<div id="menu">
+<div onclick="SwitchMenu('menu_selected_1.1', 'skin/')" id="menu_selected_1.1Title" class="menutitle" style="background-image: url('skin/images/chapter_open.gif');">Overview</div>
+<div id="menu_selected_1.1" class="selectedmenuitemgroup" style="display: block;">
+<div class="menuitem">
+<a href="index.html">Welcome</a>
+</div>
+<div class="menuitem">
+<a href="zookeeperOver.html">Overview</a>
+</div>
+<div class="menupage">
+<div class="menupagetitle">Getting Started</div>
+</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 &amp; 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="zookeeperStarted.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br>
+        PDF</a>
+</div>
+<h1>ZooKeeper Getting Started Guide</h1>
+<div id="front-matter">
+<div id="minitoc-area">
+<ul class="minitoc">
+<li>
+<a href="#ch_GettingStarted">Getting Started: Coordinating Distributed Applications with
+      ZooKeeper</a>
+<ul class="minitoc">
+<li>
+<a href="#sc_Prerequisites">Pre-requisites</a>
+</li>
+<li>
+<a href="#sc_Download">Download</a>
+</li>
+<li>
+<a href="#sc_InstallingSingleMode">Standalone Operation</a>
+</li>
+<li>
+<a href="#sc_FileManagement">Managing ZooKeeper Storage</a>
+</li>
+<li>
+<a href="#sc_ConnectingToZooKeeper">Connecting to ZooKeeper</a>
+</li>
+<li>
+<a href="#sc_ProgrammingToZooKeeper">Programming to ZooKeeper</a>
+</li>
+<li>
+<a href="#sc_RunningReplicatedZooKeeper">Running Replicated ZooKeeper</a>
+</li>
+<li>
+<a href="#Other+Optimizations">Other Optimizations</a>
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+  
+
+  
+
+  
+<a name="ch_GettingStarted"></a>
+<h2 class="h3">Getting Started: Coordinating Distributed Applications with
+      ZooKeeper</h2>
+<div class="section">
+<p>This document contains information to get you started quickly with
+    ZooKeeper. It is aimed primarily at developers hoping to try it out, and
+    contains simple installation instructions for a single ZooKeeper server, a
+    few commands to verify that it is running, and a simple programming
+    example. Finally, as a convenience, there are a few sections regarding
+    more complicated installations, for example running replicated
+    deployments, and optimizing the transaction log. However for the complete
+    instructions for commercial deployments, please refer to the <a href="zookeeperAdmin.html">ZooKeeper
+    Administrator's Guide</a>.</p>
+<a name="sc_Prerequisites"></a>
+<h3 class="h4">Pre-requisites</h3>
+<p>See <a href="zookeeperAdmin.html#sc_systemReq">
+          System Requirements</a> in the Admin guide.</p>
+<a name="sc_Download"></a>
+<h3 class="h4">Download</h3>
+<p>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="sc_InstallingSingleMode"></a>
+<h3 class="h4">Standalone Operation</h3>
+<p>Setting up a ZooKeeper server in standalone mode is
+      straightforward. The server is contained in a single JAR file,
+      so installation consists of creating a configuration.</p>
+<p>Once you've downloaded a stable ZooKeeper release unpack
+      it and cd to the root</p>
+<p>To start ZooKeeper you need a configuration file. Here is a sample,
+      create it in <strong>conf/zoo.cfg</strong>:</p>
+<pre class="code">
+tickTime=2000
+dataDir=/var/lib/zookeeper
+clientPort=2181
+</pre>
+<p>This file can be called anything, but for the sake of this
+      discussion call
+      it <strong>conf/zoo.cfg</strong>. Change the
+      value of <strong>dataDir</strong> to specify an
+      existing (empty to start with) directory.  Here are the meanings
+      for each of the fields:</p>
+<dl>
+        
+<dt>
+<term>
+<strong>tickTime</strong>
+</term>
+</dt>
+<dd>
+<p>the basic time unit in milliseconds used by ZooKeeper. It is
+            used to do heartbeats and the minimum session timeout will be
+            twice the tickTime.</p>
+</dd>
+      
+</dl>
+<dl>
+        
+<dt>
+<term>
+<strong>dataDir</strong>
+</term>
+</dt>
+<dd>
+<p>the location to store the in-memory database snapshots and,
+            unless specified otherwise, the transaction log of updates to the
+            database.</p>
+</dd>
+
+        
+<dt>
+<term>
+<strong>clientPort</strong>
+</term>
+</dt>
+<dd>
+<p>the port to listen for client connections</p>
+</dd>
+      
+</dl>
+<p>Now that you created the configuration file, you can start
+      ZooKeeper:</p>
+<pre class="code">bin/zkServer.sh start</pre>
+<p>ZooKeeper logs messages using log4j -- more detail
+      available in the
+      <a href="zookeeperProgrammers.html#Logging">Logging</a>
+      section of the Programmer's Guide. You will see log messages
+      coming to the console (default) and/or a log file depending on
+      the log4j configuration.</p>
+<p>The steps outlined here run ZooKeeper in standalone mode. There is
+      no replication, so if ZooKeeper process fails, the service will go down.
+      This is fine for most development situations, but to run ZooKeeper in
+      replicated mode, please see <a href="#sc_RunningReplicatedZooKeeper">Running Replicated
+      ZooKeeper</a>.</p>
+<a name="sc_FileManagement"></a>
+<h3 class="h4">Managing ZooKeeper Storage</h3>
+<p>For long running production systems ZooKeeper storage must
+      be managed externally (dataDir and logs). See the section on
+      <a href="zookeeperAdmin.html#sc_maintenance">maintenance</a> for
+      more details.</p>
+<a name="sc_ConnectingToZooKeeper"></a>
+<h3 class="h4">Connecting to ZooKeeper</h3>
+<p>Once ZooKeeper is running, you have several options for connection
+      to it:</p>
+<ul>
+        
+<li>
+          
+<p>
+<strong>Java</strong>: Use</p>
+
+          
+<pre class="code">bin/zkCli.sh -server 127.0.0.1:2181</pre>
+
+          
+<p>This lets you perform simple, file-like operations.</p>
+        
+</li>
+
+        
+<li>
+          
+<p>
+<strong>C</strong>: compile cli_mt
+          (multi-threaded) or cli_st (single-threaded) by running
+          <span class="codefrag command">make cli_mt</span> or <span class="codefrag command">make
+          cli_st</span> in
+          the <strong>src/c</strong> subdirectory in
+          the ZooKeeper sources. See the README contained within
+          <strong>src/c</strong> for full details.</p>
+
+          
+<p>You can run the program
+          from <strong>src/c</strong> using:</p>
+
+          
+<pre class="code">LD_LIBRARY_PATH=. cli_mt 127.0.0.1:2181</pre>
+
+          
+<p>or</p>
+
+          
+<pre class="code">LD_LIBRARY_PATH=. cli_st 127.0.0.1:2181</pre>
+          
+<p>This will give you a simple shell to execute file
+          system like operations on ZooKeeper.</p>
+        
+</li>
+      
+</ul>
+<p>Once you have connected, you should see something like:
+        </p>
+<pre class="code">
+
+Connecting to localhost:2181
+log4j:WARN No appenders could be found for logger (org.apache.zookeeper.ZooKeeper).
+log4j:WARN Please initialize the log4j system properly.
+Welcome to ZooKeeper!
+JLine support is enabled
+[zkshell: 0]
+        </pre>
+<p>
+        From the shell, type <span class="codefrag command">help</span> to get a listing of commands that can be executed from the client, as in:
+      </p>
+<pre class="code">
+
+[zkshell: 0] help
+ZooKeeper host:port cmd args
+        get path [watch]
+        ls path [watch]
+        set path data [version]
+        delquota [-n|-b] path
+        quit
+        printwatches on|off
+        createpath data acl
+        stat path [watch]
+        listquota path
+        history
+        setAcl path acl
+        getAcl path
+        sync path
+        redo cmdno
+        addauth scheme auth
+        delete path [version]
+        setquota -n|-b val path
+
+        </pre>
+<p>From here, you can try a few simple commands to get a feel for this simple command line interface.  First, start by issuing the list command, as
+      in <span class="codefrag command">ls</span>, yielding:
+      </p>
+<pre class="code">
+
+[zkshell: 8] ls /
+[zookeeper]
+        </pre>
+<p>Next, create a new znode by running <span class="codefrag command">create /zk_test my_data</span>. This creates a new znode and associates the string "my_data" with the node.
+      You should see:</p>
+<pre class="code">
+
+[zkshell: 9] create /zk_test my_data
+Created /zk_test
+      </pre>
+<p>  Issue another <span class="codefrag command">ls /</span> command to see what the directory looks like:
+        </p>
+<pre class="code">
+
+[zkshell: 11] ls /
+[zookeeper, zk_test]
+
+        </pre>
+<p>
+      Notice that the zk_test directory has now been created.
+      </p>
+<p>Next, verify that the data was associated with the znode by running the <span class="codefrag command">get</span> command, as in:
+      </p>
+<pre class="code">
+
+[zkshell: 12] get /zk_test
+my_data
+cZxid = 5
+ctime = Fri Jun 05 13:57:06 PDT 2009
+mZxid = 5
+mtime = Fri Jun 05 13:57:06 PDT 2009
+pZxid = 5
+cversion = 0
+dataVersion = 0
+aclVersion = 0
+ephemeralOwner = 0
+dataLength = 7
+numChildren = 0
+        </pre>
+<p>We can change the data associated with zk_test by issuing the <span class="codefrag command">set</span> command, as in:
+        </p>
+<pre class="code">
+
+[zkshell: 14] set /zk_test junk
+cZxid = 5
+ctime = Fri Jun 05 13:57:06 PDT 2009
+mZxid = 6
+mtime = Fri Jun 05 14:01:52 PDT 2009
+pZxid = 5
+cversion = 0
+dataVersion = 1
+aclVersion = 0
+ephemeralOwner = 0
+dataLength = 4
+numChildren = 0
+[zkshell: 15] get /zk_test
+junk
+cZxid = 5
+ctime = Fri Jun 05 13:57:06 PDT 2009
+mZxid = 6
+mtime = Fri Jun 05 14:01:52 PDT 2009
+pZxid = 5
+cversion = 0
+dataVersion = 1
+aclVersion = 0
+ephemeralOwner = 0
+dataLength = 4
+numChildren = 0
+      </pre>
+<p>
+       (Notice we did a <span class="codefrag command">get</span> after setting the data and it did, indeed, change.</p>
+<p>Finally, let's <span class="codefrag command">delete</span> the node by issuing:
+      </p>
+<pre class="code">
+
+[zkshell: 16] delete /zk_test
+[zkshell: 17] ls /
+[zookeeper]
+[zkshell: 18]
+</pre>
+<p>That's it for now.  To explore more, continue with the rest of this document and see the <a href="zookeeperProgrammers.html">Programmer's Guide</a>. </p>
+<a name="sc_ProgrammingToZooKeeper"></a>
+<h3 class="h4">Programming to ZooKeeper</h3>
+<p>ZooKeeper has a Java bindings and C bindings. They are
+      functionally equivalent. The C bindings exist in two variants: single
+      threaded and multi-threaded. These differ only in how the messaging loop
+      is done. For more information, see the <a href="zookeeperProgrammers.html#ch_programStructureWithExample">Programming
+      Examples in the ZooKeeper Programmer's Guide</a> for
+      sample code using of the different APIs.</p>
+<a name="sc_RunningReplicatedZooKeeper"></a>
+<h3 class="h4">Running Replicated ZooKeeper</h3>
+<p>Running ZooKeeper in standalone mode is convenient for evaluation,
+      some development, and testing. But in production, you should run
+      ZooKeeper in replicated mode. A replicated group of servers in the same
+      application is called a <em>quorum</em>, and in replicated
+      mode, all servers in the quorum have copies of the same configuration
+      file. The file is similar to the one used in standalone mode, but with a
+      few differences. Here is an example:</p>
+<pre class="code">
+tickTime=2000
+dataDir=/var/lib/zookeeper
+clientPort=2181
+initLimit=5
+syncLimit=2
+server.1=zoo1:2888:3888
+server.2=zoo2:2888:3888
+server.3=zoo3:2888:3888
+</pre>
+<p>The new entry, <strong>initLimit</strong> is
+      timeouts ZooKeeper uses to limit the length of time the ZooKeeper
+      servers in quorum have to connect to a leader. The entry <strong>syncLimit</strong> limits how far out of date a server can
+      be from a leader.</p>
+<p>With both of these timeouts, you specify the unit of time using
+      <strong>tickTime</strong>. In this example, the timeout
+      for initLimit is 5 ticks at 2000 milleseconds a tick, or 10
+      seconds.</p>
+<p>The entries of the form <em>server.X</em> list the
+      servers that make up the ZooKeeper service. When the server starts up,
+      it knows which server it is by looking for the file
+      <em>myid</em> in the data directory. That file has the 
+      contains the server number, in ASCII.</p>
+<p>Finally, note the two port numbers after each server
+       name: " 2888" and "3888". Peers use the former port to connect
+       to other peers. Such a connection is necessary so that peers
+       can communicate, for example, to agree upon the order of
+       updates. More specifically, a ZooKeeper server uses this port
+       to connect followers to the leader. When a new leader arises, a
+       follower opens a TCP connection to the leader using this
+       port. Because the default leader election also uses TCP, we
+       currently require another port for leader election. This is the
+       second port in the server entry.
+       </p>
+<div class="note">
+<div class="label">Note</div>
+<div class="content">
+        
+<p>If you want to test multiple servers on a single
+        machine, specify the servername
+        as <em>localhost</em> with unique quorum &amp;
+        leader election ports (i.e. 2888:3888, 2889:3889, 2890:3890 in
+        the example above) for each server.X in that server's config
+        file. Of course separate <em>dataDir</em>s and
+        distinct <em>clientPort</em>s are also necessary
+        (in the above replicated example, running on a
+        single <em>localhost</em>, you would still have
+        three config files).</p>
+      
+</div>
+</div>
+<a name="Other+Optimizations"></a>
+<h3 class="h4">Other Optimizations</h3>
+<p>There are a couple of other configuration parameters that can
+      greatly increase performance:</p>
+<ul>
+        
+<li>
+          
+<p>To get low latencies on updates it is important to
+          have a dedicated transaction log directory. By default
+          transaction logs are put in the same directory as the data
+          snapshots and <em>myid</em> file. The dataLogDir
+          parameters indicates a different directory to use for the
+          transaction logs.</p>
+        
+</li>
+
+        
+<li>
+          
+<p>
+<em>[tbd: what is the other config param?]</em>
+</p>
+        
+</li>
+      
+</ul>
+</div>
+
+<p align="right">
+<font size="-2"></font>
+</p>
+</div>
+<!--+
+    |end content
+    +-->
+<div class="clearboth">&nbsp;</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 &copy;
+         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/r3.4.1/zookeeperStarted.pdf
==============================================================================
Binary file - no diff available.

Propchange: websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperStarted.pdf
------------------------------------------------------------------------------
    svn:mime-type = application/octet-stream

Added: websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperTutorial.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperTutorial.html (added)
+++ websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperTutorial.html Fri Dec 16 23:33:33 2011
@@ -0,0 +1,894 @@
+<!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>Programming with ZooKeeper - A basic tutorial</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> &gt; <a href="http://hadoop.apache.org/">Hadoop</a> &gt; <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">&nbsp; 
+                    <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 3.4 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">
+
+             &nbsp;
+           </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_selected_1.2', 'skin/')" id="menu_selected_1.2Title" class="menutitle" style="background-image: url('skin/images/chapter_open.gif');">Developer</div>
+<div id="menu_selected_1.2" class="selectedmenuitemgroup" style="display: block;">
+<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="menupage">
+<div class="menupagetitle">Barrier and Queue Tutorial</div>
+</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 &amp; 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="zookeeperTutorial.pdf"><img alt="PDF -icon" src="skin/images/pdfdoc.gif" class="skin"><br>
+        PDF</a>
+</div>
+<h1>Programming with ZooKeeper - A basic tutorial</h1>
+<div id="front-matter">
+<div id="minitoc-area">
+<ul class="minitoc">
+<li>
+<a href="#ch_Introduction">Introduction</a>
+</li>
+<li>
+<a href="#sc_barriers">Barriers</a>
+</li>
+<li>
+<a href="#sc_producerConsumerQueues">Producer-Consumer Queues</a>
+</li>
+<li>
+<a href="#sc_sourceListing">Complete Source Listing</a>
+</li>
+</ul>
+</div>
+</div>
+  
+
+  
+
+  
+<a name="ch_Introduction"></a>
+<h2 class="h3">Introduction</h2>
+<div class="section">
+<p>In this tutorial, we show simple implementations of barriers and 
+    producer-consumer queues using ZooKeeper. We call the respective classes Barrier and Queue. 
+    These examples assume that you have at least one ZooKeeper server running.</p>
+<p>Both primitives use the following common excerpt of code:</p>
+<pre class="code">
+    static ZooKeeper zk = null;
+    static Integer mutex;
+
+    String root;
+
+    SyncPrimitive(String address) {
+        if(zk == null){
+            try {
+                System.out.println("Starting ZK:");
+                zk = new ZooKeeper(address, 3000, this);
+                mutex = new Integer(-1);
+                System.out.println("Finished starting ZK: " + zk);
+            } catch (IOException e) {
+                System.out.println(e.toString());
+                zk = null;
+            }
+        }
+    }
+
+    synchronized public void process(WatchedEvent event) {
+        synchronized (mutex) {
+            mutex.notify();
+        }
+    }
+</pre>
+<p>Both classes extend SyncPrimitive. In this way, we execute steps that are 
+common to all primitives in the constructor of SyncPrimitive. To keep the examples 
+simple, we create a ZooKeeper object the first time we instantiate either a barrier 
+object or a queue object, and we declare a static variable that is a reference 
+to this object. The subsequent instances of Barrier and Queue check whether a 
+ZooKeeper object exists. Alternatively, we could have the application creating a
+ZooKeeper object and passing it to the constructor of Barrier and Queue.</p>
+<p>
+We use the process() method to process notifications triggered due to watches. 
+In the following discussion, we present code that sets watches. A watch is internal 
+structure that enables ZooKeeper to notify a client of a change to a node. For example, 
+if a client is waiting for other clients to leave a barrier, then it can set a watch and 
+wait for modifications to a particular node, which can indicate that it is the end of the wait. 
+This point becomes clear once we go over the examples.
+</p>
+</div>
+   
+ 
+<a name="sc_barriers"></a>
+<h2 class="h3">Barriers</h2>
+<div class="section">
+<p>
+ A barrier is a primitive that enables a group of processes to synchronize the 
+ beginning and the end of a computation. The general idea of this implementation 
+ is to have a barrier node that serves the purpose of being a parent for individual 
+ process nodes. Suppose that we call the barrier node "/b1". Each process "p" then 
+ creates a node "/b1/p". Once enough processes have created their corresponding 
+ nodes, joined processes can start the computation.
+ </p>
+<p>In this example, each process instantiates a Barrier object, and its constructor takes as parameters:</p>
+<ul>
+<li>
+<p>the address of a ZooKeeper server (e.g., "zoo1.foo.com:2181")</p>
+</li>
+
+<li>
+<p>the path of the barrier node on ZooKeeper (e.g., "/b1")</p>
+</li>
+
+<li>
+<p>the size of the group of processes</p>
+</li>
+
+</ul>
+<p>The constructor of Barrier passes the address of the Zookeeper server to the 
+constructor of the parent class. The parent class creates a ZooKeeper instance if 
+one does not exist. The constructor of Barrier then creates a 
+barrier node on ZooKeeper, which is the parent node of all process nodes, and 
+we call root (<strong>Note:</strong> This is not the ZooKeeper root "/").</p>
+<pre class="code">
+        /**
+         * Barrier constructor
+         *
+         * @param address
+         * @param root
+         * @param size
+         */
+        Barrier(String address, String root, int size) {
+            super(address);
+            this.root = root;
+            this.size = size;
+
+            // Create barrier node
+            if (zk != null) {
+                try {
+                    Stat s = zk.exists(root, false);
+                    if (s == null) {
+                        zk.create(root, new byte[0], Ids.OPEN_ACL_UNSAFE,
+                                CreateMode.PERSISTENT);
+                    }
+                } catch (KeeperException e) {
+                    System.out
+                            .println("Keeper exception when instantiating queue: "
+                                    + e.toString());
+                } catch (InterruptedException e) {
+                    System.out.println("Interrupted exception");
+                }
+            }
+
+            // My node name
+            try {
+                name = new String(InetAddress.getLocalHost().getCanonicalHostName().toString());
+            } catch (UnknownHostException e) {
+                System.out.println(e.toString());
+            }
+
+        }
+</pre>
+<p>
+To enter the barrier, a process calls enter(). The process creates a node under 
+the root to represent it, using its host name to form the node name. It then wait 
+until enough processes have entered the barrier. A process does it by checking 
+the number of children the root node has with "getChildren()", and waiting for 
+notifications in the case it does not have enough. To receive a notification when 
+there is a change to the root node, a process has to set a watch, and does it 
+through the call to "getChildren()". In the code, we have that "getChildren()" 
+has two parameters. The first one states the node to read from, and the second is
+a boolean flag that enables the process to set a watch. In the code the flag is true.
+</p>
+<pre class="code">
+        /**
+         * Join barrier
+         *
+         * @return
+         * @throws KeeperException
+         * @throws InterruptedException
+         */
+
+        boolean enter() throws KeeperException, InterruptedException{
+            zk.create(root + "/" + name, new byte[0], Ids.OPEN_ACL_UNSAFE,
+                    CreateMode.EPHEMERAL_SEQUENTIAL);
+            while (true) {
+                synchronized (mutex) {
+                    List&lt;String&gt; list = zk.getChildren(root, true);
+
+                    if (list.size() &lt; size) {
+                        mutex.wait();
+                    } else {
+                        return true;
+                    }
+                }
+            }
+        }
+</pre>
+<p>
+Note that enter() throws both KeeperException and InterruptedException, so it is 
+the reponsability of the application to catch and handle such exceptions.</p>
+<p>
+Once the computation is finished, a process calls leave() to leave the barrier. 
+First it deletes its corresponding node, and then it gets the children of the root 
+node. If there is at least one child, then it waits for a notification (obs: note 
+that the second parameter of the call to getChildren() is true, meaning that 
+ZooKeeper has to set a watch on the the root node). Upon reception of a notification, 
+it checks once more whether the root node has any child.</p>
+<pre class="code">
+        /**
+         * Wait until all reach barrier
+         *
+         * @return
+         * @throws KeeperException
+         * @throws InterruptedException
+         */
+
+        boolean leave() throws KeeperException, InterruptedException{
+            zk.delete(root + "/" + name, 0);
+            while (true) {
+                synchronized (mutex) {
+                    List&lt;String&gt; list = zk.getChildren(root, true);
+                        if (list.size() &gt; 0) {
+                            mutex.wait();
+                        } else {
+                            return true;
+                        }
+                    }
+                }
+        }
+    }
+</pre>
+</div>
+
+<a name="sc_producerConsumerQueues"></a>
+<h2 class="h3">Producer-Consumer Queues</h2>
+<div class="section">
+<p>
+A producer-consumer queue is a distributed data estructure thata group of processes 
+use to generate and consume items. Producer processes create new elements and add 
+them to the queue. Consumer processes remove elements from the list, and process them. 
+In this implementation, the elements are simple integers. The queue is represented 
+by a root node, and to add an element to the queue, a producer process creates a new node, 
+a child of the root node.
+</p>
+<p>
+The following excerpt of code corresponds to the constructor of the object. As 
+with Barrier objects, it first calls the constructor of the parent class, SyncPrimitive, 
+that creates a ZooKeeper object if one doesn't exist. It then verifies if the root 
+node of the queue exists, and creates if it doesn't.
+</p>
+<pre class="code">
+        /**
+         * Constructor of producer-consumer queue
+         *
+         * @param address
+         * @param name
+         */
+        Queue(String address, String name) {
+            super(address);
+            this.root = name;
+            // Create ZK node name
+            if (zk != null) {
+                try {
+                    Stat s = zk.exists(root, false);
+                    if (s == null) {
+                        zk.create(root, new byte[0], Ids.OPEN_ACL_UNSAFE,
+                                CreateMode.PERSISTENT);
+                    }
+                } catch (KeeperException e) {
+                    System.out
+                            .println("Keeper exception when instantiating queue: "
+                                    + e.toString());
+                } catch (InterruptedException e) {
+                    System.out.println("Interrupted exception");
+                }
+            }
+        }
+</pre>
+<p>
+A producer process calls "produce()" to add an element to the queue, and passes 
+an integer as an argument. To add an element to the queue, the method creates a 
+new node using "create()", and uses the SEQUENCE flag to instruct ZooKeeper to 
+append the value of the sequencer counter associated to the root node. In this way, 
+we impose a total order on the elements of the queue, thus guaranteeing that the 
+oldest element of the queue is the next one consumed.
+</p>
+<pre class="code">
+        /**
+         * Add element to the queue.
+         *
+         * @param i
+         * @return
+         */
+
+        boolean produce(int i) throws KeeperException, InterruptedException{
+            ByteBuffer b = ByteBuffer.allocate(4);
+            byte[] value;
+
+            // Add child with value i
+            b.putInt(i);
+            value = b.array();
+            zk.create(root + "/element", value, Ids.OPEN_ACL_UNSAFE,
+                        CreateMode.PERSISTENT_SEQUENTIAL);
+
+            return true;
+        }
+</pre>
+<p>
+To consume an element, a consumer process obtains the children of the root node, 
+reads the node with smallest counter value, and returns the element. Note that 
+if there is a conflict, then one of the two contending processes won't be able to 
+delete the node and the delete operation will throw an exception.</p>
+<p>
+A call to getChildren() returns the list of children in lexicographic order. 
+As lexicographic order does not necessary follow the numerical order of the counter 
+values, we need to decide which element is the smallest. To decide which one has 
+the smallest counter value, we traverse the list, and remove the prefix "element" 
+from each one.</p>
+<pre class="code">
+        /**
+         * Remove first element from the queue.
+         *
+         * @return
+         * @throws KeeperException
+         * @throws InterruptedException
+         */
+        int consume() throws KeeperException, InterruptedException{
+            int retvalue = -1;
+            Stat stat = null;
+
+            // Get the first element available
+            while (true) {
+                synchronized (mutex) {
+                    List&lt;String&gt; list = zk.getChildren(root, true);
+                    if (list.size() == 0) {
+                        System.out.println("Going to wait");
+                        mutex.wait();
+                    } else {
+                        Integer min = new Integer(list.get(0).substring(7));
+                        for(String s : list){
+                            Integer tempValue = new Integer(s.substring(7));
+                            //System.out.println("Temporary value: " + tempValue);
+                            if(tempValue &lt; min) min = tempValue;
+                        }
+                        System.out.println("Temporary value: " + root + "/element" + min);
+                        byte[] b = zk.getData(root + "/element" + min,
+                                    false, stat);
+                        zk.delete(root + "/element" + min, 0);
+                        ByteBuffer buffer = ByteBuffer.wrap(b);
+                        retvalue = buffer.getInt();
+
+                        return retvalue;
+                    }
+                }
+            }
+        }
+    }
+</pre>
+</div>
+
+<a name="sc_sourceListing"></a>
+<h2 class="h3">Complete Source Listing</h2>
+<div class="section">
+<div class="note example">
+<div class="label">SyncPrimitive.Java</div>
+<div class="content">
+
+<title>SyncPrimitive.Java</title>
+
+<pre class="code">
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.Random;
+
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.WatchedEvent;
+import org.apache.zookeeper.Watcher;
+import org.apache.zookeeper.ZooKeeper;
+import org.apache.zookeeper.ZooDefs.Ids;
+import org.apache.zookeeper.data.Stat;
+
+public class SyncPrimitive implements Watcher {
+
+    static ZooKeeper zk = null;
+    static Integer mutex;
+
+    String root;
+
+    SyncPrimitive(String address) {
+        if(zk == null){
+            try {
+                System.out.println("Starting ZK:");
+                zk = new ZooKeeper(address, 3000, this);
+                mutex = new Integer(-1);
+                System.out.println("Finished starting ZK: " + zk);
+            } catch (IOException e) {
+                System.out.println(e.toString());
+                zk = null;
+            }
+        }
+        //else mutex = new Integer(-1);
+    }
+
+    synchronized public void process(WatchedEvent event) {
+        synchronized (mutex) {
+            //System.out.println("Process: " + event.getType());
+            mutex.notify();
+        }
+    }
+
+    /**
+     * Barrier
+     */
+    static public class Barrier extends SyncPrimitive {
+        int size;
+        String name;
+
+        /**
+         * Barrier constructor
+         *
+         * @param address
+         * @param root
+         * @param size
+         */
+        Barrier(String address, String root, int size) {
+            super(address);
+            this.root = root;
+            this.size = size;
+
+            // Create barrier node
+            if (zk != null) {
+                try {
+                    Stat s = zk.exists(root, false);
+                    if (s == null) {
+                        zk.create(root, new byte[0], Ids.OPEN_ACL_UNSAFE,
+                                CreateMode.PERSISTENT);
+                    }
+                } catch (KeeperException e) {
+                    System.out
+                            .println("Keeper exception when instantiating queue: "
+                                    + e.toString());
+                } catch (InterruptedException e) {
+                    System.out.println("Interrupted exception");
+                }
+            }
+
+            // My node name
+            try {
+                name = new String(InetAddress.getLocalHost().getCanonicalHostName().toString());
+            } catch (UnknownHostException e) {
+                System.out.println(e.toString());
+            }
+
+        }
+
+        /**
+         * Join barrier
+         *
+         * @return
+         * @throws KeeperException
+         * @throws InterruptedException
+         */
+
+        boolean enter() throws KeeperException, InterruptedException{
+            zk.create(root + "/" + name, new byte[0], Ids.OPEN_ACL_UNSAFE,
+                    CreateMode.EPHEMERAL_SEQUENTIAL);
+            while (true) {
+                synchronized (mutex) {
+                    List&lt;String&gt; list = zk.getChildren(root, true);
+
+                    if (list.size() &lt; size) {
+                        mutex.wait();
+                    } else {
+                        return true;
+                    }
+                }
+            }
+        }
+
+        /**
+         * Wait until all reach barrier
+         *
+         * @return
+         * @throws KeeperException
+         * @throws InterruptedException
+         */
+
+        boolean leave() throws KeeperException, InterruptedException{
+            zk.delete(root + "/" + name, 0);
+            while (true) {
+                synchronized (mutex) {
+                    List&lt;String&gt; list = zk.getChildren(root, true);
+                        if (list.size() &gt; 0) {
+                            mutex.wait();
+                        } else {
+                            return true;
+                        }
+                    }
+                }
+        }
+    }
+
+    /**
+     * Producer-Consumer queue
+     */
+    static public class Queue extends SyncPrimitive {
+
+        /**
+         * Constructor of producer-consumer queue
+         *
+         * @param address
+         * @param name
+         */
+        Queue(String address, String name) {
+            super(address);
+            this.root = name;
+            // Create ZK node name
+            if (zk != null) {
+                try {
+                    Stat s = zk.exists(root, false);
+                    if (s == null) {
+                        zk.create(root, new byte[0], Ids.OPEN_ACL_UNSAFE,
+                                CreateMode.PERSISTENT);
+                    }
+                } catch (KeeperException e) {
+                    System.out
+                            .println("Keeper exception when instantiating queue: "
+                                    + e.toString());
+                } catch (InterruptedException e) {
+                    System.out.println("Interrupted exception");
+                }
+            }
+        }
+
+        /**
+         * Add element to the queue.
+         *
+         * @param i
+         * @return
+         */
+
+        boolean produce(int i) throws KeeperException, InterruptedException{
+            ByteBuffer b = ByteBuffer.allocate(4);
+            byte[] value;
+
+            // Add child with value i
+            b.putInt(i);
+            value = b.array();
+            zk.create(root + "/element", value, Ids.OPEN_ACL_UNSAFE,
+                        CreateMode.PERSISTENT_SEQUENTIAL);
+
+            return true;
+        }
+
+
+        /**
+         * Remove first element from the queue.
+         *
+         * @return
+         * @throws KeeperException
+         * @throws InterruptedException
+         */
+        int consume() throws KeeperException, InterruptedException{
+            int retvalue = -1;
+            Stat stat = null;
+
+            // Get the first element available
+            while (true) {
+                synchronized (mutex) {
+                    List&lt;String&gt; list = zk.getChildren(root, true);
+                    if (list.size() == 0) {
+                        System.out.println("Going to wait");
+                        mutex.wait();
+                    } else {
+                        Integer min = new Integer(list.get(0).substring(7));
+                        for(String s : list){
+                            Integer tempValue = new Integer(s.substring(7));
+                            //System.out.println("Temporary value: " + tempValue);
+                            if(tempValue &lt; min) min = tempValue;
+                        }
+                        System.out.println("Temporary value: " + root + "/element" + min);
+                        byte[] b = zk.getData(root + "/element" + min,
+                                    false, stat);
+                        zk.delete(root + "/element" + min, 0);
+                        ByteBuffer buffer = ByteBuffer.wrap(b);
+                        retvalue = buffer.getInt();
+
+                        return retvalue;
+                    }
+                }
+            }
+        }
+    }
+
+    public static void main(String args[]) {
+        if (args[0].equals("qTest"))
+            queueTest(args);
+        else
+            barrierTest(args);
+
+    }
+
+    public static void queueTest(String args[]) {
+        Queue q = new Queue(args[1], "/app1");
+
+        System.out.println("Input: " + args[1]);
+        int i;
+        Integer max = new Integer(args[2]);
+
+        if (args[3].equals("p")) {
+            System.out.println("Producer");
+            for (i = 0; i &lt; max; i++)
+                try{
+                    q.produce(10 + i);
+                } catch (KeeperException e){
+
+                } catch (InterruptedException e){
+
+                }
+        } else {
+            System.out.println("Consumer");
+
+            for (i = 0; i &lt; max; i++) {
+                try{
+                    int r = q.consume();
+                    System.out.println("Item: " + r);
+                } catch (KeeperException e){
+                    i--;
+                } catch (InterruptedException e){
+
+                }
+            }
+        }
+    }
+
+    public static void barrierTest(String args[]) {
+        Barrier b = new Barrier(args[1], "/b1", new Integer(args[2]));
+        try{
+            boolean flag = b.enter();
+            System.out.println("Entered barrier: " + args[2]);
+            if(!flag) System.out.println("Error when entering the barrier");
+        } catch (KeeperException e){
+
+        } catch (InterruptedException e){
+
+        }
+
+        // Generate random integer
+        Random rand = new Random();
+        int r = rand.nextInt(100);
+        // Loop for rand iterations
+        for (int i = 0; i &lt; r; i++) {
+            try {
+                Thread.sleep(100);
+            } catch (InterruptedException e) {
+
+            }
+        }
+        try{
+            b.leave();
+        } catch (KeeperException e){
+
+        } catch (InterruptedException e){
+
+        }
+        System.out.println("Left barrier");
+    }
+}
+</pre>
+</div>
+</div>
+</div>
+
+
+<p align="right">
+<font size="-2"></font>
+</p>
+</div>
+<!--+
+    |end content
+    +-->
+<div class="clearboth">&nbsp;</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 &copy;
+         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/r3.4.1/zookeeperTutorial.pdf
==============================================================================
Binary file - no diff available.

Propchange: websites/staging/zookeeper/trunk/content/doc/r3.4.1/zookeeperTutorial.pdf
------------------------------------------------------------------------------
    svn:mime-type = application/octet-stream

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperConfig.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperConfig.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperConfig.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperOverview.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperOverview.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperOverview.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperProgrammer.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperProgrammer.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperProgrammer.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperStarted.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperStarted.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperStarted.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperStream.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperStream.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/bookkeeperStream.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/index.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/index.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/index.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/javaExample.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/javaExample.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/javaExample.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/linkmap.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/linkmap.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/linkmap.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/recipes.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/trunk/recipes.html (original)
+++ websites/staging/zookeeper/trunk/content/doc/trunk/recipes.html Fri Dec 16 23:33:33 2011
@@ -210,6 +210,9 @@ document.write("Last Published: " + docu
 <a href="#ch_recipes">A Guide to Creating Higher-level Constructs with ZooKeeper</a>
 <ul class="minitoc">
 <li>
+<a href="#sc_recipes_errorHandlingNote">Important Note About Error Handling</a>
+</li>
+<li>
 <a href="#sc_outOfTheBox">Out of the Box Applications: Name Service, Configuration, Group
     Membership</a>
 </li>
@@ -233,6 +236,9 @@ document.write("Last Published: " + docu
 <a href="#sc_recipes_Locks">Locks</a>
 <ul class="minitoc">
 <li>
+<a href="#sc_recipes_GuidNote">Recoverable Errors and the GUID</a>
+</li>
+<li>
 <a href="#Shared+Locks">Shared Locks</a>
 </li>
 <li>
@@ -281,6 +287,17 @@ document.write("Last Published: " + docu
     as event handles or queues, a more practical means of performing the same
     function. In general, the examples in this section are designed to
     stimulate thought.</p>
+<a name="sc_recipes_errorHandlingNote"></a>
+<h3 class="h4">Important Note About Error Handling</h3>
+<p>When implementing the recipes you must handle recoverable exceptions 
+	(see the <a href="http://wiki.apache.org/hadoop/ZooKeeper/FAQ">FAQ</a>). In 
+	particular, several of the recipes employ sequential ephemeral 
+	nodes. When creating a sequential ephemeral node there is an error case in 
+	which the create() succeeds on the server but the server crashes before 
+	returning the name of the node to the client. When the client reconnects its 
+	session is still valid and, thus, the node is not removed. The implication is 
+	that it is difficult for the client to know if its node was created or not. The 
+	recipes below include measures to handle this.</p>
 <a name="sc_outOfTheBox"></a>
 <h3 class="h4">Out of the Box Applications: Name Service, Configuration, Group
     Membership</h3>
@@ -454,7 +471,7 @@ document.write("Last Published: " + docu
 <li>
                     
 <p>if <em>p</em> is the lowest process
-                      node in L, wait on highest process node in L</p>
+                      node in L, wait on highest process node in P</p>
                   
 </li>
 
@@ -563,8 +580,9 @@ document.write("Last Published: " + docu
 <li>
         
 <p>Call <strong>create( )</strong> with a pathname
-        of "_locknode_/lock-" and the <em>sequence</em> and
-        <em>ephemeral</em> flags set.</p>
+        of "_locknode_/guid-lock-" and the <em>sequence</em> and
+        <em>ephemeral</em> flags set. The <em>guid</em> 
+		is needed in case the create() result is missed. See the note below.</p>
       
 </li>
 
@@ -639,6 +657,22 @@ document.write("Last Published: " + docu
 </li>
     
 </ul>
+<a name="sc_recipes_GuidNote"></a>
+<h4>Recoverable Errors and the GUID</h4>
+<ul>
+      
+<li>
+        
+<p>If a recoverable error occurs calling <strong>create()</strong> the 
+		client should call <strong>getChildren()</strong> and check for a node 
+		containing the <em>guid</em> used in the path name. 
+		This handles the case (noted <a href="#sc_recipes_errorHandlingNote">above</a>) of 
+		the create() succeeding on the server but the server crashing before returning the name 
+		of the new node.</p>
+      
+</li>
+    
+</ul>
 <a name="Shared+Locks"></a>
 <h4>Shared Locks</h4>
 <p>You can implement shared locks by with a few changes to the lock
@@ -666,7 +700,7 @@ document.write("Last Published: " + docu
                     
 <p>Call <strong>create( )</strong> to
                     create a node with pathname
-                    "<span class="codefrag filename">_locknode_/read-</span>". This is the
+                    "<span class="codefrag filename">guid-/read-</span>". This is the
                     lock node use later in the protocol. Make sure to set both
                     the <em>sequence</em> and
                     <em>ephemeral</em> flags.</p>
@@ -731,7 +765,7 @@ document.write("Last Published: " + docu
                     
 <p>Call <strong>create( )</strong> to
                     create a node with pathname
-                    "<span class="codefrag filename">_locknode_/write-</span>". This is the
+                    "<span class="codefrag filename">guid-/write-</span>". This is the
                     lock node spoken of later in the protocol. Make sure to
                     set both <em>sequence</em> and
                     <em>ephemeral</em> flags.</p>
@@ -784,9 +818,10 @@ document.write("Last Published: " + docu
           
       
 </table>
-<div class="note">
-<div class="label">Note</div>
-<div class="content">
+<p>Notes:</p>
+<ul>
+      
+<li>
         
 <p>It might appear that this recipe creates a herd effect:
           when there is a large group of clients waiting for a read
@@ -796,11 +831,20 @@ document.write("Last Published: " + docu
           as all those waiting reader clients should be released since
           they have the lock. The herd effect refers to releasing a
           "herd" when in fact only a single or a small number of
-          machines can proceed.
-        </p>
+          machines can proceed.</p>
       
-</div>
-</div>
+</li>
+    
+</ul>
+<ul>
+      
+<li>
+        
+<p>See the <a href="#sc_recipes_GuidNote">note for Locks</a> on how to use the guid in the node.</p>
+      
+</li>
+    
+</ul>
 <a name="sc_recoverableSharedLocks"></a>
 <h4>Recoverable Shared Locks</h4>
 <p>With minor modifications to the Shared Lock protocol, you make
@@ -860,7 +904,7 @@ document.write("Last Published: " + docu
 <p>A simple way of doing leader election with ZooKeeper is to use the
     <strong>SEQUENCE|EPHEMERAL</strong> flags when creating
     znodes that represent "proposals" of clients. The idea is to have a znode,
-    say "/election", such that each znode creates a child znode "/election/n_"
+    say "/election", such that each znode creates a child znode "/election/guid-n_"
     with both flags SEQUENCE|EPHEMERAL. With the sequence flag, ZooKeeper
     automatically appends a sequence number that is greater that any one
     previously appended to a child of "/election". The process that created
@@ -889,7 +933,7 @@ document.write("Last Published: " + docu
       
 <li>
         
-<p>Create znode z with path "ELECTION/n_" with both SEQUENCE and
+<p>Create znode z with path "ELECTION/guid-n_" with both SEQUENCE and
         EPHEMERAL flags;</p>
       
 </li>
@@ -905,7 +949,7 @@ document.write("Last Published: " + docu
       
 <li>
         
-<p>Watch for changes on "ELECTION/n_j", where j is the smallest
+<p>Watch for changes on "ELECTION/guid-n_j", where j is the smallest
         sequence number such that j &lt; i and n_j is a znode in C;</p>
       
 </li>
@@ -931,17 +975,35 @@ document.write("Last Published: " + docu
       
 <li>
         
-<p>Otherwise, watch for changes on "ELECTION/n_j", where j is the
+<p>Otherwise, watch for changes on "ELECTION/guid-n_j", where j is the
         smallest sequence number such that j &lt; i and n_j is a znode in C;
         </p>
       
 </li>
     
 </ol>
+<p>Notes:</p>
+<ul>
+      
+<li>
+	    
 <p>Note that the znode having no preceding znode on the list of
-    children does not imply that the creator of this znode is aware that it is
-    the current leader. Applications may consider creating a separate to znode
-    to acknowledge that the leader has executed the leader procedure. </p>
+	    children does not imply that the creator of this znode is aware that it is
+	    the current leader. Applications may consider creating a separate to znode
+	    to acknowledge that the leader has executed the leader procedure. </p>
+      
+</li>
+    
+</ul>
+<ul>
+      
+<li>
+        
+<p>See the <a href="#sc_recipes_GuidNote">note for Locks</a> on how to use the guid in the node.</p>
+      
+</li>
+    
+</ul>
 </div>
 
 <p align="right">

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/recipes.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/recipes.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/recipes.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/releasenotes.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/releasenotes.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/releasenotes.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperAdmin.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperAdmin.html (original)
+++ websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperAdmin.html Fri Dec 16 23:33:33 2011
@@ -291,6 +291,9 @@ document.write("Last Published: " + docu
 <a href="#sc_authOptions">Authentication &amp; Authorization Options</a>
 </li>
 <li>
+<a href="#Experimental+Options%2FFeatures">Experimental Options/Features</a>
+</li>
+<li>
 <a href="#Unsafe+Options">Unsafe Options</a>
 </li>
 <li>
@@ -1155,6 +1158,21 @@ server.3=zoo3:2888:3888</pre>
               the <strong>tickTime</strong>.</p>
 </dd>
            
+           
+<dt>
+<term>fsync.warningthresholdms</term>
+</dt>
+<dd>
+<p>(Java system property: <strong>fsync.warningthresholdms</strong>)</p>
+<p>
+<strong>New in 3.3.4:</strong> A
+               warning message will be output to the log whenever an
+               fsync in the Transactional Log (WAL) takes longer than
+               this value. The values is specified in milliseconds and
+               defaults to 1000. This value can only be set as a
+               system property.</p>
+</dd>
+
           
 <dt>
 <term>autopurge.snapRetainCount</term>
@@ -1372,6 +1390,31 @@ server.3=zoo3:2888:3888</pre>
 </dd>
         
 </dl>
+<a name="Experimental+Options%2FFeatures"></a>
+<h4>Experimental Options/Features</h4>
+<p>New features that are currently considered experimental.</p>
+<dl>
+          
+<dt>
+<term>Read Only Mode Server</term>
+</dt>
+<dd>
+<p>(Java system property: <strong>readonlymode.enabled</strong>)</p>
+<p>
+<strong>New in 3.4.0:</strong>
+              Setting this value to true enables Read Only Mode server
+              support (disabled by default). ROM allows clients
+              sessions which requested ROM support to connect to the
+              server even when the server might be partitioned from
+              the quorum. In this mode ROM clients can still read
+              values from the ZK service, but will be unable to write
+              values and see changes from other clients. See
+              ZOOKEEPER-784 for more details.
+              </p>
+</dd>
+
+        
+</dl>
 <a name="Unsafe+Options"></a>
 <h4>Unsafe Options</h4>
 <p>The following options can be useful, but be careful when you use

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperAdmin.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperAdmin.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperAdmin.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperHierarchicalQuorums.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperHierarchicalQuorums.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperHierarchicalQuorums.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperInternals.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperInternals.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperInternals.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperJMX.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperJMX.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperJMX.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperObservers.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperObservers.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperObservers.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperOver.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperOver.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperOver.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperProgrammers.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperProgrammers.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperProgrammers.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperQuotas.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperQuotas.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperQuotas.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperStarted.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperStarted.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperStarted.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperTutorial.pdf
==============================================================================
Files websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperTutorial.pdf (original) and websites/staging/zookeeper/trunk/content/doc/trunk/zookeeperTutorial.pdf Fri Dec 16 23:33:33 2011 differ

Modified: websites/staging/zookeeper/trunk/content/index.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/index.html (original)
+++ websites/staging/zookeeper/trunk/content/index.html Fri Dec 16 23:33:33 2011
@@ -120,8 +120,8 @@
 <h3>Documentation</h3>
 
 <ul>
-<li><a href="./doc/r3.4.0">Release 3.4.0</a></li>
-<li><a href="./doc/r3.3.4">Release 3.3.4&#40;current&#41;</a></li>
+<li><a href="./doc/r3.4.1">Release 3.4.1&#40;current&#41;</a></li>
+<li><a href="./doc/r3.3.4">Release 3.3.4&#40;stable&#41;</a></li>
 <li><a href="./doc/r3.3.3">Release 3.3.3</a></li>
 <li><a href="./doc/r3.3.2">Release 3.3.2</a></li>
 <li><a href="./doc/r3.2.2">Release 3.2.2</a></li>

Modified: websites/staging/zookeeper/trunk/content/irc.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/irc.html (original)
+++ websites/staging/zookeeper/trunk/content/irc.html Fri Dec 16 23:33:33 2011
@@ -96,8 +96,8 @@
 <h3>Documentation</h3>
 
 <ul>
-<li><a href="./doc/r3.4.0">Release 3.4.0</a></li>
-<li><a href="./doc/r3.3.4">Release 3.3.4&#40;current&#41;</a></li>
+<li><a href="./doc/r3.4.1">Release 3.4.1&#40;current&#41;</a></li>
+<li><a href="./doc/r3.3.4">Release 3.3.4&#40;stable&#41;</a></li>
 <li><a href="./doc/r3.3.3">Release 3.3.3</a></li>
 <li><a href="./doc/r3.3.2">Release 3.3.2</a></li>
 <li><a href="./doc/r3.2.2">Release 3.2.2</a></li>

Modified: websites/staging/zookeeper/trunk/content/lists.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/lists.html (original)
+++ websites/staging/zookeeper/trunk/content/lists.html Fri Dec 16 23:33:33 2011
@@ -136,8 +136,8 @@ In order to post to the list, it is nece
 <h3>Documentation</h3>
 
 <ul>
-<li><a href="./doc/r3.4.0">Release 3.4.0</a></li>
-<li><a href="./doc/r3.3.4">Release 3.3.4&#40;current&#41;</a></li>
+<li><a href="./doc/r3.4.1">Release 3.4.1&#40;current&#41;</a></li>
+<li><a href="./doc/r3.3.4">Release 3.3.4&#40;stable&#41;</a></li>
 <li><a href="./doc/r3.3.3">Release 3.3.3</a></li>
 <li><a href="./doc/r3.3.2">Release 3.3.2</a></li>
 <li><a href="./doc/r3.2.2">Release 3.2.2</a></li>

Modified: websites/staging/zookeeper/trunk/content/privacy.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/privacy.html (original)
+++ websites/staging/zookeeper/trunk/content/privacy.html Fri Dec 16 23:33:33 2011
@@ -108,8 +108,8 @@
 <h3>Documentation</h3>
 
 <ul>
-<li><a href="./doc/r3.4.0">Release 3.4.0</a></li>
-<li><a href="./doc/r3.3.4">Release 3.3.4&#40;current&#41;</a></li>
+<li><a href="./doc/r3.4.1">Release 3.4.1&#40;current&#41;</a></li>
+<li><a href="./doc/r3.3.4">Release 3.3.4&#40;stable&#41;</a></li>
 <li><a href="./doc/r3.3.3">Release 3.3.3</a></li>
 <li><a href="./doc/r3.3.2">Release 3.3.2</a></li>
 <li><a href="./doc/r3.2.2">Release 3.2.2</a></li>

Modified: websites/staging/zookeeper/trunk/content/releases.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/releases.html (original)
+++ websites/staging/zookeeper/trunk/content/releases.html Fri Dec 16 23:33:33 2011
@@ -73,6 +73,14 @@
 
 <h2 id="news">News</h2>
 
+<h3>16 Dec, 2011: release 3.4.1 available</h3>
+
+<p>This release fixes a critical bug with data loss in 3.4.0. See<br />
+<a href="http://zookeeper.apache.org/doc/r3.4.1/releasenotes.html">ZooKeeper 3.4.1 Release Notes</a> for details.<br />
+In case you are already using 3.4.0 release please upgrade <span class="caps">ASAP.</span></p>
+
+<p>Please note that this is an alpha release and not ready for production as of now.</p>
+
 <h3>26 Nov, 2011: release 3.3.4 available</h3>
 
 <p>The release fixes a number of critical bugs that could cause data corruption. See<br />
@@ -80,8 +88,7 @@
 
 <h3>22 Nov, 2011: release 3.4.0 available</h3>
 
-<p>This a major release coming after a long time. This has many features including security, multi update api&#39;s, rpm/deb support, C native windows support. See <br />
-<a href="http://zookeeper.apache.org/doc/r3.4.0/releasenotes.html">ZooKeeper 3.4.0 Release Notes</a> for details. Please note that this is beta release. The current stable release is 3.3.3.</p>
+<p>Due to data loss issues, this release has been removed from the downloads page. Release 3.4.1 is now available. </p>
 
 <h3>27 Feb, 2011: release 3.3.3 available</h3>
 
@@ -191,8 +198,8 @@
 <h3>Documentation</h3>
 
 <ul>
-<li><a href="./doc/r3.4.0">Release 3.4.0</a></li>
-<li><a href="./doc/r3.3.4">Release 3.3.4&#40;current&#41;</a></li>
+<li><a href="./doc/r3.4.1">Release 3.4.1&#40;current&#41;</a></li>
+<li><a href="./doc/r3.3.4">Release 3.3.4&#40;stable&#41;</a></li>
 <li><a href="./doc/r3.3.3">Release 3.3.3</a></li>
 <li><a href="./doc/r3.3.2">Release 3.3.2</a></li>
 <li><a href="./doc/r3.2.2">Release 3.2.2</a></li>

Modified: websites/staging/zookeeper/trunk/content/svn.html
==============================================================================
--- websites/staging/zookeeper/trunk/content/svn.html (original)
+++ websites/staging/zookeeper/trunk/content/svn.html Fri Dec 16 23:33:33 2011
@@ -106,8 +106,8 @@
 <h3>Documentation</h3>
 
 <ul>
-<li><a href="./doc/r3.4.0">Release 3.4.0</a></li>
-<li><a href="./doc/r3.3.4">Release 3.3.4&#40;current&#41;</a></li>
+<li><a href="./doc/r3.4.1">Release 3.4.1&#40;current&#41;</a></li>
+<li><a href="./doc/r3.3.4">Release 3.3.4&#40;stable&#41;</a></li>
 <li><a href="./doc/r3.3.3">Release 3.3.3</a></li>
 <li><a href="./doc/r3.3.2">Release 3.3.2</a></li>
 <li><a href="./doc/r3.2.2">Release 3.2.2</a></li>



Mime
View raw message