Added: helix/site-content/1.4.2-docs/tutorial_controller.html
URL: 
http://svn.apache.org/viewvc/helix/site-content/1.4.2-docs/tutorial_controller.html?rev=1921943&view=auto
==============================================================================
--- helix/site-content/1.4.2-docs/tutorial_controller.html (added)
+++ helix/site-content/1.4.2-docs/tutorial_controller.html Mon Nov 18 23:26:11 
2024
@@ -0,0 +1,383 @@
+
+<!DOCTYPE html>
+
+
+
+
+
+
+<!--
+ Generated by Apache Maven Doxia at 2024-11-18  Rendered using Reflow Maven 
Skin 2.0.0 (https://olamy.github.io/reflow-maven-skin)
+-->
+<html  xml:lang="en" lang="en">
+
+       <head>
+               <meta charset="UTF-8" />
+               <title>Apache Helix &#x2013; Tutorial - Controller</title>
+               <meta name="viewport" content="width=device-width, 
initial-scale=1.0" />
+               <meta name="description" content="" />
+               <meta http-equiv="content-language" content="en" />
+
+               <link href="./css/bootstrap.min.css" rel="stylesheet" />
+               <link href="./css/bootstrap-responsive.min.css" 
rel="stylesheet" />
+               <link href="./css/docs.css" rel="stylesheet" />
+               <link href="./css/reflow-skin.css" rel="stylesheet" />
+
+
+               <link href="./css/lightbox.css" rel="stylesheet" />
+
+               <link href="./css/site.css" rel="stylesheet" />
+               <link href="./css/print.css" rel="stylesheet" media="print" />
+
+               <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
+               <!--[if lt IE 9]>
+                       <script src="./js/html5.js"></script>
+               <![endif]-->
+
+
+
+
+
+    
+<!-- Matomo -->
+<script>
+    var _paq = window._paq = window._paq || [];
+                        _paq.push(['disableCookies']);
+                                    _paq.push(['trackPageView']);
+                                    _paq.push(['enableLinkTracking']);
+                    
+    (function() {
+        var u="https://analytics.apache.org";;
+        _paq.push(['setTrackerUrl', u+'/matomo.php']);
+        _paq.push(['setSiteId', '15']);
+        var d=document, g=d.createElement('script'), 
s=d.getElementsByTagName('script')[0];
+        g.async=true; g.src=u+'/matomo.js'; s.parentNode.insertBefore(g,s);
+    })();
+</script>
+<!-- End Matomo Code -->
+       </head>
+
+       <body class="page-tutorial_controller project-142-docs" 
data-spy="scroll" data-offset="60" data-target="#toc-scroll-target">
+
+    
+               <div class="navbar navbar-fixed-top">
+                       <div class="navbar-inner">
+                               <div class="container">
+                                       <a class="btn btn-navbar" 
data-toggle="collapse" data-target="#top-nav-collapse">
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                       </a>
+                                       <a class="brand" 
href="http://helix.apache.org";>Apache Helix</a>
+                                       <div class="nav-collapse collapse" 
id="top-nav-collapse">
+                                               <ul class="nav pull-right">
+                                                       <li ><a 
href="index.html" title="Helix 1.4.2">Helix 1.4.2</a></li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Get Helix <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="download.html" title="Download">Download</a></li>
+                                                                       <li ><a 
href="Building.html" title="Building">Building</a></li>
+                                                                       <li ><a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release 
Notes</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Hands-On <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="Quickstart.html" title="Quick Start">Quick Start</a></li>
+                                                                       <li ><a 
href="Tutorial.html" title="Tutorial">Tutorial</a></li>
+                                                                       <li ><a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Recipes <b class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a></li>
+                                                                       <li ><a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a></li>
+                                                                       <li ><a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a></li>
+                                                                       <li ><a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a></li>
+                                                                       <li ><a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a></li>
+                                                               </ul>
+                                                       </li>
+                                               </ul>
+                                       </div><!--/.nav-collapse -->
+                               </div>
+                       </div>
+               </div>
+
+       <div class="container">
+
+       <!-- Masthead
+       ================================================== -->
+
+       <header>
+       <div class="jumbotron subhead">
+               <div class="row" id="banner">
+                       <div class="span12">
+                               <div class="pull-left">
+                                       <a href="http://helix.apache.org/"; 
id="bannerLeft"><img src="../images/helix-logo.jpg" alt='"''"' /></a>
+                                       <p class="lead">A cluster management 
framework for partitioned and replicated distributed resources</p>
+                               </div>
+                               <div class="pull-right">
+                                       <a href="http://www.apache.org/"; 
id="bannerRight"><img src="../images/feather_small.gif" alt='"''"' /></a>
+                               </div>
+                       </div>
+               </div>
+       </div>
+               <div>
+                       <ul class="breadcrumb">
+                               <li><a href="../" title="Apache Helix">Apache 
Helix</a></li>
+                               <li class="divider">/</li>
+                               <li><a href="./" title="Release 1.4.2">Release 
1.4.2</a></li>
+                               <li class="divider">/</li>
+                               <li>Tutorial - Controller</li>
+                               <li class="publishDate version-date 
pull-right">Last Published: 2024-11-18</li>
+                       </ul>
+               </div>
+       </header>
+
+       <div class="main-body">
+       <div class="row">
+               <div class="span12">
+                       <div class="body-content">
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+--> 
+<section> 
+ <div class="page-header">
+  <h2 id="Helix_Tutorial:_Controller"><a href="./Tutorial.html">Helix 
Tutorial</a>: Controller</h2>
+ </div> 
+ <p>Next, let's implement the controller. This is the brain of the cluster. 
Helix makes sure there is exactly one active controller running the 
cluster.</p> 
+ <section> 
+  <h3 id="Start_a_Connection">Start a Connection</h3> 
+  <p>The Helix manager requires the following parameters:</p> 
+  <ul> 
+   <li>clusterName: A logical name to represent the group of nodes</li> 
+   <li>instanceName: A logical name of the process creating the manager 
instance. Generally this is host:port</li> 
+   <li>instanceType: Type of the process. This can be one of the following 
types, in this case use CONTROLLER: 
+    <ul> 
+     <li>CONTROLLER: Process that controls the cluster, any number of 
controllers can be started but only one will be active at any given time</li> 
+     <li>PARTICIPANT: Process that performs the actual task in the distributed 
system</li> 
+     <li>SPECTATOR: Process that observes the changes in the cluster</li> 
+     <li>ADMIN: To carry out system admin actions</li> 
+    </ul> </li> 
+   <li>zkConnectString: Connection string to ZooKeeper. This is of the form 
host1:port1,host2:port2,host3:port3</li> 
+  </ul> 
+  <div class="source"> 
+   <pre><code>manager = HelixManagerFactory.getZKHelixManager(clusterName,
+                                                instanceName,
+                                                instanceType,
+                                                zkConnectString);
+</code></pre> 
+  </div> 
+ </section> 
+ <section> 
+  <h3 id="Controller_Code">Controller Code</h3> 
+  <p>The Controller needs to know about all changes in the cluster. Helix 
takes care of this with the default implementation. If you need additional 
functionality, see GenericHelixController on how to configure the pipeline.</p> 
+  <div class="source"> 
+   <pre><code>manager = HelixManagerFactory.getZKHelixManager(clusterName,
+                                                instanceName,
+                                                InstanceType.CONTROLLER,
+                                                zkConnectString);
+manager.connect();
+</code></pre> 
+  </div> 
+  <p>The snippet above shows how the controller is started. You can also start 
the controller using command line interface.</p> 
+  <div class="source"> 
+   <pre><code>cd helix/helix-core/target/helix-core-pkg/bin
+./run-helix-controller.sh --zkSvr &lt;Zookeeper ServerAddress (Required)&gt;  
--cluster &lt;Cluster name (Required)&gt;
+</code></pre> 
+  </div> 
+ </section> 
+ <section> 
+  <h3 id="Controller_Deployment_Modes">Controller Deployment Modes</h3> 
+  <p>Helix provides multiple options to deploy the controller.</p> 
+  <section> 
+   <h4 id="STANDALONE">STANDALONE</h4> 
+   <p>The Controller can be started as a separate process to manage a cluster. 
This is the recommended approach. However, since one controller can be a single 
point of failure, multiple controller processes are required for reliability. 
Even if multiple controllers are running, only one will be actively managing 
the cluster at any time and is decided by a leader-election process. If the 
leader fails, another leader will take over managing the cluster.</p> 
+   <p>Even though we recommend this method of deployment, it has the drawback 
of having to manage an additional service for each cluster. See the Controller 
as a Service option.</p> 
+  </section> 
+  <section> 
+   <h4 id="EMBEDDED">EMBEDDED</h4> 
+   <p>If setting up a separate controller process is not viable, then it is 
possible to embed the controller as a library in each of the participants.</p> 
+  </section> 
+  <section> 
+   <h4 id="CONTROLLER_AS_A_SERVICE">CONTROLLER AS A SERVICE</h4> 
+   <p>One of the cool features we added in Helix was to use a set of 
controllers to manage a large number of clusters.</p> 
+   <p>For example if you have X clusters to be managed, instead of deploying 
X*3 (3 controllers for fault tolerance) controllers for each cluster, one can 
deploy just 3 controllers. Each controller can manage X/3 clusters. If any 
controller fails, the remaining two will manage X/2 clusters.</p> 
+   <p>Next, let's implement the controller. This is the brain of the cluster. 
Helix makes sure there is exactly one active controller running the 
cluster.</p> 
+  </section> 
+ </section> 
+ <section> 
+  <h3 id="Start_the_Helix_agent">Start the Helix agent</h3> 
+  <p>It requires the following parameters:</p> 
+  <ul> 
+   <li>clusterName: A logical name to represent the group of nodes</li> 
+   <li>instanceName: A logical name of the process creating the manager 
instance. Generally this is host:port.</li> 
+   <li>instanceType: Type of the process. This can be one of the following 
types, in this case use CONTROLLER: 
+    <ul> 
+     <li>CONTROLLER: Process that controls the cluster, any number of 
controllers can be started but only one will be active at any given time.</li> 
+     <li>PARTICIPANT: Process that performs the actual task in the distributed 
system.</li> 
+     <li>SPECTATOR: Process that observes the changes in the cluster.</li> 
+     <li>ADMIN: To carry out system admin actions.</li> 
+    </ul> </li> 
+   <li>zkConnectString: Connection string to Zookeeper. This is of the form 
host1:port1,host2:port2,host3:port3.</li> 
+  </ul> 
+  <div class="source"> 
+   <pre><code>      manager = 
HelixManagerFactory.getZKHelixManager(clusterName,
+                                                      instanceName,
+                                                      instanceType,
+                                                      zkConnectString);
+</code></pre> 
+  </div> 
+ </section> 
+ <section> 
+  <h3 id="Controller_Code">Controller Code</h3> 
+  <p>The Controller needs to know about all changes in the cluster. Helix 
takes care of this with the default implementation. If you need additional 
functionality, see GenericHelixController on how to configure the pipeline.</p> 
+  <div class="source"> 
+   <pre><code>      manager = 
HelixManagerFactory.getZKHelixManager(clusterName,
+                                                          instanceName,
+                                                          
InstanceType.CONTROLLER,
+                                                          zkConnectString);
+     manager.connect();
+     GenericHelixController controller = new GenericHelixController();
+     manager.addControllerListener(controller);
+     manager.addInstanceConfigChangeListener(controller);
+     manager.addResourceConfigChangeListener(controller);
+     manager.addClusterfigChangeListener(controller);
+     manager.addCustomizedStateConfigChangeListener(controller);
+     manager.addLiveInstanceChangeListener(controller);
+     manager.addIdealStateChangeListener(controller);
+</code></pre> 
+  </div> 
+  <p>The snippet above shows how the controller is started. You can also start 
the controller using command line interface.</p> 
+  <div class="source"> 
+   <pre><code>cd helix/helix-core/target/helix-core-pkg/bin
+./run-helix-controller.sh --zkSvr &lt;Zookeeper ServerAddress (Required)&gt;  
--cluster &lt;Cluster name (Required)&gt;
+</code></pre> 
+  </div> 
+ </section> 
+ <section> 
+  <h3 id="Controller_Deployment_Modes">Controller Deployment Modes</h3> 
+  <p>Helix provides multiple options to deploy the controller.</p> 
+  <section> 
+   <h4 id="STANDALONE">STANDALONE</h4> 
+   <p>The Controller can be started as a separate process to manage a cluster. 
This is the recommended approach. However, since one controller can be a single 
point of failure, multiple controller processes are required for reliability. 
Even if multiple controllers are running, only one will be actively managing 
the cluster at any time and is decided by a leader-election process. If the 
leader fails, another leader will take over managing the cluster.</p> 
+   <p>Even though we recommend this method of deployment, it has the drawback 
of having to manage an additional service for each cluster. See Controller As a 
Service option.</p> 
+  </section> 
+  <section> 
+   <h4 id="EMBEDDED">EMBEDDED</h4> 
+   <p>If setting up a separate controller process is not viable, then it is 
possible to embed the controller as a library in each of the participants.</p> 
+  </section> 
+  <section> 
+   <h4 id="CONTROLLER_AS_A_SERVICE">CONTROLLER AS A SERVICE</h4> 
+   <p>One of the cool features we added in Helix is to use a set of 
controllers to manage a large number of clusters.</p> 
+   <p>For example if you have X clusters to be managed, instead of deploying 
X*3 (3 controllers for fault tolerance) controllers for each cluster, one can 
deploy just 3 controllers. Each controller can manage X/3 clusters. If any 
controller fails, the remaining two will manage X/2 clusters.</p> 
+  </section> 
+ </section> 
+</section>
+                       </div>
+               </div>
+       </div>
+       </div>
+
+       </div><!-- /container -->
+
+       <!-- Footer
+       ================================================== -->
+       <footer class="well">
+               <div class="container">
+                       <div class="row">
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li class="nav-header">Get 
Helix</li>
+                                               <li >
+                                                       <a href="download.html" 
title="Download">Download</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Building.html" 
title="Building">Building</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release Notes</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Hands-On</li>
+                                               <li >
+                                                       <a 
href="Quickstart.html" title="Quick Start">Quick Start</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Tutorial.html" 
title="Tutorial">Tutorial</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Recipes</li>
+                                               <li >
+                                                       <a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                       </div>
+               </div>
+       </footer>
+
+       <div class="container subfooter">
+               <div class="row">
+                       <div class="span12">
+                               <p class="pull-right"><a href="#">Back to 
top</a></p>
+                               <p class="copyright">Copyright &copy;2024 <a 
href="http://www.apache.org";>Apache Software Foundation</a>. All Rights 
Reserved.</p>
+                               <p><a 
href="https://github.com/olamy/reflow-maven-skin"; title="Reflow Maven 
skin">Reflow Maven skin</a> maintained by <a href="https://twitter.com/olamy"; 
target="_blank" title="Olivier Lamy">Olivier Lamy</a>.</p>
+               <div class="row span16"><div>Apache Helix, Apache, the Apache 
feather logo, and the Apache Helix project logos are trademarks of The Apache 
Software Foundation.
+        All other marks mentioned may be trademarks or registered trademarks 
of their respective owners.</div>
+        <a 
href="https://helix.apache.org/1.4.2-docs/privacy-policy.html";>Privacy 
Policy</a>
+      </div>
+                       </div>
+               </div>
+       </div>
+
+       <!-- Le javascript
+       ================================================== -->
+       <!-- Placed at the end of the document so the pages load faster -->
+       <script src="./js/jquery.min.js"></script>
+
+       <script src="./js/bootstrap.min.js"></script>
+       <script src="./js/lightbox.min.js"></script>
+       <script src="./js/reflow-scroll.js"></script>
+
+       <script src="./js/reflow-skin.js"></script>
+
+       </body>
+</html>
\ No newline at end of file

Added: helix/site-content/1.4.2-docs/tutorial_customized_view.html
URL: 
http://svn.apache.org/viewvc/helix/site-content/1.4.2-docs/tutorial_customized_view.html?rev=1921943&view=auto
==============================================================================
--- helix/site-content/1.4.2-docs/tutorial_customized_view.html (added)
+++ helix/site-content/1.4.2-docs/tutorial_customized_view.html Mon Nov 18 
23:26:11 2024
@@ -0,0 +1,436 @@
+
+<!DOCTYPE html>
+
+
+
+
+
+
+<!--
+ Generated by Apache Maven Doxia at 2024-11-18  Rendered using Reflow Maven 
Skin 2.0.0 (https://olamy.github.io/reflow-maven-skin)
+-->
+<html  xml:lang="en" lang="en">
+
+       <head>
+               <meta charset="UTF-8" />
+               <title>Apache Helix &#x2013; Tutorial - Customized View</title>
+               <meta name="viewport" content="width=device-width, 
initial-scale=1.0" />
+               <meta name="description" content="" />
+               <meta http-equiv="content-language" content="en" />
+
+               <link href="./css/bootstrap.min.css" rel="stylesheet" />
+               <link href="./css/bootstrap-responsive.min.css" 
rel="stylesheet" />
+               <link href="./css/docs.css" rel="stylesheet" />
+               <link href="./css/reflow-skin.css" rel="stylesheet" />
+
+
+               <link href="./css/lightbox.css" rel="stylesheet" />
+
+               <link href="./css/site.css" rel="stylesheet" />
+               <link href="./css/print.css" rel="stylesheet" media="print" />
+
+               <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
+               <!--[if lt IE 9]>
+                       <script src="./js/html5.js"></script>
+               <![endif]-->
+
+
+
+
+
+    
+<!-- Matomo -->
+<script>
+    var _paq = window._paq = window._paq || [];
+                        _paq.push(['disableCookies']);
+                                    _paq.push(['trackPageView']);
+                                    _paq.push(['enableLinkTracking']);
+                    
+    (function() {
+        var u="https://analytics.apache.org";;
+        _paq.push(['setTrackerUrl', u+'/matomo.php']);
+        _paq.push(['setSiteId', '15']);
+        var d=document, g=d.createElement('script'), 
s=d.getElementsByTagName('script')[0];
+        g.async=true; g.src=u+'/matomo.js'; s.parentNode.insertBefore(g,s);
+    })();
+</script>
+<!-- End Matomo Code -->
+       </head>
+
+       <body class="page-tutorial_customized_view project-142-docs" 
data-spy="scroll" data-offset="60" data-target="#toc-scroll-target">
+
+    
+               <div class="navbar navbar-fixed-top">
+                       <div class="navbar-inner">
+                               <div class="container">
+                                       <a class="btn btn-navbar" 
data-toggle="collapse" data-target="#top-nav-collapse">
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                       </a>
+                                       <a class="brand" 
href="http://helix.apache.org";>Apache Helix</a>
+                                       <div class="nav-collapse collapse" 
id="top-nav-collapse">
+                                               <ul class="nav pull-right">
+                                                       <li ><a 
href="index.html" title="Helix 1.4.2">Helix 1.4.2</a></li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Get Helix <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="download.html" title="Download">Download</a></li>
+                                                                       <li ><a 
href="Building.html" title="Building">Building</a></li>
+                                                                       <li ><a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release 
Notes</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Hands-On <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="Quickstart.html" title="Quick Start">Quick Start</a></li>
+                                                                       <li ><a 
href="Tutorial.html" title="Tutorial">Tutorial</a></li>
+                                                                       <li ><a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Recipes <b class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a></li>
+                                                                       <li ><a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a></li>
+                                                                       <li ><a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a></li>
+                                                                       <li ><a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a></li>
+                                                                       <li ><a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a></li>
+                                                               </ul>
+                                                       </li>
+                                               </ul>
+                                       </div><!--/.nav-collapse -->
+                               </div>
+                       </div>
+               </div>
+
+       <div class="container">
+
+       <!-- Masthead
+       ================================================== -->
+
+       <header>
+       <div class="jumbotron subhead">
+               <div class="row" id="banner">
+                       <div class="span12">
+                               <div class="pull-left">
+                                       <a href="http://helix.apache.org/"; 
id="bannerLeft"><img src="../images/helix-logo.jpg" alt='"''"' /></a>
+                                       <p class="lead">A cluster management 
framework for partitioned and replicated distributed resources</p>
+                               </div>
+                               <div class="pull-right">
+                                       <a href="http://www.apache.org/"; 
id="bannerRight"><img src="../images/feather_small.gif" alt='"''"' /></a>
+                               </div>
+                       </div>
+               </div>
+       </div>
+               <div>
+                       <ul class="breadcrumb">
+                               <li><a href="../" title="Apache Helix">Apache 
Helix</a></li>
+                               <li class="divider">/</li>
+                               <li><a href="./" title="Release 1.4.2">Release 
1.4.2</a></li>
+                               <li class="divider">/</li>
+                               <li>Tutorial - Customized View</li>
+                               <li class="publishDate version-date 
pull-right">Last Published: 2024-11-18</li>
+                       </ul>
+               </div>
+       </header>
+
+       <div class="main-body">
+       <div class="row">
+               <div class="span12">
+                       <div class="body-content">
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+--> 
+<section> 
+ <div class="page-header">
+  <h2 id="Helix_Tutorial:_Customized_View"><a href="./Tutorial.html">Helix 
Tutorial</a>: Customized View</h2>
+ </div> 
+ <p>Helix supports users to define their own per partition states that are 
different from the states appeared in the state model. These states are called 
customized states. Helix also provides aggregation function for these per 
partition states across all participants to facilitate the use of them. The 
aggregated customized state result is called customized view. Usually users 
would only need to listen on the customized view change to capture customized 
state updates.</p> 
+ <p>The relationship between customized states and customized view is very 
similar to that between current states and external view. Helix controller uses 
similar logic to aggregate external view and customized view. But the two views 
are designed for different purposes. External view is mainly used to represent 
Helix state transition status, while customized view is to record users' own 
state status. This tutorial provides information for users to get started with 
using customized view, which needs more user input than external view.</p> 
+ <p>The following figure shows the high level architecture of customized view 
aggregation. <img src="./images/CustomizedViewSystemArchitecture.jpeg" 
alt="CustomizedViewSystemArchitecture"></p> 
+ <section> 
+  <h3 id="Terminologies">Terminologies</h3> 
+  <ul> 
+   <li>Customized state: A per partition state defined by users in a string 
format. Customized state exists under each participant. It may include 
different types of states. Each type of state is represented as a Znode itself 
and has different resources as its child Znode.</li> 
+   <li>Customized state config: A cluster level config specifically used for 
customized state related config. For example, it can include a list of 
customized states that should be aggregated.</li> 
+   <li>Customized view: An aggregation result for customized states across all 
participants. It exists under the cluster and can also have a few different 
types of states depending on users' input. Each type of state is represented as 
a Znode itself and has different resources as its child Znode.</li> 
+  </ul> 
+ </section> 
+ <section> 
+  <h3 id="How_to_Use_Customized_View">How to Use Customized View</h3> 
+  <section> 
+   <h4 id="Define_Your_Own_Customized_State">Define Your Own Customized 
State</h4> 
+   <p>Users are responsible for updating customized states in their 
application code. Helix provides a singleton factory called <a 
class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/customizedstate/CustomizedStateProviderFactory.java";>Customized
 State Provider Factory</a>, and users should instantiate it if they want to 
use customized state.</p> 
+   <p>After instantiation, users should call the function in the factory with 
user defined parameters to build a <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/customizedstate/CustomizedStateProvider.java";>Customized
 State Provider</a> object.</p> 
+   <p>There are two ways to build <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/customizedstate/CustomizedStateProvider.java";>Customized
 State Provider</a>, and the difference is what kind of <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/HelixManager.java";>HelixManager</a>
 is passed in. As the following code shows, the first one relies on a Helix 
provided manager, while the second one needs a user-created Helix manager.</p> 
+   <div class="source"> 
+    <pre><code>  public CustomizedStateProvider 
buildCustomizedStateProvider(String instanceName,
+      String clusterName, String zkAddress) {
+    HelixManager helixManager = HelixManagerFactory
+        .getZKHelixManager(clusterName, instanceName, 
InstanceType.ADMINISTRATOR, zkAddress);
+    return new CustomizedStateProvider(helixManager, instanceName);
+  }
+
+  public CustomizedStateProvider buildCustomizedStateProvider(HelixManager 
helixManager,
+      String instanceName) {
+    return new CustomizedStateProvider(helixManager, instanceName);
+  }
+</code></pre> 
+   </div> 
+   <p>Helix provides a a couple of functions in <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/customizedstate/CustomizedStateProvider.java";>Customized
 State Provider</a> that handle operations such as update, get, delete, etc. 
The underlying logic is already written in an efficient and thread safe way. 
Users only need to call these functions to update customized states to 
Zookeeper whenever they want.</p> 
+   <div class="source"> 
+    <pre><code>  public void updateCustomizedState(String customizedStateName, 
String resourceName,
+      String partitionName, String customizedState);
+
+  public void updateCustomizedState(String customizedStateName, String 
resourceName,
+      String partitionName, Map&lt;String, String&gt; customizedStateMap);
+
+  public CustomizedState getCustomizedState(String customizedStateName, String 
resourceName);
+
+  public Map&lt;String, String&gt; getPerPartitionCustomizedState(String 
customizedStateName,
+      String resourceName, String partitionName);
+
+  public void deletePerPartitionCustomizedState(String customizedStateName, 
String resourceName,
+      String partitionName);
+</code></pre> 
+   </div> 
+   <p>Here are some additional guidelines about how to use <a 
class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/customizedstate/CustomizedStateProvider.java";>Customized
 State Provider</a>:</p> 
+   <ul> 
+    <li> <p>When a user would like to drop a certain instance by calling Helix 
delete instance API, Helix will delete the instance as well as all sub-paths 
under it with recursive deletion. Therefore, the customized state will also be 
deleted, and customized view will be updated when the instance is gone.</p> 
</li> 
+    <li> <p>When a user would like to drop a certain resource by calling Helix 
delete resource API, he/she will be responsible for deleting customized state 
of all partitions for that resource across all instances. This operation can be 
implemented in users' state transition logic.</p> </li> 
+    <li> <p>When Helix rebalance happens, and a certain partition on a certain 
instance is moved to another instance, customers will need to handle the 
cleanup in the callback function currently provided by Helix in the state 
transition logic.</p> </li> 
+    <li> <p>When an unexpected disconnection happens in client side from 
Zookeeper, but does not trigger rebalance, Helix will still keep the customized 
state as it is and wait for the connection to be reset.</p> </li> 
+   </ul> 
+  </section> 
+  <section> 
+   <h4 id="Enable_Customized_State_Aggregation_in_Config">Enable Customized 
State Aggregation in Config</h4> 
+   <p>To use Helix customized state and aggregated view, users should firstly 
call a Helix REST API or a Helix java API to set a cluster level config, called 
<a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/model/CustomizedStateConfig.java";>Customized
 State Config</a>. If users do not config this field properly, they can still 
use Helix to record their customized states, but Helix will by default skip the 
aggregation process, as the aggregation will take a fair amount of computing 
and storage resources. Only when users correctly notify Helix that they want 
the aggregation by adding the state type in the aggregation config list field, 
Helix will do the aggregation and output the results to Zookeeper.</p> 
+   <p>There are two ways to update customized state config. One is through 
JAVA API inside <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/manager/zk/ZKHelixAdmin.java";>ZK
 Helix Admin</a>, and the other is through REST API in <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-rest/src/main/java/org/apache/helix/rest/server/resources/helix/ClusterAccessor.java";>Cluster
 Accessor</a>.</p> 
+   <p>The JAVA API provides four different functions as follows.</p> 
+   <div class="source"> 
+    <pre><code>  public void addCustomizedStateConfig(String clusterName, 
CustomizedStateConfig customizedStateConfig);
+
+  public void removeCustomizedStateConfig(String clusterName);
+
+  public void addTypeToCustomizedStateConfig(String clusterName, String type);
+
+  public void removeTypeFromCustomizedStateConfig(String clusterName, String 
type);
+</code></pre> 
+   </div> 
+   <p>Every JAVA API has a corresponding REST API. For example, the function 
<code>addCustomizedStateConfig</code> can be performed by the following REST 
call.</p> 
+   <div class="source"> 
+    <pre><code>  $curl -X PUT -H "Content-Type: application/json" 
http://localhost:1234/admin/v2/clusters/myCluster/customized-state-config -d '
+    {
+     "id" : "CustomizedStateConfig",
+      "listFields" : {
+        "AGGREGATION_ENABLED_TYPES" : ["CUSTOMIZED_STATE_TYPE_0", 
"CUSTOMIZED_STATE_TYPE_1""]
+      },
+      "simpleFields" : {
+      },
+      "mapFields" : {
+      }
+    }'
+</code></pre> 
+   </div> 
+  </section> 
+  <section> 
+   <h4 id="Update_Consuming_Logic_to_Listen_on_Customized_View_Change">Update 
Consuming Logic to Listen on Customized View Change</h4> 
+   <p>The aggregated results is updated in <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/spectator/RoutingTableProvider.java";>RoutingTableProvider</a>.
 Users need to properly construct the routing table provider in their consuming 
logic to use the snapshot that contains customized view. <a 
class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/spectator/RoutingTableProvider.java";>RoutingTableProvider</a>
 has three different constructors for backward compatibility.</p> 
+   <div class="source"> 
+    <pre><code>  public RoutingTableProvider(HelixManager helixManager) throws 
HelixException {
+    this(helixManager, ImmutableMap.of(PropertyType.EXTERNALVIEW, 
Collections.emptyList()), true,
+        DEFAULT_PERIODIC_REFRESH_INTERVAL);
+  }
+
+  public RoutingTableProvider(HelixManager helixManager, PropertyType 
sourceDataType)
+      throws HelixException {
+    this(helixManager, ImmutableMap.of(sourceDataType, 
Collections.emptyList()), true,
+        DEFAULT_PERIODIC_REFRESH_INTERVAL);
+  }
+
+  public RoutingTableProvider(HelixManager helixManager, Map&lt;PropertyType, 
List&lt;String&gt;&gt; sourceDataTypeMap) {
+    this(helixManager, sourceDataTypeMap, true, 
DEFAULT_PERIODIC_REFRESH_INTERVAL);
+  }
+</code></pre> 
+   </div> 
+   <p>If users would like to use customized states and customized view, they 
need to initialize <a class="externalLink" 
href="https://github.com/apache/helix/blob/master/helix-core/src/main/java/org/apache/helix/spectator/RoutingTableProvider.java";>RoutingTableProvider</a>
 with the last constructor. They also need to define the 
<code>sourceDataMap</code>. For example, if users would like to listen to both 
external view and customized view, they can do</p> 
+   <div class="source"> 
+    <pre><code>Map&lt;PropertyType, List&lt;String&gt;&gt; sourceDataTypeMap = 
new Hashmap&lt;&gt;();
+sourceDataTypeMap.put(PropertyType.CUSTOMIZEDVIEW, 
Arrays.asList(CUSTOMIZED_STATE_0, CUSTOMIZED_STATE_1))
+sourceDataTypeMap.put(PropertyType.EXTERNALVIEW, Collections.emptyList());
+
+routingTableProvider = new RoutingTableProvider(helixManager, 
sourceDataTypeMap);
+</code></pre> 
+   </div> 
+  </section> 
+  <section> 
+   <h4 id="Verify_Customized_View_Generated_Properly">Verify Customized View 
Generated Properly</h4> 
+   <p>After finishing all the steps above, users could verify whether the 
customized view is generated probably based on customized states. For example, 
if you have two instances: P0 and P1, one resource: MyResource, with two 
partitions: MyResource_0 and MyResource_1, and each partition has one state in 
CUSTOMIZED_STATE_TYPE_1, which includes STATE_NAME_0, STATE_NAME_1 and 
STATE_NAME_2. At a certain time, the customized states may look like something 
similar to the following.</p> 
+   <div class="source"> 
+    <pre><code>P0: 
+{
+ "id": "MyResource",
+    "listFields": {},
+     "mapFields": {
+          "MyResource_0": {
+              "CURRENT_STATE": "STATE_NAME_1",
+              "PREVIOUS_STATE": "STATE_NAME_0",
+              "START_TIME": "1580221789100",
+              "END_TIME": "1580221.4.297",
+          },
+          "MyResource_1": {
+              "CURRENT_STATE": "STATE_NAME_2",
+              "PREVIOUS_STATE": "STATE_NAME1",
+              "START_TIME": "1580221789880",
+              "END_TIME": "1580221.4.217"
+          }   
+     }
+}                          
+
+P1: 
+{
+ "id": "MyResource",
+    "listFields": {},
+     "mapFields": {
+          "MyResource_0": {
+              "CURRENT_STATE": "STATE_NAME_2",
+              "PREVIOUS_STATE": "STATE_NAME_0",
+              "START_TIME": "1570221125566",
+              "END_TIME": "15744432835197",
+          },
+          "MyResource_1": {
+              "CURRENT_STATE": "STATE_NAME_0",
+              "PREVIOUS_STATE": "STATE_NAME1",
+              "START_TIME": "1570221723440",
+              "END_TIME": "1570321.4.217"
+          }   
+     }
+}   
+</code></pre> 
+   </div> 
+   <p>After Helix controller aggregation, the customized view should look like 
the following:</p> 
+   <div class="source"> 
+    <pre><code>{ "id": "MyResource",
+  "listFields": {},
+  "mapFields": {
+     "MyResource_0": {
+      "P0": "STATE_NAME_1",
+      "P1": "STATE_NAME_2"
+    },
+    "MyResource_1": {
+      "P0": "STATE_NAME_2",
+      "P1": "STATE_NAME_0"
+    }
+}
+</code></pre> 
+   </div> 
+  </section> 
+ </section> 
+</section>
+                       </div>
+               </div>
+       </div>
+       </div>
+
+       </div><!-- /container -->
+
+       <!-- Footer
+       ================================================== -->
+       <footer class="well">
+               <div class="container">
+                       <div class="row">
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li class="nav-header">Get 
Helix</li>
+                                               <li >
+                                                       <a href="download.html" 
title="Download">Download</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Building.html" 
title="Building">Building</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release Notes</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Hands-On</li>
+                                               <li >
+                                                       <a 
href="Quickstart.html" title="Quick Start">Quick Start</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Tutorial.html" 
title="Tutorial">Tutorial</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Recipes</li>
+                                               <li >
+                                                       <a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                       </div>
+               </div>
+       </footer>
+
+       <div class="container subfooter">
+               <div class="row">
+                       <div class="span12">
+                               <p class="pull-right"><a href="#">Back to 
top</a></p>
+                               <p class="copyright">Copyright &copy;2024 <a 
href="http://www.apache.org";>Apache Software Foundation</a>. All Rights 
Reserved.</p>
+                               <p><a 
href="https://github.com/olamy/reflow-maven-skin"; title="Reflow Maven 
skin">Reflow Maven skin</a> maintained by <a href="https://twitter.com/olamy"; 
target="_blank" title="Olivier Lamy">Olivier Lamy</a>.</p>
+               <div class="row span16"><div>Apache Helix, Apache, the Apache 
feather logo, and the Apache Helix project logos are trademarks of The Apache 
Software Foundation.
+        All other marks mentioned may be trademarks or registered trademarks 
of their respective owners.</div>
+        <a 
href="https://helix.apache.org/1.4.2-docs/privacy-policy.html";>Privacy 
Policy</a>
+      </div>
+                       </div>
+               </div>
+       </div>
+
+       <!-- Le javascript
+       ================================================== -->
+       <!-- Placed at the end of the document so the pages load faster -->
+       <script src="./js/jquery.min.js"></script>
+
+       <script src="./js/bootstrap.min.js"></script>
+       <script src="./js/lightbox.min.js"></script>
+       <script src="./js/reflow-scroll.js"></script>
+
+       <script src="./js/reflow-skin.js"></script>
+
+       </body>
+</html>
\ No newline at end of file

Added: helix/site-content/1.4.2-docs/tutorial_distributed_lock.html
URL: 
http://svn.apache.org/viewvc/helix/site-content/1.4.2-docs/tutorial_distributed_lock.html?rev=1921943&view=auto
==============================================================================
--- helix/site-content/1.4.2-docs/tutorial_distributed_lock.html (added)
+++ helix/site-content/1.4.2-docs/tutorial_distributed_lock.html Mon Nov 18 
23:26:11 2024
@@ -0,0 +1,435 @@
+
+<!DOCTYPE html>
+
+
+
+
+
+
+<!--
+ Generated by Apache Maven Doxia at 2024-11-18  Rendered using Reflow Maven 
Skin 2.0.0 (https://olamy.github.io/reflow-maven-skin)
+-->
+<html  xml:lang="en" lang="en">
+
+       <head>
+               <meta charset="UTF-8" />
+               <title>Apache Helix &#x2013; Tutorial - Distributed Lock</title>
+               <meta name="viewport" content="width=device-width, 
initial-scale=1.0" />
+               <meta name="description" content="" />
+               <meta http-equiv="content-language" content="en" />
+
+               <link href="./css/bootstrap.min.css" rel="stylesheet" />
+               <link href="./css/bootstrap-responsive.min.css" 
rel="stylesheet" />
+               <link href="./css/docs.css" rel="stylesheet" />
+               <link href="./css/reflow-skin.css" rel="stylesheet" />
+
+
+               <link href="./css/lightbox.css" rel="stylesheet" />
+
+               <link href="./css/site.css" rel="stylesheet" />
+               <link href="./css/print.css" rel="stylesheet" media="print" />
+
+               <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
+               <!--[if lt IE 9]>
+                       <script src="./js/html5.js"></script>
+               <![endif]-->
+
+
+
+
+
+    
+<!-- Matomo -->
+<script>
+    var _paq = window._paq = window._paq || [];
+                        _paq.push(['disableCookies']);
+                                    _paq.push(['trackPageView']);
+                                    _paq.push(['enableLinkTracking']);
+                    
+    (function() {
+        var u="https://analytics.apache.org";;
+        _paq.push(['setTrackerUrl', u+'/matomo.php']);
+        _paq.push(['setSiteId', '15']);
+        var d=document, g=d.createElement('script'), 
s=d.getElementsByTagName('script')[0];
+        g.async=true; g.src=u+'/matomo.js'; s.parentNode.insertBefore(g,s);
+    })();
+</script>
+<!-- End Matomo Code -->
+       </head>
+
+       <body class="page-tutorial_distributed_lock project-142-docs" 
data-spy="scroll" data-offset="60" data-target="#toc-scroll-target">
+
+    
+               <div class="navbar navbar-fixed-top">
+                       <div class="navbar-inner">
+                               <div class="container">
+                                       <a class="btn btn-navbar" 
data-toggle="collapse" data-target="#top-nav-collapse">
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                       </a>
+                                       <a class="brand" 
href="http://helix.apache.org";>Apache Helix</a>
+                                       <div class="nav-collapse collapse" 
id="top-nav-collapse">
+                                               <ul class="nav pull-right">
+                                                       <li ><a 
href="index.html" title="Helix 1.4.2">Helix 1.4.2</a></li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Get Helix <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="download.html" title="Download">Download</a></li>
+                                                                       <li ><a 
href="Building.html" title="Building">Building</a></li>
+                                                                       <li ><a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release 
Notes</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Hands-On <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="Quickstart.html" title="Quick Start">Quick Start</a></li>
+                                                                       <li ><a 
href="Tutorial.html" title="Tutorial">Tutorial</a></li>
+                                                                       <li ><a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Recipes <b class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a></li>
+                                                                       <li ><a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a></li>
+                                                                       <li ><a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a></li>
+                                                                       <li ><a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a></li>
+                                                                       <li ><a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a></li>
+                                                               </ul>
+                                                       </li>
+                                               </ul>
+                                       </div><!--/.nav-collapse -->
+                               </div>
+                       </div>
+               </div>
+
+       <div class="container">
+
+       <!-- Masthead
+       ================================================== -->
+
+       <header>
+       <div class="jumbotron subhead">
+               <div class="row" id="banner">
+                       <div class="span12">
+                               <div class="pull-left">
+                                       <a href="http://helix.apache.org/"; 
id="bannerLeft"><img src="../images/helix-logo.jpg" alt='"''"' /></a>
+                                       <p class="lead">A cluster management 
framework for partitioned and replicated distributed resources</p>
+                               </div>
+                               <div class="pull-right">
+                                       <a href="http://www.apache.org/"; 
id="bannerRight"><img src="../images/feather_small.gif" alt='"''"' /></a>
+                               </div>
+                       </div>
+               </div>
+       </div>
+               <div>
+                       <ul class="breadcrumb">
+                               <li><a href="../" title="Apache Helix">Apache 
Helix</a></li>
+                               <li class="divider">/</li>
+                               <li><a href="./" title="Release 1.4.2">Release 
1.4.2</a></li>
+                               <li class="divider">/</li>
+                               <li>Tutorial - Distributed Lock</li>
+                               <li class="publishDate version-date 
pull-right">Last Published: 2024-11-18</li>
+                       </ul>
+               </div>
+       </header>
+
+       <div class="main-body">
+       <div class="row">
+               <div class="span12">
+                       <div class="body-content">
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+--> 
+<section> 
+ <div class="page-header">
+  <h2 id="Helix_Tutorial:_Distributed_Lock"><a href="./Tutorial.html">Helix 
Tutorial</a>: Distributed Lock</h2>
+ </div> 
+ <p>In a distributed system, there are many cases that we need a mechanism to 
make sure different processes can cooperate correctly. For example, if two 
processes that run on different machines, or different networks, or even 
different data centers would like to work on the same resource, we must have a 
mutually exclusive lock to ensure that their operations do not step on each 
other. Only when a process acquires the lock, it can perform the operation.</p> 
+ <p>Since Helix is built on top of ZooKeeper, which is a widely used framework 
to manage coordination across a cluster of machines, a natural solution for 
implementing a distributed lock is to leverage ZooKeeper. Specifically, we can 
represent the lock itself as a znode. Currently, many distributed systems use 
Apache Helix as a generic cluster management framework to automatically manage 
resources hosted on a cluster of nodes. Implementing a distributed lock in 
Helix would allow Helix's existing customers to use a reliable lock with little 
overhead.</p> 
+ <section> 
+  <h3 id="Helix_Lock_Interface">Helix Lock Interface</h3> 
+  <p>Helix provides a generic lock interface that can be implemented with 
different kinds of locks. Several key functions are defined in the 
interface.</p> 
+  <div class="source"> 
+   <pre><code>/**
+ * Generic interface for Helix distributed lock
+ */
+public interface DistributedLock {
+  /**
+   * Blocking call to acquire a lock if it is free at the time of request
+   * @return true if the lock was successfully acquired,
+   * false if the lock could not be acquired
+   */
+  boolean tryLock();
+
+  /**
+   * Blocking call to unlock a lock
+   * @return true if the lock was successfully released or if the locked is 
not currently locked,
+   * false if the lock is not locked by the user or the unlock operation failed
+   */
+  boolean unlock();
+
+  /**
+   * Retrieve the information of the current lock on the resource this lock 
object specifies, e.g. lock timeout, lock message, etc.
+   * @return lock metadata information
+   */
+  LockInfo getCurrentLockInfo();
+
+  /**
+   * If the user is current lock owner of the resource
+   * @return true if the user is the lock owner,
+   * false if the user is not the lock owner or the lock doesn't have a owner
+   */
+  boolean isCurrentOwner();
+
+  /**
+   * Call this method to close the lock's zookeeper connection
+   * The lock has to be unlocked or expired before this method can be called
+   */
+  void close();
+}
+</code></pre> 
+  </div> 
+  <p>Currently, Helix supports two kinds of locks. One is basic lock, and the 
other is priority lock. We will describe their definition and usage as 
follows.</p> 
+ </section> 
+ <section> 
+  <h3 id="Helix_Basic_Lock">Helix Basic Lock</h3> 
+  <section> 
+   <h4 id="Features">Features</h4> 
+   <ul> 
+    <li> <p>Non-blocking lock. It means every request to acquire the lock will 
immediately get a result (success or failure) instead of waiting until the lock 
is successfully acquired.</p> </li> 
+    <li> <p>Timeout support. A client needs to input the timeout when it tries 
to acquire the lock. We use lazy timeout for the lock. It means even after the 
timeout, if no other client tries to get the lock, the client can still keep 
the lock, if other client tries to acquire the lock, and finds the previous 
client already timed out, the previous client will automatically lose the 
lock.</p> </li> 
+    <li> <p>Lock message support. A client can input the reason for the lock 
(as a string) when it tries to acquire the lock. This enables future lock 
operation, when fails, can know the reason from the lock message of the current 
lock.</p> </li> 
+    <li> <p>Java API support for clients to use the lock.</p> </li> 
+    <li> <p>No notification support. When a client loses its lock after the 
timeout or due to some urgent maintenance work who does not check the lock, 
there is no notification sent out to the previous lock owner.</p> </li> 
+   </ul> 
+  </section> 
+  <section> 
+   <h4 id="How_to_Use_Helix_Basic_Lock">How to Use Helix Basic Lock</h4> 
+   <p>The implementation of Helix lock is called “ZkHelixNonblockingLock”. 
It has two different constructors as shown below. One constructor takes 
clusterName, and HelixConfigScope as inputs. HelixConfigScope can be 
“cluster”, “participant”, or “resource”. The other constructor 
takes a lockPath string as input.</p> 
+   <div class="source"> 
+    <pre><code>  /**
+   * Initialize the lock with Helix scope.
+   */
+  public ZKHelixNonblockingLock(String clusterName, HelixConfigScope scope, 
String zkAddress,
+      Long timeout, String lockMsg) 
+ 
+  /**
+   * Initialize the lock with lock path under zookeeper.
+   */
+  public ZKHelixNonblockingLock(String lockPath, String zkAddress, Long 
timeout, String lockMsg) 
+</code></pre> 
+   </div> 
+   <p>The client can use the lock in two different ways. If the client would 
like to use the lock for some specific Helix resource, it can use the first 
constructor which requires clusterName and HelixConfigScope. We show an example 
below on how to use Helix scope. Or the client may choose to use the lock for 
generic purpose, basically on any resource they have. In this case, the client 
needs to provide the lock path, which is a string, and it represents where the 
lock should exist under zookeeper.</p> 
+   <div class="source"> 
+    <pre><code>    List&lt;String&gt; pathKeys = new ArrayList&lt;&gt;();
+    pathKeys.add(clusterName);
+    HelixLockScope participantScope = new 
HelixLockScope(HelixLockScope.LockScopeProperty.CLUSTER, pathKeys);
+</code></pre> 
+   </div> 
+   <p>Note that if users have onboarded to ZooScalability that has multiple 
realms, they should instead use the builder instead of the above 
constructors.</p> 
+  </section> 
+ </section> 
+ <section> 
+  <h3 id="Helix_Priority_Lock">Helix Priority Lock</h3> 
+  <section> 
+   <h4 id="Features">Features</h4> 
+   <ul> 
+    <li>Priority support. A client with higher priority can override lock 
owned by a client with lower priority.</li> 
+    <li>Notification support. After the higher priority client overrides the 
lock owned by lower priority client, the low priority client will get 
notified.</li> 
+    <li>Cleanup support. The low priority client will be given some time to do 
the cleanup and roll back the system to normal state when its lock is 
preempted.</li> 
+   </ul> 
+  </section> 
+  <section> 
+   <h4 id="Priority_Lock_Definitions">Priority Lock Definitions</h4> 
+   <p>There are a few concepts defined for priority lock.</p> 
+   <section> 
+    <h5 id="Definition_1:_Priority_of_the_lock.">Definition 1: Priority of the 
lock.</h5> 
+    <p>Any client that wants to acquire a lock needs to have a priority so 
that Helix knows what to do when there are multiple clients that want the same 
lock. We accept non-negative integers as meaningful priority representation. 
The lowest priority is 0. The larger the number, the higher the priority is. 
Same number denotes the same priority. We do not have an upper limit for the 
priority definition. However, we reserve the value of INT_MAX for emergency use 
by SREs, i.e., they may override all other priorities in case of urgent 
operations. If a client does not have a priority defined when it tries to 
acquire the lock, the default value 0 will be assigned to the client and thus 
the client is with lowest priority.</p> 
+   </section> 
+   <section> 
+    <h5 id="Definition_2:_Timeout_of_the_lock.">Definition 2: Timeout of the 
lock.</h5> 
+    <p>When a request for a lock is issued, there can be three types of 
timeout associated with the lock. We explain them respectively as follows.</p> 
+    <ul> 
+     <li> <p>lease timeout: it is the user's requirement of how long the lease 
it needs. It denotes how long it takes to finish the work by the client that 
requires the locked resource. This is the same concept as the timeout in basic 
lock. This field must be set to a positive value. Otherwise the lock is 
meaningless.</p> </li> 
+     <li> <p>cleanup timeout: it defines how long it takes for a client to 
clean up the work done with the locked resource and bring back the resource to 
a clean state if the client is preempted by a higher priority client. If a user 
does not define this field, the clean up timeout will be set to the default 
value 0, meaning no cleanup work is needed. Once there is a higher priority 
client requested the lock, the lock will be immediately given to the high 
priority one after the notification is sent to the low priority client.</p> 
</li> 
+     <li> <p>waiting timeout: it defines how long the client that requests the 
lock can wait for the lower priority client to finish the cleanup work. 
Specifically, if the work is urgent to get executed, a client should set a 
shorter waiting timeout. To the extreme, if users set the waiting timeout to be 
0, the lock will be acquired immediately. If the waiting timeout is not set, it 
will be default as infinite, meaning that the high priority client will not get 
the lock until the low priority client finishes all the cleanup work.</p> </li> 
+    </ul> 
+    <p>The three timeout are specific to the particular client that requests 
the lock and should be independent of each other. In short, the lease timeout 
includes all the time needed in normal operation (perform the work, clean up 
when work is completed, etc.); cleanup timeout is user's best estimate of time 
needed for reverting the system to previous stable state in case of preemption; 
waiting timeout shows how urgent the client needs to acquire the lock. Please 
note that it is possible that a client's waiting timeout is shorter than the 
other client's cleanup timeout. In this case, the client's waiting timeout will 
override the other client's cleanup timeout. We always honor the waiting 
timeout of the high priority client before cleanup timeout of the low priority 
client when there is a contention for the lock. Lock users should be 
responsible for setting up different timeout of their locks. However, it is 
possible that at the beginning they can only provide an estimation for the
  timeout which is not accurate enough. Either Helix or user code could 
implement some statistic logic to analyze the real execution or clean up times 
used. For example, Helix may be able to calculate how many times the workflow 
finishes the cleanup job in the designated cleanup timeout, and if not, what is 
the real cleanup time (in case that the waiting timeout is larger). Based on 
the results, users could tune their timeout to better handle lock 
preemption.</p> 
+   </section> 
+   <section> 
+    <h5 id="Definition_3:_Forcefulness_of_the_lock">Definition 3: Forcefulness 
of the lock</h5> 
+    <p>Forcefulness means whether a lock requested by a client is forceful or 
not in case of a preemption. If it is a forceful lock, when time is out, no 
matter whether the cleanup work of low priority client is finished or not, the 
high priority client will grab the lock from low priority client. However, if 
it is not a forceful lock, the high priority client will receive an exception, 
knowing that the low priority client has not finished its work yet. Then it is 
up to human beings to decide what is the next step. We could trigger an alert 
based on this kind of exception. Users can set up an approval workflow to act 
based on the alert. They may manually check the exception and the previous lock 
owner to make the decision on whether they will respect the previous owner's 
work or forcefully grab the lock. Or later with some experience on handling 
these exceptions, they can also make the process fully automatic. For example, 
with low priority client A and high priority client B, if in
  the case of exception thrown during preemption, user always chooses to 
forcefully grab the lock and assign the lock owner to B, we may have a rule set 
up for this condition which will automatically transfer the lock owner.</p> 
+   </section> 
+  </section> 
+  <section> 
+   <h4 id="Priority_Lock_Workflow">Priority Lock Workflow</h4> 
+   <p>To better visualize the above analysis, we draw the following diagram 
shows how a client may go through the possible scenarios. <img 
src="./images/HelixPriorityLockWorkflow.jpeg" 
alt="HelixPriorityLockWorkflow"></p> 
+  </section> 
+  <section> 
+   <h4 id="Priority_Lock_Usage">Priority Lock Usage</h4> 
+   <section> 
+    <h5 id="Lock_information_Definition">Lock information Definition</h5> 
+    <div class="source"> 
+     <pre><code>  public enum LockInfoAttribute {
+    OWNER,
+    MESSAGE,
+    TIMEOUT,
+    PRIORITY,
+    WAITING_TIMEOUT,
+    CLEANUP_TIMEOUT,
+    REQUESTOR_ID,
+    REQUESTOR_PRIORITY,
+    REQUESTOR_WAITING_TIMEOUT,
+    REQUESTING_TIMESTAMP
+  }
+</code></pre> 
+    </div> 
+   </section> 
+   <section> 
+    <h5 id="Priority_Lock_Constructor">Priority Lock Constructor</h5> 
+    <div class="source"> 
+     <pre><code>  /**
+   * Internal construction of the lock with user provided information, e.g., 
lock path under
+   * zookeeper, etc.
+   * @param lockPath the path of the lock under Zookeeper
+   * @param leaseTimeout the leasing timeout period of the lock
+   * @param lockMsg the reason for having this lock
+   * @param userId a universal unique userId for lock owner identity
+   * @param priority the priority of the lock
+   * @param waitingTimeout the waiting timeout period of the lock when the 
tryLock request is issued
+   * @param cleanupTimeout the time period needed to finish the cleanup work 
by the lock when it
+   *                      is preempted
+   * @param isForceful whether the lock is a forceful one. This determines the 
behavior when the
+   *                   lock encountered an exception during preempting lower 
priority lock
+   * @param lockListener the listener associated to the lock
+   * @param baseDataAccessor baseDataAccessor instance to do I/O against ZK 
with
+   */
+  private ZKDistributedNonblockingLock(String lockPath, Long leaseTimeout, 
String lockMsg,
+      String userId, int priority, long waitingTimeout, long cleanupTimeout, 
boolean isForceful,
+      LockListener lockListener, BaseDataAccessor&lt;ZNRecord&gt; 
baseDataAccessor) 
+</code></pre> 
+    </div> 
+   </section> 
+   <section> 
+    <h5 id="Priority_Lock_Usage_Example:">Priority Lock Usage Example:</h5> 
+    <div class="source"> 
+     <pre><code>    ZKDistributedNonblockingLock.Builder lockBuilder = new 
ZKDistributedNonblockingLock.Builder();
+    lockBuilder.setLockScope(new 
HelixLockScope(HelixLockScope.LockScopeProperty.CLUSTER, 
pathKeys)).setZkAddress(ZK_ADDR).setTimeout(3600000L)
+        .setLockMsg("test lock").setUserId("test 
Id").setPriority(0).setWaitingTimeout(1000)
+        .setCleanupTimeout(2000).setIsForceful(false)
+        .setLockListener(new LockListener() {@Override public void 
onCleanupNotification() {});
+    ZKDistributedNonblockingLock testLock = lockBuilder.build();
+</code></pre> 
+    </div> 
+   </section> 
+  </section> 
+ </section> 
+</section>
+                       </div>
+               </div>
+       </div>
+       </div>
+
+       </div><!-- /container -->
+
+       <!-- Footer
+       ================================================== -->
+       <footer class="well">
+               <div class="container">
+                       <div class="row">
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li class="nav-header">Get 
Helix</li>
+                                               <li >
+                                                       <a href="download.html" 
title="Download">Download</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Building.html" 
title="Building">Building</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release Notes</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Hands-On</li>
+                                               <li >
+                                                       <a 
href="Quickstart.html" title="Quick Start">Quick Start</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Tutorial.html" 
title="Tutorial">Tutorial</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Recipes</li>
+                                               <li >
+                                                       <a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                       </div>
+               </div>
+       </footer>
+
+       <div class="container subfooter">
+               <div class="row">
+                       <div class="span12">
+                               <p class="pull-right"><a href="#">Back to 
top</a></p>
+                               <p class="copyright">Copyright &copy;2024 <a 
href="http://www.apache.org";>Apache Software Foundation</a>. All Rights 
Reserved.</p>
+                               <p><a 
href="https://github.com/olamy/reflow-maven-skin"; title="Reflow Maven 
skin">Reflow Maven skin</a> maintained by <a href="https://twitter.com/olamy"; 
target="_blank" title="Olivier Lamy">Olivier Lamy</a>.</p>
+               <div class="row span16"><div>Apache Helix, Apache, the Apache 
feather logo, and the Apache Helix project logos are trademarks of The Apache 
Software Foundation.
+        All other marks mentioned may be trademarks or registered trademarks 
of their respective owners.</div>
+        <a 
href="https://helix.apache.org/1.4.2-docs/privacy-policy.html";>Privacy 
Policy</a>
+      </div>
+                       </div>
+               </div>
+       </div>
+
+       <!-- Le javascript
+       ================================================== -->
+       <!-- Placed at the end of the document so the pages load faster -->
+       <script src="./js/jquery.min.js"></script>
+
+       <script src="./js/bootstrap.min.js"></script>
+       <script src="./js/lightbox.min.js"></script>
+       <script src="./js/reflow-scroll.js"></script>
+
+       <script src="./js/reflow-skin.js"></script>
+
+       </body>
+</html>
\ No newline at end of file

Added: helix/site-content/1.4.2-docs/tutorial_health.html
URL: 
http://svn.apache.org/viewvc/helix/site-content/1.4.2-docs/tutorial_health.html?rev=1921943&view=auto
==============================================================================
--- helix/site-content/1.4.2-docs/tutorial_health.html (added)
+++ helix/site-content/1.4.2-docs/tutorial_health.html Mon Nov 18 23:26:11 2024
@@ -0,0 +1,270 @@
+
+<!DOCTYPE html>
+
+
+
+
+
+
+<!--
+ Generated by Apache Maven Doxia at 2024-11-18  Rendered using Reflow Maven 
Skin 2.0.0 (https://olamy.github.io/reflow-maven-skin)
+-->
+<html  xml:lang="en" lang="en">
+
+       <head>
+               <meta charset="UTF-8" />
+               <title>Apache Helix &#x2013; Tutorial - Customizing Heath 
Checks</title>
+               <meta name="viewport" content="width=device-width, 
initial-scale=1.0" />
+               <meta name="description" content="" />
+               <meta http-equiv="content-language" content="en" />
+
+               <link href="./css/bootstrap.min.css" rel="stylesheet" />
+               <link href="./css/bootstrap-responsive.min.css" 
rel="stylesheet" />
+               <link href="./css/docs.css" rel="stylesheet" />
+               <link href="./css/reflow-skin.css" rel="stylesheet" />
+
+
+               <link href="./css/lightbox.css" rel="stylesheet" />
+
+               <link href="./css/site.css" rel="stylesheet" />
+               <link href="./css/print.css" rel="stylesheet" media="print" />
+
+               <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
+               <!--[if lt IE 9]>
+                       <script src="./js/html5.js"></script>
+               <![endif]-->
+
+
+
+
+
+    
+<!-- Matomo -->
+<script>
+    var _paq = window._paq = window._paq || [];
+                        _paq.push(['disableCookies']);
+                                    _paq.push(['trackPageView']);
+                                    _paq.push(['enableLinkTracking']);
+                    
+    (function() {
+        var u="https://analytics.apache.org";;
+        _paq.push(['setTrackerUrl', u+'/matomo.php']);
+        _paq.push(['setSiteId', '15']);
+        var d=document, g=d.createElement('script'), 
s=d.getElementsByTagName('script')[0];
+        g.async=true; g.src=u+'/matomo.js'; s.parentNode.insertBefore(g,s);
+    })();
+</script>
+<!-- End Matomo Code -->
+       </head>
+
+       <body class="page-tutorial_health project-142-docs" data-spy="scroll" 
data-offset="60" data-target="#toc-scroll-target">
+
+    
+               <div class="navbar navbar-fixed-top">
+                       <div class="navbar-inner">
+                               <div class="container">
+                                       <a class="btn btn-navbar" 
data-toggle="collapse" data-target="#top-nav-collapse">
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                               <span class="icon-bar"></span>
+                                       </a>
+                                       <a class="brand" 
href="http://helix.apache.org";>Apache Helix</a>
+                                       <div class="nav-collapse collapse" 
id="top-nav-collapse">
+                                               <ul class="nav pull-right">
+                                                       <li ><a 
href="index.html" title="Helix 1.4.2">Helix 1.4.2</a></li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Get Helix <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="download.html" title="Download">Download</a></li>
+                                                                       <li ><a 
href="Building.html" title="Building">Building</a></li>
+                                                                       <li ><a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release 
Notes</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Hands-On <b 
class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="Quickstart.html" title="Quick Start">Quick Start</a></li>
+                                                                       <li ><a 
href="Tutorial.html" title="Tutorial">Tutorial</a></li>
+                                                                       <li ><a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a></li>
+                                                               </ul>
+                                                       </li>
+                                                       <li class="dropdown">
+                                                               <a href="#" 
class="dropdown-toggle" data-toggle="dropdown">Recipes <b class="caret"></b></a>
+                                                               <ul 
class="dropdown-menu">
+                                                                       <li ><a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a></li>
+                                                                       <li ><a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a></li>
+                                                                       <li ><a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a></li>
+                                                                       <li ><a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a></li>
+                                                                       <li ><a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a></li>
+                                                               </ul>
+                                                       </li>
+                                               </ul>
+                                       </div><!--/.nav-collapse -->
+                               </div>
+                       </div>
+               </div>
+
+       <div class="container">
+
+       <!-- Masthead
+       ================================================== -->
+
+       <header>
+       <div class="jumbotron subhead">
+               <div class="row" id="banner">
+                       <div class="span12">
+                               <div class="pull-left">
+                                       <a href="http://helix.apache.org/"; 
id="bannerLeft"><img src="../images/helix-logo.jpg" alt='"''"' /></a>
+                                       <p class="lead">A cluster management 
framework for partitioned and replicated distributed resources</p>
+                               </div>
+                               <div class="pull-right">
+                                       <a href="http://www.apache.org/"; 
id="bannerRight"><img src="../images/feather_small.gif" alt='"''"' /></a>
+                               </div>
+                       </div>
+               </div>
+       </div>
+               <div>
+                       <ul class="breadcrumb">
+                               <li><a href="../" title="Apache Helix">Apache 
Helix</a></li>
+                               <li class="divider">/</li>
+                               <li><a href="./" title="Release 1.4.2">Release 
1.4.2</a></li>
+                               <li class="divider">/</li>
+                               <li>Tutorial - Customizing Heath Checks</li>
+                               <li class="publishDate version-date 
pull-right">Last Published: 2024-11-18</li>
+                       </ul>
+               </div>
+       </header>
+
+       <div class="main-body">
+       <div class="row">
+               <div class="span12">
+                       <div class="body-content">
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+--> 
+<section> 
+ <div class="page-header">
+  <h2 id="Helix_Tutorial:_Customizing_Health_Checks"><a 
href="./Tutorial.html">Helix Tutorial</a>: Customizing Health Checks</h2>
+ </div> 
+ <p>In this chapter, we'll learn how to customize health checks based on 
metrics of your distributed system.</p> 
+ <section> 
+  <h3 id="Health_Checks">Health Checks</h3> 
+  <p>Note: <i>this in currently in development mode, not yet ready for 
production.</i></p> 
+  <p>Helix provides the ability for each node in the system to report health 
metrics on a periodic basis.</p> 
+  <p>Helix supports multiple ways to aggregate these metrics:</p> 
+  <ul> 
+   <li>SUM</li> 
+   <li>AVG</li> 
+   <li>EXPONENTIAL DECAY</li> 
+   <li>WINDOW</li> 
+  </ul> 
+  <p>Helix persists the aggregated value only.</p> 
+  <p>Applications can define a threshold on the aggregate values according to 
the SLAs, and when the SLA is violated Helix will fire an alert. Currently 
Helix only fires an alert, but in a future release we plan to use these metrics 
to either mark the node dead or load balance the partitions. This feature will 
be valuable for distributed systems that support multi-tenancy and have a large 
variation in work load patterns. In addition, this can be used to detect skewed 
partitions (hotspots) and rebalance the cluster.</p> 
+ </section> 
+</section>
+                       </div>
+               </div>
+       </div>
+       </div>
+
+       </div><!-- /container -->
+
+       <!-- Footer
+       ================================================== -->
+       <footer class="well">
+               <div class="container">
+                       <div class="row">
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li class="nav-header">Get 
Helix</li>
+                                               <li >
+                                                       <a href="download.html" 
title="Download">Download</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Building.html" 
title="Building">Building</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="releasenotes/release-1.4.2.html" title="Release Notes">Release Notes</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Hands-On</li>
+                                               <li >
+                                                       <a 
href="Quickstart.html" title="Quick Start">Quick Start</a>
+                                               </li>
+                                               <li >
+                                                       <a href="Tutorial.html" 
title="Tutorial">Tutorial</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="../javadocs/1.4.2" title="Javadocs">Javadocs</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                               <div class="span3 bottom-nav">
+                                       <ul class="nav nav-list">
+                                               <li 
class="nav-header">Recipes</li>
+                                               <li >
+                                                       <a 
href="recipes/lock_manager.html" title="Distributed lock manager">Distributed 
lock manager</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rabbitmq_consumer_group.html" title="Rabbit MQ consumer 
group">Rabbit MQ consumer group</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/rsync_replicated_file_store.html" title="Rsync replicated file 
store">Rsync replicated file store</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/service_discovery.html" title="Service discovery">Service 
discovery</a>
+                                               </li>
+                                               <li >
+                                                       <a 
href="recipes/task_dag_execution.html" title="Distributed task DAG 
execution">Distributed task DAG execution</a>
+                                               </li>
+                                       </ul>
+                               </div>
+                       </div>
+               </div>
+       </footer>
+
+       <div class="container subfooter">
+               <div class="row">
+                       <div class="span12">
+                               <p class="pull-right"><a href="#">Back to 
top</a></p>
+                               <p class="copyright">Copyright &copy;2024 <a 
href="http://www.apache.org";>Apache Software Foundation</a>. All Rights 
Reserved.</p>
+                               <p><a 
href="https://github.com/olamy/reflow-maven-skin"; title="Reflow Maven 
skin">Reflow Maven skin</a> maintained by <a href="https://twitter.com/olamy"; 
target="_blank" title="Olivier Lamy">Olivier Lamy</a>.</p>
+               <div class="row span16"><div>Apache Helix, Apache, the Apache 
feather logo, and the Apache Helix project logos are trademarks of The Apache 
Software Foundation.
+        All other marks mentioned may be trademarks or registered trademarks 
of their respective owners.</div>
+        <a 
href="https://helix.apache.org/1.4.2-docs/privacy-policy.html";>Privacy 
Policy</a>
+      </div>
+                       </div>
+               </div>
+       </div>
+
+       <!-- Le javascript
+       ================================================== -->
+       <!-- Placed at the end of the document so the pages load faster -->
+       <script src="./js/jquery.min.js"></script>
+
+       <script src="./js/bootstrap.min.js"></script>
+       <script src="./js/lightbox.min.js"></script>
+       <script src="./js/reflow-scroll.js"></script>
+
+       <script src="./js/reflow-skin.js"></script>
+
+       </body>
+</html>
\ No newline at end of file


Reply via email to