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| <title>2. Remote Event Notification Framework</title><link rel="stylesheet" href="css/docbook.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.72.0"><link rel="start" href="manual.html" title="Apache OpenJPA User's Guide"><link rel="up" href="ref_guide_remote.html" title="Chapter 11. Remote and Offline Operation"><link rel="prev" href="ref_guide_remote.html" title="Chapter 11. Remote and Offline Operation"><link rel="next" href="ref_guide_integration.html" title="Chapter 12. Third Party Integration"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2. |
| Remote Event Notification Framework |
| </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ref_guide_remote.html">Prev</a> </td><th width="60%" align="center">Chapter 11. |
| Remote and Offline Operation |
| </th><td width="20%" align="right"> <a accesskey="n" href="ref_guide_integration.html">Next</a></td></tr></table><hr></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ref_guide_event"></a>2. |
| Remote Event Notification Framework |
| </h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf">2.1. |
| Remote Commit Provider Configuration |
| </a></span></dt><dd><dl><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf_jms">2.1.1. |
| JMS |
| </a></span></dt><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf_tcp">2.1.2. |
| TCP |
| </a></span></dt><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf_common">2.1.3. |
| Common Properties |
| </a></span></dt></dl></dd><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_customization">2.2. |
| Customization |
| </a></span></dt></dl></div><a class="indexterm" name="d0e29289"></a><a class="indexterm" name="d0e29294"></a><p> |
| <a class="indexterm" name="d0e29303"></a> |
| <a class="indexterm" name="d0e29311"></a> |
| The remote event notification framework allows a subset of the information |
| available through OpenJPA's transaction events (see |
| <a href="ref_guide_runtime_pm_event.html" title="7. Transaction Events">Section 7, “ |
| Transaction Events |
| ”</a>) to be broadcast to remote |
| listeners. OpenJPA's <a href="ref_guide_caching.html#ref_guide_cache" title="1. Data Cache">data cache</a>, for |
| example, uses remote events to remain synchronized when deployed in multiple |
| JVMs. |
| </p><p> |
| To enable remote events, you must configure the <code class="classname"> EntityManagerFactory |
| </code> to use a <code class="literal">RemoteCommitProvider</code> (see below). |
| </p><p> |
| When a <code class="literal">RemoteCommitProvider</code> is properly configured, you can |
| register |
| <a xmlns:xlink="http://www.w3.org/1999/xlink" href="../javadoc/org/apache/openjpa/event/RemoteCommitListener.html" target="_top"> |
| <code class="classname">RemoteCommitListener</code></a>s that will be alerted with |
| a list of modified object ids whenever a transaction on a remote machine |
| successfully commits. |
| </p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ref_guide_event_conf"></a>2.1. |
| Remote Commit Provider Configuration |
| </h3></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf_jms">2.1.1. |
| JMS |
| </a></span></dt><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf_tcp">2.1.2. |
| TCP |
| </a></span></dt><dt><span class="section"><a href="ref_guide_event.html#ref_guide_event_conf_common">2.1.3. |
| Common Properties |
| </a></span></dt></dl></div><a class="indexterm" name="d0e29345"></a><p> |
| OpenJPA includes built in remote commit providers for JMS and TCP communication. |
| </p><div class="section" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="ref_guide_event_conf_jms"></a>2.1.1. |
| JMS |
| </h4></div></div></div><a class="indexterm" name="d0e29357"></a><p> |
| The JMS remote commit provider can be configured by setting the |
| <a href="ref_guide_conf_openjpa.html#openjpa.RemoteCommitProvider" title="5.52. openjpa.RemoteCommitProvider"><code class="literal"> |
| openjpa.RemoteCommitProvider</code></a> property to contain the |
| appropriate configuration properties. The JMS provider understands the following |
| properties: |
| </p><div class="itemizedlist"><ul type="disc"><li><p> |
| <code class="literal">Topic</code>: The topic that the remote commit provider should |
| publish notifications to and subscribe to for notifications sent from other |
| JVMs. Defaults to <code class="literal">topic/OpenJPACommitProviderTopic</code> |
| </p></li><li><p> |
| <code class="literal">TopicConnectionFactory</code>: The JNDI name of a <code class="classname"> |
| javax.jms.TopicConnectionFactory</code> factory to use for finding topics. |
| Defaults to <code class="literal"> java:/ConnectionFactory</code>. This setting may vary |
| depending on the application server in use; consult the application server's |
| documentation for details of the default JNDI name for the <code class="classname"> |
| javax.jms.TopicConnectionFactory</code> instance. For example, under |
| Weblogic, the JNDI name for the TopicConnectionFactory is <code class="literal"> |
| javax.jms.TopicConnectionFactory</code>. |
| </p></li><li><p> |
| <code class="literal">ExceptionReconnectAttempts</code>: The number of times to attempt |
| to reconnect if the JMS system notifies OpenJPA of a serious connection error. |
| Defaults to 0, meaning OpenJPA will log the error but otherwise ignore it, |
| hoping the connection is still valid. |
| </p></li><li><p> |
| <code class="literal">*</code>: All other configuration properties will be interpreted as |
| settings to pass to the JNDI <code class="classname">InitialContext</code> on |
| construction. For example, you might set the <code class="literal">java.naming.provider.url |
| </code> property to the URL of the context provider. |
| </p></li></ul></div><p> |
| To configure a factory to use the JMS provider, your properties might look like |
| the following: |
| </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> |
| Because of the nature of JMS, it is important that you invoke <code class="methodname"> |
| EntityManagerFactory.close</code> when finished with a factory. If you do |
| not do so, a daemon thread will stay up in the JVM, preventing the JVM from |
| exiting. |
| </p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="ref_guide_event_conf_tcp"></a>2.1.2. |
| TCP |
| </h4></div></div></div><a class="indexterm" name="d0e29427"></a><p> |
| The TCP remote commit provider has several options that are defined as host |
| specifications containing a host name or IP address and an optional port |
| separated by a colon. For example, the host specification <code class="literal"> |
| saturn.bea.com:1234</code> represents an <code class="classname">InetAddress</code> |
| retrieved by invoking <code class="methodname">InetAddress.getByName("saturn.bea.com") |
| </code> and a port of 1234. |
| </p><p> |
| <a class="indexterm" name="d0e29447"></a> |
| The TCP provider can be configured by setting the <code class="literal"> |
| openjpa.RemoteCommitProvider</code> plugin property to contain the |
| appropriate configuration settings. The TCP provider understands the following |
| properties: |
| </p><div class="itemizedlist"><ul type="disc"><li><p> |
| <code class="literal">Port</code>: The TCP port that the provider should listen on for |
| commit notifications. Defaults to 5636. |
| </p></li><li><p> |
| <code class="literal">Addresses</code>: A semicolon-separated list of IP addresses to |
| which notifications should be sent. No default value. |
| </p></li><li><p> |
| <code class="literal">NumBroadcastThreads</code>: The number of threads to create for the |
| purpose of transmitting events to peers. You sould increase this value as the |
| number of concurrent transactions increases. The maximum number of concurrent |
| transactions is a function of the size of the connection pool. See the the |
| <code class="literal">MaxActive</code> property of <code class="literal"> |
| openjpa.ConnectionFactoryProperties</code> in |
| <a href="ref_guide_dbsetup.html#ref_guide_dbsetup_builtin" title="1. Using the OpenJPA DataSource">Section 1, “ |
| Using the OpenJPA DataSource |
| ”</a>. Setting a value of 0 will |
| result in behavior where the thread invoking <code class="methodname">commit</code> |
| will perform the broadcast directly. Defaults to 2. |
| </p></li><li><p> |
| <code class="literal">RecoveryTimeMillis</code>: Amount of time to wait in milliseconds |
| before attempting to reconnect to a peer of the cluster when connectivity to the |
| peer is lost. Defaults to 15000. |
| </p></li><li><p> |
| <code class="literal">MaxIdle</code>: The number of TCP sockets (channels) to keep open |
| to each peer in the cluster for the transmission of events. Defaults to 2. |
| </p></li><li><p> |
| <code class="literal">MaxActive</code>: The maximum allowed number of TCP sockets |
| (channels) to open simultaneously between each peer in the cluster. Defaults to |
| 2. |
| </p></li></ul></div><p> |
| To configure a factory to use the TCP provider, your properties might look like |
| the following: |
| </p><div class="example"><a name="ref_guide_event_conf_tcpex"></a><p class="title"><b>Example 11.2. |
| TCP Remote Commit Provider Configuration |
| </b></p><div class="example-contents"><pre class="programlisting"> |
| <property name="openjpa.RemoteCommitProvider" |
| value="tcp(Addresses=10.0.1.10;10.0.1.11;10.0.1.12;10.0.1.13)"/> |
| </pre></div></div><br class="example-break"></div><div class="section" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="ref_guide_event_conf_common"></a>2.1.3. |
| Common Properties |
| </h4></div></div></div><a class="indexterm" name="d0e29512"></a><p> |
| In addition to the provider-specific configuration options above, all providers |
| accept the following plugin properties: |
| </p><div class="itemizedlist"><ul type="disc"><li><p> |
| <code class="literal">TransmitPersistedObjectIds</code>: Whether remote commit events |
| will include the object ids of instances persisted in the transaction. By |
| default only the class names of types persisted in the transaction are sent. |
| This results in smaller events and more efficient network utilization. If you |
| have registered your own remote commit listeners, however, you may require the |
| persisted object ids as well. |
| </p></li></ul></div><p> |
| To transmit persisted object ids in our remote commit events using the JMS |
| provider, we modify the previous example as follows: |
| </p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ref_guide_event_customization"></a>2.2. |
| Customization |
| </h3></div></div></div><a class="indexterm" name="d0e29533"></a><p> |
| You can develop additional mechanisms for remote event notification be by |
| creating an implementation of the |
| <a xmlns:xlink="http://www.w3.org/1999/xlink" href="../javadoc/org/apache/openjpa/event/RemoteCommitProvider.html" target="_top"> |
| <code class="classname"> RemoteCommitProvider</code></a> interface, possibly by |
| extending the |
| <a xmlns:xlink="http://www.w3.org/1999/xlink" href="../javadoc/org/apache/openjpa/event/AbstractRemoteCommitProvider.html" target="_top"> |
| <code class="classname">AbstractRemoteCommitProvider</code></a> abstract class.. |
| </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ref_guide_remote.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ref_guide_remote.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ref_guide_integration.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 11. |
| Remote and Offline Operation |
| </td><td width="20%" align="center"><a accesskey="h" href="manual.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 12. |
| Third Party Integration |
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