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| <title>4. Configuration Properties</title><base href="display"><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL-NS Stylesheets V1.76.1"><link rel="home" href="manual.html" title="Apache OpenJPA 2.2 User's Guide"><link rel="up" href="ref_guide_slice.html" title="Chapter 13. Slice: Distributed Persistence"><link rel="prev" href="slice_configuration.html" title="3. Usage"><link rel="next" href="ref_guide_integration.html" title="Chapter 14. 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">4. Configuration Properties</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="slice_configuration.html">Prev</a> </td><th width="60%" align="center">Chapter 13. |
| Slice: Distributed Persistence |
| </th><td width="20%" align="right"> <a accesskey="n" href="ref_guide_integration.html">Next</a></td></tr></table><hr></div><div class="section" title="4. Configuration Properties"><div class="titlepage"><div><div><h2 class="title" style="clear: both" id="d5e16863">4. Configuration Properties</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ch29s04.html#d5e16868">4.1. Global Properties</a></span></dt><dd><dl><dt><span class="section"><a href="ch29s04.html#d5e16870">4.1.1. openjpa.slice.DistributionPolicy</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16876">4.1.2. openjpa.slice.Lenient</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16883">4.1.3. openjpa.slice.Master</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16891">4.1.4. openjpa.slice.Names</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16899">4.1.5. openjpa.slice.ThreadingPolicy</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16925">4.1.6. openjpa.slice.TransactionPolicy</a></span></dt></dl></dd><dt><span class="section"><a href="ch29s04.html#d5e16943">4.2. Per-Slice Properties</a></span></dt></dl></div> |
| |
| <p> |
| The properties to configure Slice can be classified in two broad groups. |
| The <span class="emphasis"><em>global</em></span> properties apply to all the slices, for example, |
| the thread pool used to execute the queries in parallel or the transaction |
| manager used to coordinate transaction across multiple slices. |
| The <span class="emphasis"><em>per-slice</em></span> properties apply to individual slice, for example, |
| the JDBC connection URL of a slice. |
| </p> |
| |
| <div class="section" title="4.1. Global Properties"><div class="titlepage"><div><div><h3 class="title" id="d5e16868">4.1. Global Properties</h3></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ch29s04.html#d5e16870">4.1.1. openjpa.slice.DistributionPolicy</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16876">4.1.2. openjpa.slice.Lenient</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16883">4.1.3. openjpa.slice.Master</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16891">4.1.4. openjpa.slice.Names</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16899">4.1.5. openjpa.slice.ThreadingPolicy</a></span></dt><dt><span class="section"><a href="ch29s04.html#d5e16925">4.1.6. openjpa.slice.TransactionPolicy</a></span></dt></dl></div> |
| |
| |
| <div class="section" title="4.1.1. openjpa.slice.DistributionPolicy"><div class="titlepage"><div><div><h4 class="title" id="d5e16870">4.1.1. openjpa.slice.DistributionPolicy</h4></div></div></div> |
| |
| <p> |
| This <span class="emphasis"><em>mandatory</em></span> plug-in property determines how newly |
| persistent instances are distributed across individual slices. |
| The value of this property is a fully-qualified class name that implements |
| <a class="ulink" href="../javadoc/org/apache/openjpa/slice/DistributionPolicy.html" target="_top"> |
| <code class="classname">org.apache.openjpa.slice.DistributionPolicy</code> |
| </a> interface. |
| </p> |
| </div> |
| |
| <div class="section" title="4.1.2. openjpa.slice.Lenient"><div class="titlepage"><div><div><h4 class="title" id="d5e16876">4.1.2. openjpa.slice.Lenient</h4></div></div></div> |
| <p> |
| This boolean plug-in property controls the behavior when one or more slice |
| can not be connected or unavailable for some other reasons. |
| If <code class="classname">true</code>, the unreachable slices are ignored. If |
| <code class="classname">false</code> then any unreachable slice will raise an exception |
| during startup. |
| </p> |
| <p> |
| By default this value is set to <code class="classname">false</code> i.e. all configured |
| slices must be available. |
| </p> |
| </div> |
| |
| <div class="section" title="4.1.3. openjpa.slice.Master"><div class="titlepage"><div><div><h4 class="title" id="d5e16883">4.1.3. openjpa.slice.Master</h4></div></div></div> |
| |
| <p> |
| The user application often directs OpenJPA to generate primary keys |
| for persistence instances automatically or from a specific database |
| sequence. For such primary key value generation strategy where |
| a database instance is required, Slice uses a designated slice |
| referred to as <span class="emphasis"><em>master</em></span> slice. |
| </p> |
| <p> |
| The master slice can be specified explicitly via |
| <code class="classname">openjpa.slice.Master</code> property and whose value is one |
| of the configured slice names. If this property is not explicitly |
| specified then, by default, the master slice is the first slice |
| in the list of configured slice names. |
| </p> |
| <p> |
| </p><div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3> |
| Currently, there is no provision to use sequence from |
| multiple slices. |
| </div><p> |
| </p> |
| </div> |
| |
| <div class="section" title="4.1.4. openjpa.slice.Names"><div class="titlepage"><div><div><h4 class="title" id="d5e16891">4.1.4. openjpa.slice.Names</h4></div></div></div> |
| |
| <p> |
| This plug-in property can be used to register the logical slice names. |
| The value of this property is comma-separated list of slice names. |
| The ordering of the names in this list is |
| <span class="emphasis"><em>significant</em></span> because |
| <a class="link" href="slice_configuration.html#distribution_policy" title="3.3. Implement DistributionPolicy interface">DistributionPolicy</a> and |
| <a class="link" href="slice_configuration.html#replication_policy" title="3.4. Implement ReplicationPolicy interface">ReplicationPolicy</a> receive |
| the input argument of the slice names in the same order. |
| </p> |
| <p> |
| If logical slice names are not registered explicitly via this property, |
| then all logical slice names available in the persistence unit are |
| registered. The ordering of the slice names in this case is alphabetical. |
| </p> |
| <p> |
| If logical slice names are registered explicitly via this property, then |
| any logical slice that is available in the persistence unit but excluded |
| from this list is ignored. |
| </p> |
| </div> |
| |
| <div class="section" title="4.1.5. openjpa.slice.ThreadingPolicy"><div class="titlepage"><div><div><h4 class="title" id="d5e16899">4.1.5. openjpa.slice.ThreadingPolicy</h4></div></div></div> |
| |
| <p> |
| This plug-in property determines the nature of thread pool being used |
| for database operations such as query or flush on individual slices. |
| The value of the property is a |
| fully-qualified class name that implements |
| <a class="ulink" href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ExecutorService.html" target="_top"> |
| <code class="classname">java.util.concurrent.ExecutorService</code> |
| </a> interface. |
| Two pre-defined pools can be chosen via their aliases namely |
| <code class="classname">fixed</code> or <code class="classname">cached</code>. |
| </p> |
| <p> |
| The pre-defined alias <code class="classname">cached</code> activates a |
| <a class="ulink" href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/Executors.html#newCachedThreadPool()" target="_top">cached thread pool</a>. |
| A cached thread pool creates new threads as needed, but will reuse |
| previously constructed threads when they are available. This pool |
| is suitable in scenarios that execute many short-lived asynchronous tasks. |
| The way Slice uses the thread pool to execute database operations is |
| akin to such scenario and hence <code class="classname">cached</code> is the default |
| value for this plug-in property. |
| </p> |
| <p> |
| The <code class="classname">fixed</code> alias activates a |
| <a class="ulink" href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/Executors.html#newFixedThreadPool(int)" target="_top">fixed thread pool</a>. |
| The fixed thread pool can be further parameterized with |
| <code class="classname">CorePoolSize</code>, <code class="classname">MaximumPoolSize</code>, |
| <code class="classname">KeepAliveTime</code> and <code class="classname">RejectedExecutionHandler</code>. |
| The meaning of these parameters are described in |
| <a class="ulink" href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.html" target="_top">JavaDoc</a>. |
| The users can exercise finer control on thread pool behavior via these |
| parameters. |
| By default, the core pool size is <code class="classname">10</code>, maximum pool size is |
| also <code class="classname">10</code>, keep alive time is <code class="classname">60</code> seconds and |
| rejected execution is |
| <a class="ulink" href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.AbortPolicy.html" target="_top">aborted</a>. |
| </p> |
| <p> |
| Both of the pre-defined aliases can be parameterized with a fully-qualified |
| class name that implements |
| <a class="ulink" href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadFactory.html" target="_top"> |
| <code class="classname">java.util.concurrent.ThreadFactory</code> |
| </a> interface. |
| </p> |
| </div> |
| |
| <div class="section" title="4.1.6. openjpa.slice.TransactionPolicy"><div class="titlepage"><div><div><h4 class="title" id="d5e16925">4.1.6. openjpa.slice.TransactionPolicy</h4></div></div></div> |
| |
| <p> |
| This plug-in property determines the policy for transaction commit |
| across multiple slices. The value of this property is a fully-qualified |
| class name that implements |
| <a class="ulink" href="http://download.oracle.com/javaee/6/api/javax/transaction/TransactionManager.html" target="_top"> |
| <code class="classname">javax.transaction.TransactionManager</code> |
| </a> interface. |
| </p> |
| <p> |
| Three pre-defined policies can be chosen |
| by their aliases namely <code class="classname">default</code>, |
| <code class="classname">xa</code> and <code class="classname">jndi</code>. |
| </p> |
| <p> |
| The <code class="classname">default</code> policy employs |
| a Transaction Manager that commits or rolls back transaction on individual |
| slices <span class="emphasis"><em>without</em></span> a two-phase commit protocol. |
| It does <span class="emphasis"><em>not</em></span> |
| guarantee atomic nature of transaction across all the slices because if |
| one or more slice fails to commit, there is no way to rollback the transaction |
| on other slices that committed successfully. |
| </p> |
| <p> |
| The <code class="classname">xa</code> policy employs a Transaction Manager that that commits |
| or rolls back transaction on individual |
| slices using a two-phase commit protocol. The prerequisite to use this scheme |
| is, of course, that all the slices must be configured to use |
| XA-compliant JDBC driver. |
| </p> |
| <p> |
| The <code class="classname">jndi</code> policy employs a Transaction Manager by looking up the |
| JNDI context. The prerequisite to use this transaction |
| manager is, of course, that all the slices must be configured to use |
| XA-compliant JDBC driver. |
| </p><div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3>This JNDI based policy is not available currently.</div><p> |
| </p> |
| </div> |
| </div> |
| |
| <div class="section" title="4.2. Per-Slice Properties"><div class="titlepage"><div><div><h3 class="title" id="d5e16943">4.2. Per-Slice Properties</h3></div></div></div> |
| |
| <p> |
| Any OpenJPA property can be configured for each individual slice. The property name |
| is of the form <code class="classname">openjpa.slice.[Logical slice name].[OpenJPA Property Name]</code>. |
| For example, <code class="classname">openjpa.slice.One.ConnectionURL</code> where <code class="classname">One</code> |
| is the logical slice name and <code class="classname">ConnectionURL</code> is an OpenJPA property |
| name. |
| </p> |
| <p> |
| If a property is not configured for a specific slice, then the value for |
| the property equals to the corresponding <code class="classname">openjpa.*</code> property. |
| </p> |
| </div> |
| |
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