src/site/xdoc/guide/async.xml (50 lines of code) (raw):
<?xml version="1.0" encoding="UTF-8"?>
<!--
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.
-->
<document xmlns="http://maven.apache.org/XDOC/2.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 http://maven.apache.org/xsd/xdoc-2.0.xsd">
<properties>
<title>Apache Commons Digester | Guide | Asynchronous Parser</title>
<author email="dev@commons.apache.org">Commons Documentation Team</author>
</properties>
<body>
<section name="Asynchronous Digester">
<p>Since version 3.1 the Digester component offers asynchronous <code>parse()</code> methods.</p>
<p>Users can take advantage from that feature when need to process large XML streams without mapping to
intermediary POJOs. Take in consideration applications that need to import data from XML documents
- maybe obtained by a REST invocation - and transfer to a DataBase.<br/>
Putting the data processor in a non-blocking executor would help clients on:</p>
<ul>
<li>increasing the number of parse operations at the same time;</li>
<li></li>
</ul>
<p><strong>Note</strong> keep always in mind the every single <code>Digester</code> instance is NOT thread-safety,
so please use the <i>asynchronous</i> feature carefully!!!</p>
<subsection name="Using Digester Loader">
<p>First of all, setup the <code>DigesterLoader</code> with <code>java.util.concurrent.ExecutorService</code>:</p>
<source>final DigesterLoader digesterLoader = newLoader( new AbstractRulesModule()
{
@Override
protected void configure()
{
forPattern( "employee" ).createObject().ofType( Employee.class );
...
}
} ).setExecutorService( java.util.concurrent.Executors.newFixedThreadPool( 10 ) );</source>
<p>Then create the Digester and run the <code>parse</code> method asynchronously:</p>
<source>Digester digester = digesterLoader.newDigester();
...
Future<Employee> future = digester.asyncParse( new URL( "http://my.rest.server/employees/10" ) );</source>
</subsection>
<subsection name="Using directly with the Digester">
<p>First of all, setup the <code>Digester</code> with <code>java.util.concurrent.ExecutorService</code>:</p>
<source>Digester digester = new Digester();
digester.addObjectCreate( "employee", Employee.class);
...
digester.setExecutorService( java.util.concurrent.Executors.newFixedThreadPool( 10 ) );
</source>
<p>Then run the <code>parse</code> method asynchronously:</p>
<source>Future<Employee> future = digester.asyncParse( new URL( "http://my.rest.server/employees/10" ) );</source>
</subsection>
</section>
</body>
</document>