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Merge pull request #511 from ghillert/INT-2444

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Gary Russell
2012-06-21 13:43:55 -04:00
parent 92c62932dc 24abdf65b1
commit af4dfbaa94
1 changed files with 42 additions and 29 deletions
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src/reference/docbook/endpoint.xml
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@@ -76,42 +76,45 @@ EventDrivenConsumer consumer = new EventDrivenConsumer(channel, exampleHandler);
<para>
Spring Integration also provides a <classname>PollingConsumer</classname>, and it can be instantiated in
the same way except that the channel must implement <interfacename>PollableChannel</interfacename>:
<programlisting language="java">PollableChannel channel = context.getBean("pollableChannel", PollableChannel.class);
</para>
<programlisting language="java">PollableChannel channel = context.getBean("pollableChannel", PollableChannel.class);
PollingConsumer consumer = new PollingConsumer(channel, exampleHandler);</programlisting>
</para>
<note>
For more information regarding Polling Consumers, please also read
<xref linkend="polling-consumer"/> as well as <xref linkend="channel-adapter"/>.
</note>
<para>
There are many other configuration options for the Polling Consumer. For example, the trigger is a required property:
<programlisting language="java">
PollingConsumer consumer = new PollingConsumer(channel, handler);
<para>
There are many other configuration options for the Polling Consumer. For example, the trigger is a required property:
</para>
<programlisting language="java">PollingConsumer consumer = new PollingConsumer(channel, handler);
consumer.setTrigger(new IntervalTrigger(30, TimeUnit.SECONDS));</programlisting>
<para>
Spring Integration currently provides two implementations of the <interfacename>Trigger</interfacename>
interface: <classname>IntervalTrigger</classname> and <classname>CronTrigger</classname>. The
<classname>IntervalTrigger</classname> is typically defined with a simple interval (in milliseconds), but
also supports an <emphasis>initialDelay</emphasis> property and a boolean <emphasis>fixedRate</emphasis> property (the default is false, i.e.
fixed delay):
</para>
<programlisting language="java">IntervalTrigger trigger = new IntervalTrigger(1000);
trigger.setInitialDelay(5000);
trigger.setFixedRate(true);</programlisting>
The <classname>CronTrigger</classname> simply requires a valid cron expression (see the Javadoc for details):
<para>
The <classname>CronTrigger</classname> simply requires a valid cron
expression (see the Javadoc for details):
</para>
<programlisting language="java">CronTrigger trigger = new CronTrigger("*/10 * * * * MON-FRI");</programlisting>
</para>
<para>
In addition to the trigger, several other polling-related configuration properties may be specified:
<programlisting language="java">
PollingConsumer consumer = new PollingConsumer(channel, handler);
<para>
In addition to the trigger, several other polling-related configuration
properties may be specified:
</para>
<programlisting language="java">PollingConsumer consumer = new PollingConsumer(channel, handler);
consumer.setMaxMessagesPerPoll(10);
consumer.setReceiveTimeout(5000);</programlisting>
</para>
<para>
The <emphasis>maxMessagesPerPoll</emphasis> property specifies the maximum number of messages to receive within a given poll
operation. This means that the poller will continue calling receive() <emphasis>without waiting</emphasis>
@@ -131,22 +134,33 @@ consumer.setReceiveTimeout(5000);</programlisting>
option requires a thread to wait, but as a result it is able to respond much more quickly to arriving messages.
This technique, known as <emphasis>long polling</emphasis>, can be used to emulate event-driven behavior on a polled source.
</para>
<para>
A Polling Consumer may also delegate to a Spring <interfacename>TaskExecutor</interfacename>, and it can
be configured to participate in Spring-managed transactions. The following example shows the configuration of both:
<programlisting language="java">
PollingConsumer consumer = new PollingConsumer(channel, handler);
<para>
A Polling Consumer may also delegate to a Spring <interfacename>TaskExecutor</interfacename>,
as illustrated in the following example:
</para>
<programlisting language="java">PollingConsumer consumer = new PollingConsumer(channel, handler);
TaskExecutor taskExecutor = context.getBean("exampleExecutor", TaskExecutor.class);
consumer.setTaskExecutor(taskExecutor);
PlatformTransactionManager txManager = context.getBean("exampleTxManager", PlatformTransationManager.class);
consumer.setTransactionManager(txManager);</programlisting>
The examples above show dependency lookups, but keep in mind that these consumers will most often be configured
as Spring <emphasis>bean definitions</emphasis>. In fact, Spring Integration also provides a
<interfacename>FactoryBean</interfacename> that creates the appropriate consumer type based on the type of
channel, and there is full XML namespace support to even further hide those details. The namespace-based
configuration will be featured as each component type is introduced.
consumer.setTaskExecutor(taskExecutor);</programlisting>
<para>
Furthermore, a <classname>PollingConsumer</classname> has a property called
<emphasis>adviceChain</emphasis>. This property allows you to specify a
<interfacename>List</interfacename> of AOP Advices for handling additional
cross cutting concerns including transactions. These advices are applied
around the <methodname>doPoll()</methodname> method. For more in-depth
information, please see the sections <emphasis>AOP Advice chains</emphasis>
and <emphasis>Transaction Support</emphasis> under <xref linkend="endpoint-namespace"/>.
</para>
<para>
The examples above show dependency lookups, but keep in mind that these
consumers will most often be configured as Spring <emphasis>bean definitions</emphasis>.
In fact, Spring Integration also provides a <interfacename>FactoryBean</interfacename>
called <classname>ConsumerEndpointFactoryBean</classname> that creates
the appropriate consumer type based on the type of channel, and there is
full XML namespace support to even further hide those details. The
namespace-based configuration will be featured as each component type is
introduced.
</para>
<note>
Many of the <interfacename>MessageHandler</interfacename> implementations are also capable of generating reply
Messages. As mentioned above, sending Messages is trivial when compared to the Message reception. Nevertheless,
@@ -158,7 +172,6 @@ consumer.setTransactionManager(txManager);</programlisting>
class, the <classname>AbstractReplyProducingMessageHandler</classname>, and it provides a
<methodname>setOutputChannel(..)</methodname> method.
</note>
</para>
</section>
<section id="endpoint-namespace">