59 lines
3.3 KiB
XML
59 lines
3.3 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<chapter id="channel-adapter">
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<title>Channel Adapter</title>
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<para>
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A Channel Adapter is a Message Endpoint that enables connecting a single sender or receiver to a Message Channel.
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Spring Integration provides a number of adapters out of the box to support various transports, such as JMS, File,
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etc. Those will be discussed in upcoming chapters of this reference guide. However, this chapter focuses on the
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simple but flexible Method-invoking Channel Adapter support. There is an inbound and outbound adapter, and each
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may be configured with XML elements provided in the core namespace.
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</para>
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<section id="channel-adapter-namespace-inbound">
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<title>The <inbound-channel-adapter> element</title>
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<para>
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An "inbound-channel-adapter" element can invoke any method on a Spring-managed Object and send a non-null return
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value to a <interfacename>MessageChannel</interfacename> after converting it to a <classname>Message</classname>.
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When the adapter's subscription is activated, a poller will attempt to receive messages from the source. The
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poller will be scheduled with the <interfacename>TaskScheduler</interfacename> according to the provided
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configuration. To configure the polling 'interval' or 'cronExpression' for an individual channel-adapter's
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schedule, provide a 'poller' element with either an 'interval-trigger' (in milliseconds) or 'cron-trigger'
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sub-element:
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<programlisting language="xml"><![CDATA[<inbound-channel-adapter ref="source1" method="method1" channel="channel1">
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<poller>
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<interval-trigger interval="5000"/>
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</poller>
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</inbound-channel-adapter>
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<inbound-channel-adapter ref="source2" method="method2" channel="channel2">
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<poller>
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<cron-trigger expression="30 * * * * MON-FRI"/>
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</poller>
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</channel-adapter>]]></programlisting>
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</para>
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</section>
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<section id="channel-adapter-namespace-outbound">
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<title>The <outbound-channel-adapter/> element</title>
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<para>
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An "outbound-channel-adapter" element can also connect a <interfacename>MessageChannel</interfacename> to any
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method that should be invoked with the payload of any Message sent to that channel.
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<programlisting language="xml"><![CDATA[<outbound-channel-adapter channel="channel1" ref="target1" method="method1"/>]]></programlisting>
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If the channel being adapted is a <interfacename>PollableChannel</interfacename>, provide a poller sub-element:
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<programlisting language="xml"><![CDATA[<outbound-channel-adapter channel="channel2" ref="target2" method="method2">
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]]><emphasis><![CDATA[<poller>
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<interval-trigger interval="3000"/>
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</poller>]]></emphasis><![CDATA[
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</outbound-channel-adapter>]]></programlisting>
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</para>
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<para>
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Any Channel Adapter can be created without a "channel" reference in which case it will implicitly create an
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instance of <classname>DirectChannel</classname>. The created channel's name will match the "id" attribute
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of the <inbound-channel-adapter/> or <outbound-channel-adapter>l; element. Therefore, if the "channel"
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is not provided, the "id" is required.
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</para>
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</section>
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</chapter> |