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INT-2722: Document Delayer's <advice-chain>

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* describe delayer's `<transactional>` & `<advice-chain>` abilities
* polishing delayer's doc: it looks bad in the PDF
* fix typo for 'proxying'

JIRA: https://jira.springsource.org/browse/INT-2722

INT-2722: Polishing - PR comments
This commit is contained in:
Artem Bilan
2012-08-27 12:55:24 +03:00
committed by Gary Russell
parent 0345a381b2
commit 600a347652
2 changed files with 33 additions and 10 deletions
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33
src/reference/docbook/delayer.xml
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@@ -57,7 +57,7 @@
delay-header-name="delay"
scheduler="exampleTaskScheduler"/>
<task:scheduler id="exampleTaskScheduler" pool-size="3"/>]]></programlisting>
<task:scheduler id="exampleTaskScheduler" pool-size="3"/>]]></programlisting>
<tip>
If you configure an external <classname>ThreadPoolTaskScheduler</classname>
you can set on this scheduler property <code>waitForTasksToCompleteOnShutdown = true</code>.
@@ -95,14 +95,37 @@
If a delayed Message remained in the <interfacename>MessageStore</interfacename> more
than its 'delay', it will be sent immediately after startup.
</para>
<para>
The <code>&lt;delayer&gt;</code> can be enriched with mutually exclusive sub-elements <code>&lt;transactional&gt;</code>
or <code>&lt;advice-chain&gt;</code>. The List of these AOP Advices is applied to the proxied internal
<classname>DelayHandler.ReleaseMessageHandler</classname>, which has the responsibility to release the Message, after the delay,
on a <classname>Thread</classname> of the scheduled task. It might be used, for example, when the downstream message flow throws an
Exception and the <classname>ReleaseMessageHandler</classname>'s transaction will be rolled back. In this case the delayed
Message will remain in the persistent <interfacename>MessageStore</interfacename>. You can use any custom
<interfacename>org.aopalliance.aop.Advice</interfacename> implementation within the <code>&lt;advice-chain&gt;</code>.
A sample configuration of the <code>&lt;delayer&gt;</code> may look like this:
<programlisting language="xml"><![CDATA[ <int:delayer id="delayer" input-channel="input" output-channel="output"
delay-header-name="delay"
message-store="jdbcMessageStore">
<int:advice-chain>
<beans:ref bean="customAdviceBean"/>
<tx:advice>
<tx:attributes>
<tx:method name="*" read-only="true"/>
</tx:attributes>
</tx:advice>
</int:advice-chain>
</int:delayer>]]></programlisting>
</para>
<para>
The <classname>DelayHandler</classname> can be exported as a JMX <code>MBean</code>
with managed operations <code>getDelayedMessageCount</code> and <code>reschedulePersistedMessages</code>,
which allows the rescheduling of delayed persisted Messages at runtime, for example, if the
<interfacename>TaskScheduler</interfacename> has previously been stopped. These operations can be invoked via a <code>Control Bus</code> command:
<programlisting language="java"><![CDATA[
Message<String> delayerReschedulingMessage = MessageBuilder.withPayload("@'delayer.handler'.reschedulePersistedMessages()").build();
controlBusChannel.send(delayerReschedulingMessage);]]></programlisting>
<interfacename>TaskScheduler</interfacename> has previously been stopped.
These operations can be invoked via a <code>Control Bus</code> command:
<programlisting language="java"><![CDATA[ Message<String> delayerReschedulingMessage =
MessageBuilder.withPayload("@'delayer.handler'.reschedulePersistedMessages()").build();
controlBusChannel.send(delayerReschedulingMessage);]]></programlisting>
</para>
<note>
For more information regarding the Message Store, JMX and the Control Bus, please read <xref linkend="system-management-chapter"/>.