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INT-2763 Send AdviceMessage from Advice

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The ExpressionEvaluatingMessageHandlerAdvice now sends an
AdviceMessage which has a payload of the original message, and
a property 'inputMessage' referencing the message that was
sent to the advised handler.

INT-2763 Expression Advice Reference Doc Update

Update to reflect the new behavior.
This commit is contained in:
Gary Russell
2012-09-21 17:55:50 +01:00
committed by Oleg Zhurakousky
parent c8da0532d7
commit 2340e6f442
5 changed files with 214 additions and 132 deletions
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46
src/reference/docbook/handler-advice.xml
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@@ -369,46 +369,24 @@ Caused by: java.lang.RuntimeException: foo
<classname>org.springframework.integration.handler.advice.ExpressionEvaluatingRequestHandlerAdvice</classname>.
This advice is more general than the other two advices. It provides a mechanism to evaluate an expression on the
original inbound message sent to the endpoint. Separate expressions are available to be evaluated, either after
success, or failure. Optionally, the original message, together with the result of the evaluation in a
header, can be sent to a message channel.
success, or failure. Optionally, a message containing the evaluation result, together with the input message,
can be sent to a message channel.
</para>
<para>
A typical use case for this advice might be with an &lt;ftp:outbound-channel-adapter /&gt;, perhaps to move
the file to one directory if the transfer was successful, or to another directory if it fails:
</para>
<para><programlisting><![CDATA[<int-ftp:outbound-channel-adapter id="ftpOutbound" cache-sessions="false"
channel="ftpChannel"
remote-directory="."
session-factory="ftpClientFactory">
<int-ftp:request-handler-advice-chain>
<bean class="org.springframework.integration.handler.advice.ExpressionEvaluatingRequestHandlerAdvice">
<constructor-arg name="onSuccessExpression" value="payload.renameTo('/tmp/good/' + payload.name)"/>
<constructor-arg name="successChannel" ref="successChannel" />
<constructor-arg name="onFailureExpression" value="payload.renameTo('/tmp/bad/' + payload.name)"/>
<constructor-arg name="failureChannel" ref="failureChannel" />
</bean>
</int-ftp:request-handler-advice-chain>
</int-ftp:outbound-channel-adapter>
DEBUG [main] preSend on channel 'ftpChannel', message: [Payload=target/toSend/b.txt][Headers=...]
DEBUG [main] Connected to server [localhost:21]
INFO [main] File has been successfully transfered to: ./b.txt.writing
INFO [main] File has been successfully renamed from: ./b.txt.writing to ./b.txt
DEBUG [main] preSend on channel 'successChannel', message: [Payload=target/toSend/b.txt][Headers={..., postProcessResult=true}]
...
DEBUG [main] preSend on channel 'ftpChannel', message: [Payload=target/toSend/a.txt][Headers=...]
DEBUG [main] Connected to server [localhost:21]
...
DEBUG [main] preSend on channel 'failureChannel', message: [Payload=target/toSend/a.txt][Headers={..., postProcessResult=true}]]]></programlisting></para>
<para>
As you can see, in the first case, the successful transfer resulted in a message sent to
<emphasis>successChannel</emphasis>; the second case shows the result being sent to
<emphasis>failureChannel</emphasis>. In both cases, you can see the <emphasis>postProcessResult</emphasis>
header containing the result of the evaluation (true because the rename operations were successful -
<classname>java.io.File.renameTo(...)</classname> returns a <emphasis>boolean</emphasis>).
The Advice has properties to set an expression when successful, an expression for failures,
and corresponding channels for each. For the successful case, the message sent to the
<emphasis>successChannel</emphasis> is an <classname>AdviceMessage</classname>, with
the payload being the result of the expression evaluation, and an additional property
<code>inputMessage</code> which contains the original message sent to the handler. A message
sent to the <emphasis>failureChannel</emphasis> (when the handler throws an excecption)
is an ErrorMessage with a payload of <classname>MessageHandlingExpressionEvaluatingAdviceException</classname>.
Like all <classname>MessagingException</classname>s, this payload has <code>failedMessage</code>
and <code>cause</code> properties, as well as an additional property <code>evaluationResult</code>,
containing the result of the expression evaluation.
</para>
</section>
</section>