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INT-789 Updated documentation

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Oleg Zhurakousky
2010-06-17 23:55:15 +00:00
parent 799afe484c
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src/docbkx/channel.xml
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@@ -530,31 +530,34 @@ public Message<?> receive(final PollableChannel<?> channel) { ... }]]></programl
Channel Interceptors allow you for a clean and concise way of applying cross-cutting behavior per individual channel.
But what if the same behavior should be applied on multiple channels, configuring the same set of interceptors for
each channel <emphasis>would not be</emphasis> the most efficient way. The better way would be to configure interceptors globally and apply
them on multiple channels in one shot. Spring Integration provides capabilities to configure <emphasis>Global Interceptor Chains</emphasis>
them on multiple channels in one shot. Spring Integration provides capabilities to configure <emphasis>Global Interceptors</emphasis>
and apply them on multiple channels.
Look at the example below:
<programlisting language="xml"><![CDATA[<int:channel-interceptor-chain channel-name-pattern="input*, bar*, foo" order="3">
<programlisting language="xml"><![CDATA[<int:channel-interceptor pattern="input*, bar*, foo" order="3">
<bean class="foo.barSampleInterceptor"/>
<ref bean="someOtherInterceptor"/>
</int:channel-interceptor-chain>]]></programlisting>
&lt;channel-interceptor-chain&gt; element will assemble the chain of interceptors and will apply them on all the
channels defined in the &lt;channel-name-patter&gt; attribute. In the above case the two interceptors that are defined
within the chain are going to be applied on 'foo' channel and all other channels that begin with 'bar' and 'input'.
The &lt;order&gt; attribute allows you to manage the place where this interceptor chain will be injected.
</int:channel-interceptor>]]></programlisting>
or
<programlisting language="xml"><![CDATA[<int:channel-interceptor ref="myInterceptor" pattern="input*, bar*, foo" order="3"/>
<bean id="myInterceptor" class="foo.barSampleInterceptor"/>]]></programlisting>
&lt;channel-interceptor&gt; element allows you to define a global interceptor which will be applied on all
channels that match patterns defined via &lt;pattern&gt; attribute. In the above case the global interceptor will be applied on
'foo' channel and all other channels that begin with 'bar' and 'input'.
The &lt;order&gt; attribute allows you to manage the place where this interceptor will be injected.
For example, channel 'inputChannel' could have individual interceptors configured locally (see below):
<programlisting language="xml"><![CDATA[<int:channel id="inputChannel"> 
<int:interceptors>
<int:wire-tap channel="logger"/> 
</int:interceptors>
</int:channel>]]></programlisting>
The reasonable question would be where interceptors defined by <emphasis>channel-interceptor-cahin</emphasis> should be injected
in relation to the existing one(s) (configured locally or through other global chains)? Current implementation provides
The reasonable question would be how global interceptor will be injected in relation to other interceptors
configured locally or through other global interceptor definitions? Current implementation provides
a very simple and clever mechanism of handling this. Positive number in the <emphasis>order</emphasis> attribute will ensure interceptor injection
after existing interceptors and negative number will ensure that such interceptors injected before.
This means that in the above example interceptors configured in global interceptor chain would be injected after
'wire-tap' interceptor configured locally. If there was another global chain with matching <emphasis>channel-name-pattern</emphasis> the
order between the interceptors defined in two chains would be determined based on who's got the higher or lower
value in <emphasis>order</emphasis> attribute.
This means that in the above example global interceptor will be injected <emphasis>AFTER</emphasis> (since its order is greater then 0)
'wire-tap' interceptor configured locally. If there was another global interceptor with matching <emphasis>pattern</emphasis> their
order would be determined based on who's got the higher or lower value in <emphasis>order</emphasis> attribute.
To inject global interceptor <emphasis>BEFORE</emphasis> the existing interceptors use negative value for the <emphasis>order</emphasis> attribute.
</para>
</section>