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This commit is contained in:
Mark Fisher
2011-12-02 14:13:25 -05:00
parent 85a602fa1c
commit dec71f27c8
1 changed files with 7 additions and 4 deletions
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docs/src/reference/docbook/channel-adapter.xml
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@@ -122,10 +122,13 @@
is not provided, the "id" is required.
</para>
<para>
As many other Spring Integration components <code>&lt;inbound-channel-adapter&gt;</code> and <code>&lt;outbound-channel-adapter&gt;</code>
also provide support for SpEL expression via 'expression' attribute in contrast to method-invocation via 'bean reference/method', while following the same contract where:
<emphasis>expression</emphasis> for <code>&lt;inbound-channel-adapter&gt;</code> must always return <emphasis>non-null</emphasis> value,
while the one for <code>&lt;outbound-channel-adapter&gt;</code> must be equivalent of <emphasis>void</emphasis> return type.
Like many other Spring Integration components, the <code>&lt;inbound-channel-adapter&gt;</code> and
<code>&lt;outbound-channel-adapter&gt;</code> also provide support for SpEL expression evaluation. To use SpEL, provide the
expression string via the 'expression' attribute instead of providing the 'ref' and 'method' attributes that are used for
method-invocation on a bean. When an Expression is evaluated, it follows the same contract as method-invocation where:
the <emphasis>expression</emphasis> for an <code>&lt;inbound-channel-adapter&gt;</code> will generate a message anytime the
evaluation result is a <emphasis>non-null</emphasis> value, while the <emphasis>expression</emphasis> for an
<code>&lt;outbound-channel-adapter&gt;</code> must be the equivalent of a <emphasis>void</emphasis> returning method invocation.
</para>
</section>