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Mark Fisher
2011-01-17 15:25:11 -05:00
parent c63094492b
commit 4b4413628d
1 changed files with 7 additions and 7 deletions
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docs/src/reference/docbook/transformer.xml
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@@ -67,13 +67,13 @@
Message (the keys must be Strings).
</para>
<para>
Since Spring Integration 2.0 after many debates we've changed the behavior of Message Transformer for the cases where
transformation method returns <code>null</code>. Returning <code>null</code> will now result in the exception. In other
words Message Transformer should no longer be used as Message Filter (that is what Message Filter is for). Message Transformer
should always be expected to transform the source Message into a valid target Message.
However, if you still need this type of behavior (where component might return NULL and not be considered an error), a
<emphasis>service-activator</emphasis> could be used. Its <code>requires-reply</code> value is FALSE by default, but can
be set to TRUE in order to have Exceptions thrown for NULL return values.
As of Spring Integration 2.0, a Message Transformer's transformation method can no longer return <code>null</code>.
Returning <code>null</code> will result in an exception since a Message Transformer should always be expected to
transform each source Message into a valid target Message. In other words, a Message Transformer should not be used
as a Message Filter since there is a dedicated &lt;filter&gt; option for that. However, if you do need this type of
behavior (where a component might return NULL and that should not be considered an error), a
<emphasis>service-activator</emphasis> could be used. Its <code>requires-reply</code> value is FALSE by default,
but that can be set to TRUE in order to have Exceptions thrown for NULL return values as with the transformer.
</para>
<para>