THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Loop
The Loop allows for processing a message a number of times, possibly in a different way for each iteration. Useful mostly during testing.
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Notice by default the loop uses the same exchange throughout the looping. So the result from the previous iteration will be used for the next (eg Pipes And Filters). From Camel 2.8 onwards you can enable copy mode instead. See the options table for more details. |
Options
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h2. Loop The Loop allows for processing a message a number of times, possibly in a different way for each iteration. Useful mostly during testing. {info:title=Default mode} Notice by default the loop uses the same exchange throughout the looping. So the result from the previous iteration will be used for the next (eg [Pipes And Filters]). From *Camel 2.8* onwards you can enable copy mode instead. See the options table for more details. {info} h3. Options {div:class=confluenceTableSmall} || Name || Default Value || Description || | {{copy}} | {{false}} | *Camel {div} |
Name | Default Value | Description |
|---|---|---|
| | Camel 2.8: |
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Whether |
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or |
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not |
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copy |
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mode |
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is |
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used. |
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If |
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|
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then |
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the |
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same |
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Exchange |
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will |
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be |
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used |
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for |
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each |
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iteration. |
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So |
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the |
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result |
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from |
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the |
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previous |
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iteration |
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will |
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be |
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visible |
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for |
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the |
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next |
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iteration. |
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Instead |
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you |
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can |
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enable |
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copy |
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mode, |
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and |
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then |
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each |
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iteration |
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restarts |
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with |
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a |
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fresh |
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copy |
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of |
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the |
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input |
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Exchange properties
For each iteration two properties are set on the Exchange. Processors can rely on these properties to process the Message in different ways.
Property | Description |
|---|---|
| Total number of loops |
| Index of the current iteration (0 based) |
Examples
The following example shows how to take a request from the direct:x endpoint, then send the message repetitively to mock:result. The number of times the message is sent is either passed as an argument to loop(), or determined at runtime by evaluating an expression. The expression must evaluate to an int, otherwise a RuntimeCamelException is thrown.
Using the Fluent Builders
Pass loop count as an argument
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]. | h3. Exchange properties For each iteration two properties are set on the {{Exchange}}. Processors can rely on these properties to process the [Message] in different ways. || Property || Description || | {{CamelLoopSize}} | Total number of loops | | {{CamelLoopIndex}} | Index of the current iteration (0 based) | h4. Examples The following example shows how to take a request from the *direct:x* endpoint, then send the message repetitively to *mock:result*. The number of times the message is sent is either passed as an argument to {{loop()}}, or determined at runtime by evaluating an expression. The expression *must* evaluate to an {{int}}, otherwise a {{RuntimeCamelException}} is thrown. *Using the [Fluent Builders]* Pass loop count as an argument {snippet:id=ex1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/LoopTest.java} |
Use
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expression
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to
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determine
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loop count
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count {snippet:id=ex2|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/LoopTest.java} |
Use
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expression
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to
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determine
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loop count
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count {snippet:id=ex3|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/LoopTest.java} * |
Using
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the
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...
...
...
Pass
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loop
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count
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as
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an argument
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argument {snippet:id=ex1|lang=xml|url=camel/trunk/components/camel-spring/src/test/resources/org/apache/camel/spring/processor/loop.xml} |
Use
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expression
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to
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determine
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loop count
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count {snippet:id=ex2|lang=xml|url=camel/trunk/components/camel-spring/src/test/resources/org/apache/camel/spring/processor/loop.xml} |
For
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further
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examples
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of
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this
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pattern
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in
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use
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you
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could
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look
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at
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one
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of
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the
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...
...
Using copy mode
Available as of Camel 2.8
Now suppose we send a message to "direct:start"
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endpoint
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containing
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the
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letter
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A.
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The
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output
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of
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processing
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this
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route
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will
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be
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that,
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each
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"mock:loop"
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endpoint
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will
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receive
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"AB"
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as
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message.
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/LoopCopyTest.java} |
However
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if
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we
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do
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not
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enable
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copy
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mode
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then
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"mock:loop"
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will
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receive
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"AB",
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"ABB",
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"ABBB",
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etc.
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messages.
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/LoopNoCopyTest.java} |
The
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equivalent
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example
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in
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XML
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DSL
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in
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copy
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mode
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is
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as
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follows:
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{snippet:id=e1|lang=xml|url=camel/trunk/components/camel-spring/src/test/resources/org/apache/camel/spring/processor/SpringLoopCopyTest.xml} {include:Using This Pattern} |
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