Loop
The Loop allows for processing a message a number of times, possibly in a different way for each iteration. Useful mostly during testing.
Default modeNotice 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
confluenceTableSmallName | Default Value | Description |
---|---|---|
|
| Camel 2.8: Whether or not copy mode is used. If |
doWhile | Camel 2.17: Enables the while loop that loops until the predicate evaluates to false or null. |
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. This is not available if running the loop in while loop mode. |
| 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
Pass loop count as an argument
Using copy mode
Available as of Camel 2.8
Now suppose we send a message to "direct:start" endpoint containing the letter A.
The output of processing this route will be that, each "mock:loop" endpoint will receive "AB" as message.
Using while mode
Available as of Camel 2.17
The loop can act like a while loop that loops until the expression evaluates to false or null.
For example the route below loops while the length of the message body is 5 or less characters. Notice that the DSL uses loopDoWhile.
And the same example in XML:
xmlNotice in XML that the while loop is turned on using the doWhile attribute.