The document describes the choice flow control in Mulesoft, which dynamically routes messages based on message properties or payload. It uses expressions to evaluate the message and route it to the first matching routing option, or the default route if none match. The document provides details on adding, configuring, and changing the default route of the choice flow control, and includes an example code snippet.

1. Choice Flow Control Reference
in Mulesoft

2. • The choice flow control dynamically routes messages based
on message payload or properties. It adds conditional
programming to a flow, similar to an if/then/else code
block.
• A choice flow control uses expressions to evaluate the
content of a message, then it routes the message to one of
the routing options within its scope (see image below). It
directs messages to the first routing option in the scope
that matches the routing configurations (evaluates to true).
If none of expressions evaluate to true, the choice flow
control directs the message to the default (else) route.

3. • Adding the Choice Flow Control
• Configuring the Choice Flow Control
• Changing the Default Route
• Complete Example Code

4. Adding the Choice Flow Control
• <flow name="New_Studio_ProjectFlow1"
doc:name="New_Studio_ProjectFlow1">
• <http:listener config-ref="HTTP_Listener_Configuration" path="/"
doc:name="HTTP"/>
• <expression-filter expression="#[message.inboundProperties.'http.request.uri'
!= '/favicon.ico']" doc:name="Expression"/>
• <set-variable variableName="language"
value="#[message.inboundProperties.'http.query.params'.language]"
doc:name="Set Language Variable"/>
• <choice doc:name="Choice">
• <when expression="">
• </when>
• <otherwise>
• </otherwise>
• </choice>
• <logger message="#[payload]" level="INFO" doc:name="Logger"/>
• </flow>

5. Configuring the Choice Flow Control
• To configure the choice flow control, you need to
determine the following message routing details:
• Content the choice flow router should evaluate to
determine routing
• Number of routing options with which to supply
the choice flow control
• What processing Mule should perform for each
routing option
• Default routing option

6. Changing the Default Route
• You can change the choice flow control configuration
to identify a different default routing option
• Adjust your XML configuration to swap the contents of
a when element and the otherwise element.
• The code sample below has been adjusted to make the
Spanish language the default routing option and
change the English language to a when element. Note
that the otherwise element requires no further
configuration, but we defined a new expression for the
new when element.

7. Example
• <choice doc:name="Choice">
• <when expression="#[flowVars.language == 'french']">
• <set-payload value="Bonjour!" doc:name="Reply in French"/>
• </when>
• <when expression="#[flowVars.language == 'spanish']">
• <set-payload value="Hola!" doc:name="Reply in Spanish"/>
• </when>
• <otherwise >
• <set-variable variableName="language" value="English"
doc:name="Set Language to English"/>
• <set-payload value="Hello!" doc:name="Reply in English"/>
• </otherwise>
• </choice>