The Splitter Flow Control splits a message into fragments based on an expression, usually written in Mule Expression Language. A Collection Aggregator can then reassemble the original message parts. Together, the splitter and aggregator allow processing of split message parts on separate servers while reassembling the message. The splitter adds correlation variables to fragments used by the Aggregator for reassembly.

1. Splitter Flow Control Reference
in Mulesoft

2. • The Splitter Flow Control splits a message into
separate fragments, then sends these
fragments one at a time to the next message
processor in the flow. Segments are identified
based on an expression parameter, usually
written in Mule Expression Language (MEL),
but other formats can be employed also. You
can then use a Collection Aggregator Flow
Control to reassemble the parts of the original
message.

3. • You can also include a Resequencer Flow Control
to put the parts back into the original sequence in
case they are shuffled out of order.
• Splitting and aggregating the message is
especially useful when you intend to process the
split parts in asynchronous flows running on
separate servers. Together, the splitter and
aggregator flow controls allow you to share the
workload among several servers and still be able
to reassemble the message after it's processed.

4. • Splitter Configuration
• Simple Splitter
• Advanced Splitter Including a Child Element
• Basic Splitter Example
• Full Example Code
• Aggregating the Payload

5. • Aggregator Configuration
• Simple Collection Aggregator
• Advanced Collection Aggregator Including a Child
Element
• Example Splitting and Aggregating with
Asynchronous Flows
• Full Example Code
• Example Reordering Before Aggregating
• Full Example Code

6. Aggregating the Payload
• When the splitter splits a message, it adds three
new outbound variables into each of the output
fragments. These three variables are later used by
the Aggregator to reassemble the message:
• MULE_CORRELATION_GROUP_SIZE: number of
fragments into which the original message was split
• MULE_CORRELATION_SEQUENCE: position of a
fragment within the group
• MULE_CORRELATION_ID: single ID for entire group (all
output fragments of the same original message share
the same value)

7. • <flow name="splitterFlow1" doc:name="splitterFlow1">
• <http:listener config-ref="HTTP_Listener_Configuration" path="gettweets"
doc:name="HTTP"/>
• <splitter expression="#[xpath3('//actor')]" doc:name="Splitter"/>
• <vm:outbound-endpoint exchange-pattern="one-way" path="step2"
doc:name="VM"/>
• </flow>
• <flow name="splitterFlow2" doc:name="splitterFlow2">
• <vm:inbound-endpoint exchange-pattern="one-way" path="step2"
doc:name="VM"/>
• <logger level="INFO" doc:name="Logger" message="#[payload]"/>
• <resequencer failOnTimeout="true" doc:name="Resequencer"/>
• <logger message="#[payload]" level="INFO" doc:name="Logger"/>
• <collection-aggregator failOnTimeout="true" doc:name="Collection
Aggregator"/>
• <logger message="#[payload]" level="INFO" doc:name="Logger"/>
• </flow>