### Introduction to Split-Join

The Split-Join is a mediation pattern that can be used by a transport typed business service in an ALSB message flow. Split-Join allows you to send message requests to multiple services concurrently, thus enhancing performance in comparison to sending them sequentially. Split-Join achieves this task by splitting an input message into individual messages, routing them concurrently to their destinations, and then aggregating the responses into one overall message.

You design a Split-Join in the WorkSpace Studio Split-Join editor, then export it to the ALSB console for testing and production.

Note: | In the ALSB console, a Split-Join is associated with a business service using the Flow transport protocol. Therefore, the Split-Join has a .flow file name extension in WorkSpace Studio even though it is always referred to simply as a "Split-Join" in this document.

There are two types of Split-Join pattern: static Split-Join and dynamic Split-Join, as described in Designing a Split-Join.

For more information on invoking a business service from an ALSB message flow, see Proxy Services: Message Flow in the ALSB console help system.