IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Services and service-related functions > Building mediation flows

Aggregating and broadcasting messages

When you aggregate messages, you combine a number of response messages from the invocation of one or more services into a single message. When you broadcast messages you send notification to the service and do not expect a response.

The most common way to aggregate messages is to use Fan Out and Fan In primitives in combination. Another way to aggregate messages is to perform a chained aggregation using Service Invoke. You broadcast messages using the Fan Out primitive.

• Shared context
  Shared context is a thread-based memory location that is shared across all instances of the service message object that are running within the same thread for the request or response flow. The shared context is used during a Fan Out / Fan In aggregation to temporarily store service responses.
• Combining results from different services
  

  You can send one request to multiple services by using the Fan Out primitive, receive responses from those services and then use a Fan in primitive and a Mapping primitive to combine the responses into a new message.

• Broadcasting messages
  For broadcasting, you use the Fan Out primitive in isolation to send a message one way such as when you want to send a notification and do not need a response.
• Performing chained aggregation
  

  You can invoke multiple services sequentially from a mediation flow using the Service Invoke primitive and aggregate the response from each service. This type of chained aggregation is achieved by using the Service Invoke primitive to invoke the first service, and then storing the service response in a placing the service response in the transient context by using a Mapping primitive. The message is then propagated to a second Service Invoke primitive.

• Example: Fan Out and Fan In
  This example shows how elements in an array of business objects are updated with the result of a service invocation response. This is achieved by using the Fan Out, Service Invoke, Mapping (using XSL Transformation) and Fan In primitives.

Building mediation flows

Related information:
Service Invoke mediation primitive