A correlation set is a character string used to uniquely identify the messages sent by service requesters. The XML type is the only message type that can be used in correlation sets.

If the HCSC server contains multiple process instances that can receive messages from service requesters for a single business process, the HCSC server uses the value of the correlation set included in the message to identify the process instances.

The service requester creates a request message that includes the correlation set, and requests invocation of the service components (invocation of the business process) to the HCSC server. The correlation set is also included in the response from the business process, and enables the user to identify the result for any sent message. Correlation sets are defined in the Define Business Process window in the development environment.

Note that a new correlation set can be specified and a message can be sent even when the business process invokes a service component or receives a response from the service component.

For details about identifying process instances based on the correlation set, see 5.5.2 Defining correlation sets in the Service Platform Basic Development Guide.