About Document Correlation
Correlation is used to enable external documents to join running process instances. Each step that receives input (a subscription document) can use a correlation. Each of these steps has a Correlation page in the Properties view. A message start event, a signal start event, or a receive task designated Allow this receive task to start new process instance can start a new process instance.
Catching message intermediate events, Catching signal intermediate events, and receive tasks NOT designated Allow this receive task to start new process instance also use correlations.
In a typical run-time environment, instances of many different process models can be running simultaneously. When a published document arrives in the run-time environment, the Process Engine must determine which of the running processes the document is intended for. You must provide a means of correlating a particular document instance with a particular process instance. This can be done in two ways:
By creating a correlation service the flow service editor in
Designer and associating it with a receive step.
By specifying a field in an incoming document to serve as a correlation field when configuring a receive step.
When you create a receive task in a process model, you can specify that it uses either a correlation field or a correlation service for document correlation, or no correlation. Correlation IDs are stored and tracked by the
Process Engine; for more information, see
Tracking Correlation IDs.
Correlation services are written in the flow service editor in
Designer, and establish or match the correlation ID used by a process instance. For more information about using correlation services, see
About Correlation Services.
Tip:
When an Integration Server connection is required but not available, Designer prompts you to connect. If no Integration Server is configured, Designer prompts you to configure one so you can connect to it.
Note:
For intermediate receive steps, correlation retry behavior is defined in the subscription trigger. See the PDF publication Publish-Subscribe Developer’s Guide.
Related Topics