Consider the Order In Which You Configure Assigns

Configuring your processes is likely to involve situations in which a service needs to obtain parameters from both process data and messages. Your process definition may need to indicate whether services first request values from messages or process data.

These kinds of scenarios involve multiple assigns, possibly both implicit and explicit, and the order in which the step processes the assigns is crucial to successful processing of the step.

Essentially, in cases where message data and process data are both involved in a step, you need to ensure that the assignments happen in the appropriate order, either by direct-coding them such that they process in the order you need, or by setting the order in the GPM Service Editor. You can specify different settings for input and output messages within the same service. In the GPM, you can select the following instructions for input and output messages:

Message To Service (Output Message) Message From Service (Input Message)
  • Messages Only – No process data is involved with this option.
  • Allow Process Data write
  • Obtain Message first, then Process Data – Use this to provide overrides for parameters. For example, if all but one parameter is set in process data, the one missing parameter could be put into the message for the service to pick up.
  • Allow message write
  • Obtain Process Data first, then Messages – In this scenario, when the service needs to look up data, it first checks the process data and then goes to the message. You can use this setting to provide defaults for parameters, such as when some parameters are not specified in process data.