Logical destinations
Message routing for an MSC network uses logical destinations, as does a single-system environment.
A destination is either an LTERM or a transaction code. A local destination resides in the local system, and a remote destination resides in a remote system. Within each local system, all local and remote destinations must be defined with unique names. In the figure below, all of the local and remote destinations are uniquely defined within each local system. Destinations that are defined remotely are not also defined locally within the same IMS. Similarly, destinations that are defined locally are not also defined remotely.
The same destination names can be used for local destinations in different IMS systems that are connected by MSC. The destination names cannot conflict with the global intent of the destination within the MSC network. For example, in the figure below, TRANAB is a local transaction in IMS B and IMS A. It is a remote transaction in IMS C. IMS C is referencing the local TRANAB in IMS A only and not the one in IMS B. IMS C cannot remotely reference TRANAB in IMS B. The destination system that is referenced in a remote destination is determined by the system identification (SYSID) value.
With directed routing and the TM and MSC Message Routing and Control User exit routine, you can send messages from an application program to a remote destination that is not explicitly defined in the destination system. The validation of the destination name in the transaction processing system is delayed until the message arrives in the local system. Delaying this validation provides more flexibility in the resource naming requirements.
