Two programs involved in a conversation are called partners in the conversation. If a CRM-CRM logical connection exists, or can be created, between the nodes containing the partner programs, two programs can communicate through the network with a conversation.
The terms local and remote are used to differentiate between different ends of a conversation. If a program is being discussed as local, its partner program is said to be the remote program for that conversation. For example, if Program A is being discussed, Program A is the local program and Program C is the remote program. Similarly, if Program C is being discussed as the local program, Program A is the remote program. Thus, a program can be both local and remote for a given conversation, depending on the circumstances.
Although program partners generally reside in different nodes in a network, the local and remote programs may, in fact, reside in the same node. Two programs communicate with each other the same way, whether they are in the same or different nodes.
CICS application programs on the same host can communicate using CPI Communications if they are running on different CICS systems, but not if they are running on the same CICS system. The ability for CICS applications to communicate with other CICS applications executing on the same CICS system is provided by other CICS services that do not involve communications protocols. Multiple CICS systems can run on a single host, using VTAM*-supported LU 6.2 intersystem communication.
Note: A CPI Communications program may establish a conversation with a program that is using a product-specific programming interface for a particular environment and not CPI Communications. The conversation between Program B and Program D in Figure 1 is an example of such a situation. Some restrictions may apply in this situation, since CPI Communications does not support all available network functions.