What happens in a conversation

A conversation is defined as a dialog between a user at a terminal and IMS through a scratchpad area (SPA) and one or more application programs.

During a conversation, the user at the terminal enters a request, receives the information from IMS, and enters another request. Although it is not apparent to the user, a conversation can be processed by several application programs or by one application program.

To continue a conversation, the program must have the necessary information to continue processing. IMS stores data from one step of the conversation to the next in a SPA. When the same program or a different program continues the conversation, IMS gives the program the SPA for the conversation associated with that terminal.

In the preceding airline example, the first program might save the flight number and the names of the people traveling, and then pass control to another application program to reserve seats for those people on that flight. The first program saves this information in the SPA. If the second application program did not have the flight number and names of the people traveling, it would not be able to do its processing.