Pseudo-conversational
The CICS programming style where a program ends after sending each screen, rather than waiting for the user to reply.
Also written pseudo conversational, conversational
This is the design pattern that lets CICS support thousands of users at once, and it is the concept newcomers find least intuitive.
The obvious way to write an interactive program is to send a screen and wait for the answer. That is called conversational, and it is a disaster at scale: while the program waits, it holds memory and resources, and a user who goes to lunch holds them for an hour.
Pseudo-conversational inverts it. The program sends the screen and then ends. CICS keeps nothing running. When the user finally presses a key, CICS starts the program again from the beginning, and it works out where it had got to and carries on.
Because the program ends each time, any information it needs to remember has to be saved somewhere CICS will hand back on the next call. A small communication area passed between invocations is the usual mechanism.
The result is that a thousand users staring at screens consume almost no resources. Only the ones actively pressing a key are running anything.
Related terms
- CICSThe transaction manager that runs online mainframe applications, and the software behind a great many screens bank staff use.
- CICS transactionOne unit of online work in CICS: the whole exchange of receiving a request, doing the work, and sending a response.
- BMS mapThe definition of a CICS screen: where each field sits, how long it is, and how it is highlighted.
- CICS regionOne running copy of CICS, with its own programs, files and users. A site typically runs several.
- Online transaction processingHandling many small pieces of work in real time while someone waits: a card payment, a balance check, a seat booking.