This section covers the following information on formatting messages via the use of an IBM product called Message Format Service (MFS).
The IMS Message Format Service (MFS) is a facility of the IMS Transaction Manager environment that formats messages to and from terminal devices, so that IMS application programs do not deal with device-specific characteristics in input or output messages.
In addition, MFS formats messages to and from user-written programs in remote controllers and subsystems, so that application programs do not deal with transmission-specific characteristics of the remote controller.
MFS uses control blocks you specify to indicate to IMS how input and output messages are arranged.
For input messages, MFS control blocks define how the message sent by the device to the application program is arranged in the program's I/O area.
For output messages, MFS control blocks define how the message sent by the application program to the device is arranged on the screen or at the printer. Data that appears on the screen but not in the program's I/O area, such as a literal, can also be defined.
In IMS Transaction Manager systems, data passing between the application program and terminals or remote programs can be edited by MFS or basic edit. Whether an application program uses MFS depends on the type of terminals or secondary logical units (SLUs) your network uses.
By using MFS, you can simplify the developing and maintaining of terminal-oriented applications, and improve online performance by using control blocks for online processing.
We will going to see below point in upcoming chapter.
MFS Control Blocks
Device Input Format (DIF)
Message Input Descriptor (MID)
Message Output Descriptor (MOD)
Device Output Format (DOF)
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