IMS terminal network

An IMS network is characterized by physical terminals and other devices. IMS supports many terminals, including display devices, printers, and remote intelligent controllers.

IMS uses an access method, such as VTAM®, to communicate with a physical terminal. Be sure to understand the difference between:
  • VTAM's view of terminals that are connected to a host
  • IMS's supervision of those connections
VTAM's responsibilities include:
  • Receiving the input message and processing it
  • Transmitting data
  • Managing line and terminal communication status
IMS's responsibilities include:
  • Monitoring the message traffic
  • Routing messages to application programs
  • Handling message storage, scheduling, and recording

Although IMS uses the network facilities of VTAM, it can also control devices that use BSAM.

VTAM is the preferred access method for IMS. You can use OTMA for non-VTAM networks.

To describe a physical terminal configuration to IMS, you code system definition macros, such as the TYPE macro, that describe the terminal attachments and their characteristics (such as communication type, features, or options). You also define ETO and LU 6.2 descriptors.