TS/MP Pathsend and Server Programming Manual (G06.24+, H06.03+)

Designing Your Application
NonStop TS/MP Pathsend and Server Programming Manual–132500
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SCREEN COBOL Requesters
SCREEN COBOL Requesters
Screen programs for Pathway terminals perform a variety of front-end functions for your
Pathway application and are typically written as single-threaded programs in the
SCREEN COBOL language. This language offers a simple programming environment
and screen-management system to drive Tandem terminals and IBM 3270 terminals.
SCREEN COBOL supports both conversational mode (for either block-mode or
conversational-mode terminals) and intelligent mode (for intelligent devices and
communications lines).
When you write a screen program in SCREEN COBOL, you can take advantage of the
features of the Pathway/TS TCP. As supplied by Tandem, the TCP supports:
•
Fault tolerance
•
TMF transactions
•
Multitasking of single-threaded screen programs
•
Access to server processes with Pathway server classes
•
Unsolicited message processing (UMP)
•
System management interfaces (that is, PATHCOM or the Pathway management
programming interface)
SCREEN COBOL requester programs do not perform any file I/O operations except to
terminals and server classes. A file I/O operation to a server class, which is in the form
of a request message, is initiated by the requester program by using the SCREEN
COBOL SEND statement.
For information about designing and coding SCREEN COBOL requesters, refer to the
Pathway/TS TCP and Terminal Programming Guide.
IDS Requesters
Standard SCREEN COBOL requesters are screen oriented; they send data back and
forth between the Working-Storage Section of the program and a terminal’s display
screen by way of screen templates defined in the Screen Section. Standard SCREEN
COBOL requesters use SCREEN COBOL ACCEPT and DISPLAY statements in the
Procedure Division to interact with display terminals.
SCREEN COBOL requesters that employ the IDS facility within the TCP send data
back and forth between the Working-Storage Section and an intelligent device (or a
front-end process that controls the device) by way of message templates defined in the
Message Section. IDS requesters use SCREEN COBOL SEND MESSAGE statements
and their associated REPLY clauses in the Procedure Division to interact with the
intelligent devices or front-end processes.
Although IDS sends and receives data through Message Section templates instead of
Screen Section templates, the TCP still provides:
•
Link management for access to Pathway server classes
•
TMF support to ensure transaction protection and database integrity