Pathway/iTS SCREEN COBOL Reference Manual (H06.10+, J06.03+)

Introduction to SCREEN COBOL
HP NonStop Pathway/iTS SCREEN COBOL Reference Manual—426750-003
1-5
Pathway System Components
In a Pathway environment, the TCP executing SCREEN COBOL code at a terminal
constitutes a requester process. However, in this manual, discussions of requester-
server functions refer to a SCREEN COBOL program unit as a requester program.
Requesters
Requesters usually provide presentation services for terminal devices and
communicate with server processes. Requesters may be tasks executing SCREEN
COBOL code within a (multithreaded) terminal control process, or they may be
Pathsend processes written in Transaction Application Language (TAL), C, COBOL85,
or Pascal.
Pathway/iTS requesters are written as SCREEN COBOL programs. SCREEN COBOL
programs control screen displays, manage terminals, manage messages for intelligent
devices, and perform calls to other SCREEN COBOL programs. SCREEN COBOL
programs also send data to and receive replies from Pathway server processes. A
request to a server, generated by the execution of a SCREEN COBOL SEND
statement, is managed by a terminal control process (TCP).
Requester programs may also be written as Guardian processes in the Transaction
Application Language (TAL), C, COBOL85, or Pascal. Such requester programs
include calls to the Pathsend procedures provided as part of the NonStop TS/MP
product. For information about writing Pathsend requesters, see the NonStop TS/MP
Pathsend and Server Programming Manual .
Servers
Servers are programs written in C, C++, COBOL85, pTAL, TAL, FORTRAN, or Pascal
in the Guardian environment to respond to requests to perform database operations.
The requests are made in the form of interprocess messages. When a SCREEN
COBOL requester program is used, these messages are generated according to the
Figure 1-2. Multiple Terminal Control Through the TCP
002CDT .CDD
TCP
SCREEN
COBOL
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