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

Introduction to SCREEN COBOL
HP NonStop Pathway/iTS SCREEN COBOL Reference Manual—426750-003
1-7
Communication Between Processes
An executing SCREEN COBOL program is called a terminal-program unit in
Pathway/iTS. To communicate with TMF, the terminal-program unit must be
configured for TMF by issuing commands to PATHCOM.
Inspect
Inspect is an interactive symbolic program-debugging tool that you can use to examine
and modify SCREEN COBOL programs. Inspect runs as a separate process that
communicates through the TCP with the SCREEN COBOL program running on a
Pathway/iTS terminal. By issuing commands to Inspect, you can control and modify an
executing program.
Before you can use Inspect, the PATHMON environment must be configured for
communication with Inspect. In addition, a symbol-table file generated for the program
by the SCREEN COBOL compiler must be available to the TCP.
Communication Between Processes
SCREEN COBOL programs running at terminals communicate with servers by
exchanging interprocess messages through the TCP. The TCP runs a SCREEN
COBOL SEND statement, which builds a message and specifies a server class. The
TCP obtains a link to a server class from the PATHMON process and actually sends
the message. A server replies with an interprocess message that reaches the
appropriate terminal, again through the TCP.
When a SCREEN COBOL program provides instructions to communicate with a server
in a different PATHMON environment, the program becomes location sensitive. In this
situation, the SCREEN COBOL SEND statement indicates an external server by
specifying the Guardian node name and PATHMON name for the PATHMON process
controlling the external server. An external server is one that runs under a PATHMON
environment different from that of the requesting SCREEN COBOL program.
Specifying the node name and PATHMON name makes communication possible
among multiple PATHMON environments on the same Guardian node or on different
Guardian nodes.
Figure 1-4 illustrates the communication between PATHMON environment processes
active in requester-server message exchange. The SCREEN COBOL library contains
the object code run by the TCP.