Chapter 4. Data Communications Programming With Cobol; Uses Of Data Communications Programs; Eligible Systems; Cobol Programs And The Communications Access Method - IBM 5280 Programmer's Manual

Chapter 4. Data Communications Programming with COBOL
This chapter provides the information necessary to code the COBOL
statements that allow data exchange between two systems over a
communications link; throughout this chapter and book, this exchange of data
is called data communications.
Also, the chapter has the following information:
• A summary of COBOL data communications capabilities
• The IBM 5280 facilities needed to execute a COBOL program
COBOL also provides suppor·t of data communications giving more direct
control over all communication facilities than as described in this chapter.
See Appendix A for a description of direct data communications support.
To execute a COBOL program using data communications, the proper
communications environment must be established using the preparation
utilities. Information on this subject can be found in the
Communications
Reference Manual.
Uses of Data Communications Programs
Eligible Systems
You might want to write a COBOL data communications program:
• When you want to interact with an operator within one system and need
to access data in a remote system.
When you want to process data online as it is received from the host.
• When you want to match your 5280 communications program with a
host application program.
• When the IBM 5280 Data Communications Utilities don't meet your
needs. The functions provided by these utilities are sending batch data,
receiving batch data, and sending inquiries and receiving replies.
Complete information on the functions of the utilities and how to use
them is given in the
Communications Reference Manual.
The systems with which a COBOL program can communicate are the same as
those for an assembler language program. See the chapter "Data
Communications with Assembler Language" in the Communications
Reference Manual under "BSC Programming with Assembler Language"
and "SNA Programming with Assembler Language" for a list of the eligible
systems.
COBOL Programs and the Communications Access Method
A COBOL program works with the communications access method (CAM) to
transfer data. Part of the tasks in communicating is done by CAM; you
must code the others in your COBOL program.
Chapter 4. Data Communications Programming with COBOL 4- I