Channels in COBOL

IDENTIFICATION DIVISION.
PROGRAM-ID. CHANNELS-EXAMPLE.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-MESSAGE PIC X(10).

PROCEDURE DIVISION.
MAIN-PROCEDURE.
    PERFORM SEND-MESSAGE
    PERFORM RECEIVE-MESSAGE
    STOP RUN.

SEND-MESSAGE.
    MOVE "ping" TO WS-MESSAGE.

RECEIVE-MESSAGE.
    DISPLAY WS-MESSAGE.

In COBOL, we don’t have direct equivalents to channels or goroutines. However, we can demonstrate a similar concept using a shared variable and separate procedures.

The WORKING-STORAGE SECTION defines our shared variable WS-MESSAGE, which acts as our “channel”.

The MAIN-PROCEDURE calls two separate procedures: SEND-MESSAGE and RECEIVE-MESSAGE. These procedures simulate the sending and receiving operations of a channel.

In the SEND-MESSAGE procedure, we set the value of WS-MESSAGE to “ping”. This is analogous to sending a value into a channel.

In the RECEIVE-MESSAGE procedure, we display the value of WS-MESSAGE. This is similar to receiving a value from a channel.

To run the program:

$ cobc -x channels-example.cob
$ ./channels-example
ping

When we run the program, the “ping” message is successfully passed from the SEND-MESSAGE procedure to the RECEIVE-MESSAGE procedure via our shared variable.

In COBOL, procedures are executed sequentially by default. There’s no built-in concurrency model like goroutines. For concurrent operations in COBOL, you would typically rely on the operating system’s multitasking capabilities or use specific extensions provided by your COBOL compiler.

This example demonstrates a basic form of communication between different parts of a COBOL program, which is conceptually similar to channel communication in concurrent programming, albeit without the concurrent execution.