COBOL Tutorial

COBOL COMMUNICATION SECTION - Quick Reference

Progress0 of 0 lessons

Overview

The COMMUNICATION SECTION is a specialized section within the DATA DIVISION used to define data structures for communication operations. It provides a standardized way to organize communication-related data and message structures.

Purpose and Usage

Communication data - Define structures for communication operations
Message handling - Organize message-related data structures
Protocol support - Support communication protocols and standards
Status information - Define communication status and control data
Queue management - Handle message queue structures

Communication Section Concept

DATA DIVISION

├── FILE SECTION

├── WORKING-STORAGE SECTION

├── COMMUNICATION SECTION ←

└── LINKAGE SECTION

Specialized section for communication data

COMMUNICATION SECTION is one of the four main sections in DATA DIVISION.

Syntax

The COMMUNICATION SECTION follows specific syntax patterns and can contain various types of data definitions for communication operations.

Basic Syntax

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
* Basic COMMUNICATION SECTION syntax
DATA DIVISION.
COMMUNICATION SECTION.
CD communication-name
    [SYMBOLIC QUEUE IS queue-name]
    [SYMBOLIC SUB-QUEUE IS sub-queue-name]
    [MESSAGE COUNT IS count-field]
    [MESSAGE DATE IS date-field]
    [MESSAGE TIME IS time-field]
    [SYMBOLIC SOURCE IS source-name]
    [TEXT LENGTH IS length-field]
    [END KEY IS key-field]
    [STATUS KEY IS status-field]
    [MESSAGE TYPE IS type-field].
 
01 communication-data-item PIC X(n).

COMMUNICATION SECTION can contain CD statements and 01 level data items.

CD Statement Clauses

Clause	Purpose	Example
SYMBOLIC QUEUE	Define queue name	SYMBOLIC QUEUE IS MSG-QUEUE
MESSAGE COUNT	Track message count	MESSAGE COUNT IS WS-MSG-COUNT
MESSAGE DATE	Message date field	MESSAGE DATE IS WS-MSG-DATE
MESSAGE TIME	Message time field	MESSAGE TIME IS WS-MSG-TIME
STATUS KEY	Communication status	STATUS KEY IS WS-STATUS

Communication Data Structures

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
* Message header structure
01 MESSAGE-HEADER.
    05 MSG-TYPE           PIC X(10).
    05 MSG-LENGTH         PIC 9(5).
    05 MSG-PRIORITY       PIC 9(1).
    05 MSG-SENDER         PIC X(20).
    05 MSG-RECEIVER       PIC X(20).
    05 MSG-TIMESTAMP      PIC X(26).
 
* Communication status structure
01 COMM-STATUS.
    05 STATUS-CODE        PIC X(2).
    05 STATUS-MESSAGE     PIC X(50).
    05 QUEUE-STATUS       PIC X(1).
    05 MESSAGE-COUNT      PIC 9(4).
 
* Protocol-specific data
01 PROTOCOL-DATA.
    05 PROTOCOL-VERSION   PIC X(5).
    05 PROTOCOL-TYPE      PIC X(10).
    05 PROTOCOL-FLAGS     PIC X(8).

Common data structures for communication operations.

Practical Examples

These examples demonstrate how to use the COMMUNICATION SECTION effectively in different communication scenarios.

Basic Message Communication

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
IDENTIFICATION DIVISION.
PROGRAM-ID. MESSAGE-COMMUNICATION.
 
DATA DIVISION.
COMMUNICATION SECTION.
CD MESSAGE-QUEUE
    SYMBOLIC QUEUE IS "MSG-QUEUE"
    MESSAGE COUNT IS WS-MESSAGE-COUNT
    MESSAGE DATE IS WS-MESSAGE-DATE
    MESSAGE TIME IS WS-MESSAGE-TIME
    STATUS KEY IS WS-STATUS-KEY.
 
01 MESSAGE-STRUCTURE.
    05 MSG-HEADER.
        10 MSG-TYPE       PIC X(10).
        10 MSG-LENGTH     PIC 9(5).
        10 MSG-PRIORITY   PIC 9(1).
    05 MSG-BODY           PIC X(100).
    05 MSG-TRAILER.
        10 MSG-CHECKSUM   PIC X(8).
 
WORKING-STORAGE SECTION.
01  WS-MESSAGE-COUNT      PIC 9(4).
01  WS-MESSAGE-DATE       PIC 9(8).
01  WS-MESSAGE-TIME       PIC 9(6).
01  WS-STATUS-KEY         PIC X(2).
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    * Initialize message structure
    MOVE "DATA" TO MSG-TYPE
    MOVE 100 TO MSG-LENGTH
    MOVE 1 TO MSG-PRIORITY
    MOVE "This is a test message" TO MSG-BODY
    
    * Process communication
    PERFORM PROCESS-MESSAGE
    
    STOP RUN.
 
PROCESS-MESSAGE.
    DISPLAY "Message Type: " MSG-TYPE
    DISPLAY "Message Length: " MSG-LENGTH
    DISPLAY "Message Body: " MSG-BODY.

Basic message communication using CD statement and message structure.

Queue-Based Communication

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
IDENTIFICATION DIVISION.
PROGRAM-ID. QUEUE-COMMUNICATION.
 
DATA DIVISION.
COMMUNICATION SECTION.
CD INPUT-QUEUE
    SYMBOLIC QUEUE IS "INPUT-QUEUE"
    SYMBOLIC SUB-QUEUE IS "HIGH-PRIORITY"
    MESSAGE COUNT IS WS-INPUT-COUNT
    STATUS KEY IS WS-INPUT-STATUS.
 
CD OUTPUT-QUEUE
    SYMBOLIC QUEUE IS "OUTPUT-QUEUE"
    MESSAGE COUNT IS WS-OUTPUT-COUNT
    STATUS KEY IS WS-OUTPUT-STATUS.
 
01 QUEUE-MESSAGE.
    05 QMSG-HEADER.
        10 QMSG-ID         PIC X(20).
        10 QMSG-TYPE       PIC X(10).
        10 QMSG-PRIORITY   PIC 9(1).
    05 QMSG-DATA           PIC X(200).
    05 QMSG-METADATA.
        10 QMSG-TIMESTAMP  PIC X(26).
        10 QMSG-SOURCE     PIC X(20).
 
WORKING-STORAGE SECTION.
01  WS-INPUT-COUNT        PIC 9(4).
01  WS-INPUT-STATUS       PIC X(2).
01  WS-OUTPUT-COUNT       PIC 9(4).
01  WS-OUTPUT-STATUS      PIC X(2).
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    * Check input queue status
    IF WS-INPUT-COUNT > 0
        PERFORM PROCESS-INPUT-MESSAGE
    END-IF
    
    * Send output message
    PERFORM SEND-OUTPUT-MESSAGE
    
    STOP RUN.
 
PROCESS-INPUT-MESSAGE.
    DISPLAY "Processing input message from queue"
    DISPLAY "Queue count: " WS-INPUT-COUNT.
 
SEND-OUTPUT-MESSAGE.
    MOVE "MSG001" TO QMSG-ID
    MOVE "RESPONSE" TO QMSG-TYPE
    MOVE 2 TO QMSG-PRIORITY
    MOVE "Response data" TO QMSG-DATA
    DISPLAY "Sending output message".

Queue-based communication with input and output queues.

Protocol-Specific Communication

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
IDENTIFICATION DIVISION.
PROGRAM-ID. PROTOCOL-COMMUNICATION.
 
DATA DIVISION.
COMMUNICATION SECTION.
CD PROTOCOL-QUEUE
    SYMBOLIC QUEUE IS "PROTOCOL-QUEUE"
    MESSAGE TYPE IS WS-MESSAGE-TYPE
    TEXT LENGTH IS WS-TEXT-LENGTH
    STATUS KEY IS WS-PROTOCOL-STATUS.
 
01 PROTOCOL-MESSAGE.
    05 PROTOCOL-HEADER.
        10 PROTOCOL-VERSION    PIC X(5).
        10 PROTOCOL-TYPE       PIC X(10).
        10 PROTOCOL-FLAGS      PIC X(8).
        10 PROTOCOL-SEQUENCE   PIC 9(6).
    05 PROTOCOL-BODY.
        10 PROTOCOL-COMMAND    PIC X(20).
        10 PROTOCOL-PARAMETERS PIC X(100).
    05 PROTOCOL-TRAILER.
        10 PROTOCOL-CHECKSUM   PIC X(8).
        10 PROTOCOL-END-MARKER PIC X(2).
 
WORKING-STORAGE SECTION.
01  WS-MESSAGE-TYPE        PIC X(10).
01  WS-TEXT-LENGTH         PIC 9(5).
01  WS-PROTOCOL-STATUS     PIC X(2).
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    * Initialize protocol message
    MOVE "1.0" TO PROTOCOL-VERSION
    MOVE "REQUEST" TO PROTOCOL-TYPE
    MOVE "00000001" TO PROTOCOL-FLAGS
    MOVE 1 TO PROTOCOL-SEQUENCE
    MOVE "GET_DATA" TO PROTOCOL-COMMAND
    MOVE "PARAM1=value1" TO PROTOCOL-PARAMETERS
    
    * Process protocol communication
    PERFORM PROCESS-PROTOCOL-MESSAGE
    
    STOP RUN.
 
PROCESS-PROTOCOL-MESSAGE.
    DISPLAY "Protocol Version: " PROTOCOL-VERSION
    DISPLAY "Protocol Type: " PROTOCOL-TYPE
    DISPLAY "Protocol Command: " PROTOCOL-COMMAND
    DISPLAY "Protocol Parameters: " PROTOCOL-PARAMETERS.

Protocol-specific communication with structured message format.

Status Monitoring Communication

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
IDENTIFICATION DIVISION.
PROGRAM-ID. STATUS-COMMUNICATION.
 
DATA DIVISION.
COMMUNICATION SECTION.
CD STATUS-QUEUE
    SYMBOLIC QUEUE IS "STATUS-QUEUE"
    MESSAGE COUNT IS WS-STATUS-COUNT
    MESSAGE DATE IS WS-STATUS-DATE
    MESSAGE TIME IS WS-STATUS-TIME
    STATUS KEY IS WS-STATUS-KEY.
 
01 STATUS-MESSAGE.
    05 STATUS-HEADER.
        10 STATUS-SOURCE      PIC X(20).
        10 STATUS-TIMESTAMP   PIC X(26).
        10 STATUS-SEQUENCE    PIC 9(6).
    05 STATUS-DATA.
        10 STATUS-CODE        PIC X(2).
        10 STATUS-LEVEL       PIC X(1).
        10 STATUS-DESCRIPTION PIC X(100).
    05 STATUS-METRICS.
        10 STATUS-CPU-USAGE   PIC 9(3).
        10 STATUS-MEMORY-USAGE PIC 9(3).
        10 STATUS-DISK-USAGE  PIC 9(3).
 
WORKING-STORAGE SECTION.
01  WS-STATUS-COUNT        PIC 9(4).
01  WS-STATUS-DATE         PIC 9(8).
01  WS-STATUS-TIME         PIC 9(6).
01  WS-STATUS-KEY          PIC X(2).
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    * Initialize status message
    MOVE "SYSTEM-MONITOR" TO STATUS-SOURCE
    MOVE "00" TO STATUS-CODE
    MOVE "I" TO STATUS-LEVEL
    MOVE "System operating normally" TO STATUS-DESCRIPTION
    MOVE 25 TO STATUS-CPU-USAGE
    MOVE 60 TO STATUS-MEMORY-USAGE
    MOVE 45 TO STATUS-DISK-USAGE
    
    * Send status update
    PERFORM SEND-STATUS-UPDATE
    
    STOP RUN.
 
SEND-STATUS-UPDATE.
    DISPLAY "Status Source: " STATUS-SOURCE
    DISPLAY "Status Code: " STATUS-CODE
    DISPLAY "Status Description: " STATUS-DESCRIPTION
    DISPLAY "CPU Usage: " STATUS-CPU-USAGE "%"
    DISPLAY "Memory Usage: " STATUS-MEMORY-USAGE "%"
    DISPLAY "Disk Usage: " STATUS-DISK-USAGE "%".

Status monitoring communication with system metrics.

Best Practices and Considerations

Understanding best practices ensures proper communication data organization and system integration.

Communication Section Best Practices

Use descriptive names - Choose meaningful names for CD statements and data items
Organize logically - Group related communication data together
Document structures - Clearly document message formats and protocols
Handle errors - Include error handling in communication operations
Validate data - Validate communication data before processing

Common Pitfalls to Avoid

Pitfall	Problem	Solution
Inconsistent naming	Confusion and errors	Use consistent naming conventions
Missing status handling	Communication failures	Always check status codes
Inadequate documentation	Maintenance difficulties	Document all structures and protocols
Poor error handling	System failures	Implement comprehensive error handling
Protocol mismatches	Communication errors	Ensure protocol compatibility

Modern Communication Considerations

cobol

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
* Traditional mainframe communication
CD MAINFRAME-QUEUE
    SYMBOLIC QUEUE IS "CICS-QUEUE"
    MESSAGE COUNT IS WS-QUEUE-COUNT.
 
* Modern web service communication
01 WEB-SERVICE-REQUEST.
    05 WS-HEADER.
        10 WS-CONTENT-TYPE    PIC X(50).
        10 WS-AUTHORIZATION   PIC X(100).
    05 WS-BODY               PIC X(1000).
 
* Database communication
01 DB-COMMUNICATION.
    05 DB-COMMAND            PIC X(200).
    05 DB-PARAMETERS         PIC X(500).
    05 DB-RESULT-STATUS      PIC X(2).

Consider modern communication needs when designing structures.

COMMUNICATION SECTION Quick Reference

Component	Syntax	Purpose
Section Declaration	COMMUNICATION SECTION.	Declare communication section
CD Statement	CD name [clauses]	Define communication description
SYMBOLIC QUEUE	SYMBOLIC QUEUE IS name	Define queue name
MESSAGE COUNT	MESSAGE COUNT IS field	Track message count
STATUS KEY	STATUS KEY IS field	Communication status

Test Your Knowledge

1. What is the primary purpose of the COMMUNICATION SECTION in COBOL?

To define file structures
To define communication-related data structures
To define working storage
To define linkage data

2. In which division is the COMMUNICATION SECTION typically used?

IDENTIFICATION DIVISION
ENVIRONMENT DIVISION
DATA DIVISION
PROCEDURE DIVISION

3. What type of data is typically defined in the COMMUNICATION SECTION?

File records
Communication messages and status information
Working variables
Program parameters

4. Which of the following is commonly used in the COMMUNICATION SECTION?

FD statements
CD statements
01 level data items
All of the above

5. When is the COMMUNICATION SECTION most useful?

When working with files
When working with communication protocols or message passing
When defining variables
When opening files

Frequently Asked Questions

Related Concepts

DATA DIVISION

Understanding the DATA DIVISION structure and sections.

CD Statement

Communication Description statements and usage.

Message Handling

Message processing and string operations.

Queue Management

Queue-based data processing techniques.

Protocol Communication

Protocol-specific data validation and handling.

CALL-CONVENTION COMPUTE ROUNDED

COBOL Tutorial

COBOL COMMUNICATION SECTION - Quick Reference

Overview

Purpose and Usage

Communication Section Concept

Syntax

Basic Syntax

CD Statement Clauses

Communication Data Structures

Practical Examples

Basic Message Communication

Queue-Based Communication

Protocol-Specific Communication

Status Monitoring Communication

Best Practices and Considerations

Communication Section Best Practices

Common Pitfalls to Avoid

Modern Communication Considerations

COMMUNICATION SECTION Quick Reference

Test Your Knowledge

Frequently Asked Questions

What is the difference between COMMUNICATION SECTION and other DATA DIVISION sections?

What are CD statements and how are they used in the COMMUNICATION SECTION?

How does the COMMUNICATION SECTION relate to modern communication protocols?

What are some common data structures defined in the COMMUNICATION SECTION?

How do you use the COMMUNICATION SECTION in practical applications?

Related Concepts

DATA DIVISION

CD Statement

Message Handling

Queue Management

Protocol Communication

Related Pages