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CICS CONVERSE - Program-to-Program Communication

CICS CONVERSE provides program-to-program communication capabilities for programs and transactions. It enables programs to initiate conversations, manage program communication, and handle program-to-program conversations in CICS environments.

What is CICS CONVERSE?

CICS CONVERSE is a command that allows programs to initiate conversations with other programs. It provides program-to-program communication capabilities, conversation management, and program communication for CICS applications.

Command Syntax

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EXEC CICS CONVERSE
    CONVID(conversation-id)
    [FROM(data-area)]
    [FROMLENGTH(data-length)]
    [INTO(data-area)]
    [SET(pointer-variable)]
    [LENGTH(data-length)]
    [RESP(response-code)]
END-EXEC

Parameters

Required Parameters

  • CONVID(conversation-id) - Conversation identifier

Optional Parameters

  • FROM(data-area) - Data to send
  • FROMLENGTH(data-length) - Length of data to send
  • INTO(data-area) - Data area to receive
  • SET(pointer-variable) - Pointer to data
  • LENGTH(data-length) - Length of data received
  • RESP(response-code) - Response code variable

Conversation Types

Synchronous Conversations

Conversations with immediate response

  • • REQUEST-RESPONSE - Request-response conversations
  • • QUERY-RESPONSE - Query-response conversations
  • • COMMAND-RESPONSE - Command-response conversations
  • • INQUIRY-RESPONSE - Inquiry-response conversations

Asynchronous Conversations

Conversations with delayed response

  • • NOTIFICATION - Notification conversations
  • • EVENT-DRIVEN - Event-driven conversations
  • • CALLBACK - Callback conversations
  • • MESSAGE-QUEUE - Message queue conversations

Bidirectional Conversations

Conversations with two-way communication

  • • PEER-TO-PEER - Peer-to-peer conversations
  • • CLIENT-SERVER - Client-server conversations
  • • MASTER-SLAVE - Master-slave conversations
  • • COLLABORATIVE - Collaborative conversations

Multicast Conversations

Conversations with multiple participants

  • • BROADCAST - Broadcast conversations
  • • MULTICAST - Multicast conversations
  • • GROUP-CHAT - Group chat conversations
  • • CONFERENCE - Conference conversations

Programming Examples

Basic Program Conversation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CONVERSE01.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  CONVERSATION-ID PIC X(8) VALUE 'CONV001'.
       01  SEND-DATA PIC X(80) VALUE 'Hello from program'.
       01  SEND-LENGTH PIC S9(4) COMP VALUE 18.
       01  RECEIVE-DATA PIC X(80).
       01  RECEIVE-LENGTH PIC S9(4) COMP.
       01  RESPONSE-CODE PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           DISPLAY 'Starting conversation with program'
           
           EXEC CICS CONVERSE
               CONVID(CONVERSATION-ID)
               FROM(SEND-DATA)
               FROMLENGTH(SEND-LENGTH)
               INTO(RECEIVE-DATA)
               LENGTH(RECEIVE-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           IF RESPONSE-CODE = DFHRESP(NORMAL)
               DISPLAY 'Conversation successful'
               DISPLAY 'Received: ' RECEIVE-DATA(1:RECEIVE-LENGTH)
           ELSE
               DISPLAY 'Conversation failed'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Advanced Conversation Management

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CONVERSE02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  CONVERSATION-ID PIC X(8).
       01  SEND-DATA PIC X(80).
       01  SEND-LENGTH PIC S9(4) COMP.
       01  RECEIVE-DATA PIC X(80).
       01  RECEIVE-LENGTH PIC S9(4) COMP.
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  CONVERSATION-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-CONVERSATIONS PIC S9(2) COMP VALUE 3.
       01  CONVERSATION-LIST.
           05  CONVERSATION-ITEM OCCURS 3 TIMES.
               10  CONV-ID PIC X(8).
               10  CONV-MESSAGE PIC X(80).
               10  CONV-LENGTH PIC S9(4) COMP.
       
       PROCEDURE DIVISION.
           PERFORM INITIALIZE-CONVERSATIONS
           PERFORM CONDUCT-MULTIPLE-CONVERSATIONS
           
           EXEC CICS RETURN END-EXEC.
       
       INITIALIZE-CONVERSATIONS.
           MOVE 'CONV001' TO CONV-ID(1)
           MOVE 'Request data from service A' TO CONV-MESSAGE(1)
           MOVE 26 TO CONV-LENGTH(1)
           
           MOVE 'CONV002' TO CONV-ID(2)
           MOVE 'Request data from service B' TO CONV-MESSAGE(2)
           MOVE 26 TO CONV-LENGTH(2)
           
           MOVE 'CONV003' TO CONV-ID(3)
           MOVE 'Request data from service C' TO CONV-MESSAGE(3)
           MOVE 26 TO CONV-LENGTH(3).
       
       CONDUCT-MULTIPLE-CONVERSATIONS.
           PERFORM VARYING CONVERSATION-COUNT FROM 1 BY 1
               UNTIL CONVERSATION-COUNT > MAX-CONVERSATIONS
               
               MOVE CONV-ID(CONVERSATION-COUNT) TO CONVERSATION-ID
               MOVE CONV-MESSAGE(CONVERSATION-COUNT) TO SEND-DATA
               MOVE CONV-LENGTH(CONVERSATION-COUNT) TO SEND-LENGTH
               
               PERFORM CONDUCT-SINGLE-CONVERSATION
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   DISPLAY 'Conversation ' CONVERSATION-COUNT ' successful'
                   DISPLAY 'Response: ' RECEIVE-DATA(1:RECEIVE-LENGTH)
               ELSE
                   DISPLAY 'Conversation ' CONVERSATION-COUNT ' failed'
               END-IF
           END-PERFORM.
       
       CONDUCT-SINGLE-CONVERSATION.
           EXEC CICS CONVERSE
               CONVID(CONVERSATION-ID)
               FROM(SEND-DATA)
               FROMLENGTH(SEND-LENGTH)
               INTO(RECEIVE-DATA)
               LENGTH(RECEIVE-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC.

Error Handling with Conversations

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CONVERSE03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  CONVERSATION-ID PIC X(8) VALUE 'CONV001'.
       01  SEND-DATA PIC X(80) VALUE 'Test message'.
       01  SEND-LENGTH PIC S9(4) COMP VALUE 12.
       01  RECEIVE-DATA PIC X(80).
       01  RECEIVE-LENGTH PIC S9(4) COMP.
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  RETRY-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-RETRIES PIC S9(2) COMP VALUE 3.
       01  CONVERSATION-SUCCESSFUL PIC X(1) VALUE 'N'.
       
       PROCEDURE DIVISION.
           PERFORM CONDUCT-CONVERSATION-WITH-RETRY
           
           EXEC CICS RETURN END-EXEC.
       
       CONDUCT-CONVERSATION-WITH-RETRY.
           PERFORM CONDUCT-CONVERSATION
           
           IF RESPONSE-CODE NOT = DFHRESP(NORMAL)
               AND RETRY-COUNT < MAX-RETRIES
               ADD 1 TO RETRY-COUNT
               DISPLAY 'Retry ' RETRY-COUNT ' conversation'
               PERFORM CONDUCT-CONVERSATION-WITH-RETRY
           END-IF.
       
       CONDUCT-CONVERSATION.
           EXEC CICS CONVERSE
               CONVID(CONVERSATION-ID)
               FROM(SEND-DATA)
               FROMLENGTH(SEND-LENGTH)
               INTO(RECEIVE-DATA)
               LENGTH(RECEIVE-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   MOVE 'Y' TO CONVERSATION-SUCCESSFUL
                   DISPLAY 'Conversation successful'
               WHEN DFHRESP(NOTAUTH)
                   DISPLAY 'Not authorized for conversation'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid conversation request'
               WHEN DFHRESP(CONVIDERR)
                   DISPLAY 'Invalid conversation ID'
               WHEN DFHRESP(CONVFAILED)
                   DISPLAY 'Conversation failed'
               WHEN DFHRESP(CONVTIMEOUT)
                   DISPLAY 'Conversation timeout'
               WHEN OTHER
                   DISPLAY 'Unexpected conversation error'
           END-EVALUATE.

Conversation Management

Conversation Control

  • • Conversation Initiation - Start conversations
  • • Conversation Management - Manage conversation state
  • • Conversation Termination - End conversations
  • • Conversation Monitoring - Monitor conversation status

Data Exchange

  • • Data Sending - Send data in conversations
  • • Data Receiving - Receive data from conversations
  • • Data Validation - Validate conversation data
  • • Data Processing - Process conversation data

Error Recovery

  • • Error Detection - Detect conversation errors
  • • Error Recovery - Recover from conversation errors
  • • Retry Mechanisms - Implement retry logic
  • • Fallback Procedures - Use fallback procedures

Performance Optimization

  • • Conversation Pooling - Use conversation pooling
  • • Load Balancing - Balance conversation load
  • • Timeout Management - Manage conversation timeouts
  • • Resource Management - Manage conversation resources

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - Conversation successful
  • DFHRESP(NOTAUTH) - Not authorized for conversation
  • DFHRESP(INVREQ) - Invalid conversation request
  • DFHRESP(CONVIDERR) - Invalid conversation ID
  • DFHRESP(CONVFAILED) - Conversation failed
  • DFHRESP(CONVTIMEOUT) - Conversation timeout

Performance Considerations

Conversation Efficiency

  • • Optimize conversation operations - Use efficient conversation handling
  • • Minimize conversation overhead - Reduce conversation processing overhead
  • • Use conversation pooling - Implement conversation pooling
  • • Monitor conversation frequency - Track conversation patterns

System Impact

  • • Monitor system impact - Track how conversations affect the system
  • • Optimize conversation handling - Ensure efficient conversation processing
  • • Manage conversation usage - Monitor conversation consumption
  • • Track performance metrics - Monitor conversation handling performance

Best Practices

Program-to-Program Communication Best Practices

  • • Use appropriate conversation types for your needs
  • • Implement proper error handling for conversation operations
  • • Validate conversation data before processing
  • • Use appropriate conversation management techniques
  • • Monitor conversation activities and performance
  • • Maintain conversation audit trails
  • • Handle conversation errors gracefully

Explain It Like I'm 5 Years Old

Think of CICS CONVERSE like talking to a friend on the phone:

  • • Call Friend: "Call your friend" - Start conversation
  • • Say Hello: "Say hello to your friend" - Send message
  • • Listen Back: "Listen to what friend says" - Receive response
  • • Keep Talking: "Keep talking back and forth" - Continue conversation
  • • Say Goodbye: "Say goodbye when done" - End conversation

Exercises

Exercise 1: Basic Program Conversation

Create a program that conducts a simple conversation with another program.

Exercise 2: Advanced Conversation Management

Write a program that manages multiple conversation operations.

Exercise 3: Error Handling

Implement comprehensive error handling for conversation failures.

Related Concepts

Program-to-Program Communication

Communicating between programs

Conversation Management

Managing program conversations

APPC Communication

APPC communication protocols

Message Handling

Handling program messages

Error Handling

Managing conversation errors