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CICS CONVERSE (APPC) - APPC Conversational Communication

CICS CONVERSE (APPC) provides conversational communication capabilities for APPC sessions. It enables programs to engage in conversational communication, manage APPC conversations, and handle bidirectional communication in CICS environments.

What is CICS CONVERSE (APPC)?

CICS CONVERSE (APPC) is a command that allows programs to engage in conversational communication over APPC sessions. It provides bidirectional communication capabilities, conversation management, and interactive communication for CICS applications.

Command Syntax

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

Parameters

Required Parameters

  • CONVID(conversation-id) - Conversation ID for the APPC session
  • FROM(data-area) - Data area containing data to send
  • LENGTH(data-length) - Length of data to send

Optional Parameters

  • INTO(response-area) - Data area to receive response
  • TOLENGTH(response-length) - Length of response area
  • RESP(response-code) - Response code variable

Conversational Communication Types

Send and Receive

Send data and receive response in one operation

  • • BIDIRECTIONAL COMMUNICATION - Send and receive in one call
  • • INTERACTIVE EXCHANGE - Interactive data exchange
  • • REQUEST-RESPONSE - Request-response pattern
  • • CONVERSATIONAL FLOW - Natural conversation flow

Send Only

Send data without expecting immediate response

  • • ONE-WAY COMMUNICATION - Send data without response
  • • NOTIFICATION PATTERN - Send notifications
  • • ASYNCHRONOUS SEND - Asynchronous data sending
  • • FIRE-AND-FORGET - Fire-and-forget communication

Receive Only

Receive data without sending

  • • LISTENING MODE - Listen for incoming data
  • • PASSIVE RECEPTION - Passive data reception
  • • EVENT-DRIVEN - Event-driven communication
  • • NOTIFICATION RECEPTION - Receive notifications

Conversational Flow

Manage conversation state and flow

  • • STATE MANAGEMENT - Manage conversation state
  • • FLOW CONTROL - Control conversation flow
  • • CONTEXT PRESERVATION - Preserve conversation context
  • • SESSION MANAGEMENT - Manage conversation session

Programming Examples

Basic Conversational Communication

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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(100) VALUE 'Hello from CICS'.
       01  SEND-LENGTH      PIC S9(8) COMP VALUE 100.
       01  RECEIVE-DATA      PIC X(100).
       01  RECEIVE-LENGTH    PIC S9(8) COMP.
       01  RESPONSE-CODE    PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           EXEC CICS CONVERSE
               CONVID(CONVERSATION-ID)
               FROM(SEND-DATA)
               LENGTH(SEND-LENGTH)
               INTO(RECEIVE-DATA)
               TOLENGTH(RECEIVE-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           IF RESPONSE-CODE = DFHRESP(NORMAL)
               DISPLAY 'Conversational communication successful'
               DISPLAY 'Sent: ' SEND-DATA(1:SEND-LENGTH)
               DISPLAY 'Received: ' RECEIVE-DATA(1:RECEIVE-LENGTH)
           ELSE
               DISPLAY 'Failed to converse'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Advanced Conversational Communication

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CONVERSE02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  CONVERSATION-ID  PIC X(8) VALUE 'CONV002'.
       01  SEND-DATA        PIC X(200) VALUE 'Request for data processing'.
       01  SEND-LENGTH      PIC S9(8) COMP VALUE 200.
       01  RECEIVE-DATA      PIC X(500).
       01  RECEIVE-LENGTH    PIC S9(8) COMP.
       01  RESPONSE-CODE    PIC S9(8) COMP.
       01  CONVERSATION-COUNT PIC S9(4) COMP VALUE 0.
       01  MAX-CONVERSATIONS PIC S9(4) COMP VALUE 5.
       
       PROCEDURE DIVISION.
           PERFORM CONVERSATIONAL-LOOP
               UNTIL CONVERSATION-COUNT >= MAX-CONVERSATIONS
           
           EXEC CICS RETURN END-EXEC.
       
       CONVERSATIONAL-LOOP.
           ADD 1 TO CONVERSATION-COUNT
           
           EXEC CICS CONVERSE
               CONVID(CONVERSATION-ID)
               FROM(SEND-DATA)
               LENGTH(SEND-LENGTH)
               INTO(RECEIVE-DATA)
               TOLENGTH(RECEIVE-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           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.

Error Handling with Conversational Communication

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CONVERSE03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  CONVERSATION-ID  PIC X(8) VALUE 'CONV003'.
       01  SEND-DATA        PIC X(100) VALUE 'Test message'.
       01  SEND-LENGTH      PIC S9(8) COMP VALUE 100.
       01  RECEIVE-DATA      PIC X(100).
       01  RECEIVE-LENGTH    PIC S9(8) COMP.
       01  RESPONSE-CODE    PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           EXEC CICS CONVERSE
               CONVID(CONVERSATION-ID)
               FROM(SEND-DATA)
               LENGTH(SEND-LENGTH)
               INTO(RECEIVE-DATA)
               TOLENGTH(RECEIVE-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   DISPLAY 'Conversational communication successful'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid conversation request'
               WHEN DFHRESP(LENGERR)
                   DISPLAY 'Length error in conversation'
               WHEN DFHRESP(APPCERR)
                   DISPLAY 'APPC-specific error occurred'
               WHEN DFHRESP(CONVERR)
                   DISPLAY 'Conversation error occurred'
               WHEN OTHER
                   DISPLAY 'Unexpected error occurred'
           END-EVALUATE
           
           EXEC CICS RETURN END-EXEC.

Conversational Communication Management

Conversation State

  • • State Tracking - Track conversation state
  • • State Transitions - Manage state transitions
  • • State Validation - Validate conversation state
  • • State Recovery - Recover from state errors

Data Management

  • • Data Validation - Validate conversation data
  • • Data Processing - Process conversation data
  • • Data Storage - Store conversation data
  • • Data Cleanup - Clean up conversation data

Flow Control

  • • Flow Management - Manage conversation flow
  • • Flow Optimization - Optimize conversation flow
  • • Flow Monitoring - Monitor conversation flow
  • • Flow Recovery - Recover from flow errors

Error Recovery

  • • Error Detection - Detect conversation errors
  • • Error Recovery - Recover from conversation errors
  • • Error Reporting - Report conversation errors
  • • Error Prevention - Prevent conversation errors

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - Conversational communication successful
  • DFHRESP(INVREQ) - Invalid conversation request
  • DFHRESP(LENGERR) - Length error in conversation
  • DFHRESP(APPCERR) - APPC-specific error
  • DFHRESP(CONVERR) - Conversation error
  • DFHRESP(NOTAUTH) - Not authorized for conversation

Performance Considerations

Conversation Efficiency

  • • Optimize conversation patterns - Use appropriate conversation patterns for different scenarios
  • • Minimize conversation overhead - Reduce the computational cost of conversations
  • • Use efficient conversation strategies - Implement conversation strategies that minimize resource usage
  • • Monitor conversation performance - Track the performance impact of conversations

Resource Impact

  • • Monitor resource usage - Track how conversations consume system resources
  • • Optimize resource allocation - Ensure efficient allocation of resources for conversations
  • • Manage resource cleanup - Properly clean up resources after conversations
  • • Track resource utilization - Monitor the overall resource consumption patterns

Best Practices

Conversational Communication Best Practices

  • • Always check response codes
  • • Use appropriate conversation parameters
  • • Implement proper error handling
  • • Ensure proper conversation management
  • • Validate conversational operations
  • • Optimize conversational operations
  • • Clean up resources properly

Explain It Like I'm 5 Years Old

Think of CICS CONVERSE (APPC) like having a conversation with a friend:

  • • Start Conversation: "You start talking to your friend" - Begin conversation
  • • Send Message: "You tell your friend something" - Send data
  • • Wait for Reply: "You wait for your friend to answer" - Wait for response
  • • Get Reply: "Your friend tells you something back" - Receive response
  • • Continue Talking: "You keep talking back and forth" - Continue conversation

Exercises

Exercise 1: Basic Conversational Communication

Create a program that engages in basic conversational communication using CONVERSE.

Exercise 2: Multi-Turn Conversation

Write a program that manages multi-turn conversations with proper state management.

Exercise 3: Error Handling

Implement comprehensive error handling for conversational communication failures.

Related Concepts

APPC Communication

Advanced Program-to-Program Communication

Conversational Programming

Conversational programming patterns

Session Management

Managing APPC sessions

Inter-System Communication

Communication between systems

Error Handling

Managing conversation errors