MainframeMaster

COBOL Communication Handling

Communication handling in COBOL involves managing data exchange and coordination between different programs, systems, and processes. Effective communication handling ensures that programs can work together seamlessly, share data reliably, and handle communication errors gracefully. This is essential for building integrated business applications.

Understanding Communication Handling

Communication handling in COBOL encompasses all the mechanisms used to exchange data and coordinate activities between programs. This includes synchronous communication through CALL statements, asynchronous communication through message queues, shared data through communication areas, and file-based communication for batch processing scenarios.

Program-to-Program Communication

1. CALL Statement Communication

The CALL statement is the primary method for synchronous communication between COBOL programs. It allows one program to invoke another program and pass data through parameters. The calling program waits for the called program to complete before continuing execution.

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CALLING-PROGRAM.
       *> This program demonstrates how to call other programs and handle communication
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       *> Data to be passed to called program
       01 CALL-PARAMETERS.
           05 CUSTOMER-ID           PIC 9(8) VALUE 12345678.
           05 TRANSACTION-AMOUNT    PIC 9(8)V99 VALUE 1000.00.
           05 TRANSACTION-TYPE      PIC X(1) VALUE 'D'.
           05 PROCESSING-REQUEST    PIC X(20) VALUE 'VALIDATE-ACCOUNT'.
       
       *> Data returned from called program
       01 CALL-RESULTS.
           05 PROCESSING-STATUS     PIC X(1).
               88 PROCESSING-SUCCESS VALUE 'S'.
               88 PROCESSING-FAILURE VALUE 'F'.
           05 RETURN-CODE           PIC 9(2).
           05 ERROR-MESSAGE         PIC X(100).
           05 PROCESSED-AMOUNT      PIC 9(8)V99.
       
       *> Communication control variables
       01 COMMUNICATION-CONTROLS.
           05 CALL-ATTEMPT-COUNT    PIC 9(2) VALUE 0.
           05 MAX-CALL-ATTEMPTS     PIC 9(2) VALUE 3.
           05 COMMUNICATION-STATUS  PIC X(1).
               88 COMMUNICATION-OK   VALUE 'O'.
               88 COMMUNICATION-ERROR VALUE 'E'.
       
       PROCEDURE DIVISION.
       MAIN-COMMUNICATION-LOGIC.
           DISPLAY 'Starting program-to-program communication'
           
       *> Initialize communication parameters
           PERFORM INITIALIZE-COMMUNICATION-PARAMETERS
           
       *> Call the validation program
           PERFORM CALL-VALIDATION-PROGRAM
           
       *> Process the results
           PERFORM PROCESS-COMMUNICATION-RESULTS
           
       *> Handle any communication errors
           PERFORM HANDLE-COMMUNICATION-ERRORS
           
           STOP RUN.
       
       INITIALIZE-COMMUNICATION-PARAMETERS.
       *> Set up parameters for program communication
           MOVE 0 TO CALL-ATTEMPT-COUNT
           SET COMMUNICATION-OK TO TRUE
           MOVE SPACES TO ERROR-MESSAGE
           MOVE 0 TO RETURN-CODE
           
           DISPLAY 'Communication parameters initialized'
           DISPLAY 'Customer ID: ' CUSTOMER-ID
           DISPLAY 'Transaction Amount: ' TRANSACTION-AMOUNT
           DISPLAY 'Transaction Type: ' TRANSACTION-TYPE.
       
       CALL-VALIDATION-PROGRAM.
       *> Call the account validation program with error handling
           ADD 1 TO CALL-ATTEMPT-COUNT
           
           DISPLAY 'Calling validation program (attempt ' CALL-ATTEMPT-COUNT ')'
           
       *> Call the program with parameters
           CALL 'ACCOUNT-VALIDATOR' USING CALL-PARAMETERS
                                        CALL-RESULTS
           
       *> Check for communication success
           IF RETURN-CODE = 0
               SET COMMUNICATION-OK TO TRUE
               DISPLAY 'Communication successful'
           ELSE
               SET COMMUNICATION-ERROR TO TRUE
               DISPLAY 'Communication error - Return code: ' RETURN-CODE
           END-IF.
       
       PROCESS-COMMUNICATION-RESULTS.
       *> Process the results returned from the called program
           IF COMMUNICATION-OK
               IF PROCESSING-SUCCESS
                   DISPLAY 'Validation successful'
                   DISPLAY 'Processed amount: ' PROCESSED-AMOUNT
                   PERFORM CONTINUE-WITH-PROCESSING
               ELSE
                   DISPLAY 'Validation failed: ' ERROR-MESSAGE
                   PERFORM HANDLE-VALIDATION-FAILURE
               END-IF
           ELSE
               PERFORM HANDLE-COMMUNICATION-ERRORS
           END-IF.
       
       CONTINUE-WITH-PROCESSING.
       *> Continue with main processing after successful validation
           DISPLAY 'Continuing with main processing...'
           *> Add main processing logic here.
       
       HANDLE-VALIDATION-FAILURE.
       *> Handle validation failure from called program
           DISPLAY 'Validation failed - stopping processing'
           *> Add error handling logic here.
       
       HANDLE-COMMUNICATION-ERRORS.
       *> Handle communication errors and retry logic
           IF COMMUNICATION-ERROR
               IF CALL-ATTEMPT-COUNT < MAX-CALL-ATTEMPTS
                   DISPLAY 'Retrying communication...'
                   PERFORM CALL-VALIDATION-PROGRAM
               ELSE
                   DISPLAY 'Maximum call attempts reached - aborting'
                   MOVE 8 TO RETURN-CODE
               END-IF
           END-IF.

This example demonstrates how to use the CALL statement for program-to-program communication. The calling program passes parameters to the called program and receives results back. The code includes error handling, retry logic, and status checking to ensure reliable communication. The CALL statement provides synchronous communication where the calling program waits for the called program to complete.

2. Communication Areas

Communication areas are shared memory regions that allow programs to exchange data and status information. They are particularly useful for passing data between programs that are called sequentially or for maintaining state information across program invocations.

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. COMMUNICATION-AREA-EXAMPLE.
       *> This program demonstrates communication area usage
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       *> Communication area structure for data exchange
       01 COMMUNICATION-AREA.
           05 CA-PROGRAM-ID        PIC X(8) VALUE 'COMMAREA'.
           05 CA-VERSION           PIC X(4) VALUE 'V1.0'.
           05 CA-TRANSACTION-DATA.
               10 CA-CUSTOMER-ID   PIC 9(8).
               10 CA-ACCOUNT-NUMBER PIC 9(10).
               10 CA-TRANSACTION-AMOUNT PIC 9(8)V99.
               10 CA-TRANSACTION-TYPE PIC X(1).
                   88 CA-DEPOSIT    VALUE 'D'.
                   88 CA-WITHDRAWAL VALUE 'W'.
                   88 CA-TRANSFER   VALUE 'T'.
           05 CA-PROCESSING-STATUS.
               10 CA-STATUS-CODE   PIC X(1).
                   88 CA-SUCCESS    VALUE 'S'.
                   88 CA-FAILURE    VALUE 'F'.
                   88 CA-WARNING    VALUE 'W'.
               10 CA-ERROR-CODE    PIC X(4).
               10 CA-ERROR-MESSAGE PIC X(100).
           05 CA-AUDIT-INFORMATION.
               10 CA-USER-ID       PIC X(8).
               10 CA-TIMESTAMP     PIC X(20).
               10 CA-PROCESSING-TIME PIC 9(8).
       
       *> Local processing variables
       01 LOCAL-PROCESSING-DATA.
           05 PROCESSING-START-TIME PIC 9(8).
           05 PROCESSING-END-TIME   PIC 9(8).
           05 PROCESSING-DURATION   PIC 9(8).
       
       PROCEDURE DIVISION USING COMMUNICATION-AREA.
       MAIN-COMMUNICATION-PROCESSING.
           DISPLAY 'Starting communication area processing'
           
       *> Validate communication area
           PERFORM VALIDATE-COMMUNICATION-AREA
           
       *> Process the transaction
           PERFORM PROCESS-TRANSACTION
           
       *> Update communication area with results
           PERFORM UPDATE-COMMUNICATION-AREA
           
           DISPLAY 'Communication area processing completed'
           GOBACK.
       
       VALIDATE-COMMUNICATION-AREA.
       *> Validate the communication area structure and data
           IF CA-PROGRAM-ID NOT = 'COMMAREA'
               SET CA-FAILURE TO TRUE
               MOVE 'INVA' TO CA-ERROR-CODE
               MOVE 'Invalid communication area identifier' TO CA-ERROR-MESSAGE
               DISPLAY 'ERROR: Invalid communication area'
           ELSE
               IF CA-CUSTOMER-ID = 0
                   SET CA-FAILURE TO TRUE
                   MOVE 'CUST' TO CA-ERROR-CODE
                   MOVE 'Customer ID is required' TO CA-ERROR-MESSAGE
                   DISPLAY 'ERROR: Customer ID missing'
               ELSE
                   IF CA-TRANSACTION-AMOUNT <= 0
                       SET CA-FAILURE TO TRUE
                       MOVE 'AMNT' TO CA-ERROR-CODE
                       MOVE 'Transaction amount must be positive' TO CA-ERROR-MESSAGE
                       DISPLAY 'ERROR: Invalid transaction amount'
                   ELSE
                       SET CA-SUCCESS TO TRUE
                       MOVE '0000' TO CA-ERROR-CODE
                       MOVE SPACES TO CA-ERROR-MESSAGE
                       DISPLAY 'Communication area validation successful'
                   END-IF
               END-IF
           END-IF.
       
       PROCESS-TRANSACTION.
       *> Process the transaction based on type
           IF CA-SUCCESS
               ACCEPT PROCESSING-START-TIME FROM TIME
               
               EVALUATE CA-TRANSACTION-TYPE
                   WHEN 'D'
                       PERFORM PROCESS-DEPOSIT-TRANSACTION
                   WHEN 'W'
                       PERFORM PROCESS-WITHDRAWAL-TRANSACTION
                   WHEN 'T'
                       PERFORM PROCESS-TRANSFER-TRANSACTION
                   WHEN OTHER
                       SET CA-FAILURE TO TRUE
                       MOVE 'TYPE' TO CA-ERROR-CODE
                       MOVE 'Invalid transaction type' TO CA-ERROR-MESSAGE
               END-EVALUATE
               
               ACCEPT PROCESSING-END-TIME FROM TIME
               COMPUTE PROCESSING-DURATION = PROCESSING-END-TIME - PROCESSING-START-TIME
           END-IF.
       
       PROCESS-DEPOSIT-TRANSACTION.
       *> Process deposit transaction
           DISPLAY 'Processing deposit transaction'
           *> Add deposit processing logic here
           SET CA-SUCCESS TO TRUE.
       
       PROCESS-WITHDRAWAL-TRANSACTION.
       *> Process withdrawal transaction
           DISPLAY 'Processing withdrawal transaction'
           *> Add withdrawal processing logic here
           SET CA-SUCCESS TO TRUE.
       
       PROCESS-TRANSFER-TRANSACTION.
       *> Process transfer transaction
           DISPLAY 'Processing transfer transaction'
           *> Add transfer processing logic here
           SET CA-SUCCESS TO TRUE.
       
       UPDATE-COMMUNICATION-AREA.
       *> Update communication area with processing results
           MOVE PROCESSING-DURATION TO CA-PROCESSING-TIME
           ACCEPT CA-TIMESTAMP FROM DATE YYYYMMDD
           ACCEPT CA-TIMESTAMP(9:8) FROM TIME
           
           IF CA-SUCCESS
               DISPLAY 'Transaction processed successfully'
               DISPLAY 'Processing time: ' CA-PROCESSING-TIME ' milliseconds'
           ELSE
               DISPLAY 'Transaction processing failed'
               DISPLAY 'Error code: ' CA-ERROR-CODE
               DISPLAY 'Error message: ' CA-ERROR-MESSAGE
           END-IF.

This example demonstrates how to use communication areas for data exchange between programs. The communication area contains structured data including transaction information, processing status, and audit information. The program validates the communication area, processes the transaction, and updates the area with results. This approach allows for rich data exchange and status reporting between programs.

Message Queue Communication

1. Asynchronous Message Handling

Message queues provide asynchronous communication between programs, allowing programs to send and receive messages without waiting for immediate responses. This is useful for decoupled systems and background processing scenarios.

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. MESSAGE-QUEUE-HANDLER.
       *> This program demonstrates message queue communication
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       *> Message queue structure
       01 MESSAGE-QUEUE-DATA.
           05 MQ-MESSAGE-ID       PIC X(16).
           05 MQ-MESSAGE-TYPE     PIC X(10).
           05 MQ-PRIORITY         PIC 9(2).
           05 MQ-TIMESTAMP        PIC X(20).
           05 MQ-SENDER-PROGRAM   PIC X(8).
           05 MQ-RECEIVER-PROGRAM PIC X(8).
           05 MQ-MESSAGE-BODY     PIC X(1000).
       
       *> Message processing controls
       01 MESSAGE-PROCESSING-CONTROLS.
           05 MESSAGE-COUNT       PIC 9(6) VALUE 0.
           05 PROCESSED-COUNT     PIC 9(6) VALUE 0.
           05 ERROR-COUNT         PIC 9(6) VALUE 0.
           05 PROCESSING-STATUS   PIC X(1).
               88 PROCESSING-ACTIVE VALUE 'A'.
               88 PROCESSING-STOPPED VALUE 'S'.
       
       *> Queue management variables
       01 QUEUE-MANAGEMENT.
           05 QUEUE-NAME          PIC X(20) VALUE 'TRANSACTION-QUEUE'.
           05 QUEUE-STATUS        PIC X(1).
               88 QUEUE-OPEN      VALUE 'O'.
               88 QUEUE-CLOSED    VALUE 'C'.
           05 MESSAGE-AVAILABLE   PIC X(1).
               88 MESSAGE-READY   VALUE 'Y'.
               88 NO-MESSAGE      VALUE 'N'.
       
       PROCEDURE DIVISION.
       MAIN-MESSAGE-PROCESSING.
           DISPLAY 'Starting message queue processing'
           
       *> Initialize message queue
           PERFORM INITIALIZE-MESSAGE-QUEUE
           
       *> Process messages from queue
           PERFORM PROCESS-MESSAGE-QUEUE
           
       *> Clean up and close queue
           PERFORM CLOSE-MESSAGE-QUEUE
           
           STOP RUN.
       
       INITIALIZE-MESSAGE-QUEUE.
       *> Set up message queue for processing
           SET PROCESSING-ACTIVE TO TRUE
           SET QUEUE-OPEN TO TRUE
           MOVE 0 TO MESSAGE-COUNT
           MOVE 0 TO PROCESSED-COUNT
           MOVE 0 TO ERROR-COUNT
           
           DISPLAY 'Message queue initialized: ' QUEUE-NAME.
       
       PROCESS-MESSAGE-QUEUE.
       *> Main message processing loop
           PERFORM UNTIL PROCESSING-STOPPED
               PERFORM CHECK-FOR-MESSAGES
               IF MESSAGE-READY
                   PERFORM RECEIVE-MESSAGE
                   PERFORM PROCESS-MESSAGE
                   PERFORM SEND-RESPONSE
               ELSE
                   PERFORM WAIT-FOR-MESSAGES
               END-IF
           END-PERFORM.
       
       CHECK-FOR-MESSAGES.
       *> Check if messages are available in the queue
           *> In a real implementation, this would check the actual queue
           *> For demonstration, we'll simulate message availability
           IF MESSAGE-COUNT < 10
               SET MESSAGE-READY TO TRUE
               ADD 1 TO MESSAGE-COUNT
           ELSE
               SET NO-MESSAGE TO TRUE
               SET PROCESSING-STOPPED TO TRUE
           END-IF.
       
       RECEIVE-MESSAGE.
       *> Receive message from the queue
           DISPLAY 'Receiving message from queue...'
           
       *> Simulate receiving message data
           MOVE 'MSG' TO MQ-MESSAGE-TYPE
           MOVE 1 TO MQ-PRIORITY
           ACCEPT MQ-TIMESTAMP FROM DATE YYYYMMDD
           ACCEPT MQ-TIMESTAMP(9:8) FROM TIME
           MOVE 'SENDER01' TO MQ-SENDER-PROGRAM
           MOVE 'RECEIVER1' TO MQ-RECEIVER-PROGRAM
           MOVE 'Transaction processing request' TO MQ-MESSAGE-BODY
           
           DISPLAY 'Message received: ' MQ-MESSAGE-TYPE
           DISPLAY 'From: ' MQ-SENDER-PROGRAM
           DISPLAY 'Body: ' MQ-MESSAGE-BODY.
       
       PROCESS-MESSAGE.
       *> Process the received message
           DISPLAY 'Processing message...'
           
           EVALUATE MQ-MESSAGE-TYPE
               WHEN 'MSG'
                   PERFORM PROCESS-TRANSACTION-MESSAGE
               WHEN 'REQ'
                   PERFORM PROCESS-REQUEST-MESSAGE
               WHEN 'RSP'
                   PERFORM PROCESS-RESPONSE-MESSAGE
               WHEN OTHER
                   PERFORM PROCESS-UNKNOWN-MESSAGE
           END-EVALUATE
           
           ADD 1 TO PROCESSED-COUNT.
       
       PROCESS-TRANSACTION-MESSAGE.
       *> Process transaction-related messages
           DISPLAY 'Processing transaction message'
           *> Add transaction processing logic here.
       
       PROCESS-REQUEST-MESSAGE.
       *> Process request messages
           DISPLAY 'Processing request message'
           *> Add request processing logic here.
       
       PROCESS-RESPONSE-MESSAGE.
       *> Process response messages
           DISPLAY 'Processing response message'
           *> Add response processing logic here.
       
       PROCESS-UNKNOWN-MESSAGE.
       *> Handle unknown message types
           DISPLAY 'Unknown message type: ' MQ-MESSAGE-TYPE
           ADD 1 TO ERROR-COUNT.
       
       SEND-RESPONSE.
       *> Send response back to sender
           DISPLAY 'Sending response to: ' MQ-SENDER-PROGRAM
           *> Add response sending logic here.
       
       WAIT-FOR-MESSAGES.
       *> Wait for messages to arrive
           DISPLAY 'Waiting for messages...'
           *> In a real implementation, this would wait for actual messages.
       
       CLOSE-MESSAGE-QUEUE.
       *> Clean up and close the message queue
           SET QUEUE-CLOSED TO TRUE
           SET PROCESSING-STOPPED TO TRUE
           
           DISPLAY 'Message queue processing completed'
           DISPLAY 'Messages processed: ' PROCESSED-COUNT
           DISPLAY 'Errors encountered: ' ERROR-COUNT.

This example demonstrates asynchronous message queue communication. The program receives messages from a queue, processes them based on message type, and can send responses back. This approach allows for decoupled communication where programs don't need to wait for each other, making the system more responsive and scalable.

2. Error Handling in Communication

Effective error handling is crucial for reliable communication between programs. This includes handling communication failures, timeout conditions, data validation errors, and system-level communication issues.

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. COMMUNICATION-ERROR-HANDLER.
       *> This program demonstrates comprehensive error handling in communication
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       *> Error handling structure
       01 COMMUNICATION-ERROR-DATA.
           05 ERROR-TYPE           PIC X(1).
               88 CONNECTION-ERROR VALUE 'C'.
               88 TIMEOUT-ERROR    VALUE 'T'.
               88 DATA-ERROR       VALUE 'D'.
               88 SYSTEM-ERROR     VALUE 'S'.
           05 ERROR-SEVERITY       PIC X(1).
               88 CRITICAL-ERROR   VALUE 'C'.
               88 WARNING-ERROR    VALUE 'W'.
               88 INFO-ERROR       VALUE 'I'.
           05 ERROR-CODE           PIC X(4).
           05 ERROR-MESSAGE        PIC X(100).
           05 ERROR-TIMESTAMP      PIC X(20).
       
       *> Communication retry controls
       01 RETRY-CONTROLS.
           05 RETRY-COUNT          PIC 9(2) VALUE 0.
           05 MAX-RETRY-ATTEMPTS   PIC 9(2) VALUE 3.
           05 RETRY-DELAY          PIC 9(4) VALUE 1000.
           05 RETRY-STATUS         PIC X(1).
               88 RETRY-SUCCESS    VALUE 'S'.
               88 RETRY-FAILED     VALUE 'F'.
       
       *> Communication monitoring
       01 COMMUNICATION-MONITORING.
           05 COMMUNICATION-STATUS PIC X(1).
               88 COMM-ACTIVE      VALUE 'A'.
               88 COMM-INACTIVE    VALUE 'I'.
               88 COMM-ERROR       VALUE 'E'.
           05 LAST-COMMUNICATION-TIME PIC X(20).
           05 COMMUNICATION-COUNT  PIC 9(6) VALUE 0.
           05 ERROR-COUNT          PIC 9(6) VALUE 0.
       
       PROCEDURE DIVISION.
       MAIN-ERROR-HANDLING.
           DISPLAY 'Starting communication error handling demonstration'
           
       *> Initialize error handling
           PERFORM INITIALIZE-ERROR-HANDLING
           
       *> Demonstrate various error scenarios
           PERFORM DEMONSTRATE-CONNECTION-ERRORS
           PERFORM DEMONSTRATE-TIMEOUT-ERRORS
           PERFORM DEMONSTRATE-DATA-ERRORS
           PERFORM DEMONSTRATE-SYSTEM-ERRORS
           
       *> Show error recovery procedures
           PERFORM DEMONSTRATE-ERROR-RECOVERY
           
           STOP RUN.
       
       INITIALIZE-ERROR-HANDLING.
       *> Set up error handling mechanisms
           SET COMM-ACTIVE TO TRUE
           MOVE 0 TO RETRY-COUNT
           MOVE 0 TO COMMUNICATION-COUNT
           MOVE 0 TO ERROR-COUNT
           MOVE SPACES TO ERROR-MESSAGE
           
           DISPLAY 'Error handling initialized'.
       
       DEMONSTRATE-CONNECTION-ERRORS.
       *> Demonstrate handling of connection errors
           DISPLAY 'Demonstrating connection error handling...'
           
           SET CONNECTION-ERROR TO TRUE
           SET CRITICAL-ERROR TO TRUE
           MOVE 'CONN' TO ERROR-CODE
           MOVE 'Unable to establish connection to target program' TO ERROR-MESSAGE
           ACCEPT ERROR-TIMESTAMP FROM DATE YYYYMMDD
           ACCEPT ERROR-TIMESTAMP(9:8) FROM TIME
           
           PERFORM HANDLE-COMMUNICATION-ERROR
           PERFORM ATTEMPT-ERROR-RECOVERY.
       
       DEMONSTRATE-TIMEOUT-ERRORS.
       *> Demonstrate handling of timeout errors
           DISPLAY 'Demonstrating timeout error handling...'
           
           SET TIMEOUT-ERROR TO TRUE
           SET WARNING-ERROR TO TRUE
           MOVE 'TIME' TO ERROR-CODE
           MOVE 'Communication timeout - no response received' TO ERROR-MESSAGE
           ACCEPT ERROR-TIMESTAMP FROM DATE YYYYMMDD
           ACCEPT ERROR-TIMESTAMP(9:8) FROM TIME
           
           PERFORM HANDLE-COMMUNICATION-ERROR
           PERFORM ATTEMPT-ERROR-RECOVERY.
       
       DEMONSTRATE-DATA-ERRORS.
       *> Demonstrate handling of data validation errors
           DISPLAY 'Demonstrating data error handling...'
           
           SET DATA-ERROR TO TRUE
           SET WARNING-ERROR TO TRUE
           MOVE 'DATA' TO ERROR-CODE
           MOVE 'Invalid data format received from communication partner' TO ERROR-MESSAGE
           ACCEPT ERROR-TIMESTAMP FROM DATE YYYYMMDD
           ACCEPT ERROR-TIMESTAMP(9:8) FROM TIME
           
           PERFORM HANDLE-COMMUNICATION-ERROR
           PERFORM ATTEMPT-ERROR-RECOVERY.
       
       DEMONSTRATE-SYSTEM-ERRORS.
       *> Demonstrate handling of system-level errors
           DISPLAY 'Demonstrating system error handling...'
           
           SET SYSTEM-ERROR TO TRUE
           SET CRITICAL-ERROR TO TRUE
           MOVE 'SYS' TO ERROR-CODE
           MOVE 'System-level communication failure detected' TO ERROR-MESSAGE
           ACCEPT ERROR-TIMESTAMP FROM DATE YYYYMMDD
           ACCEPT ERROR-TIMESTAMP(9:8) FROM TIME
           
           PERFORM HANDLE-COMMUNICATION-ERROR
           PERFORM ATTEMPT-ERROR-RECOVERY.
       
       HANDLE-COMMUNICATION-ERROR.
       *> Handle communication errors based on type and severity
           ADD 1 TO ERROR-COUNT
           SET COMM-ERROR TO TRUE
           
           DISPLAY 'Communication Error Detected:'
           DISPLAY 'Error Type: ' ERROR-TYPE
           DISPLAY 'Severity: ' ERROR-SEVERITY
           DISPLAY 'Error Code: ' ERROR-CODE
           DISPLAY 'Message: ' ERROR-MESSAGE
           DISPLAY 'Timestamp: ' ERROR-TIMESTAMP
           
           EVALUATE ERROR-SEVERITY
               WHEN 'C'
                   PERFORM HANDLE-CRITICAL-ERROR
               WHEN 'W'
                   PERFORM HANDLE-WARNING-ERROR
               WHEN 'I'
                   PERFORM HANDLE-INFO-ERROR
           END-EVALUATE.
       
       HANDLE-CRITICAL-ERROR.
       *> Handle critical errors that require immediate attention
           DISPLAY 'CRITICAL ERROR: Immediate action required'
           PERFORM LOG-CRITICAL-ERROR
           PERFORM NOTIFY-SYSTEM-ADMINISTRATOR
           PERFORM INITIATE-EMERGENCY-PROCEDURES.
       
       HANDLE-WARNING-ERROR.
       *> Handle warning errors that should be logged but don't stop processing
           DISPLAY 'WARNING: Error logged but processing continues'
           PERFORM LOG-WARNING-ERROR
           PERFORM CONTINUE-PROCESSING.
       
       HANDLE-INFO-ERROR.
       *> Handle informational errors for monitoring purposes
           DISPLAY 'INFO: Error logged for monitoring'
           PERFORM LOG-INFO-ERROR.
       
       ATTEMPT-ERROR-RECOVERY.
       *> Attempt to recover from communication errors
           IF RETRY-COUNT < MAX-RETRY-ATTEMPTS
               ADD 1 TO RETRY-COUNT
               DISPLAY 'Attempting error recovery (attempt ' RETRY-COUNT ')'
               
               PERFORM WAIT-FOR-RETRY-DELAY
               PERFORM RETRY-COMMUNICATION
               
               IF RETRY-SUCCESS
                   DISPLAY 'Error recovery successful'
                   SET COMM-ACTIVE TO TRUE
               ELSE
                   DISPLAY 'Error recovery failed'
               END-IF
           ELSE
               DISPLAY 'Maximum retry attempts reached - giving up'
               SET RETRY-FAILED TO TRUE
           END-IF.
       
       WAIT-FOR-RETRY-DELAY.
       *> Wait before retrying communication
           DISPLAY 'Waiting ' RETRY-DELAY ' milliseconds before retry...'
           *> In a real implementation, this would wait for the specified time.
       
       RETRY-COMMUNICATION.
       *> Retry the failed communication
           DISPLAY 'Retrying communication...'
           *> In a real implementation, this would retry the actual communication.
           SET RETRY-SUCCESS TO TRUE  *> Simulate successful retry.
       
       LOG-CRITICAL-ERROR.
       *> Log critical errors for system monitoring
           DISPLAY 'Logging critical error to system log'.
       
       LOG-WARNING-ERROR.
       *> Log warning errors for monitoring
           DISPLAY 'Logging warning error to system log'.
       
       LOG-INFO-ERROR.
       *> Log informational errors
           DISPLAY 'Logging info error to system log'.
       
       NOTIFY-SYSTEM-ADMINISTRATOR.
       *> Notify system administrator of critical errors
           DISPLAY 'Notifying system administrator of critical error'.
       
       INITIATE-EMERGENCY-PROCEDURES.
       *> Initiate emergency procedures for critical errors
           DISPLAY 'Initiating emergency procedures'.
       
       CONTINUE-PROCESSING.
       *> Continue processing after handling warning errors
           DISPLAY 'Continuing with normal processing'.
       
       DEMONSTRATE-ERROR-RECOVERY.
       *> Demonstrate comprehensive error recovery procedures
           DISPLAY 'Error Recovery Summary:'
           DISPLAY 'Total errors handled: ' ERROR-COUNT
           DISPLAY 'Recovery attempts: ' RETRY-COUNT
           DISPLAY 'Final communication status: ' COMMUNICATION-STATUS.

This example demonstrates comprehensive error handling for communication between programs. It shows how to handle different types of errors (connection, timeout, data, system), implement retry logic, and provide appropriate responses based on error severity. The error handling includes logging, notification, and recovery procedures to ensure robust communication.

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