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CICS GDS ISSUE SIGNAL - Signal Transmission

CICS GDS ISSUE SIGNAL sends a signal to the partner system in a General Data Stream (GDS) conversation in CICS APPC environments. It provides a mechanism for event notification, status signaling, and communication coordination.

What is CICS GDS ISSUE SIGNAL?

CICS GDS ISSUE SIGNAL sends a signal to the partner system in a GDS conversation, providing a mechanism for event notification, status communication, and coordination between systems. It enables asynchronous communication and event-driven processing in APPC environments.

Command Syntax

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EXEC CICS GDS ISSUE SIGNAL
    CONVID(conversation-id)
    SIGNAL(signal-type)
    SIGNALTEXT(signal-text)
    RESP(response-code)
    RESP2(response-code-2)
END-EXEC.

Parameters Explained

CONVID Parameter

Specifies the conversation identifier:

  • Must be obtained from GDS ALLOCATE
  • Identifies the active conversation
  • Required for all GDS operations
  • Must be valid and active

SIGNAL Parameter

Specifies the signal type:

  • Identifies the type of signal
  • Used for signal classification
  • Determines signal processing
  • Must be a valid signal type

SIGNALTEXT Parameter

Specifies the signal text:

  • Provides signal description
  • Contains signal details
  • Used for signal context
  • Can be null or empty

Common Signal Types

1. Status Signals

  • STATUS: Status update signal
  • READY: Ready state signal
  • BUSY: Busy state signal
  • IDLE: Idle state signal

2. Event Signals

  • EVENT: General event signal
  • ALERT: Alert notification signal
  • NOTIFY: Notification signal
  • WARNING: Warning signal

3. Control Signals

  • CONTROL: Control signal
  • SYNC: Synchronization signal
  • FLOW: Flow control signal
  • RESET: Reset signal

Implementation Example

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WORKING-STORAGE SECTION.
01 WS-CONVERSATION-ID     PIC S9(8) COMP.
01 WS-RESPONSE            PIC S9(8) COMP.
01 WS-RESPONSE2           PIC S9(8) COMP.
01 WS-SIGNAL-TYPE         PIC X(8) VALUE 'STATUS'.
01 WS-SIGNAL-TEXT         PIC X(50) VALUE 'Processing completed successfully'.
 
PROCEDURE DIVISION.
    * Complete processing
    PERFORM PROCESS-DATA
    
    * Send status signal
    EXEC CICS GDS ISSUE SIGNAL
        CONVID(WS-CONVERSATION-ID)
        SIGNAL(WS-SIGNAL-TYPE)
        SIGNALTEXT(WS-SIGNAL-TEXT)
        RESP(WS-RESPONSE)
        RESP2(WS-RESPONSE2)
    END-EXEC.
    
    IF WS-RESPONSE NOT EQUAL DFHRESP(NORMAL)
        EXEC CICS WRITE OPERATOR
            TEXT('GDS ISSUE SIGNAL failed')
        END-EXEC
    END-IF.
    
    * Signal sent successfully

When to Use Signal Transmission

1. Status Updates

Use signals for status updates:

  • Processing completion
  • State changes
  • Progress updates
  • Status notifications

2. Event Notification

Use for event notification:

  • Event occurrence
  • Alert conditions
  • Warning situations
  • Exception handling

3. Coordination

Use for coordination:

  • Synchronization points
  • Flow control
  • Process coordination
  • Resource management

Signal Processing

1. Signal Reception

Partner system receives:

  • Signal type
  • Signal text
  • Signal context
  • Signal timestamp

2. Signal Handling

Signal handling includes:

  • Signal classification
  • Signal processing
  • Action execution
  • Response generation

3. Signal Logging

Signal logging involves:

  • Signal recording
  • Context information
  • Timestamp recording
  • Audit trail maintenance

Common Response Codes

Success Response Codes

  • NORMAL (0): Signal sent successfully
  • CONVERSATION (4): Signal processed

Error Response Codes

  • INVREQ (16): Invalid request
  • NOTFND (20): Conversation not found
  • CONVERSATION (24): Conversation error
  • SYSTEM (28): System error

Best Practices

1. Signal Design

  • Use consistent signal types
  • Provide meaningful signal text
  • Classify signals appropriately
  • Document signal usage

2. Error Handling

  • Check all response codes
  • Handle signal failures
  • Implement retry logic
  • Log error conditions

3. Performance Optimization

  • Minimize signal overhead
  • Batch signals when possible
  • Optimize signal timing
  • Monitor signal patterns

Explain It Like I'm 5 Years Old

Imagine you're playing a game and want to tell your friend something:

Sometimes when you're playing a game, you want to tell your friend something important. Maybe you want to say "I'm done with my turn" or "I need help" or "Something cool just happened!"

CICS GDS ISSUE SIGNAL is like waving your hand to get your friend's attention and then telling them something important. It's a way to send a message that doesn't need a big conversation, just a quick "Hey, this happened!"

Just like you might wave and say "I'm ready!" or "I need help!", the computer waves to the other computer and says "I'm done!" or "I need something!" so they know what's happening.

Exercises

Exercise 1: Signal Transmission

Write a CICS GDS ISSUE SIGNAL command to send a status signal indicating that processing is complete.

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EXEC CICS GDS ISSUE SIGNAL
    CONVID(WS-CONVERSATION-ID)
    SIGNAL('STATUS')
    SIGNALTEXT('Processing completed')
    RESP(WS-RESPONSE)
END-EXEC.

Exercise 2: Signal Strategy

Design a signal strategy for a data processing application. What types of signals would you send, and when would you send them?

Answer: Send STATUS signals for processing updates, EVENT signals for important occurrences, ALERT signals for error conditions, and CONTROL signals for flow management. Send signals at key processing points and state changes.

Quiz

Question 1

What is the primary purpose of CICS GDS ISSUE SIGNAL?

Answer: B) To send signal to partner system

Question 2

Which parameter specifies the type of signal being sent?

Answer: B) SIGNAL

Related Concepts

CICS GDS Commands

General Data Stream commands for APPC communication

CICS Event Processing

Event processing and notification in CICS

CICS Asynchronous Communication

Asynchronous communication patterns in CICS