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CICS GETNEXT EVENT - Event Browse Navigation

CICS GETNEXT EVENT provides event browse navigation capabilities in CICS environments. It enables programs to navigate event browse operations, retrieve next events, and manage event browsing sessions in CICS applications.

What is CICS GETNEXT EVENT?

CICS GETNEXT EVENT is a command that allows programs to navigate event browse operations, retrieve next events, and manage event browsing sessions in CICS environments. It provides event browse navigation capabilities, sequential access, and browse management for CICS applications.

Command Syntax

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EXEC CICS GETNEXT EVENT
    [REQID(request-id)]
    [EVENTID(event-id)]
    [INTO(data-area)]
    [LENGTH(data-length)]
    [RESP(response-code)]
END-EXEC

Parameters

Optional Parameters

  • REQID - Request identifier for the browse operation
  • EVENTID - Event identifier to receive next event
  • INTO - Data area to receive event information
  • LENGTH - Length of data to retrieve
  • RESP - Response code variable

Event Browse Navigation Types

Sequential Navigation

Navigate through events in sequence

  • • FORWARD NAVIGATION - Navigate forward through event list
  • • NEXT EVENT NAVIGATION - Move to next event in sequence
  • • SEQUENTIAL ACCESS - Access events in sequential order
  • • LINEAR NAVIGATION - Navigate linearly through events

Event Type Navigation

Navigate through events by type

  • • TYPE-SPECIFIC NAVIGATION - Navigate through events of specific types
  • • MULTI-TYPE NAVIGATION - Navigate across multiple event types
  • • TYPE-GROUP NAVIGATION - Navigate through event type groups
  • • TYPE-PATTERN NAVIGATION - Navigate through events matching type patterns

Conditional Navigation

Navigate based on specific conditions

  • • CONDITIONAL NAVIGATION - Navigate only when conditions are met
  • • STATE-BASED NAVIGATION - Navigate based on event state
  • • PRIORITY-BASED NAVIGATION - Navigate based on event priority
  • • FILTERED NAVIGATION - Navigate through filtered events

Batch Navigation

Navigate through multiple events

  • • BATCH NAVIGATION - Navigate through multiple events in batch
  • • GROUP NAVIGATION - Navigate through related event groups
  • • CATEGORY NAVIGATION - Navigate through event categories
  • • PATTERN NAVIGATION - Navigate through events matching patterns

Programming Examples

Basic Event Navigation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GETNEXT01.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  REQUEST-ID      PIC X(8) VALUE 'REQ001'.
       01  EVENT-ID        PIC X(8).
       01  DATA-AREA       PIC X(1000).
       01  DATA-LENGTH     PIC S9(8) COMP.
       01  RESPONSE-CODE   PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           EXEC CICS GETNEXT EVENT
               REQID(REQUEST-ID)
               EVENTID(EVENT-ID)
               INTO(DATA-AREA)
               LENGTH(DATA-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           IF RESPONSE-CODE = DFHRESP(NORMAL)
               DISPLAY 'Next event retrieved successfully'
               DISPLAY 'Event ID: ' EVENT-ID
               DISPLAY 'Data length: ' DATA-LENGTH
           ELSE
               DISPLAY 'Failed to retrieve next event'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Event Navigation Loop

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GETNEXT02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  REQUEST-ID      PIC X(8) VALUE 'REQ002'.
       01  EVENT-ID        PIC X(8).
       01  DATA-AREA       PIC X(1000).
       01  DATA-LENGTH     PIC S9(8) COMP.
       01  RESPONSE-CODE   PIC S9(8) COMP.
       01  EVENT-COUNT     PIC 9(3) VALUE 0.
       
       PROCEDURE DIVISION.
           PERFORM UNTIL RESPONSE-CODE NOT = DFHRESP(NORMAL)
               EXEC CICS GETNEXT EVENT
                   REQID(REQUEST-ID)
                   EVENTID(EVENT-ID)
                   INTO(DATA-AREA)
                   LENGTH(DATA-LENGTH)
                   RESP(RESPONSE-CODE)
               END-EXEC
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   ADD 1 TO EVENT-COUNT
                   DISPLAY 'Event ' EVENT-COUNT ': ' EVENT-ID
               END-IF
           END-PERFORM
           
           DISPLAY 'Total events processed: ' EVENT-COUNT
           
           EXEC CICS RETURN END-EXEC.

Error Handling with Event Navigation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GETNEXT03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  REQUEST-ID      PIC X(8) VALUE 'REQ003'.
       01  EVENT-ID        PIC X(8).
       01  DATA-AREA       PIC X(1000).
       01  DATA-LENGTH     PIC S9(8) COMP.
       01  RESPONSE-CODE   PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           EXEC CICS GETNEXT EVENT
               REQID(REQUEST-ID)
               EVENTID(EVENT-ID)
               INTO(DATA-AREA)
               LENGTH(DATA-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   DISPLAY 'Next event retrieved successfully'
                   DISPLAY 'Event ID: ' EVENT-ID
               WHEN DFHRESP(ENDFILE)
                   DISPLAY 'End of event list reached'
               WHEN DFHRESP(NOTFND)
                   DISPLAY 'Browse operation not found'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid navigation request'
               WHEN DFHRESP(EVENTERR)
                   DISPLAY 'Event-specific error occurred'
               WHEN OTHER
                   DISPLAY 'Unexpected error occurred'
           END-EVALUATE
           
           EXEC CICS RETURN END-EXEC.

Event Browse Management

Browse State Management

  • • Browse Position Tracking - Track current position in browse operation
  • • Browse State Maintenance - Maintain browse state across operations
  • • Browse Context Management - Manage browse context and environment
  • • Browse Session Management - Manage browse session lifecycle

Event Management

  • • Event Data Management - Manage event data during navigation
  • • Event State Management - Manage event state during navigation
  • • Event Metadata Management - Manage event metadata during navigation
  • • Event Access Management - Manage event access during navigation

Handler Management

  • • Handler Registration - Register event handlers during navigation
  • • Handler Execution - Execute event handlers during navigation
  • • Handler Cleanup - Clean up event handlers after navigation
  • • Handler Monitoring - Monitor event handler performance

Error Management

  • • Error Detection - Detect errors during navigation
  • • Error Recovery - Recover from navigation errors
  • • Error Reporting - Report navigation errors
  • • Error Prevention - Prevent future navigation errors

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - Next event retrieved successfully
  • DFHRESP(ENDFILE) - End of event list reached
  • DFHRESP(NOTFND) - Browse operation not found
  • DFHRESP(INVREQ) - Invalid navigation request
  • DFHRESP(EVENTERR) - Event-specific error
  • DFHRESP(GETNEXTERR) - Get next-specific error

Performance Considerations

Navigation Efficiency

  • • Optimize navigation operations - Use appropriate navigation methods for different event types
  • • Minimize navigation overhead - Reduce the computational cost of navigation operations
  • • Use efficient navigation patterns - Implement navigation strategies that minimize resource usage
  • • Monitor navigation performance - Track the performance impact of navigation operations

Resource Impact

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

Best Practices

Event Browse Navigation Best Practices

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

Explain It Like I'm 5 Years Old

Think of CICS GETNEXT EVENT like looking through a calendar:

  • • Calendar Name: "Which calendar to look through" - The request ID
  • • Look at Next Day: "Look at the next day" - Get next event
  • • See What's Happening: "See what's happening that day" - Access event data
  • • Keep Looking: "Look at more days" - Continue navigation
  • • All Done: "Finished looking through the calendar" - End of events

Exercises

Exercise 1: Basic Event Navigation

Create a program that navigates through events using GETNEXT EVENT.

Exercise 2: Event Navigation Loop

Write a program that loops through all events using GETNEXT EVENT.

Exercise 3: Error Handling

Implement comprehensive error handling for event navigation failures and end-of-list conditions.

Related Concepts

Event Management

Managing system events

Browse Operations

Managing browse operations

Event Handlers

Managing event handlers

Event Processing

Processing system events

Error Handling

Managing navigation errors