gtpc2m4uC/C++ Language Support User's Guide

MQBACK-Back Out a Queue

This function indicates to the queue manager that all MQPUT, MQPUT1, and MQGET function calls that have occurred since the last syncpoint are to be backed out. Messages put as part of a unit of work are deleted; messages retrieved as part of a unit of work are reinstated on the queue. This call is available only for remote client programs. For local TPF MQSeries applications, use the tx_rollback function.

Format

#include  <cmqc.h>
void      MQBACK (MQHCONN Hconn,
                 PMQLONG pCompCode,
                 PMQLONG pReason);

Hconn
The connection handle, which represents the connection to the TPF MQSeries queue manager. The value of Hconn was returned by a previous MQCONN call.

pCompCode
A pointer to the location to store the completion code, which is one of the following:

MQCC_OK
Successfully completed.

MQCC_FAILED
The call failed.

pReason
A pointer to the location to store the reason code that qualifies the completion code.

If the completion code is MQCC_OK, the reason code is MQRC_NONE, which indicates a normal return.

If the completion code is MQCC_FAILED, see Error Return for the corresponding reason codes.

See MQSeries Application Programming Reference and MQSeries Message Queue Interface Technical Reference for more information about MQSeries data types and parameters.

Normal Return

MQCC_OK
Completion code completed successfully.

MQRC_NONE
Reason code completed successfully.

Error Return

If the completion code is MQCC_FAILED, the function failed with one of the following reason codes:

MQRC_CONNECTION_BROKEN
The connection to the queue manager is lost.

MQRC_ENVIRONMENT_ERROR
The call was not valid in this environment.

MQRC_HCONN_ERROR
The connection handle is not valid.

MQRC_Q_MGR_STOPPING
The queue manager is stopping.

MQRC_STORAGE_NOT_AVAILABLE
There is not enough storage available.

MQRC_UNEXPECTED_ERROR
An unexpected error occurred.

Programming Considerations

If the Hconn parameter is not for the local TPF MQSeries queue manager, this MQBACK function call will be sent by TPF MQSeries client support to the remote queue manager for processing. The options supported by the remote queue manager can differ from the options specified for the local TPF MQSeries queue manager.

Examples

The following example backs out a queue.

#include <cmqc.h>
 
MQLONG  CompCode;                        /* completion code        */
MQLONG  Reason;                          /* reason code            */
MQHCONN Hconn;                           /* Connection Handle      */
 
/* Hconn from previous MQCONN MQOPEN                       */
MQBACK (hCon,&CompCode,&Reason);
 
if(Reason == MQRC_NONE)
   printf("MQBACK successfully issued\n");

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