Callback - MQ_CALLBACK_EXIT

MQ_CALLBACK_EXIT provides an exit function to perform before and after callback processing. Use function identifier MQXF_CALLBACK with exit reasons MQXR_BEFORE and MQXR_AFTER to register before and after callback call exit functions.

The interface to this function is: 
MQ_CALLBACK_EXIT (&ExitParms, &ExitContext, &Hconn, &pMsgDesc, &pGetMsgOpts,
                  &pBuffer, &pMQCBContext)
where the parameters are:

    ExitParms (MQAXP) - input/output
    Exit parameter structure

    ExitContext (MQAXC) - input/output
    Exit context structure

    Hconn (MQHCONN) - input/output
    Connection handle

    pMsgDesc
    Message descriptor

    pGetMsgOpts
    Options that control the action of MQGET

    pBuffer
    Area to contain the message data

    pMQCBContext
    Context data for the callback


C language invocation

The queue manager logically defines the following variables: 
        MQAXP    ExitParms;      /* Exit parameter structure */
        MQAXC    ExitContext;    /* Exit context structure */
        MQHCONN  Hconn;          /* Connection handle */
        PMQMD    pMsgDesc;       /* Message descriptor */
        PMQGMO   pGetMsgOpts;    /* Options that define the operation of the consumer */
        PMQVOID  pBuffer;        /* Area to contain the message data */
        PMQCBC   pContext;       /* Context data for the callback */
The queue manager then logically calls the exit as follows: 
MQ_SUBRQ_EXIT (&ExitParms, &ExitContext, &Hconn, &pMsgDesc, &pGetMsgOpts, &pBuffer,
               &pContext);
Your exit must match the following C function prototype: 
void MQENTRY MQ_CALLBACK_EXIT (
PMQAXP    pExitParms;    /* Exit parameter structure */
PMQAXC    pExitContext;  /* Exit context structure */
PMQHCONN  pHconn;        /* Connection handle */
PPMQMD    ppMsgDesc;     /* Message descriptor */
PPMQGMO   ppGetMsgOpts;  /* Options that define the operation of the consumer */
PPMQVOID  ppBuffer;      /* Area to contain the message data */
PPMQCBC   ppContext;)    /* Context data for the callback */


Usage notes

  1. The Callback exit is invoked before the consumer is invoked and after the consumer's consumer function has completed. Although the MQMD and MQGMO structures are alterable, changing the values in the before exit does not redrive the retrieval of a message from the queue as the message has already been removed from the queue to be delivered to the consumer function