Overview of the exit and schema

Syntax, and parameters used to establish a connection to a queue manager.

void MQENTRY MQ_PRECONNECT_EXIT ( PMQNXP pExitParms
                              , PMQCHAR pQMgrName
                              , PPMQCNO ppConnectOpts
                              , PMQLONG pCompCode
                              , PMQLONG pReason)

During the MQCONN/X call execution, IBM MQ C Client loads the exit module containing an implementation of the function syntax. It then invokes an exit function to retrieve channel definitions. The retrieved channel definitions are then used to establish connection to a queue manager.

Parameters

pExitParms

Type: PMQNXP input/output

The PreConnection exit parameter structure. The structure is allocated and maintained by the caller of the exit.

struct tagMQNXP
{
  MQCHAR4    StrucId;             /* Structure identifier */
  MQLONG     Version;             /* Structure version number */
  MQLONG     ExitId;              /* Type of exit */
  MQLONG     ExitReason;          /* Reason for invoking exit */
  MQLONG     ExitResponse;        /* Response from exit */
  MQLONG     ExitResponse2;       /* Secondary response from exit */
  MQLONG     Feedback;            /* Feedback code (reserved) */
  MQLONG     ExitDataLength;      /* Exit data length */
  PMQCHAR    pExitDataPtr;        /* Exit data */
  MQPTR      pExitUserAreaPtr;    /* Exit user area */
  PMQCD *    ppMQCDArrayPtr;      /* Array of pointers to MQCDs */
  MQLONG     MQCDArrayCount;      /* Number of entries found */
  MQLONG     MaxMQCDVersion;      /* Maximum MQCD version */
};

pQMgrName

Type: PMQCHAR input/output

Name of the queue manager. On input, this parameter is the filter string supplied to the MQCONN API call through the QMgrName parameter. This field might be blank, explicit, or contain certain wildcard characters. The field is changed by the exit. The parameter is NULL when the exit is called with MQXR_TERM.

ppConnectOpts

Type: ppConnectOpts input/output

Options that control the action of MQCONNX. This is a pointer to an MQCNO connection options structure that controls the action of the MQCONN API call. The parameter is NULL when the exit is called with MQXR_TERM. The MQI client always provides an MQCNO structure to the exit, even if it was not originally provided by the application. If an application provides an MQCNO structure, the client makes a duplicate to pass it to the exit where it is modified. The client retains the ownership of the MQCNO. An MQCD referenced through the MQCNO takes precedence over any connection definition provided through the array. The client uses the MQCNO structure to connect to the queue manager and the others are ignored.

pCompCode

Type: PMQLONG input/output

Completion code. Pointer to an MQLONG that receives the exits completion code. It must be one of the following values:

• MQCC_OK - Successful completion
• MQCC_WARNING - Warning (partial completion)
• MQCC_FAILED - Call failed

pReason

Type: PMQLONG input/output

Reason qualifying pCompCode. Pointer to an MQLONG that receives the exit reason code. If the completion code is MQCC_OK, the only valid value is: MQRC_NONE - (0, x'000') No reason to report.

If the completion code is MQCC_FAILED or MQCC_WARNING, the exit function can set the reason code field to any valid MQRC_* value.

Parent topic: Sample program for Connection Endpoint Lookup (CEPL)