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Writing exits and installable services on UNIX, Linux and Windows

We can write and compile exits without linking to any IBM MQ libraries on UNIX, Linux and Windows.


About this task

This topic applies to UNIX, Linux, and Windows systems only. For details on writing exits and installable services for other platforms, see the relevant platform specific topics.

If IBM MQ is installed in a non-default location you must write and compile your exits without linking to any IBM MQ libraries.

We can write and compile exits on UNIX, Linux, and Windows systems without linking any of these IBM MQ libraries:

Existing exits that are linked to these libraries continue to work, providing that on UNIX and Linux systems IBM MQ is installed in the default location.


Procedure

  1. Include the cmqec.h header file. Including this header file automatically includes the cmqc.h, cmqxc.h and cmqzc.h header files.
  2. Write the exit so that MQI and DCI calls are made through the MQIEP structure. For more information about the MQIEP structure, see MQIEP structure.

    • Installable services

      • Use the Hconfig parameter to point to the MQZEP call.
      • You must check that the first 4 bytes of Hconfig match the StrucId of the MQIEP structure before using the Hconfig parameter.
      • For more information about writing installable service components, see MQIEP.
    • API exits

      • Use the Hconfig parameter to point to the MQXEP call.
      • You must check that the first 4 bytes of Hconfig match the StrucId of the MQIEP structure before using the Hconfig parameter.
      • For more information about writing API exits, see Writing API exits.
    • Channel exits

      • Use the pEntryPoints parameter of the MQCXP structure to point to MQI and DCI calls.
      • You must check that the MQCXP version number is at version 8 or higher before using pEntryPoints.
      • For more information about writing channel exits, see Writing channel-exit programs.
    • Data conversion exits

    • Pre-connect exits

    • Publish exits

      • Use the pEntryPoints parameter of the MQPSXP structure to point to MQI and DCI calls.
      • You must check that the MQPSXP version number is at version 2 or higher before using pEntryPoints.
      • For more information about writing publish exits, see Writing and compiling publish exits.
    • Cluster workload exits

      • Use the pEntryPoints parameter of the MQWXP structure to point to MQXCLWLN calls.
      • You must check that the MQWXP version number is at version 4 or higher before using pEntryPoints.
      • For more information about writing cluster workload exits, see Writing and compiling cluster workload exits.
    For example, in a channel exit calling MQPUT: 
    pChannelExitParms -> pEntryPoints -> MQPUT_Call(pChannelExitParms -> Hconn,
                                                Hobj,
                                                &md,
                                                &pmo, 
                                                messlen,
                                                buffer,
                                                &CompCode,
                                                &Reason);
    Further examples can be seen in the Use the IBM MQ sample procedural programs.
  3. Compile the exit:

  4. Put the exit in one of the following places:

    • A path of your choosing that you fully qualify when configuring the exit
    • The default exit path, in a specific installation directory. For example, MQ_DATA_PATH/exits/installation2.
    • The default exit path The default exit path is MQ_DATA_PATH/exits for 32 bit exits, and MQ_DATA_PATH/exits64 for 64 bit exits. We can change these paths in the qm.ini or mqclient.ini file. For more information, see Exit path. On Windows and Linux, we can use the IBM MQ Explorer to change the path:
      1. Right click the queue manager name
      2. Click Properties...
      3. Click Exits
      4. In the exits default path field, specify the path name of the directory that holds the exit program.

    If an exit is placed in both a specific installation directory and in the default path directory, the specific installation directory exit is used by the installation of IBM MQ named in the path. For example, the exit is placed in /exits/installation2 and in /exits, but not in /exits/installation1. The IBM MQ installation installation2 uses the exit from /exits/installation2. The IBM MQ installation installation1 uses the exit from the /exits directory.

  5. If necessary, configure the exit: