Accessing client-connection channel definitions

We can make the client channel definition table (CCDT) available to client applications by copying or sharing it, then specify its location and name on the client computer. From Version 9.0, IBM MQ also provides the ability to locate a client channel definition table (CCDT) through a URL.


Before you begin

You have defined the client-connection channels that you need.

On z/OS®, we have created a CCDT.

On Multiplatforms, the CCDT is automatically created and updated.


About this task

For a client application to use the client channel definition table (CCDT), you must make the CCDT available to it and specify its location and name. There are several ways of doing this:

  • We can copy the CCDT to the client computer.
  • We can copy the CCDT to a location shared by more than one client.
  • We can make the CCDT accessible to the client as a shared file, while it remains located on the server.

From Version 9.0, IBM MQ, native (C/C++, COBOL and RPG) and unmanaged .NET applications can pull the CCDT hosted in a central location from a URL, whether that be a local file, ftp or http resource.


Procedure

  1. Make the CCDT available to the client applications in one of the following ways:
    1. Optional: Copy the CCDT to the client computer.
    2. Optional: Copy the CCDT to a location shared by more than one client.
    3. Optional: Leave the CCDT on the server but make it shareable by the client.
    4. Optional: Define a local file, ftp or http URL for a CCDT hosted in a central location so that native (C/C++, COBOL and RPG) and unmanaged .NET applications can pull the CCDT from this URL.
    Whichever location you choose for the CCDT, the location must be secure to prevent unauthorized changes to the channels.
  2. On the client, specify the location and name of the file containing the CCDT in one of three ways:
    1. Optional: Use the CHANNELS stanza of the client configuration file. For more information, see CHANNELS stanza of the client configuration file.
    2. Optional: Use the environment variables MQCHLLIB and MQCHLTAB. For example, we can set the environment variables by typing:

      • On HP Integrity NonStop Server, and UNIX and Linux systems: 
        export MQCHLLIB= MQ_INSTALLATION_PATH/qmgrs/ QUEUEMANAGERNAME /@ipcc
export MQCHLTAB=AMQCLCHL.TAB
      • On IBM i: 
        ADDENVVAR ENVVAR(MQCHLLIB) VALUE('/QIBM/UserData/mqm/qmgrs/QUEUEMANAGERNAME/@ipcc')
ADDENVVAR ENVVAR(MQCHLTAB) VALUE(AMQCLCHL.TAB)

      where MQ_INSTALLATION_PATH represents the high-level directory in which IBM MQ is installed.

    3. Optional: On Windows only, use the setmqscp control command to publish the client-connection channel definitions in Active Directory.
    4. Provide the location of a centrally hosted CCDT through a URL, either by programming using MQCNO, using environment variables, or using mqclient.ini file stanzas. For more information, see Locations for the client channel definition table and Web addressable access to the client channel definition table.
    If the MQSERVER environment variable is set, an IBM MQ client uses the client-connection channel definition specified by MQSERVER in preference to any definitions in the client channel definition table.