MQI client: Client Channel Definition Table (CCDT)

We can connect an IBM MQ MQI client application to any level of queue manager. If a client uses CCDT to connect to a queue manager, the CCDT can be at a version greater than, less than, or equal to that of the client.

Version of originating queue manager for a CCDT

In earlier releases before IBM MQ Version 9.0, clients can use a CCDT built by the same or earlier version queue manager, but there was previously a restriction on clients using a CCDT built by a later version queue manager. However, this restriction is removed in Version 9.0.

From Version 9.0, if a client uses a CCDT, it can use a CCDT built by a later version queue manager, as well as a CCDT built by the same, or earlier version of queue manager.

The same restriction on the use of CCDTs originating from later version queue managers is also removed in Version 8.0, Version 7.5, and Version 7.1 by APARs IT10863 and IT11547. for more information, see the technote MQ 7.x, MQ 8.0 and MQ 9.0 compatibility with previous versions - including usage of CCDT files, JMS .bindings, SSL/TLS.

Common migration scenarios

If, for example, you upgrade a queue manager from an earlier release to a later release, and you do not create new CCDTs for its clients, the clients connect to the later release queue manager without any changes being required. Client behavior might change as a result of changes to the queue manager.

Another common migration scenario is to update some queue managers and some clients to a later release, leaving other queue managers and clients at the earlier release. In this scenario, you want to update the CCDT for the IBM MQ MQI clients that are connected to the later release queue managers to that later release so that those clients can fully use the function in the later release. The new clients can also connect to the earlier release queue managers. Existing clients connect to queue managers in both releases. In order that the clients in the later release can use the new function in that release, you must deploy a CCDT that has been generated by a queue manager in that new release. Clients in the earlier release can continue to use the CCDT for that earlier release. Both sets of clients can connect to both sets of queue managers, regardless of the CCDT they are using.

IBM MQ MQI clients

If the client is an IBM MQ MQI client, the version of the IBM MQ MQI client libraries that are linked to by the client must be the same or greater than the version of the queue manager that was used to build the CCDT.

To upgrade an IBM MQ MQI client from an earlier release to use a CCDT for a later release, you must upgrade the IBM MQ MQI client installation to the later release. Unless you decide to do so for other reasons, do not rebuild the client application.

Java or JMS client

If the client is a Java or JMS client, then the client must be built with versions of the IBM MQ JAR files that are the same or greater than the queue manager that was used to build the CCDT.

To upgrade a Java or JMS client from an earlier release to use a CCDT for a later release, redeploy the IBM MQ JAR files to the client workstation. You do not need to rebuild the Java or JMS client with the new JAR files.