Application compatibility and interoperability with later versions of IBM MQ

IBM MQ applications run against later versions of a queue manager without recoding, recompiling, or relinking. We can connect an application that is built against libraries shipped with an earlier version of IBM MQ to a queue manager running at a later version of IBM MQ.

If you upgrade a queue manager to a later version, existing applications built against its earlier version work without change. Exceptions are noted in Changes that affect migration. Likewise applications connected to the IBM MQ Client, run against later versions of the client without recoding, recompiling, or relinking. We can deploy client applications built against earlier versions of the IBM MQ Client libraries to connect using later versions of the libraries.

All the following four cases are supported. The first two cases rely on the compatibility of later version of IBM MQ with applications built against earlier versions. The last two cases rely on the interoperability between all versions of IBM MQ.

1. Running an IBM MQ server application, built with a later version of IBM MQ, connecting to a queue manager running on a server with an earlier version of IBM MQ installed.
2. Running an IBM MQ client application, built with a later version of IBM MQ, on a client platform with an earlier client installation, connecting to a queue manager running on a server with a later version of IBM MQ installed.
3. Running an IBM MQ client application, built with a later version of IBM MQ, on a client platform with the later client installation, connecting to a queue manager running on a server with an earlier version of IBM MQ installed.
4. Exchanging messages between an IBM MQ client or server application, connected to a queue manager running on a server with a later version of IBM MQ installed, with applications connected to a queue manager running on a server with an earlier version of IBM MQ installed.

We might change the operating environment as a prerequisite of migrating to a new level of queue manager. The operating environment changes, rather than changes in IBM MQ itself, might require application change, recompilation, or relinking. Sometime the operating environment change affects only the development environment, and the operating environment supports applications built at an earlier level. In which case, you might be able to run existing applications built at the older level of the operating environment. We might not be able to build any new applications until the operating environment is upgraded.

In the future, after you have migrated queue managers and clients to the latest release level, consider changing the applications to take advantage of new capabilities.

z/OS application stubs

The stub modules that are listed are link-edited with applications and exits.

• CSQASTUB
• CSQBRSSI
• CSQBRSTB
• CSQBSTUB
• CSQCSTUB
• CSQQSTUB
• CSQXSTUB

To take advantage of the new APIs introduced in Version 7.0, for example MQSUB and MQCB, we must link-edit the application with stubs shipped with Version 7.0 or later, for an LE program, the sidedeck, see Building z/OS batch applications using Language Environment . Such an application will not run on an earlier version of the queue manager.

Parent topic: Coexistence, compatibility, and interoperability