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Multiple installations and application programs

When a local application connects to a queue manager, the application needs to load the libraries from the installation associated with the queue manager. Multiple installations introduce some complexity.


Use the setmqm command

When we use setmqm to change the installation associated with a queue manager, the libraries that need to be loaded change.

When an application connects to multiple queue managers owned by different installations, multiple sets of libraries need to be loaded. Note: If you link our applications to IBM® WebSphere MQ Version 7.1 or later libraries, the applications automatically load the appropriate libraries when the application connects to a queue manager.


Loading IBM MQ libraries in a multi-version environment

How libraries are located depends upon your environment.

If IBM WebSphere MQ Version 7.1 or later is installed in the default location, existing applications continue to work as before. Otherwise, you might need to rebuild the application or change your configuration.

The order in which libraries are searched, depends upon the platform you are using:

Table 1. Options for loading libraries
Platform Option Benefits Drawbacks
UNIX Set/change the embedded runtime search path (RPath) The path is explicit in the way the application is built You need to recompile and link

If you move IBM MQ, you must change RPath

UNIX Set LD_LIBRARY_PATH or equivalent using setmqenv Overrides RPath

No changes to existing applications

Easy to change if you move IBM MQ

Depends on environment variables

Possible impacts on other applications

Windows Set PATH using setmqenv No changes to existing applications

Easy to change if you move IBM MQ

Depends on environment variables

Possible impacts on other applications

All Set the primary installation to IBM WebSphere MQ Version 7.1 or later No changes to existing applications

Easy to change the primary installation

Similar behavior to previous versions of IBM MQ

While IBM WebSphere MQ Version 7.0.1 is installed, we cannot make IBM WebSphere MQ Version 7.1 the primary installation

UNIX: Relies on /usr/lib in the default search path