IBM WebSphere MQ XA support and Tuxedo

IBM® WebSphere® MQ on Windows,UNIX and Linux® systems can block Tuxedo-coordinated XA applications indefinitely in xa_start.

Note: This topic is also available in IBM MQ Version 8.0 and later versions. However, you cannot switch to a later version using the Change version list box. To go to the topic in a later version, edit the version number in the URL box in your browser.

This can occur only when two or more processes coordinated by Tuxedo in a single global transaction attempt to access IBM WebSphere MQ using the same transaction branch ID (XID). If Tuxedo gives each process in the global transaction a different XID to use with IBM WebSphere MQ, this cannot occur.

To avoid the problem, configure each application in Tuxedo that accesses IBM WebSphere MQ under a single global transaction ID (gtrid), within its own Tuxedo server group. Processes in the same server group use the same XID when accessing resource managers on behalf of a single gtrid, and are therefore vulnerable to blocking in xa_start in IBM WebSphere MQ. Processes in different server groups use separate XIDs when accessing resource managers and so do not have to serialize their transaction work in IBM WebSphere MQ.