Distributed publish/subscribe system queue errors

Errors can occur when distributed publish/subscribe queue manager queues are unavailable. This affects the propagation of subscription knowledge across the publish/subscribe network, and publication to subscriptions on remote queue managers.

If the fan-out request queue SYSTEM.INTER.QMGR.FANREQ is unavailable, the creation of a subscription might generate an error, and error messages will be written to the queue manager error log when proxy subscriptions need to be delivered to directly connected queue managers.

If the hierarchy relationship state queue SYSTEM.HIERARCHY.STATE is unavailable, an error message is written to the queue manager error log and the publish/subscribe engine is put into COMPAT mode. To view the publish/subscribe mode, use the command DISPLAY QMGR PSMODE.

If any other of the SYSTEM.INTER.QMGR queues are unavailable, an error message is written to the queue manager error log and, although function is not disabled, it is likely that publish/subscribe messages will build up on queues on this or remote queue managers.

If the publish/subscribe system queue or required transmission queue to a parent, child or publish/subscribe cluster queue manager is unavailable, the following outcomes occur:

• The publications are not delivered, and a publishing application might receive an error. For details of when the publishing application receives an error, see the following parameters of the DEFINE TOPIC command: PMSGDLV , NPMSGDLV , and USEDLQ .
• Received inter-queue manager publications are backed out to the input queue, and subsequently re-attempted. If the backout threshold is reached, the undelivered publications are placed on the dead letter queue. The queue manager error log will contain details of the problem.
• An undelivered proxy subscription is backed out to the fanout request queue, and subsequently attempted again. If the backout threshold is reached, the undelivered proxy subscription is not delivered to any connected queue manager, and is placed on the dead letter queue. The queue manager error log will contain details of the problem, including details of any necessary corrective administrative action required.
• Hierarchy relationship protocol messages fail, and the connection status is flagged as ERROR. To view the connection status, use the command DISPLAY PUBSUB.