Selecting on the content of a message

It is possible to subscribe based on a selection of message payload content (also known as content filtering), but the decision about which messages should be delivered to such a subscription cannot be performed directly by IBM MQ ; instead an extended message selection provider, for example IBM Integration Bus, is required to process the messages.

When an application publishes on a topic string, where one or more subscribers have a selection string selecting on the content of the message, IBM MQ will request that the extended message selection provider parse the publication and inform IBM MQ whether the publication matches the selection criteria specified by each subscriber with a content filter.

If the extended message selection provider determines that the publication matches the subscriber's selection string, the message will continue to be delivered to the subscriber.

If the extended message selection provider determines that the publication does not match, the message is not delivered to the subscriber. This might cause the MQPUT or MQPUT1 call to fail with reason code MQRC_PUBLICATION_FAILURE. If the extended message selection provider is unable to parse the publication, reason code MQRC_CONTENT_ERROR is returned and the MQPUT or MQPUT1 call fails.

If the extended message selection provider is unavailable or is unable to determine whether the subscriber should receive the publication, reason code MQRC_SELECTION_NOT_AVAILABLE is returned and the MQPUT or MQPUT1 call fails.

When a subscription is being created with a content filter and the extended message selection provider is not available, the MQSUB call fails with reason code MQRC_SELECTION_NOT_AVAILABLE. If a subscription with a content filter is being resumed and the extended message selection provider is not available, the MQSUB call returns a warning of MQRC_SELECTION_NOT_AVAILABLE, but the subscription is allowed to be resumed.