Subscription scope

The scope of a subscription controls whether a subscription on one queue manager receives publications that are published on another queue manager in a publish/subscribe cluster or hierarchy, or only publications from local publishers.

Limiting the subscription scope to a queue manager stops proxy subscriptions from being forwarded to other queue managers in the publish/subscribe topology. This reduces inter-queue manager publish/subscribe messaging traffic.

When you use a publish/subscribe cluster, the scope of subscriptions is primarily controlled by the definition of clustered topic objects at certain points in the topic tree. Subscription scope must be set to allow the flow of proxy subscriptions to other queue managers in the cluster. You should only restrict subscription scope for a clustered topic when you need fine-grain control of specific topics on certain queue managers.

When you use a publish/subscribe hierarchy, the scope of subscriptions is primarily controlled by this attribute in combination with the publication scope attribute.

The SUBSCOPE topic attribute is used to determine the scope of subscriptions made to a specific topic. You can set the attribute to one of the following values:

QMGR

A subscription receives only local publications, and proxy subscriptions are not propagated to remote queue managers.

ALL

A proxy subscription is propagated to remote queue managers in a publish/subscribe cluster or hierarchy, and the subscriber receives local and remote publications.

ASPARENT

Use the SUBSCOPE setting of the parent topic in the topic tree.

When subscription scope for a topic is set to ALL, either directly or resolved through ASPARENT, individual subscriptions to that topic can restrict their scope to QMGR by specifying MQSO_SCOPE_QMGR when creating the subscription. A subscription to a topic that has a scope of QMGR cannot widen the scope to ALL.