Everyone is interested in this area. See Next Steps discussion. So we wanted to see how the OMG Event Domain Management spec approached the problem. OMG Event Service was a low level means of providing asynchronous computing. OMG Notification Service added filtering and content based routing, QoS on events and event channels, and structured event types.
Supports push and pull models as well as proxies.
Both are publish and subscribe. Semantics is at least once. Java supports queue-based. In Telcom applications, you get complexes of events - really a partitioned, federated collection of notification service instances. Also handles propagation of subscription information.