The following patterns from this text relate to the Publish/Subscribe pattern:
Event Monitor: Clients use the Event Monitor pattern when there is no discernable event notification mechanism available on a target Web Service or when the available mechanism does not adequately fit the needs of the client.
Observer: The Observer pattern is a simple version of the Publish/ Subscribe pattern. The primary distinction between the Publish/Subscribe pattern and the Observer pattern is in the partitioning of the responsibility for event ownership out of the event service and into a separate publishing entity. The Observer pattern keeps responsibility for event ownership in the Observable object.
Faux Implementation: The Observer and Publish/Subscribe patterns are predicated on having a Web Service implemented by the client set up to receive event notifications. This is a heavy burden to place on potentially resource-constrained application environments. Fortunately, there are other lightweight mechanisms for registering and receiving event notifications, and the Faux Implementation pattern discusses these.
Physical Tiers: The Observer pattern and the Publish/Subscribe pattern, as presented, do not plug into a stand-alone application. This is obviously a problem as the usefulness of the pattern implementations is limited. The Faux Implementation pattern indirectly addresses the problem because the listener becomes a part of the primary program. On the other hand, there are environments where self-encapsulated Web Services are best for observing event notifications. For these environments, the Physical Tiers pattern helps better structure your application for logic reuse.