8.3. Notifications in GT4

GT4 currently doesn't implement the WS-Notifications family of specifications completely. For example, no support for brokered notification is included. However, GT4 does allow us to perform effective topic-based notification. One of the more interesting parts of the GT4 implementation of WS-Notifications is that it will allow us to effortlessly expose a resource property as a topic, triggering a notification each time the value of the RP changes. We will also be able to define our own topics, which need not trigger a notification every single time the value of an RP changes. In the remainder of the chapter, we will see how we can add both types of topics to our service.