The DSB implements and provides Web service notifications support as defined in the OASIS WSN specifications. It focuses on Web service Base Notification, Web service Topics and Web service Resources.
The current section describes how it is implemented and how it can be used by clients.
High level Architecture
The WSN library used to provide WSN support is described here. This library provides all the basic features needed to provide a simple and efficient notification support in any runtime. The DSB provides two different WSN implementations, the first one is provided by a DSB component (Petals JBI component) and the second one is a native WSN support inside the DSB kernel.
Implementations
DSB component
A specific DSB component is in charge of the WSN stuff. It embeds the core notification engine and expose interfaces defined in WSN such as:
- Notification producer: Subscribe and GetCurrentMessage operations support. Allows to Subscribe to notifications i.e. a client send a Subscribe message with an endpoint reference interested in receiving some notifications. The notification the subscriber is interested in are classified into a WSN Topic and is specified in a Subscribe message element.
- Notification consumer: Notify operation support. The component can receive notification messages through the Notify operation. When the client sends a notify message on a Topic, the notification engine will select all the subscribers which are interested in receiving messages for the given topic and sends notification message to all interested parties. By using the DSB, you do not have to care about the transport to use to send notifications to subscribers, it is up to the DSB to route the message to the right services with the right transport and protocol.
In all the cases, the DSB component will expose some DSB endpoints. If the DSB is configured to expose DSB endpoints, these endpoints will be exposed as Web services and reachable from external clients.
DSB service
The WSN engine is also embedded as a core kernel service. It means that a DSB developer can use WSN features in his core services to subscribe, notify to others core components.
Note : Under development
Using notifications
In this part, we describe how notifications can be used with SOAP client and services. A really simple sample is composed of several external actors : Some WS notification subscribers which will receive notifications they are interested in; A notification producer which will be in charge of sending notifications to a topic and the DSB which will route notification messages to the right notification subscribers.