J2EE Event Dispatcher Background

Introduction    Implementing    Background

The J2eeEventDispatcher replaces the standard Websydian dispatcher when deploying a Websydian Java DWA application in a J2EE environment.

The difference between a Java DWA implementation and a J2EE implementation lies in how the deployed Websydian servlet interfaces with the Websydian application.

In a traditional DWA implementation the Websydian application is launched as a server which awaits requests on a TCP port (Application Service Listener). The servlet (Relay Service) then forwards requests to the Websydian application over the network using TCP/IP.

In a Websydian J2EE implementation the Websydian application is deployed with the J2eeProxy servlet. The servlet then launches the Websydian application using a Plex Java function call.

The difference in the two implementations is reflected in the Websydian objects that have to be implemented to successfully deploy the application.

Both the J2EE and the Java DWA implementation requires a run-time servlet. For DWA it is a Relay Service that relays the request to the Application Service Listener over a TCP/IP connection. The J2EE servlet is called a Websydian J2EE Proxy and forwards the request to the EventDispatcher using a local Plex java call.

In the DWA implementation the Application Service Listener is implemented using the ApplicationServiceListener function. The Application Service Listener is pre-started and then awaits connections from the Relay Service. When a connection is established the EventDispathcer function is called. More information about DWA can be found here.

In J2EE the EventDispatcher is implemented by inheriting from the J2eeEventDispatcher function.

The differences between Java DWA and J2EE are summarized in the table below.

For more information about the Websydian J2EE architecture please look here.