Architecture

The AFWS consists of a few specialized XCAT components that provide the functionality to create and monitor applications. All the components have secure ports that provide for authentication and authorization of every method call.

Application Factory Service Component(AFSC)

This is a generic service, that uses both the static and dynamic information about an application to launch any type of application. When the AFSC comes up, generates a WSDL describing itself and binds the WSDL to a registry to facilitate discovery of this service. The AFSC does not maintain no state information about any of the application instances and is stateless.

This component has a provides port, createApplication which has a method that a client can invoke to launch the application instance.

The service can be made specific to a genre of applications by providing it with the application static information at the time of launching the service. Clients that contact a specialized factory, provide only the dynamic information to the factory.

The Application Instance

A specialized component, Application Coordinator Component(ACC), is instantiated with each application instance. This component maintains all state information about the application instance and acts as a gateway to it. All application level method calls, which are really pseudo method calls, are made on the ACC, which in turn invokes the relevant methods on the components that make up this application.

The AFWS instantiates the ACC and passes all required instance information. The ACC then sets up the application instance. To get details about the component set-up on the particular host machine, the ACC extracts it from the XML or contacts the directory service specified in the XML.

The ACC has another port with methods that the end user can invoke to obtain state information about the application instance, ping it, kill it and so on.

A WSDL describing the application ports and ACC ports is generated and bound to a registry. This WSDL describes all the ports that need to be exported by the application and also the service ports of the ACC. Hence a client can parse this WSDL to access any of the ACC services or the application services.

The following diagram depicts the flow.


Steps involved


[ IU CS ] [ Extreme! Computing ] [ XGWS ] Application Factory Service

Last modified: Tue Jul 9 10:56:28 EST 2002