org.dvb.application.plugins

Interface Plugin

public interface Plugin

This interface allows an application or service manager to control the lifecycle of applications being executed by an inter-operable plug-in. It shall be implemented by inter-operable plug-ins and shall be called by implementation of the application manager in an MHP terminal. It shall not be called by MHP applications. The usage model for this interface is the reuse of the javax.tv.xlet.Xlet interface to represent applications in formats other than DVB-J. It is the responsibility of the plug-in to provide implementations of the methods in that interface and to perform the translation between the semantics specified for DVB-J applications and the semantics of the application format which the plug-in supports. The plug-in is initialized by the application manager calling the no-argument constructor of the object implementing this interface. Plug-ins are not expected to perform any time consuming activities or hold any scarce resources in this call.

Method Summary

Methods

Modifier and Type	Method and Description
Xlet	initApplication(AppAttributes app) Request the plug-in to prepare for executing an instance of an application in a format which it supports.
Xlet	initApplication(InnerApplication app) Request the plug-in to prepare for executing an instance of an application in a format which it supports.If the application cannot be prepared then null shall be returned.
boolean	initPlugin() initialize the plug-in.
boolean	isSupported(AppAttributes app) Test whether this plug-in is able to support a particular application.
void	terminatePlugin() Terminate the plug-in.

Method Detail

isSupported

boolean isSupported(AppAttributes app)

Test whether this plug-in is able to support a particular application. This method shall work regardless of whether the plug-in has been initialized or not.

Parameters:

app - an instance of AppAttributes for the application which is to be started.

Returns:

true if the plug-in can support this application otherwise false

initApplication

Xlet initApplication(AppAttributes app)
                     throws InvalidApplicationException

Request the plug-in to prepare for executing an instance of an application in a format which it supports. If the application cannot be prepared then null shall be returned. While the plug-in is in the terminated state then this method shall always return null. The application shall only be considered to be started when the application manager calls the methods on the Xlet interface returned by this method.

Parameters:

app - an instance of AppAttributes for the application which is to be started.

Returns:

an object implementing the Xlet interface or null if the application cannot be started.

Throws:

InvalidApplicationException - if the application to be started is not valid for this plug-in

initPlugin

boolean initPlugin()

initialize the plug-in. Any time consuming initializations should be performed during this method call. This method shall be called after the no-argument constructor of the object implementing this interface and before any calls to the startApplication. It may also be called after a call to terminatePlugin if a plug-in was not removed from the virtual machine where it was executing. The behaviour of an application manager should a plug-in fail to initialize is intentionally unspecified.

Returns:

true if the plug-in initialized successfully otherwise false

terminatePlugin

void terminatePlugin()

Terminate the plug-in. This method shall only be called after all applications being executed by this plug-in have been terminated. The implementation of this method shall release all resources held by the plug-in. Once this method has returned, the plug-in shall either be unloaded from the virtual machine where it was executing or the initPlugin method shall be called again to put the plug-in again in an initialized condition. A plug-in may not refuse to terminate and throwing a runtime exception or error from this method shall result in the plug-in being removed from the virtual machine where it was executing.

initApplication

Xlet initApplication(InnerApplication app)
                     throws InvalidApplicationException

Request the plug-in to prepare for executing an instance of an application in a format which it supports.If the application cannot be prepared then null shall be returned. While the plug-in is in the terminated state then this method shall always return null. The application shall only be considered to be started when the application manager calls the methods on the Xlet interface returned by this method.

Parameters:

app - an instance of InnerApplication for the application which is to be started

Returns:

an object implementing the Xlet interface or null if the application cannot be started

Throws:

InvalidApplicationException - if the application to be started is not valid for this plug-in