Package jade.core

Class FEService

java.lang.Object

jade.core.FEService

Direct Known Subclasses:

TopicManagementFEService

public abstract class FEService
extends Object

JADE kernel services providing a service-helper and wishing this helper to be available in the split execution mode too, need to provide a FEService class. When starting a split container the services option works exactly as when starting a normal container, but the indicated classes must be concrete implementations of the FEService abstract class.
It should be noticed that a Front-End service is only intended to provide access to the service helper and not to actually implement full service functionality

Author:

Giovanni Caire - Telecom Italia

Constructor Summary

Constructors

Constructor	Description
FEService()

Method Summary

Modifier and Type	Method	Description
String	getBEServiceClassName()	In many cases for the Front-End service to work properly it is necessary that the real service (or possibly a modified version of it) is active in the Back-End.
abstract ServiceHelper	getHelper(Agent a)	Subclasses must implement this method to return the helper for accessing this service.
abstract String	getName()	Subclasses must implement this method to return the name of this service.
protected Object	invoke(String actor, String methodName, Object[] methodParams)	Subclasses can use this method to forward a front-end side invocation of a service helper method to the back-end.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FEService

public FEService()

Method Detail

getName

public abstract String getName()

Subclasses must implement this method to return the name of this service. Such name must be specified by an agent in the getHelper() method when retrieving the helper for this service.

Returns:

The name of this service

getBEServiceClassName

public String getBEServiceClassName()

In many cases for the Front-End service to work properly it is necessary that the real service (or possibly a modified version of it) is active in the Back-End. In such cases subclasses may redefine this method to return the fully qualified name of the class implementing the back-end side counterpart of this service.

Returns:

The fully qualified name of the class implementing the back-end side counterpart of this service

getHelper

public abstract ServiceHelper getHelper(Agent a)

Subclasses must implement this method to return the helper for accessing this service.

Parameters:

a - The agent which the helper is requested for.

Returns:

The ServiceHelper to be used by the agent.

invoke

protected Object invoke(String actor,
                        String methodName,
                        Object[] methodParams)
                 throws NotFoundException,
                        ServiceException,
                        IMTPException

Subclasses can use this method to forward a front-end side invocation of a service helper method to the back-end. Said A the agent invoking the method, the effect is that the same method will be invoked, with the passed parameters, on the service helper object associated to the agent image representing A in the back-end. In case the back-end side service helper method requires parameters different than those passed in the methodParams argument, a suitable "BackEnd Codec" class must be provided to perform the necessary conversions. Such class must implement the BECodec interface and must be called "BECodec"

Parameters:

actor - The name of the agent invoking the service helper method

methodName - The name of the invoked method

methodParams - The parameters to be passed to the back-end

Returns:

The result of the back-end side service helper method invocation possibly encoded by the BackEnd Codec (if any)

Throws:

NotFoundException - If the invoking agent is not found in the back-end

ServiceException - If an error occurs at the service level

IMTPException - If a communication error occurs