Package jade.wrapper.gateway

Class JadeGateway

java.lang.Object

jade.wrapper.gateway.JadeGateway

public class JadeGateway
extends Object

This class provides a simple yet powerful gateway between some non-JADE code and a JADE based multi agent system. It is particularly suited to be used inside a Servlet or a JSP. The class maintains an internal JADE agent (of class GatewayAgent that acts as entry point in the JADE based system. The activation/termination of this agent (and its underlying container) are completely managed by the JadeGateway class and developers do not need to care about them. The suggested way of using the JadeGateway class is creating proper behaviours that perform the commands that the external system must issue to the JADE based system and pass them as parameters to the execute() method. When the execute() method returns the internal agent of the JadeGateway as completely executed the behaviour and outputs (if any) can be retrieved from the behaviour object using ad hoc methods as exemplified below.
DoSomeActionBehaviour b = new DoSomeActionBehaviour(....);
JadeGateway.execute(b); // At this point b has been completely executed --> we can get results
result = b.getResult();

When using the JadeGateway class as described above null should be passed as first parameter to the init() method.

Alternatively programmers can

• create an application-specific class that extends GatewayAgent, that redefine its method processCommand and that is the agent responsible for processing all command-requests
• initialize this JadeGateway by calling its method init with the name of the class of the application-specific agent
• finally, in order to request the processing of a Command, you must call the method JadeGateway.execute(Object command). This method will cause the callback of the method processCommand of the application-specific agent. The method execute will return only after the method GatewayAgent.releaseCommand(command) has been called by your application-specific agent.

NOT available in MIDP

Version:

$Date$ $Revision$

Author:

Fabio Bellifemine, Telecom Italia LAB

Field Summary

Fields

Modifier and Type	Field	Description
static String	SPLIT_CONTAINER

Method Summary

Modifier and Type	Method	Description
static void	addListener(GatewayListener l)
static void	checkJADE()	This method checks if both the container, and the agent, are up and running.
static void	execute(Object command)	execute a command.
static void	execute(Object command, long timeout)	Execute a command specifying a timeout.
static DynamicJadeGateway	getDefaultGateway()
static String	getProfileProperty(String key, String defaultValue)	Searches for the property with the specified key in the JADE Platform Profile.
static void	init(String agentClassName, Properties jadeProfile)
static void	init(String agentClassName, Object[] agentArgs, Properties jadeProfile)	Initialize this gateway by passing the proper configuration parameters
static boolean	isGatewayActive()	Return the state of JadeGateway
void	removeListener(GatewayListener l)
static void	shutdown()	Kill the JADE Container in case it is running.

Methods inherited from class java.lang.Object

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

Field Detail

SPLIT_CONTAINER

public static final String SPLIT_CONTAINER

See Also:

Constant Field Values

Method Detail

getProfileProperty

public static final String getProfileProperty(String key,
                                              String defaultValue)

Searches for the property with the specified key in the JADE Platform Profile. The method returns the default value argument if the property is not found.

Parameters:

key - - the property key.

defaultValue - - a default value

Returns:

the value with the specified key value

See Also:

Properties.getProperty(String, String)

execute

public static final void execute(Object command)
                          throws StaleProxyException,
                                 ControllerException,
                                 InterruptedException

execute a command. This method first check if the executor Agent is alive (if not it creates container and agent), then it forwards the execution request to the agent, finally it blocks waiting until the command has been executed (i.e. the method releaseCommand is called by the executor agent)

Throws:

StaleProxyException - if the method was not able to execute the Command

ControllerException

InterruptedException

See Also:

AgentController.putO2AObject(Object, boolean)

execute

public static final void execute(Object command,
                                 long timeout)
                          throws StaleProxyException,
                                 ControllerException,
                                 InterruptedException

Execute a command specifying a timeout. This method first check if the executor Agent is alive (if not it creates container and agent), then it forwards the execution request to the agent, finally it blocks waiting until the command has been executed. In case the command is a behaviour this method blocks until the behaviour has been completely executed.

Throws:

InterruptedException - if the timeout expires or the Thread executing this method is interrupted.

StaleProxyException - if the method was not able to execute the Command

ControllerException

See Also:

AgentController.putO2AObject(Object, boolean)

checkJADE

public static final void checkJADE()
                            throws StaleProxyException,
                                   ControllerException

This method checks if both the container, and the agent, are up and running. If not, then the method is responsible for renewing myContainer. Normally programmers do not need to invoke this method explicitly.

Throws:

StaleProxyException

ControllerException

init

public static final void init(String agentClassName,
                              Object[] agentArgs,
                              Properties jadeProfile)

Initialize this gateway by passing the proper configuration parameters

Parameters:

agentClassName - is the fully-qualified class name of the JadeGateway internal agent. If null is passed the default class will be used.

agentArgs - is the list of agent arguments

jadeProfile - the properties that contain all parameters for running JADE (see jade.core.Profile). Typically these properties will have to be read from a JADE configuration file. If jadeProfile is null, then a JADE container attaching to a main on the local host is launched

init

public static final void init(String agentClassName,
                              Properties jadeProfile)

shutdown

public static final void shutdown()

Kill the JADE Container in case it is running.

isGatewayActive

public static final boolean isGatewayActive()

Return the state of JadeGateway

Returns:

true if the container and the gateway agent are active, false otherwise

addListener

public static void addListener(GatewayListener l)

removeListener

public void removeListener(GatewayListener l)

getDefaultGateway

public static final DynamicJadeGateway getDefaultGateway()