net.dpml.metro.runtime
Class DefaultStateMachine

java.lang.Object
  net.dpml.metro.runtime.DefaultStateMachine

All Implemented Interfaces:

StateMachine, EventHandler

public class DefaultStateMachine
extends Object
implements StateMachine, EventHandler

Default state-machine implementation.

Version:

1.0.4

Author:

Digital Product Meta Library

Field Summary

static String

PROPERTY_NAME Constant name used to reference a state change in a property event.

Constructor Summary

DefaultStateMachine(EventQueue queue, Logger logger, State state)
Creation of a new state machine using a state graph.

Method Summary

void	addStateListener(StateListener listener) Add a state change listener to the state machine.
State	apply(String name, Object object) Apply a named transition to the target object.
void	dispose() Dispose of the state machine.
Object	execute(String name, Object object, Object[] args) Execute a named operation on the supplied object.
EventListener[]	getEventListeners() Return the assigned state event listeners.
Action	getInitializationAction() Locate and return the most immediate initialization action defined relative to the current state.
Interface[]	getInterfaces() Return all of the available interfaces relative to the current state.
Operation[]	getOperations() Return all of the available operations relative to the current state.
State	getState() Return the current state.
Action	getTerminationAction() Locate and return the most immediate termination action defined relative to the current state.
Transition[]	getTransitions() Return all of the available transitions relative to the current state.
State	initialize(Object object) Invoke initialization of the supplied object using the initialization action declared under the current state path.
Object	invoke(Object object, String method, Object[] args) Invoke a management method on the supplied object.
boolean	isActive() Returns the active status of the state machine.
void	processEvent(EventObject event) Process the supplied event.
void	removeStateListener(StateListener listener) Remove a state listener from the state machine.
State	terminate(Object object) Invoke termination of the supplied object using the termination action declared under the current state path.
static void	validate(State state) Validate the state integrity.

Methods inherited from class java.lang.Object

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

Field Detail

PROPERTY_NAME

public static final String PROPERTY_NAME

Constant name used to reference a state change in a property event.

See Also:

Constant Field Values

Constructor Detail

DefaultStateMachine

public DefaultStateMachine(EventQueue queue,
                           Logger logger,
                           State state)
                    throws RemoteException

Creation of a new state machine using a state graph.

Parameters:

queue - the event queue

logger - the logging channel

state - the state graph

Throws:

RemoteException - if RMI exception occurs

Method Detail

validate

public static void validate(State state)

Validate the state integrity.

Parameters:

state - the state to validate

addStateListener

public void addStateListener(StateListener listener)

Add a state change listener to the state machine.

Specified by:

addStateListener in interface StateMachine

Parameters:

listener - the state listener

removeStateListener

public void removeStateListener(StateListener listener)

Remove a state listener from the state machine.

Specified by:

removeStateListener in interface StateMachine

Parameters:

listener - the state listener

getEventListeners

public EventListener[] getEventListeners()

Return the assigned state event listeners.

Specified by:

getEventListeners in interface EventHandler

Returns:

the event listeners

processEvent

public void processEvent(EventObject event)

Process the supplied event.

Specified by:

processEvent in interface EventHandler

Parameters:

event - the event to process

getState

public State getState()

Return the current state.

Specified by:

getState in interface StateMachine

Returns:

the current state

getInitializationAction

public Action getInitializationAction()

Locate and return the most immediate initialization action defined relative to the current state. If an action is located within the current state it will be return otherwise the search will continue up the state graph until either an action is located or no further parent state is available in which case a null value is returned.

Returns:

the initialization action or null if no action declared

getTerminationAction

public Action getTerminationAction()

Locate and return the most immediate termination action defined relative to the current state. If an action is located within the current state it will be return otherwise the search will continue up the state graph until either an action is located or no further parent state is available in which case a null value is returned.

Returns:

the termination action or null if no action declared

initialize

public State initialize(Object object)
                 throws InvocationTargetException

Invoke initialization of the supplied object using the initialization action declared under the current state path.

Specified by:

initialize in interface StateMachine

Parameters:

object - the object to initialize

Returns:

the state established as a sidee effect of the initialization

Throws:

InvocationTargetException - if an invocation error occurs as a result of initialization

execute

public Object execute(String name,
                      Object object,
                      Object[] args)
               throws UnknownOperationException,
                      InvocationTargetException

Execute a named operation on the supplied object.

Specified by:

execute in interface StateMachine

Parameters:

name - an operation name

object - the target object

args - operation arguments

Returns:

the result of operation invocation

Throws:

UnknownOperationException - if the operation is unknown

InvocationTargetException - if an invocation error occurs as a result of operation execution

invoke

public Object invoke(Object object,
                     String method,
                     Object[] args)
              throws UnknownOperationException,
                     InvocationTargetException,
                     IllegalStateException

Invoke a management method on the supplied object.

Specified by:

invoke in interface StateMachine

Parameters:

object - the target object

method - the method name

args - method parameter arguments

Returns:

the return value

Throws:

IllegalStateException - if the method is recognized but not available

UnknownOperationException - if the operation is unknown

InvocationTargetException - if an invocation error occurs as a result of operation execution

apply

public State apply(String name,
                   Object object)
            throws UnknownTransitionException,
                   InvocationTargetException

Apply a named transition to the target object.

Specified by:

apply in interface StateMachine

Parameters:

name - the transition name

object - the object against which any transition handler action are to be applied

Returns:

the state established by the application of the transition

Throws:

UnknownTransitionException - if the transition is unknown

InvocationTargetException - if an invocation error occurs as a result of transition invocation

getTransitions

public Transition[] getTransitions()

Return all of the available transitions relative to the current state.

Specified by:

getTransitions in interface StateMachine

Returns:

the available transitions

getOperations

public Operation[] getOperations()

Return all of the available operations relative to the current state.

Specified by:

getOperations in interface StateMachine

Returns:

the available operations

getInterfaces

public Interface[] getInterfaces()

Return all of the available interfaces relative to the current state.

Specified by:

getInterfaces in interface StateMachine

Returns:

the available interface declarations

terminate

public State terminate(Object object)

Invoke termination of the supplied object using the termination action declared under the current state path.

Specified by:

terminate in interface StateMachine

Parameters:

object - the object to terminate

Returns:

the state established as a side-effect of the termination

isActive

public boolean isActive()

Returns the active status of the state machine.

Specified by:

isActive in interface StateMachine

Returns:

TRUE if the state machine has invoked initialization and termination has not been performed otherwise FALSE

dispose

public void dispose()

Dispose of the state machine.