net.sourceforge.esw.service
Class AService

java.lang.Object
  |
  +--net.sourceforge.esw.util.SupportObject
        |
        +--net.sourceforge.esw.service.AService

All Implemented Interfaces:

IService, ISupportObject, java.io.Serializable

Direct Known Subclasses:

ADefaultService

public abstract class AService

extends SupportObject

implements IService

Base class for Service implementors to extend.

Describes the base abilities of a Service within the Services Framework.

IService instances maintain a priority property that indicates which service should be used first if there are more than one type of an IService implementor started within the enterprise. Changing the priority fires the appropriate PropertyChangeEvent. The predefined priorities used by the service framework are:

• PRIMARY
• SECONDARY
• TERTIARY
• UNAVAILABLE

All IService instances have push and pull elements to help verify livliness of the service. Those elements can be exercised using the ping() and getHeartbeatGenerator() methods.

Each service has the ability to be started and stopped. Starting or stopping an IService instance also starts/stops the IHeartbeatGenerator instance, and fires the approprate PropertyChangeEvent.

An IService instance may be started and alive, yet not be sane. The final check for the valid livliness of an IService instance is the call to isSane(). As this may cause some computation to be performed on the service, use of this method should be restricted to need only.

See Also:

IHeartbeatGenerator, ISupportObject, Serialized Form

Field Summary

protected boolean	bStarted States whether this AService instance is started.
protected IHeartbeatGenerator	heartbeatGenerator The IHeartbeatGenerator instance for pushing this AService instances livliness.
protected int	priority The priority of this AService instance.

Fields inherited from class net.sourceforge.esw.util.SupportObject

id, properties, propertyChildren, propertyListeners, vetoableChildren, vetoableListeners

Fields inherited from interface net.sourceforge.esw.service.IService

PRIMARY, SECONDARY, TERTIARY, UNAVAILABLE

Constructor Summary

AService()
Creates a new AService.

AService(java.lang.Object aId)
Creates a new AService with the specified id.

Method Summary

void	die() Requests that this IService instance to kill itself.
IHeartbeatGenerator	getHeartbeatGenerator() Returns the IHeartbeatGenterator instance for this IService instance.
int	getPriority() Returns the priority of this IService instance.
boolean	isSane() States whether this IService instance is sane.
boolean	isStarted() States whether this IService instance is started.
boolean	ping() Allows checking of connection to this IService instance.
void	setPriority(int aPriority) Sets the priority of this IService instance.
void	start() Starts this IService instance and allows it to serve client requests.
void	stop() Stops this IService instance and keeps it from serving client requests.

Methods inherited from class net.sourceforge.esw.util.SupportObject

addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, firePropertyChange, firePropertyChange, fireVetoableChange, fireVetoableChange, getID, getProperty, getPropertySize, propertyKeys, removeProperty, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener, setID, setProperty

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sourceforge.esw.util.ISupportObject

addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, firePropertyChange, firePropertyChange, fireVetoableChange, fireVetoableChange, getID, getProperty, getPropertySize, propertyKeys, removeProperty, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener, setID, setProperty

Field Detail

heartbeatGenerator

protected IHeartbeatGenerator heartbeatGenerator

The IHeartbeatGenerator instance for pushing this AService instances livliness.

bStarted

protected boolean bStarted

States whether this AService instance is started.

priority

protected int priority

The priority of this AService instance.

Constructor Detail

AService

public AService()

Creates a new AService.

AService

public AService(java.lang.Object aId)

Creates a new AService with the specified id. This id should be the name of the service, not the unique id of the service.

Parameters:

aID - the name of this AService

Method Detail

start

public void start()

Starts this IService instance and allows it to serve client requests.

The service should be registered with a lookup server regardless of whether it is started or not.

Fires an IServiceResources.START_PROPERTY property change event.

Specified by:

start in interface IService

See Also:

stop()

stop

public void stop()

Stops this IService instance and keeps it from serving client requests.

The service should be registered with a lookup server regardless of whether it is stopped or not.

Fires an IServiceResources.STOP_PROPERTY property change event.

Specified by:

stop in interface IService

See Also:

start()

isStarted

public boolean isStarted()

States whether this IService instance is started.

Specified by:

isStarted in interface IService

Returns:

whether this IService instance is started.

getHeartbeatGenerator

public IHeartbeatGenerator getHeartbeatGenerator()

Returns the IHeartbeatGenterator instance for this IService instance. The IHeartbeatGenerator is responsible for pushing telemetry for guaranteeing liveliness of this IService instance.

Specified by:

getHeartbeatGenerator in interface IService

Returns:

the IHeartbeatGenerator instance for this IService instance.

isSane

public boolean isSane()

States whether this IService instance is sane. Sanity can only be determined by an IService implementor.

This default implementation always returns true. Implementors should change this to do some useful sanity checking.

Specified by:

isSane in interface IService

Returns:

whether this IService instance is sane.

die

public void die()

Requests that this IService instance to kill itself.

This default implementation calls System.exit(0).

Fires an IServiceResources.DIE_PROPERTY property change event.

Specified by:

die in interface IService

ping

public boolean ping()

Allows checking of connection to this IService instance. This is the pull element of verifying service liveliness.

Specified by:

ping in interface IService

Returns:

true if the Service is still accessable. Otherwise, an exception is normally thrown on the client.

setPriority

public void setPriority(int aPriority)

Sets the priority of this IService instance. Priority determines which IService instance should be used in an enterprise where multiple instances of the same IService implementor should be used.

Fires an IServiceResources.PRIORITY_PROPERTY property change event.

Specified by:

setPriority in interface IService

Parameters:

aPriority - the new priority of this IService instance.

getPriority

public int getPriority()

Returns the priority of this IService instance. Priority determines which IService instance should be used in an enterprise where multiple instances of the same IService implementor should be used.

Specified by:

getPriority in interface IService

Returns:

the priority of this IService instance.