org.osgi.service.application

Class ApplicationHandle

java.lang.Object

org.osgi.service.application.ApplicationHandle

public abstract class ApplicationHandle
extends Object

ApplicationHandle is an OSGi service interface which represents an instance of an application. It provides the functionality to query and manipulate the lifecycle state of the represented application instance. It defines constants for the lifecycle states.

Field Summary

Fields

Modifier and Type	Field and Description
static String	APPLICATION_DESCRIPTOR The property key for the pid of the corresponding application descriptor.
static String	APPLICATION_PID The property key for the unique identifier (PID) of the application instance.
static String	APPLICATION_STATE The property key for the state of this application instance.
static String	APPLICATION_SUPPORTS_EXITVALUE The property key for the supports exit value property of this application instance.
static String	RUNNING The application instance is running.
static String	STOPPING The application instance is being stopped.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ApplicationHandle(String instanceId, ApplicationDescriptor descriptor) Application instance identifier is specified by the container when the instance is created.

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy() The application instance's lifecycle state can be influenced by this method.
protected abstract void	destroySpecific() Called by the destroy() method to perform application model specific steps to stop and destroy an application instance safely.
ApplicationDescriptor	getApplicationDescriptor() Retrieves the ApplicationDescriptor to which this ApplicationHandle belongs.
Object	getExitValue(long timeout) Returns the exit value for the application instance.
String	getInstanceId() Returns the unique identifier of this instance.
abstract String	getState() Get the state of the application instance.

Methods inherited from class java.lang.Object

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

Field Detail

APPLICATION_PID

public static final String APPLICATION_PID

The property key for the unique identifier (PID) of the application instance.

See Also:

Constant Field Values

APPLICATION_DESCRIPTOR

public static final String APPLICATION_DESCRIPTOR

The property key for the pid of the corresponding application descriptor.

See Also:

Constant Field Values

APPLICATION_STATE

public static final String APPLICATION_STATE

The property key for the state of this application instance.

See Also:

Constant Field Values

APPLICATION_SUPPORTS_EXITVALUE

public static final String APPLICATION_SUPPORTS_EXITVALUE

The property key for the supports exit value property of this application instance.

Since:

1.1

See Also:

Constant Field Values

RUNNING

public static final String RUNNING

The application instance is running. This is the initial state of a newly created application instance.

See Also:

Constant Field Values

STOPPING

public static final String STOPPING

The application instance is being stopped. This is the state of the application instance during the execution of the destroy() method.

See Also:

Constant Field Values

Constructor Detail

ApplicationHandle

protected ApplicationHandle(String instanceId,
                 ApplicationDescriptor descriptor)

Application instance identifier is specified by the container when the instance is created. The instance identifier must remain static for the lifetime of the instance, it must remain the same even across framework restarts for the same application instance. This value must be the same as the service.pid service property of this application handle.

The instance identifier should follow the following scheme: <application descriptor PID>.<index> where <application descriptor PID> is the PID of the corresponding ApplicationDescriptor and <index> is a unique integer index assigned by the application container. Even after destroying the application index the same index value should not be reused in a reasonably long timeframe.

Parameters:

instanceId - the instance identifier of the represented application instance. It must not be null.

descriptor - the ApplicationDescriptor of the represented application instance. It must not be null.

Throws:

NullPointerException - if any of the arguments is null.

Method Detail

getApplicationDescriptor

public final ApplicationDescriptor getApplicationDescriptor()

Retrieves the ApplicationDescriptor to which this ApplicationHandle belongs.

Returns:

The corresponding ApplicationDescriptor

getState

public abstract String getState()

Get the state of the application instance.

Returns:

the state of the application.

Throws:

IllegalStateException - if the application handle is unregistered

getExitValue

public Object getExitValue(long timeout)
                    throws ApplicationException,
                           InterruptedException

Returns the exit value for the application instance. The timeout specifies how the method behaves when the application has not yet terminated. A negative, zero or positive value may be used.

• negative - The method does not wait for termination. If the application has not terminated then an ApplicationException is thrown.
• zero - The method waits until the application terminates.
• positive - The method waits until the application terminates or the timeout expires. If the timeout expires and the application has not terminated then an ApplicationException is thrown.

The default implementation throws an UnsupportedOperationException. The application model should override this method if exit values are supported.

Parameters:

timeout - The maximum time in milliseconds to wait for the application to timeout.

Returns:

The exit value for the application instance. The value is application specific.

Throws:

UnsupportedOperationException - If the application model does not support exit values.

InterruptedException - If the thread is interrupted while waiting for the timeout.

ApplicationException - If the application has not terminated. The error code will be ApplicationException.APPLICATION_EXITVALUE_NOT_AVAILABLE.

Since:

1.1

getInstanceId

public final String getInstanceId()

Returns the unique identifier of this instance. This value is also available as a service property of this application handle's service.pid.

Returns:

the unique identifier of the instance

destroy

public final void destroy()

The application instance's lifecycle state can be influenced by this method. It lets the application instance perform operations to stop the application safely, e.g. saving its state to a permanent storage.

The method must check if the lifecycle transition is valid; a STOPPING application cannot be stopped. If it is invalid then the method must exit. Otherwise the lifecycle state of the application instance must be set to STOPPING. Then the destroySpecific() method must be called to perform any application model specific steps for safe stopping of the represented application instance.

At the end the ApplicationHandle must be unregistered. This method should free all the resources related to this ApplicationHandle.

When this method is completed the application instance has already made its operations for safe stopping, the ApplicationHandle has been unregistered and its related resources has been freed. Further calls on this application should not be made because they may have unexpected results.

Throws:

SecurityException - if the caller doesn't have "lifecycle" ApplicationAdminPermission for the corresponding application.

IllegalStateException - if the application handle is unregistered

destroySpecific

protected abstract void destroySpecific()

Called by the destroy() method to perform application model specific steps to stop and destroy an application instance safely.

Throws:

IllegalStateException - if the application handle is unregistered