Activatable class provides support for remote
* objects that require persistent access over time and that
* can be activated by the system.
*
* For the constructors and static exportObject methods,
* the stub for a remote object being exported is obtained as described in
* {@link java.rmi.server.UnicastRemoteObject}.
*
* @author Ann Wollrath
* @version 1.34, 03/12/19
* @since 1.2
*/
public abstract class Activatable extends RemoteServer {
/**
* @serial Activation Identifier for this object.
*/
private ActivationID id;
/** indicate compatibility with the Java 2 SDK v1.2 version of class */
private static final long serialVersionUID = -3120617863591563455L;
/**
* Constructor used to register and export the object on a
* specified port (an anonymous port is chosen if port=0) .
*
* A concrete subclass of this class must call this constructor to
* register and export the object during initial construction. As
* a side-effect of activatable object construction, the remote
* object is both "registered" with the activation system and
* "exported" (on an anonymous port if port=0) to the RMI runtime
* so that it is available to accept incoming calls from clients.
*
* @param location the location for classes for this object
* @param data the object's initialization data
* @param port the port on which the object is exported (an anonymous
* port is used if port=0)
* @param restart if true, the object is restarted (reactivated) when
* either the activator is restarted or the object's activation group
* is restarted after an unexpected crash; if false, the object is only
* activated on demand. Specifying restart to be
* true does not force an initial immediate activation of
* a newly registered object; initial activation is lazy.
* @exception ActivationException if object registration fails.
* @exception RemoteException if either of the following fails:
* a) registering the object with the activation system or b) exporting
* the object to the RMI runtime.
* @since 1.2
*/
protected Activatable(String location,
MarshalledObject data,
boolean restart,
int port)
throws ActivationException, RemoteException
{
super();
id = exportObject(this, location, data, restart, port);
}
/**
* Constructor used to register and export the object on a
* specified port (an anonymous port is chosen if port=0) .
*
* A concrete subclass of this class must call this constructor to
* register and export the object during initial construction. As
* a side-effect of activatable object construction, the remote
* object is both "registered" with the activation system and
* "exported" (on an anonymous port if port=0) to the RMI runtime
* so that it is available to accept incoming calls from clients.
*
* @param location the location for classes for this object
* @param data the object's initialization data
* @param restart if true, the object is restarted (reactivated) when
* either the activator is restarted or the object's activation group
* is restarted after an unexpected crash; if false, the object is only
* activated on demand. Specifying restart to be
* true does not force an initial immediate activation of
* a newly registered object; initial activation is lazy.
* @param port the port on which the object is exported (an anonymous
* port is used if port=0)
* @param csf the client-side socket factory for making calls to the
* remote object
* @param ssf the server-side socket factory for receiving remote calls
* @exception ActivationException if object registration fails.
* @exception RemoteException if either of the following fails:
* a) registering the object with the activation system or b) exporting
* the object to the RMI runtime.
* @since 1.2
*/
protected Activatable(String location,
MarshalledObject data,
boolean restart,
int port,
RMIClientSocketFactory csf,
RMIServerSocketFactory ssf)
throws ActivationException, RemoteException
{
super();
id = exportObject(this, location, data, restart, port, csf, ssf);
}
/**
* Constructor used to activate/export the object on a specified
* port. An "activatable" remote object must have a constructor that
* takes two arguments:
ActivationID), and
* MarshalledObject).
*
*
* A concrete subclass of this class must call this constructor when it is
* activated via the two parameter constructor described above. As
* a side-effect of construction, the remote object is "exported"
* to the RMI runtime (on the specified port) and is
* available to accept incoming calls from clients.
*
* @param id activation identifier for the object
* @param port the port number on which the object is exported
* @exception RemoteException if exporting the object to the RMI
* runtime fails
* @since 1.2
*/
protected Activatable(ActivationID id, int port)
throws RemoteException
{
super();
this.id = id;
exportObject(this, id, port);
}
/**
* Constructor used to activate/export the object on a specified
* port. An "activatable" remote object must have a constructor that
* takes two arguments:
ActivationID), and
* MarshalledObject).
*
*
* A concrete subclass of this class must call this constructor when it is
* activated via the two parameter constructor described above. As
* a side-effect of construction, the remote object is "exported"
* to the RMI runtime (on the specified port) and is
* available to accept incoming calls from clients.
*
* @param id activation identifier for the object
* @param port the port number on which the object is exported
* @param csf the client-side socket factory for making calls to the
* remote object
* @param ssf the server-side socket factory for receiving remote calls
* @exception RemoteException if exporting the object to the RMI
* runtime fails
* @since 1.2
*/
protected Activatable(ActivationID id, int port,
RMIClientSocketFactory csf,
RMIServerSocketFactory ssf)
throws RemoteException
{
super();
this.id = id;
exportObject(this, id, port, csf, ssf);
}
/**
* Returns the object's activation identifier. The method is
* protected so that only subclasses can obtain an object's
* identifier.
* @return the object's activation identifier
* @since 1.2
*/
protected ActivationID getID() {
return id;
}
/**
* Register an object descriptor for an activatable remote
* object so that is can be activated on demand.
*
* @param desc the object's descriptor
* @return the stub for the activatable remote object
* @exception UnknownGroupException if group id in desc
* is not registered with the activation system
* @exception ActivationException if activation system is not running
* @exception RemoteException if remote call fails
* @since 1.2
*/
public static Remote register(ActivationDesc desc)
throws UnknownGroupException, ActivationException, RemoteException
{
// register object with activator.
ActivationID id =
ActivationGroup.getSystem().registerObject(desc);
return sun.rmi.server.ActivatableRef.getStub(desc, id);
}
/**
* Informs the system that the object with the corresponding activation
* id is currently inactive. If the object is currently
* active, the object is "unexported" from the RMI runtime (only if
* there are no pending or in-progress calls)
* so the that it can no longer receive incoming calls. This call
* informs this VM's ActivationGroup that the object is inactive,
* that, in turn, informs its ActivationMonitor. If this call
* completes successfully, a subsequent activate request to the activator
* will cause the object to reactivate. The operation may still
* succeed if the object is considered active but has already
* unexported itself.
*
* @param id the object's activation identifier
* @return true if the operation succeeds (the operation will
* succeed if the object in currently known to be active and is
* either already unexported or is currently exported and has no
* pending/executing calls); false is returned if the object has
* pending/executing calls in which case it cannot be deactivated
* @exception UnknownObjectException if object is not known (it may
* already be inactive)
* @exception ActivationException if group is not active
* @exception RemoteException if call informing monitor fails
* @since 1.2
*/
public static boolean inactive(ActivationID id)
throws UnknownObjectException, ActivationException, RemoteException
{
return ActivationGroup.currentGroup().inactiveObject(id);
}
/**
* Revokes previous registration for the activation descriptor
* associated with id. An object can no longer be
* activated via that id.
*
* @param id the object's activation identifier
* @exception UnknownObjectException if object (id) is unknown
* @exception ActivationException if activation system is not running
* @exception RemoteException if remote call to activation system fails
* @since 1.2
*/
public static void unregister(ActivationID id)
throws UnknownObjectException, ActivationException, RemoteException
{
ActivationGroup.getSystem().unregisterObject(id);
}
/**
* This exportObject method may be invoked explicitly
* by an "activatable" object, that does not extend the
* Activatable class, in order to both a) register
* the object's activation descriptor, constructed from the supplied
* location, and data, with
* the activation system (so the object can be activated), and
* b) export the remote object, obj, on a specific
* port (if port=0, then an anonymous port is chosen). Once the
* object is exported, it can receive incoming RMI calls.
*
* This method does not need to be called if obj
* extends Activatable, since the first constructor
* calls this method.
*
* @param obj the object being exported
* @param location the object's code location
* @param data the object's bootstrapping data
* @param restart if true, the object is restarted (reactivated) when
* either the activator is restarted or the object's activation group
* is restarted after an unexpected crash; if false, the object is only
* activated on demand. Specifying restart to be
* true does not force an initial immediate activation of
* a newly registered object; initial activation is lazy.
* @param port the port on which the object is exported (an anonymous
* port is used if port=0)
* @return the activation identifier obtained from registering the
* descriptor, desc, with the activation system
* the wrong group
* @exception ActivationException if activation group is not active
* @exception RemoteException if object registration or export fails
* @since 1.2
*/
public static ActivationID exportObject(Remote obj,
String location,
MarshalledObject data,
boolean restart,
int port)
throws ActivationException, RemoteException
{
ActivationDesc desc = new ActivationDesc(obj.getClass().getName(),
location, data, restart);
ActivationID id = ActivationGroup.getSystem().registerObject(desc);
Remote stub = exportObject(obj, id, port);
ActivationGroup.currentGroup().activeObject(id, obj);
return id;
}
/**
* This exportObject method may be invoked explicitly
* by an "activatable" object, that does not extend the
* Activatable class, in order to both a) register
* the object's activation descriptor, constructed from the supplied
* location, and data, with
* the activation system (so the object can be activated), and
* b) export the remote object, obj, on a specific
* port (if port=0, then an anonymous port is chosen). Once the
* object is exported, it can receive incoming RMI calls.
*
* This method does not need to be called if obj
* extends Activatable, since the first constructor
* calls this method.
*
* @param obj the object being exported
* @param location the object's code location
* @param data the object's bootstrapping data
* @param restart if true, the object is restarted (reactivated) when
* either the activator is restarted or the object's activation group
* is restarted after an unexpected crash; if false, the object is only
* activated on demand. Specifying restart to be
* true does not force an initial immediate activation of
* a newly registered object; initial activation is lazy.
* @param port the port on which the object is exported (an anonymous
* port is used if port=0)
* @param csf the client-side socket factory for making calls to the
* remote object
* @param ssf the server-side socket factory for receiving remote calls
* @return the activation identifier obtained from registering the
* descriptor, desc, with the activation system
* the wrong group
* @exception ActivationException if activation group is not active
* @exception RemoteException if object registration or export fails
* @since 1.2
*/
public static ActivationID exportObject(Remote obj,
String location,
MarshalledObject data,
boolean restart,
int port,
RMIClientSocketFactory csf,
RMIServerSocketFactory ssf)
throws ActivationException, RemoteException
{
ActivationDesc desc = new ActivationDesc(obj.getClass().getName(),
location, data, restart);
ActivationID id = ActivationGroup.getSystem().registerObject(desc);
Remote stub = exportObject(obj, id, port, csf, ssf);
ActivationGroup.currentGroup().activeObject(id, obj);
return id;
}
/**
* Export the activatable remote object to the RMI runtime to make
* the object available to receive incoming calls. The object is
* exported on an anonymous port, if port is zero.
*
* During activation, this exportObject method should
* be invoked explicitly by an "activatable" object, that does not
* extend the Activatable class. There is no need for objects
* that do extend the Activatable class to invoke this
* method directly; this method is called by the second constructor
* above (which a subclass should invoke from its special activation
* constructor).
*
* @return the stub for the activatable remote object
* @param obj the remote object implementation
* @param id the object's activation identifier
* @param port the port on which the object is exported (an anonymous
* port is used if port=0)
* @exception RemoteException if object export fails
* @since 1.2
*/
public static Remote exportObject(Remote obj,
ActivationID id,
int port)
throws RemoteException
{
return exportObject(obj, new ActivatableServerRef(id, port));
}
/**
* Export the activatable remote object to the RMI runtime to make
* the object available to receive incoming calls. The object is
* exported on an anonymous port, if port is zero.
*
* During activation, this exportObject method should
* be invoked explicitly by an "activatable" object, that does not
* extend the Activatable class. There is no need for objects
* that do extend the Activatable class to invoke this
* method directly; this method is called by the second constructor
* above (which a subclass should invoke from its special activation
* constructor).
*
* @return the stub for the activatable remote object
* @param obj the remote object implementation
* @param id the object's activation identifier
* @param port the port on which the object is exported (an anonymous
* port is used if port=0)
* @param csf the client-side socket factory for making calls to the
* remote object
* @param ssf the server-side socket factory for receiving remote calls
* @exception RemoteException if object export fails
* @since 1.2
*/
public static Remote exportObject(Remote obj,
ActivationID id,
int port,
RMIClientSocketFactory csf,
RMIServerSocketFactory ssf)
throws RemoteException
{
return exportObject(obj, new ActivatableServerRef(id, port, csf, ssf));
}
/**
* Remove the remote object, obj, from the RMI runtime. If
* successful, the object can no longer accept incoming RMI calls.
* If the force parameter is true, the object is forcibly unexported
* even if there are pending calls to the remote object or the
* remote object still has calls in progress. If the force
* parameter is false, the object is only unexported if there are
* no pending or in progress calls to the object.
*
* @param obj the remote object to be unexported
* @param force if true, unexports the object even if there are
* pending or in-progress calls; if false, only unexports the object
* if there are no pending or in-progress calls
* @return true if operation is successful, false otherwise
* @exception NoSuchObjectException if the remote object is not
* currently exported
* @since 1.2
*/
public static boolean unexportObject(Remote obj, boolean force)
throws NoSuchObjectException
{
return sun.rmi.transport.ObjectTable.unexportObject(obj, force);
}
/**
* Exports the specified object using the specified server ref.
*/
private static Remote exportObject(Remote obj, ActivatableServerRef sref)
throws RemoteException
{
// if obj extends Activatable, set its ref.
if (obj instanceof Activatable) {
((Activatable) obj).ref = sref;
}
return sref.exportObject(obj, null, false);
}
}