The Activatable.java Java example source code
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package java.rmi.activation;
import java.rmi.MarshalledObject;
import java.rmi.NoSuchObjectException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.activation.UnknownGroupException;
import java.rmi.activation.UnknownObjectException;
import java.rmi.server.RMIClientSocketFactory;
import java.rmi.server.RMIServerSocketFactory;
import java.rmi.server.RemoteServer;
import sun.rmi.server.ActivatableServerRef;
/**
* The <code>Activatable class provides support for remote
* objects that require persistent access over time and that
* can be activated by the system.
*
* <p>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}.
*
* <p>An attempt to serialize explicitly an instance of this class will
* fail.
*
* @author Ann Wollrath
* @since 1.2
* @serial exclude
*/
public abstract class Activatable extends RemoteServer {
private ActivationID id;
/** indicate compatibility with the Java 2 SDK v1.2 version of class */
private static final long serialVersionUID = -3120617863591563455L;
/**
* Constructs an activatable remote object by registering
* an activation descriptor (with the specified location, data, and
* restart mode) for this object, and exporting the object with the
* specified port.
*
* <p>Note: Using the Activatable
* constructors that both register and export an activatable remote
* object is strongly discouraged because the actions of registering
* and exporting the remote object are <i>not guaranteed to be
* atomic. Instead, an application should register an activation
* descriptor and export a remote object separately, so that exceptions
* can be handled properly.
*
* <p>This method invokes the {@link
* #exportObject(Remote,String,MarshalledObject,boolean,int)
* exportObject} method with this object, and the specified location,
* data, restart mode, and port. Subsequent calls to {@link #getID}
* will return the activation identifier returned from the call to
* <code>exportObject.
*
* @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 <code>restart to be
* <code>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.
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation.
* @since 1.2
**/
protected Activatable(String location,
MarshalledObject<?> data,
boolean restart,
int port)
throws ActivationException, RemoteException
{
super();
id = exportObject(this, location, data, restart, port);
}
/**
* Constructs an activatable remote object by registering
* an activation descriptor (with the specified location, data, and
* restart mode) for this object, and exporting the object with the
* specified port, and specified client and server socket factories.
*
* <p>Note: Using the Activatable
* constructors that both register and export an activatable remote
* object is strongly discouraged because the actions of registering
* and exporting the remote object are <i>not guaranteed to be
* atomic. Instead, an application should register an activation
* descriptor and export a remote object separately, so that exceptions
* can be handled properly.
*
* <p>This method invokes the {@link
* #exportObject(Remote,String,MarshalledObject,boolean,int,RMIClientSocketFactory,RMIServerSocketFactory)
* exportObject} method with this object, and the specified location,
* data, restart mode, port, and client and server socket factories.
* Subsequent calls to {@link #getID} will return the activation
* identifier returned from the call to <code>exportObject.
*
* @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 <code>restart to be
* <code>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.
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation.
* @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: <ul>
* <li>the object's activation identifier (ActivationID), and
* <li>the object's initialization data (a MarshalledObject).
* </ul>
*
* A concrete subclass of this class must call this constructor when it is
* <i>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 <code>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
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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: <ul>
* <li>the object's activation identifier (ActivationID), and
* <li>the object's initialization data (a MarshalledObject).
* </ul>
*
* A concrete subclass of this class must call this constructor when it is
* <i>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 <code>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
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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 <code>desc
* is not registered with the activation system
* @exception ActivationException if activation system is not running
* @exception RemoteException if remote call fails
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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
* <code>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
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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 <code>id. An object can no longer be
* activated via that <code>id.
*
* @param id the object's activation identifier
* @exception UnknownObjectException if object (<code>id) is unknown
* @exception ActivationException if activation system is not running
* @exception RemoteException if remote call to activation system fails
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @since 1.2
*/
public static void unregister(ActivationID id)
throws UnknownObjectException, ActivationException, RemoteException
{
ActivationGroup.getSystem().unregisterObject(id);
}
/**
* Registers an activation descriptor (with the specified location,
* data, and restart mode) for the specified object, and exports that
* object with the specified port.
*
* <p>Note: Using this method (as well as the
* <code>Activatable constructors that both register and export
* an activatable remote object) is strongly discouraged because the
* actions of registering and exporting the remote object are
* <i>not guaranteed to be atomic. Instead, an application should
* register an activation descriptor and export a remote object
* separately, so that exceptions can be handled properly.
*
* <p>This method invokes the {@link
* #exportObject(Remote,String,MarshalledObject,boolean,int,RMIClientSocketFactory,RMIServerSocketFactory)
* exportObject} method with the specified object, location, data,
* restart mode, and port, and <code>null for both client and
* server socket factories, and then returns the resulting activation
* identifier.
*
* @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 <code>restart to be
* <code>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, <code>desc, with the activation system
* the wrong group
* @exception ActivationException if activation group is not active
* @exception RemoteException if object registration or export fails
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @since 1.2
**/
public static ActivationID exportObject(Remote obj,
String location,
MarshalledObject<?> data,
boolean restart,
int port)
throws ActivationException, RemoteException
{
return exportObject(obj, location, data, restart, port, null, null);
}
/**
* Registers an activation descriptor (with the specified location,
* data, and restart mode) for the specified object, and exports that
* object with the specified port, and the specified client and server
* socket factories.
*
* <p>Note: Using this method (as well as the
* <code>Activatable constructors that both register and export
* an activatable remote object) is strongly discouraged because the
* actions of registering and exporting the remote object are
* <i>not guaranteed to be atomic. Instead, an application should
* register an activation descriptor and export a remote object
* separately, so that exceptions can be handled properly.
*
* <p>This method first registers an activation descriptor for the
* specified object as follows. It obtains the activation system by
* invoking the method {@link ActivationGroup#getSystem
* ActivationGroup.getSystem}. This method then obtains an {@link
* ActivationID} for the object by invoking the activation system's
* {@link ActivationSystem#registerObject registerObject} method with
* an {@link ActivationDesc} constructed with the specified object's
* class name, and the specified location, data, and restart mode. If
* an exception occurs obtaining the activation system or registering
* the activation descriptor, that exception is thrown to the caller.
*
* <p>Next, this method exports the object by invoking the {@link
* #exportObject(Remote,ActivationID,int,RMIClientSocketFactory,RMIServerSocketFactory)
* exportObject} method with the specified remote object, the
* activation identifier obtained from registration, the specified
* port, and the specified client and server socket factories. If an
* exception occurs exporting the object, this method attempts to
* unregister the activation identifier (obtained from registration) by
* invoking the activation system's {@link
* ActivationSystem#unregisterObject unregisterObject} method with the
* activation identifier. If an exception occurs unregistering the
* identifier, that exception is ignored, and the original exception
* that occurred exporting the object is thrown to the caller.
*
* <p>Finally, this method invokes the {@link
* ActivationGroup#activeObject activeObject} method on the activation
* group in this VM with the activation identifier and the specified
* remote object, and returns the activation identifier to the caller.
*
* @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 <code>restart to be
* <code>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 with the activation system
* @exception ActivationException if activation group is not active
* @exception RemoteException if object registration or export fails
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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);
/*
* Register descriptor.
*/
ActivationSystem system = ActivationGroup.getSystem();
ActivationID id = system.registerObject(desc);
/*
* Export object.
*/
try {
exportObject(obj, id, port, csf, ssf);
} catch (RemoteException e) {
/*
* Attempt to unregister activation descriptor because export
* failed and register/export should be atomic (see 4323621).
*/
try {
system.unregisterObject(id);
} catch (Exception ex) {
}
/*
* Report original exception.
*/
throw e;
}
/*
* This call can't fail (it is a local call, and the only possible
* exception, thrown if the group is inactive, will not be thrown
* because the group is not inactive).
*/
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 <code>port is zero.
*
* During activation, this <code>exportObject method should
* be invoked explicitly by an "activatable" object, that does not
* extend the <code>Activatable class. There is no need for objects
* that do extend the <code>Activatable class to invoke this
* method directly because the object is exported during construction.
*
* @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
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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 <code>port is zero.
*
* During activation, this <code>exportObject method should
* be invoked explicitly by an "activatable" object, that does not
* extend the <code>Activatable class. There is no need for objects
* that do extend the <code>Activatable class to invoke this
* method directly because the object is exported during construction.
*
* @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
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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
* @exception UnsupportedOperationException if and only if activation is
* not supported by this implementation
* @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);
}
}
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