java.rmi.server
Class UnicastRemoteObject

java.lang.Object
  java.rmi.server.RemoteObject
      java.rmi.server.RemoteServer
          java.rmi.server.UnicastRemoteObject

All Implemented Interfaces:

Remote , Serializable

Direct Known Subclasses:

ActivationGroup

public class UnicastRemoteObject

extends RemoteServer

Used for exporting a remote object with JRMP and obtaining a stub that communicates to the remote object. The UnicastRemoteObject class defines a non-replicated remote object whose references are valid only while the server process is alive. The UnicastRemoteObject class provides support for point-to-point active object references (invocations, parameters, and results) using TCP streams.

For the constructors and static exportObject methods below, the stub for a remote object being exported is obtained as follows: Objects that require remote behavior should extend RemoteObject, typically via UnicastRemoteObject. If UnicastRemoteObject is not extended, the implementation class must then assume the responsibility for the correct semantics of the hashCode, equals, and toString methods inherited from the Object class, so that they behave appropriately for remote objects.

• If the remote object is exported using the UnicastRemoteObject.exportObject(Remote)
  • A "root class" is determined as follows: if the remote object's class directly implements an interface that extends Remote , then the remote object's class is the root class; otherwise, the root class is the most derived superclass of the remote object's class that directly implements an interface that extends Remote.
  • The name of the stub class to load is determined by concatenating the binary name of the root class with the suffix "_Stub".
  • The stub class is loaded by name using the class loader of the root class. The stub class must extend RemoteStub and must have a public constructor that has one parameter, of type RemoteRef .
  • Finally, an instance of the stub class is constructed with a RemoteRef
• If the appropriate stub class could not be found, or the stub class could not be loaded, or a problem occurs creating the stub instance, a StubNotFoundException

• For all other means of exporting:
  • If the remote object's stub class (as defined above) could not be loaded or the system property java.rmi.server.ignoreStubClasses is set to "true" (case insensitive), a Proxy
    • The proxy's class is defined by the class loader of the remote object's class.
    • The proxy implements all the remote interfaces implemented by the remote object's class.
    • The proxy's invocation handler is a RemoteObjectInvocationHandler instance constructed with a RemoteRef .
    • If the proxy could not be created, a StubNotFoundException

  • Otherwise, an instance of the remote object's stub class (as described above) is used as the stub.

Since:

JDK1.1

See Also:

Serialized Form RemoteServer , RemoteObject , Serialized Form

Field Summary

 

Fields inherited from class java.rmi.server. RemoteObject
ref

 

Constructor Summary
protected	UnicastRemoteObject ()           Creates and exports a new UnicastRemoteObject object using an anonymous port.
protected	UnicastRemoteObject (int port)           Creates and exports a new UnicastRemoteObject object using the particular supplied port.
protected	UnicastRemoteObject (int port, RMIClientSocketFactory  csf, RMIServerSocketFactory  ssf)           Creates and exports a new UnicastRemoteObject object using the particular supplied port and socket factories.

 

Method Summary
Object	clone ()           Returns a clone of the remote object that is distinct from the original.
static  RemoteStub	exportObject ( Remote  obj)           Exports the remote object to make it available to receive incoming calls using an anonymous port.
static  Remote	exportObject ( Remote  obj, int port)           Exports the remote object to make it available to receive incoming calls, using the particular supplied port.
static  Remote	exportObject ( Remote  obj, int port, RMIClientSocketFactory  csf, RMIServerSocketFactory  ssf)           Exports the remote object to make it available to receive incoming calls, using a transport specified by the given socket factory.
static boolean	unexportObject ( Remote  obj, boolean force)           Removes the remote object, obj, from the RMI runtime.

 

Methods inherited from class java.rmi.server. RemoteServer
getClientHost , getLog , setLog

 

Methods inherited from class java.rmi.server. RemoteObject
equals , getRef , hashCode , toString , toStub

 

Methods inherited from class java.lang. Object
finalize , getClass , notify , notifyAll , wait , wait , wait

 

Constructor Detail

UnicastRemoteObject

protected UnicastRemoteObject()
                       throws RemoteException

Creates and exports a new UnicastRemoteObject object using an anonymous port.

Throws:

RemoteException - if failed to export object

Since:

JDK1.1

UnicastRemoteObject

protected UnicastRemoteObject(int port)
                       throws RemoteException

Creates and exports a new UnicastRemoteObject object using the particular supplied port.

Parameters:

port - the port number on which the remote object receives calls (if port is zero, an anonymous port is chosen)

Throws:

RemoteException - if failed to export object

Since:

1.2

UnicastRemoteObject

protected UnicastRemoteObject(int port,
                              RMIClientSocketFactory csf,
                              RMIServerSocketFactory ssf)
                       throws RemoteException

Creates and exports a new UnicastRemoteObject object using the particular supplied port and socket factories.

Parameters:

port - the port number on which the remote object receives calls (if port is zero, an anonymous port is chosen)

csf - the client-side socket factory for making calls to the remote object

ssf - the server-side socket factory for receiving remote calls

Throws:

RemoteException - if failed to export object

Since:

1.2

clone

public Object clone()
             throws CloneNotSupportedException

Returns a clone of the remote object that is distinct from the original.

Overrides:

clone in class Object

Returns:

the new remote object

Throws:

CloneNotSupportedException - if clone failed due to a RemoteException.

Since:

JDK1.1

See Also:

Cloneable

exportObject

public static RemoteStub exportObject(Remote obj)
                               throws RemoteException

Exports the remote object to make it available to receive incoming calls using an anonymous port.

Parameters:

obj - the remote object to be exported

Returns:

remote object stub

Throws:

RemoteException - if export fails

Since:

JDK1.1

exportObject

public static Remote exportObject(Remote obj,
                                  int port)
                           throws RemoteException

Exports the remote object to make it available to receive incoming calls, using the particular supplied port.

Parameters:

obj - the remote object to be exported

port - the port to export the object on

Returns:

remote object stub

Throws:

RemoteException - if export fails

Since:

1.2

exportObject

public static Remote exportObject(Remote obj,
                                  int port,
                                  RMIClientSocketFactory csf,
                                  RMIServerSocketFactory ssf)
                           throws RemoteException

Exports the remote object to make it available to receive incoming calls, using a transport specified by the given socket factory.

Parameters:

obj - the remote object to be exported

port - the port to export the object on

csf - the client-side socket factory for making calls to the remote object

ssf - the server-side socket factory for receiving remote calls

Returns:

remote object stub

Throws:

RemoteException - if export fails

Since:

1.2

unexportObject

public static boolean unexportObject(Remote obj,
                                     boolean force)
                              throws NoSuchObjectException

Removes 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.

Parameters:

obj - the remote object to be unexported

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

Returns:

true if operation is successful, false otherwise

Throws:

NoSuchObjectException - if the remote object is not currently exported

Since:

1.2