001/* RemoteRef.java --
002   Copyright (c) 1996, 1997, 1998, 1999, 2004, 2006  
003   Free Software Foundation, Inc.
004
005This file is part of GNU Classpath.
006
007GNU Classpath is free software; you can redistribute it and/or modify
008it under the terms of the GNU General Public License as published by
009the Free Software Foundation; either version 2, or (at your option)
010any later version.
011 
012GNU Classpath is distributed in the hope that it will be useful, but
013WITHOUT ANY WARRANTY; without even the implied warranty of
014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015General Public License for more details.
016
017You should have received a copy of the GNU General Public License
018along with GNU Classpath; see the file COPYING.  If not, write to the
019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02002110-1301 USA.
021
022Linking this library statically or dynamically with other modules is
023making a combined work based on this library.  Thus, the terms and
024conditions of the GNU General Public License cover the whole
025combination.
026
027As a special exception, the copyright holders of this library give you
028permission to link this library with independent modules to produce an
029executable, regardless of the license terms of these independent
030modules, and to copy and distribute the resulting executable under
031terms of your choice, provided that you also meet, for each linked
032independent module, the terms and conditions of the license of that
033module.  An independent module is a module which is not derived from
034or based on this library.  If you modify this library, you may extend
035this exception to your version of the library, but you are not
036obligated to do so.  If you do not wish to do so, delete this
037exception statement from your version. */
038
039
040package java.rmi.server;
041
042import java.io.Externalizable;
043import java.io.ObjectOutput;
044import java.lang.reflect.Method;
045import java.rmi.Remote;
046import java.rmi.RemoteException;
047
048/**
049 * Represents a handler to the remote object. Each instance of the
050 * {@link RemoteStub} contains such handler and uses it to invoke remote
051 * methods via {@link #invoke(Remote, Method, Object[], long)}.
052 */
053public interface RemoteRef extends Externalizable
054{
055  /**
056   *  Indicates compatibility with JDK 1.1.*
057   */
058  long serialVersionUID = 3632638527362204081L;
059  
060  /**
061   * For binary compatibility with the JDK, the string "sun.rmi.server".
062   * Not actually used for anything.
063   */
064  String packagePrefix = "sun.rmi.server";
065
066  /**
067   * @deprecated use {@link #invoke(Remote, Method, Object[], long)} instead.
068   */
069  void invoke (RemoteCall call) throws Exception;
070  
071  /**
072   * Invoke a method. This method either returns the result of remote invocation
073   * or throws RemoteException if the remote call failed. Other exceptions may
074   * be thrown if some problem has occured in the application level.
075   * 
076   * @param obj the object, containing the remote reference (for instance,
077   *          remote stub, generated by rmic).
078   * @param method the method to invoke
079   * @param params the method parameters
080   * @param methodHash a persistent hash code that can be used to represent a
081   *          method
082   * @return the result of the remote invocation
083   * @throws RemoteException if the remote call has failed
084   * @throws Exception if one is raised at the application level
085   */
086  Object invoke (Remote obj, Method method, Object[] params, long methodHash)
087    throws Exception;
088  
089  /**
090   * @deprecated use {@link #invoke(Remote, Method, Object[], long)} instead.
091   */
092  RemoteCall newCall (RemoteObject obj, Operation[] op, int opnum, long hash)
093    throws RemoteException;
094
095  /**
096   * @deprecated use {@link #invoke(Remote, Method, Object[], long)} instead.
097   */
098  void done (RemoteCall call) throws RemoteException;
099  
100  /**
101   * Compare two remote objects for equality. The references are equal if
102   * they point to the same remote object.
103   * 
104   * @param ref the reference to compare.
105   * 
106   * @return true if this and passed references both point to the same remote
107   * object, false otherwise.
108   */
109  boolean remoteEquals (RemoteRef ref);
110  
111  /**
112   * Get the hashcode for a remote object. Two remote object stubs, referring
113   * to the same remote object, have the same hash code.
114   * 
115   * @return the hashcode of the remote object
116   */
117  int remoteHashCode();
118  
119  
120  /**
121   * Returns the class name of the reference type that must be written to the
122   * given stream. When writing, this returned name is passed first, and
123   * the reference.writeExternal(out) writes the reference specific data.
124   * 
125   * @param out the stream, where the data must be written 
126   * 
127   * @return the class name. 
128   */
129  String getRefClass (ObjectOutput out);
130  
131  /**
132   * Get the string representation of this remote reference.
133   * 
134   * @return the string representation.
135   */
136  String remoteToString();
137}