RemoteRef


1   /*
2    * @(#)RemoteRef.java   1.23 04/05/18
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.rmi.server;
9   
10  import java.rmi.*;
11  
12  /**
13   * <code>RemoteRef</code> represents the handle for a remote object. A
14   * <code>RemoteStub</code> uses a remote reference to carry out a
15   * remote method invocation to a remote object.
16   *
17   * @version 1.23, 05/18/04
18   * @author  Ann Wollrath
19   * @since   JDK1.1
20   * @see     java.rmi.server.RemoteStub
21   */
22  public interface RemoteRef extends java.io.Externalizable   {
23  
24      /** indicate compatibility with JDK 1.1.x version of class. */
25      static final long serialVersionUID = 3632638527362204081L;
26  
27      /**
28       * Initialize the server package prefix: assumes that the
29       * implementation of server ref classes (e.g., UnicastRef,
30       * UnicastServerRef) are located in the package defined by the
31       * prefix.
32       */
33      final static String   packagePrefix = "sun.rmi.server";
34  
35      /**
36       * Invoke a method. This form of delegating method invocation
37       * to the reference allows the reference to take care of
38       * setting up the connection to the remote host, marshaling
39       * some representation for the method and parameters, then
40       * communicating the method invocation to the remote host.
41       * This method either returns the result of a method invocation
42       * on the remote object which resides on the remote host or
43       * throws a RemoteException if the call failed or an
44       * application-level exception if the remote invocation throws
45       * an exception.
46       *    
47       * @param obj the object that contains the RemoteRef (e.g., the
48       *            RemoteStub for the object.
49       * @param method the method to be invoked
50       * @param params the parameter list
51       * @param opnum  a hash that may be used to represent the method
52       * @return result of remote method invocation
53       * @exception Exception if any exception occurs during remote method
54       * invocation
55       * @since 1.2
56       */
57      Object   invoke(Remote obj,
58            java.lang.reflect.Method   method,
59            Object  [] params,
60            long opnum)
61      throws Exception  ;
62      
63      /**
64       * Creates an appropriate call object for a new remote method
65       * invocation on this object.  Passing operation array and index,
66       * allows the stubs generator to assign the operation indexes and
67       * interpret them. The remote reference may need the operation to
68       * encode in the call.
69       *
70       * @since JDK1.1
71       * @deprecated 1.2 style stubs no longer use this method. Instead of
72       * using a sequence of method calls on the stub's the remote reference
73       * (<code>newCall</code>, <code>invoke</code>, and <code>done</code>), a
74       * stub uses a single method, <code>invoke(Remote, Method, Object[],
75       * int)</code>, on the remote reference to carry out parameter
76       * marshalling, remote method executing and unmarshalling of the return
77       * value.
78       *
79       * @param obj remote stub through which to make call
80       * @param op array of stub operations
81       * @param opnum operation number
82       * @param hash stub/skeleton interface hash
83       * @return call object representing remote call
84       * @throws RemoteException if failed to initiate new remote call
85       * @see #invoke(Remote,java.lang.reflect.Method,Object[],long)
86       */
87      @Deprecated  
88      RemoteCall   newCall(RemoteObject   obj, Operation  [] op, int opnum, long hash) 
89      throws RemoteException;
90      
91      /**
92       * Executes the remote call.
93       * 
94       * Invoke will raise any "user" exceptions which
95       * should pass through and not be caught by the stub.  If any
96       * exception is raised during the remote invocation, invoke should
97       * take care of cleaning up the connection before raising the
98       * "user" or remote exception.
99       *
100      * @since JDK1.1
101      * @deprecated 1.2 style stubs no longer use this method. Instead of
102      * using a sequence of method calls to the remote reference
103      * (<code>newCall</code>, <code>invoke</code>, and <code>done</code>), a
104      * stub uses a single method, <code>invoke(Remote, Method, Object[],
105      * int)</code>, on the remote reference to carry out parameter
106      * marshalling, remote method executing and unmarshalling of the return
107      * value.
108      *
109      * @param call object representing remote call
110      * @throws Exception if any exception occurs during remote method
111      * @see #invoke(Remote,java.lang.reflect.Method,Object[],long)
112      */
113     @Deprecated  
114     void invoke(RemoteCall   call) throws Exception  ;
115     
116     /**
117      * Allows the remote reference to clean up (or reuse) the connection.
118      * Done should only be called if the invoke returns successfully
119      * (non-exceptionally) to the stub.
120      *
121      * @since JDK1.1
122      * @deprecated 1.2 style stubs no longer use this method. Instead of
123      * using a sequence of method calls to the remote reference
124      * (<code>newCall</code>, <code>invoke</code>, and <code>done</code>), a
125      * stub uses a single method, <code>invoke(Remote, Method, Object[],
126      * int)</code>, on the remote reference to carry out parameter
127      * marshalling, remote method executing and unmarshalling of the return
128      * value.
129      *
130      * @param call object representing remote call
131      * @throws RemoteException if remote error occurs during call cleanup
132      * @see #invoke(Remote,java.lang.reflect.Method,Object[],long)
133      */
134     @Deprecated  
135     void done(RemoteCall   call) throws RemoteException;
136     
137     /**
138      * Returns the class name of the ref type to be serialized onto
139      * the stream 'out'.
140      * @param out the output stream to which the reference will be serialized
141      * @return the class name (without package qualification) of the reference
142      * type
143      * @since JDK1.1
144      */
145     String   getRefClass(java.io.ObjectOutput   out);
146     
147     /**
148      * Returns a hashcode for a remote object.  Two remote object stubs
149      * that refer to the same remote object will have the same hash code
150      * (in order to support remote objects as keys in hash tables).
151      *
152      * @return remote object hashcode
153      * @see     java.util.Hashtable
154      * @since JDK1.1
155      */
156     int remoteHashCode();
157 
158     /**
159      * Compares two remote objects for equality.
160      * Returns a boolean that indicates whether this remote object is
161      * equivalent to the specified Object. This method is used when a
162      * remote object is stored in a hashtable.
163      * @param   obj the Object to compare with
164      * @return  true if these Objects are equal; false otherwise.
165      * @see     java.util.Hashtable
166      * @since JDK1.1
167      */
168     boolean remoteEquals(RemoteRef   obj);
169 
170     /**
171      * Returns a String that represents the reference of this remote
172      * object.
173      * @return string representing remote object reference
174      * @since JDK1.1
175      */
176     String   remoteToString();
177     
178 }
179
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