Skeleton


1   /***
2    * Fractal RMI: a binder for remote method calls between Fractal components.
3    * Copyright (C) 2003 France Telecom R&D
4    *
5    * This library is free software; you can redistribute it and/or
6    * modify it under the terms of the GNU Lesser General Public
7    * License as published by the Free Software Foundation; either
8    * version 2 of the License, or (at your option) any later version.
9    *
10   * This library is distributed in the hope that it will be useful,
11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   * Lesser General Public License for more details.
14   *
15   * You should have received a copy of the GNU Lesser General Public
16   * License along with this library; if not, write to the Free Software
17   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18   *
19   * Contact: Eric.Bruneton@rd.francetelecom.com
20   *
21   * Author: Eric Bruneton
22   *
23   * with some comments copied from Jonathan:
24   *   org.objectweb.jonathan.apis.protocols.RequestSession (author: B. Dumant)
25   */
26  
27  package org.objectweb.fractal.rmi.stub;
28  
29  import org.objectweb.fractal.api.Component;
30  import org.objectweb.fractal.api.Interface;
31  import org.objectweb.fractal.api.Type;
32  
33  import org.objectweb.jonathan.apis.kernel.JonathanException;
34  import org.objectweb.jonathan.apis.presentation.Marshaller;
35  import org.objectweb.jonathan.apis.presentation.UnMarshaller;
36  import org.objectweb.jonathan.apis.protocols.ReplySession;
37  import org.objectweb.jonathan.apis.protocols.RequestSession;
38  
39  /**
40   * Super class of the skeleton classes generated by the {@link RmiStubFactory}.
41   * A skeleton gives access to a local interface of a Fractal
42   * component. It unmarshalls invocation messages and calls the corresponding
43   * methods on the local interface to which it gives access. Like stubs, a
44   * skeleton gives access to the "functional" interface provided by a server
45   * interface, and also gives access to the methods of the {@link Interface}
46   * interface implemented by this server interface.
47   */
48  
49  public abstract class Skeleton implements RequestSession {
50  
51    /**
52     * The local server interface to which this skeleton gives access.
53     */
54  
55    protected Object   target;
56  
57    /**
58     * Constructs a new {@link Skeleton}.
59     */
60  
61    public Skeleton () {
62    }
63  
64    // --------------------------------------------------------------------------
65    // Implementation of the RequestSession interface
66    // --------------------------------------------------------------------------
67  
68    /**
69     * Returns the target object represented by this request session.
70     *
71     * @return the target object represented by this request session.
72     */
73  
74    public Object   getTarget () {
75      return target;
76    }
77  
78    /**
79     * Sends a message (a request) to its recipient. The unmarshaller representing
80     * the invocation is sent together with a reply session, to be used by the
81     * recipient to send the reply. The reply session may be null if no response
82     * is expected. It is the responsibility of the recipient to make sure that
83     * the unmarshaller will properly be {@link UnMarshaller#close() closed}.
84     *
85     * @param unmarshaller the unmarshaller representing the request.
86     * @param session the session to send the reply.
87     * @throws JonathanException if something goes wrong.
88     */
89  
90    public abstract void send (UnMarshaller unmarshaller, ReplySession session)
91      throws JonathanException;
92  
93    // --------------------------------------------------------------------------
94    // Utility methods
95    // --------------------------------------------------------------------------
96  
97    /**
98     * Handles invocations messages corresponding to methods of the {@link
99     * Interface} interface.
100    *
101    * @param unmarshaller the unmarshaller representing the request.
102    * @param session the session to send the reply.
103    * @param methodIndex the index of the method to be called.
104    * @throws JonathanException if something goes wrong.
105    */
106 
107   protected void handleInterfaceMethods (
108     final UnMarshaller unmarshaller,
109     final ReplySession session,
110     final int methodIndex) throws JonathanException
111   {
112     Interface itf = (Interface)target;
113     Marshaller marshaller;
114     try {
115       switch (methodIndex) {
116         case -1:
117           unmarshaller.close();
118           Component id = itf.getFcItfOwner();
119           marshaller = session.prepareReply();
120           marshaller.writeValue(id);
121           session.send(marshaller);
122           session.close();
123           return;
124         case -2:
125           unmarshaller.close();
126           String   name = itf.getFcItfName();
127           marshaller = session.prepareReply();
128           marshaller.writeValue(name);
129           session.send(marshaller);
130           session.close();
131           return;
132         case -3:
133           unmarshaller.close();
134           Type type = itf.getFcItfType();
135           marshaller = session.prepareReply();
136           marshaller.writeValue(type);
137           session.send(marshaller);
138           session.close();
139           return;
140         case -4:
141           unmarshaller.close();
142           boolean internal = itf.isFcInternalItf();
143           marshaller = session.prepareReply();
144           marshaller.writeBoolean(internal);
145           session.send(marshaller);
146           session.close();
147           return;
148         default:
149           throw new Exception  ("No such method");
150       }
151     } catch (Exception   e) {
152       handleException(e, session);
153     }
154   }
155 
156   /**
157    * Handles an exception that happened in this skeleton. This method sends the
158    * given exception to the caller by using the given reply session.
159    *
160    * @param e the exception that happened.
161    * @param session the session to send the reply.
162    * @throws JonathanException if the given exception cannot be sent back to the
163    *      caller.
164    */
165 
166   protected void handleException (final Exception   e, final ReplySession session)
167     throws JonathanException
168   {
169     try {
170       Marshaller marshaller = session.prepareExceptionReply();
171       marshaller.writeValue(e);
172       session.send(marshaller);
173     } catch (Exception   f) {
174       f.printStackTrace();
175       throw new JonathanException(
176         "error during marshalling of exception by skeleton");
177     }
178     session.close();
179   }
180   
181   protected Object   replaceClassName (Object   o) throws ClassNotFoundException   {
182     if (o instanceof String  ) {
183       return Class.forName((String  )o);
184     } else if (o instanceof Object  []) {
185       Object  [] desc = (Object  [])o;
186       if (desc.length == 2 && desc[1] instanceof String  ) {
187         return new Object  [] { desc[0], Class.forName((String  )desc[1]) };
188       }
189     }
190     return o;
191   }
192   
193   protected Object   replaceClassValue (Object   o) {
194     if (o instanceof Class  ) {
195       return ((Class  )o).getName();
196     } else if (o instanceof Object  []) {
197       Object  [] desc = (Object  [])o;
198       if (desc.length == 2 && desc[1] instanceof Class  ) {
199         return new Object  [] { desc[0], ((Class  )desc[1]).getName() };
200       }
201     }
202     return o;
203   }
204 }
205
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