old-autovect-branch/libjava/classpath/javax/rmi/CORBA/Stub.java

   1 /* Stub.java --
   2    Copyright (C) 2004, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package javax.rmi.CORBA;
  40
  41 import gnu.javax.rmi.CORBA.DelegateFactory;
  42 import gnu.javax.rmi.CORBA.StubDelegateImpl;
  43
  44 import java.io.IOException;
  45 import java.io.ObjectInputStream;
  46 import java.io.ObjectOutputStream;
  47 import java.io.Serializable;
  48 import java.rmi.RemoteException;
  49
  50 import javax.rmi.PortableRemoteObject;
  51
  52 import org.omg.CORBA.ORB;
  53 import org.omg.CORBA_2_3.portable.ObjectImpl;
  54
  55 /**
  56  * A Stub descendants provide access to the object on the client side. This base
  57  * class implements methods, required for remote or local invocation using CORBA
  58  * mechanisms. The most of the functionality is forwarded to the stub delegate.
  59  * This delegate can be altered by setting the system property
  60  * "javax.rmi.CORBA.StubClass" to the name of the alternative class that must
  61  * implement {@link StubDelegate}. Hence Stub contains two delegates, one for
  62  * Stub-related operations and another inherited from the ObjectImpl.
  63  *
  64  * @specnote GNU Classpath uses separate delegate per each Stub. The delegate
  65  * holds information about the ORB and other data, specific for the each Stub.
  66  *
  67  * @author Audrius Meskauskas (AudriusA@Bioinformatics.org)
  68  */
  69 public abstract class Stub
  70   extends ObjectImpl
  71   implements Serializable
  72 {
  73   /**
  74    * For compatability with Sun's JDK 1.4.2 rev. 5
  75    */
  76   private static final long serialVersionUID = 1087775603798577179L;
  77
  78   /**
  79    * The hashcode, computed once (expensive operation).
  80    */
  81   transient int m_hash = Integer.MIN_VALUE;
  82
  83   /**
  84    * The stringified reference, computed once (expensive operation).
  85    */
  86   transient String m_ior;
  87
  88   /**
  89    * The ORB, where the stub is connected on the client side.
  90    */
  91   transient ORB m_orb;
  92
  93   /**
  94    * The associated delegate, responsible for the major of the functionality of
  95    * this stub.
  96    */
  97   static StubDelegate delegate = (StubDelegate) DelegateFactory.getInstance(DelegateFactory.STUB);
  98
  99   /**
 100    * Returns the same hashcode for all stubs that point to the same remote
 101    * object.
 102    */
 103   public int hashCode()
 104   {
 105     if (m_hash == Integer.MIN_VALUE)
 106       m_hash = delegate.hashCode(this);
 107     // This should finally result to the IOR comparison.
 108     return m_hash;
 109   }
 110
 111   /**
 112    * The stubs are equal if they point to the same remote object.
 113    */
 114   public boolean equals(java.lang.Object obj)
 115   {
 116     return delegate.equals(this, obj);
 117   }
 118
 119   /**
 120    * Get the string representation of this Stub.
 121    *
 122    * @return the CORBA IOR reference.
 123    */
 124   public String toString()
 125   {
 126     if (m_ior == null)
 127       m_ior = delegate.toString(this);
 128     return m_ior;
 129   }
 130
 131   /**
 132    * <p>
 133    * Finds the suitable {@link Tie} for this Stub and connects it to the given
 134    * ORB. The tie is found by the name pattern. If the found tie is derived from
 135    * {@link org.omg.CORBA.PortableServer.Servant}, it is connected to the root
 136    * POA, also activating it (if not already active).
 137    * </p>
 138    * <p>
 139    * This method does not allow to specify, to which POA the found Tie must be
 140    * connected and requires to use the deprecated method {@link ORB#connect}.
 141    * Many useful POA features remain unaccessible. A better alternative it might
 142    * be to generate a {@link org.omg.CORBA.PortableServer.Servant} - derived Tie
 143    * (-poa key in rmic) and connect it to POA in one of the many ways, listed in
 144    * the description of the {@link orb.omg.PortableServer} package). The
 145    * obtained CORBA object can be narrowed into stub using
 146    * {@link PortableRemoteObject#narrow}.
 147    * </p>
 148    * <p>
 149    * It is frequently easier to call {@link PortableRemoteObject#connect} rather
 150    * than this method.
 151    * </p>
 152    *
 153    * @param orb the ORB where the Stub must be connected.
 154    *
 155    * @throws RemoteException if the stub is already connected to some other ORB.
 156    * If the stub is already connected to the ORB that was passed as parameter,
 157    * the method returns without action.
 158    *
 159    * @throws BAD_PARAM if the name of this stub does not match the stub name
 160    * pattern, "_*_Stub" or if the Tie class, "_*Impl_Tie", does not exists or an
 161    * instance of this class cannot be instantiated.
 162    */
 163   public void connect(ORB orb)
 164     throws RemoteException
 165   {
 166     if (m_orb != null && orb != null)
 167       {
 168         if (m_orb.equals(orb))
 169           throw new RemoteException("Stub " + this
 170             + " is connected to another ORB, " + orb);
 171         else
 172           return;
 173       }
 174     m_orb = orb;
 175     delegate.connect(this, orb);
 176   }
 177
 178   /**
 179    * Required by serialized form of Java API doc.
 180    */
 181   private void readObject(ObjectInputStream input)
 182     throws IOException, ClassNotFoundException
 183   {
 184     if (delegate instanceof StubDelegateImpl)
 185       ((StubDelegateImpl) delegate).readObject(this, input, m_orb);
 186     else
 187       delegate.readObject(this, input);
 188   }
 189
 190   /**
 191    * Required by serialized form of Java API doc.
 192    */
 193   private void writeObject(ObjectOutputStream output)
 194     throws IOException
 195   {
 196     // The m_orb in this case may be either known or not.
 197     if (delegate instanceof StubDelegateImpl)
 198       ((StubDelegateImpl) delegate).writeObject(this, output, m_orb);
 199     else
 200
 201       delegate.writeObject(this, output);
 202   }
 203 }