001    /* Servant.java --
002       Copyright (C) 2005 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package org.omg.PortableServer;
040    
041    import org.omg.CORBA.BAD_OPERATION;
042    import org.omg.CORBA.BAD_INV_ORDER;
043    import org.omg.CORBA.NO_IMPLEMENT;
044    import org.omg.CORBA.OBJECT_NOT_EXIST;
045    import org.omg.CORBA.ORB;
046    import org.omg.PortableServer.POAPackage.ServantNotActive;
047    import org.omg.PortableServer.POAPackage.WrongPolicy;
048    import org.omg.PortableServer.portable.Delegate;
049    
050    import gnu.CORBA.Minor;
051    import gnu.CORBA.Poa.ORB_1_4;
052    import gnu.CORBA.Poa.gnuPOA;
053    
054    /**
055     * <p>
056     * The servant is responsible for handling the method invocation on the
057     * target object. It can be one servant per object, or the same servant can
058     * support several (possibly all) objects, associated with the given POA.
059     * </p> <p>
060     * Till JDK 1.3 inclusive, a typical IDL to java compiler generates an
061     * implementation base (name pattern _*ImplBase.java) that is derived from the
062     * {@link org.omg.CORBA.portable.ObjectImpl}. Since JDK 1.4 the implementation
063     * base is derived from the Servant, also having a different name pattern
064     * (*POA.java). This suffix may be confusing, as the servant itself is
065     * <i>not</i> POA nor it is derived from it.
066     * </p><p>
067     * In both cases, the implementation base also inherits an interface, containing
068     * definitions of the application specific methods. The application programmer
069     * writes a child of the implementation base, implementing these methods
070     * for the application-specific functionality. The ObjectImpl is connected
071     * directly to the ORB. The Servant is connected to POA that can be obtained
072     * from the ORB.
073     * </p><p>
074     * If the servant is connected to more than one object, the exact object
075     * being currently served can be identified with {@link #_object_id}.
076     * </p><p>
077     * The derivativ of Servant, being directly connected to serve requests,
078     * must inherit either from {@link org.omg.CORBA.portable.InvokeHandler}
079     * or from {@link org.omg.PortableServer.DynamicImplementation}).
080     * </p><p>
081     * The Servant type is a CORBA <code>native</code> type.
082     * </p>
083     *
084     * @see POA#servant_to_reference(Servant)
085     *
086     * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
087     */
088    public abstract class Servant
089    {
090      /**
091       * The delegate, where calls to some Servant methods are forwarded.
092       */
093      private Delegate delegate;
094    
095      /**
096       * Get the repository ids of all interfaces, supported by the
097       * CORBA object, identified by the passed Id. In the typical code the
098       * passed parameters are ignored, returning an array of repository ids,
099       * supported by the servant implementation.
100       *
101       * @param poa a POA of the given object.
102       * @param object_ID the object Id of the given object.
103       *
104       * @return an array, containing the repository ids.
105       */
106      public abstract String[] _all_interfaces(POA poa, byte[] object_ID);
107    
108      /**
109       * Get the delegate, where calls to some Servant methods are forwarded.
110       */
111      public final Delegate _get_delegate()
112      {
113        if (delegate == null) {
114          throw new BAD_INV_ORDER
115            ("The Servant has not been associated with an ORBinstance");
116        }
117        return delegate;
118      }
119    
120      /**
121      * Get the interface repository definition <code>InterfaceDef</code> for this
122      * Object. By default, forwards request to the delegate.
123      *
124      * @specnote The interface repository is officially not implemented up till
125      * JDK 1.5 inclusive. The delegate throws NO_IMPLEMENT, always.
126      */
127      public org.omg.CORBA.Object _get_interface_def()
128      {
129        throw new NO_IMPLEMENT();
130      }
131    
132      /**
133      * Checks if the passed servant is an instance of the given CORBA IDL type.
134      * By default, forwards the requet to the delegate.
135      *
136      * @param repository_id a repository ID, representing an IDL type for that the
137      * servant must be checked.
138      *
139      * @return true if the servant is an instance of the given type, false
140      * otherwise.
141      */
142      public boolean _is_a(String repository_id)
143      {
144        return delegate.is_a(this, repository_id);
145      }
146    
147      /**
148       * Determines if the server object for this reference has already
149       * been destroyed. By default, forwards request to the delegate.
150       *
151       * @return true if the object has been destroyed, false otherwise.
152       */
153      public boolean _non_existent()
154      {
155        return delegate.non_existent(this);
156      }
157    
158      /**
159      * Returns the ORB that is directly associated with the given servant.
160      * In this implementation, the method is overridden to return
161      */
162      public final ORB _orb()
163      {
164        return delegate.orb(this);
165      }
166    
167      /**
168       * Returns the root POA of the ORB instance, associated with this servant.
169       * It is the same POA that would be returned by resolving the initial
170       * reference "RootPOA" for that orb. By default, forwards request to the
171       * delegate.
172       *
173       * @see ORB#resolve_initial_references
174       */
175      public POA _default_POA()
176      {
177        return delegate == null ? null : delegate.default_POA(this);
178      }
179    
180      /**
181      * Return the invocation target object identifier as a byte array.
182      * This is typically used when the same servant serves multiple objects,
183      * and the object id can encapsulated the whole description of the
184      * object.
185      *
186      * This method returns correct values even when the same
187      * servant serves several objects in parallel threads. The ORB maintains the
188      * thread to invocation data map for all calls that are currently being
189      * processed.
190      */
191      public final byte[] _object_id()
192      {
193        if (delegate != null)
194          return delegate.object_id(this);
195        else
196          throw new OBJECT_NOT_EXIST();
197      }
198    
199      /**
200      * Get POA that is directly associated with the given servant.
201      * By default, forwards request to the delegate.
202      */
203      public final POA _poa()
204      {
205        return delegate.poa(this);
206      }
207    
208      /**
209      * Set the delegate for this servant.
210      */
211      public final void _set_delegate(Delegate a_delegate)
212      {
213        delegate = a_delegate;
214      }
215    
216      /**
217      * Obtains the CORBA object reference that is a current invocation target for
218      * the given servant. This is important when the same servant serves
219      * multiple objects. If the servant is not yet connected to the passed
220      * orb, the method will try to connect it to that orb on POA, returned
221      * by the method {@link #_default_POA}. That method can be overridden to
222      * get poa where the object must be automatically connected when
223      * calling this method.
224      *
225      * @param an_orb the ORB with relate to that the object is requested.
226      */
227      public final org.omg.CORBA.Object _this_object(ORB an_orb)
228      {
229        if (delegate != null)
230          return delegate.this_object(this);
231        else
232          {
233            if (an_orb instanceof ORB_1_4)
234              {
235                ORB_1_4 m_orb = (ORB_1_4) an_orb;
236    
237                gnuPOA dp = (gnuPOA) _default_POA();
238                if (dp == null)
239                  dp = m_orb.rootPOA;
240    
241                try
242                  {
243                    return dp.servant_to_reference(this);
244                  }
245                catch (WrongPolicy unexp)
246                  {
247                    BAD_OPERATION bad = new BAD_OPERATION();
248                    bad.minor = Minor.Policy;
249                    bad.initCause(unexp);
250                    throw bad;
251                  }
252                catch (ServantNotActive ex)
253                  {
254                    try
255                      {
256                        return dp.id_to_reference(dp.activate_object(this));
257                      }
258                    catch (Exception unexp)
259                      {
260                        unexp.initCause(ex);
261    
262                        BAD_OPERATION bad = new BAD_OPERATION();
263                        bad.minor = Minor.Activation;
264                        bad.initCause(unexp);
265                        throw bad;
266                      }
267                  }
268              }
269          }
270        throw new OBJECT_NOT_EXIST();
271      }
272    
273      /**
274      * Obtains the CORBA object reference that is a current invocation target for
275      * the given servant. This is important when the same servant serves
276      * multiple objects. This method required the servant to be connected
277      * to a single orb, and a delegate set.
278      *
279      * This method returns correct values even when the same
280      * servant serves several objects in parallel threads. The ORB maintains the
281      * thread to invocation data map for all calls that are currently being
282      * processed.
283      */
284      public final org.omg.CORBA.Object _this_object()
285      {
286        if (delegate != null)
287          return _this_object(_orb());
288        else
289          {
290            POA def = _default_POA();
291            if (def instanceof gnuPOA)
292              return _this_object(((gnuPOA) def).orb());
293          }
294        throw new OBJECT_NOT_EXIST();
295      }
296    }