001/* PortableRemoteObject.java -- 002 Copyright (C) 2004, 2004, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package javax.rmi; 040 041import gnu.javax.rmi.CORBA.DelegateFactory; 042 043import org.omg.CORBA.BAD_PARAM; 044import org.omg.CORBA.ORB; 045import org.omg.CORBA.portable.ObjectImpl; 046import org.omg.PortableServer.POA; 047import org.omg.PortableServer.Servant; 048 049import java.rmi.NoSuchObjectException; 050import java.rmi.Remote; 051import java.rmi.RemoteException; 052 053import javax.rmi.CORBA.PortableRemoteObjectDelegate; 054import javax.rmi.CORBA.Stub; 055import javax.rmi.CORBA.Tie; 056import javax.rmi.CORBA.Util; 057 058/** 059 * <p> 060 * An utility class for RMI/IDL server side object implementations. Server side 061 * implementation objects may inherit from this class, but this is not 062 * mandatory, as the needed methds are static. Server side implementations may 063 * choose to inherit from {@link ObjectImpl} or {@link Servant} instead. 064 * </p> 065 * <p> 066 * The functionality of methods in this class is forwarded to the enclosed 067 * PortableRemoteObjectDelegate. This delegate can be altered by setting the 068 * system property "javax.rmi.CORBA.PortableRemoteObjectClass" to the name of 069 * the alternative class that must implement 070 * {@link PortableRemoteObjectDelegate}. 071 * </p> 072 * 073 * @author Audrius Meskauskas (AudriusA@Bioinformatics.org) 074 */ 075public class PortableRemoteObject 076{ 077 /** 078 * A delegate where the functionality is forwarded. 079 */ 080 static PortableRemoteObjectDelegate delegate = (PortableRemoteObjectDelegate) DelegateFactory.getInstance(DelegateFactory.PORTABLE_REMOTE_OBJECT); 081 082 /** 083 * The protected constructor calls {@link exportObject} (this). 084 * 085 * @throws RemoteException if the exportObject(this) throws one. 086 */ 087 protected PortableRemoteObject() 088 throws RemoteException 089 { 090 exportObject((Remote) this); 091 } 092 093 /** 094 * <p> 095 * Makes the remote object <code>a_target</code> ready for remote 096 * communication using the same communications runtime as for the passed 097 * <code>a_source</code> parameter. The a_target is connected to the same 098 * ORB (and, if applicable, to the same {@link POA}) as the a_source. 099 * 100 * @param target the target to connect to ORB, must be an instance of either 101 * {@link ObjectImpl} (Stubs and old-style ties) or {@link Tie}. 102 * 103 * @param source the object, providing the connection information, must be 104 * an instance of either {@link ObjectImpl} (Stubs and old-style ties) or 105 * {@link Servant} (the next-generation Ties supporting {@link POA}). 106 * 107 * @throws RemoteException if the target is already connected to another ORB. 108 */ 109 public static void connect(Remote target, Remote source) 110 throws RemoteException 111 { 112 delegate.connect(target, source); 113 } 114 115 /** 116 * <p> 117 * Makes a server object ready for remote calls. The subclasses of 118 * PortableRemoteObject do not need to call this method, as it is called by 119 * the constructor. 120 * </p> 121 * <p> 122 * This method only creates a tie object and caches it for future usage. The 123 * created tie does not have a delegate or an ORB associated. 124 * </p> 125 * 126 * @param object the object to export. 127 * 128 * @throws RemoteException if export fails due any reason. 129 */ 130 public static void exportObject(Remote object) 131 throws RemoteException 132 { 133 delegate.exportObject(object); 134 } 135 136 /** 137 * Narrows the passed object to conform to the given interface or IDL type. In 138 * RMI-IIOP, this method replaces the narrow(org.omg.CORBA.Object) method that 139 * was present in the CORBA Helpers. This method frequently returns different 140 * instance and cannot be replaced by the direct cast. The typical narrowing 141 * cases (all supported by GNU Classpath) are: 142 * <ul> 143 * <li>A CORBA object (for instance, returned by the 144 * {@link ORB#string_to_object} or from the naming service) can be narrowed 145 * into interface, derived from Remote. The method will try to locate an 146 * appropriate {@link Stub} by the name pattern (_*_Stub). If the object being 147 * narrowed is connected to an ORB, the returned instance will inherit that 148 * connection, representing the same remote (or local) object, but now with 149 * the possibility to invoke remote methods. </li> 150 * <li>A CORBA object may be directly narrowed into the appropriate 151 * {@link Stub} class, if it is and passed as a second parameter. This allows 152 * to use non-standard stubs without parameterless constructors.</li> 153 * <li>Any two classes, derived from the {@link ObjectImpl} (may be Stub's) 154 * can be narrowed one into another (a delegate is transferred). </li> 155 * <li>An implementation of Remote can be narrowed into {@link Tie} that can 156 * later connected to an ORB, making the methods accessible remotely. The 157 * Remote being narrowed normally provides a local implementation, but you can 158 * also narrow remote Stub, creating "forwarding Tie".</li> 159 * <li>null is narrowed into null regardless of the second parameter.</li> 160 * <li>A {@link Tie} can be narrowed into Remote, representing the 161 * implementation for this Tie (if one is set).</li> 162 * </ul> 163 * 164 * @param object the object like CORBA Object, Stub or Remote that must be 165 * narrowed to the given interface. 166 * 167 * @param narrowToInstaceOf the class of the interface to that the object must 168 * be narrowed. 169 * 170 * @return On success, an object of type narrowTo or null, if narrowFrom = 171 * null. 172 * 173 * @throws ClassCastException if no narrowing is possible. 174 */ 175 public static Object narrow(Object object, Class narrowToInstaceOf) 176 throws ClassCastException 177 { 178 return delegate.narrow(object, narrowToInstaceOf); 179 } 180 181 /** 182 * <p> 183 * Takes a server implementation object (name pattern *imp) and returns a stub 184 * object that can be used to access that server object (target), name 185 * (pattern _*_Stub). 186 * 187 * The returned stub is not connected to any ORB and must be explicitly 188 * connected using {@link #connect}. 189 * </p> 190 * <p> 191 * The method signature prevents it from returning stubs that does not 192 * implement Remote (ClassCastException will be thrown). 193 * </p> 194 * 195 * @param target a server side object implementation. 196 * @return a stub object that can be used to access that server object. 197 * 198 * @throws NoSuchObjectException if a stub class cannot be located by supposed 199 * name pattern, or an instance of stub fails to be instantiated. 200 * 201 * @throws ClassCastException if the stub class can be located, but it does 202 * not inherit from Remote. 203 * 204 * @throws BAD_PARAM if the name of the passed class does not match the 205 * implementation name pattern (does not end by 'Impl'). 206 */ 207 public static Remote toStub(Remote targetImpl) 208 throws NoSuchObjectException 209 { 210 return delegate.toStub(targetImpl); 211 } 212 213 /** 214 * Deregister a currently exported server object from the ORB runtimes. The 215 * object to becomes available for garbage collection. This is usually 216 * impemented via {@link Util#unexportObject} 217 * 218 * @param object the object to unexport. 219 * 220 * @throws NoSuchObjectException if the passed object is not currently 221 * exported. 222 */ 223 public static void unexportObject(Remote object) 224 throws NoSuchObjectException 225 { 226 delegate.unexportObject(object); 227 } 228}