001// Copyright 2004, 2005 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.hivemind.lib.impl;
016
017import java.rmi.RemoteException;
018
019import org.apache.hivemind.lib.NameLookup;
020import org.apache.hivemind.lib.RemoteExceptionCoordinator;
021
022/**
023 * Generic EJB proxy for stateless session beans.  Acts as an InvocationHandler
024 * for a dynamic proxy.
025 *
026 * @author Howard Lewis Ship
027 */
028public abstract class AbstractEJBProxy
029{
030    private NameLookup _nameLookup;
031    private RemoteExceptionCoordinator _coordinator;
032
033    protected AbstractEJBProxy(NameLookup nameLookup, RemoteExceptionCoordinator coordinator)
034    {
035        _nameLookup = nameLookup;
036        _coordinator = coordinator;
037    }
038
039    protected Object _lookup(String name)
040    {
041        return _nameLookup.lookup(name, Object.class);
042    }
043
044    /**
045     * Clears the home and remote objects after any remote exception. 
046     */
047
048    protected abstract void _clearCachedReferences();
049        
050        /**
051         * Invoked by the fabricated subclass when a remote exception occurs.
052         * This notifies the {@link RemoteExceptionCoordinator} (which, indirectly,
053         * allows the {@link NameLookup} service to release its JNDI context).
054         * In addition, {@link #_clearCachedReferences()} is invoked.
055         */
056    protected void _handleRemoteException(RemoteException ex)
057    {
058        _clearCachedReferences();
059        _coordinator.fireRemoteExceptionDidOccur(this, ex);
060    }
061}