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1   /*
2    * Copyright 2007-2008 the original author or authors.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.gwe.utils;
18  
19  import java.net.URI;
20  import java.net.URISyntaxException;
21  import java.net.UnknownHostException;
22  import java.rmi.NotBoundException;
23  import java.rmi.Remote;
24  import java.rmi.RemoteException;
25  import java.rmi.registry.LocateRegistry;
26  import java.rmi.registry.Registry;
27  import java.rmi.server.RMIClientSocketFactory;
28  
29  import org.apache.commons.logging.Log;
30  import org.apache.commons.logging.LogFactory;
31  
32  /**
33   * @author Marco Ruiz
34   * @since Aug 15, 2007
35   */
36  public class RemoteResolver<RT extends Remote> implements Runnable {
37  
38  	private static Log log = LogFactory.getLog(RemoteResolver.class);
39  
40  	private RT remoteObj = null;
41  	private String[] servicesList = null;
42  	private RemoteException rex = null;
43  	private NotBoundException nbex = null;
44  	private URI uriObj;
45  	private Thread resolverThread = null;
46  	private boolean list = false;
47  	private RMIClientSocketFactory socketFactory;
48  
49  	public RemoteResolver(String uriStr, RMIClientSocketFactory socketFactory) throws URISyntaxException, UnknownHostException {
50  		this.uriObj = new URI(uriStr);
51  		this.socketFactory = socketFactory;
52  	}
53  
54  	public RT getRemote(long waitMillis) throws RemoteException, NotBoundException, ConnectionTimeoutException {
55  		return (RT)getRegistryInformation(waitMillis, false);
56  	}
57  	
58  	public String[] getList(long waitMillis) throws RemoteException, NotBoundException, ConnectionTimeoutException {
59  		return (String[])getRegistryInformation(waitMillis, true);
60  	}
61  
62  	public synchronized <INFO_TYPE extends Object> INFO_TYPE getRegistryInformation(long waitMillis, boolean list) throws RemoteException, NotBoundException, ConnectionTimeoutException {
63  		if (resolverThread != null) return null; // TODO: Must throw exception!!!
64  		this.list = list;
65  		resolverThread = new Thread(this);
66  		resolverThread.start();
67  		long timeout;
68  		long end = System.currentTimeMillis() + waitMillis;
69  		while ((timeout = end - System.currentTimeMillis()) > 0) {
70  			try {
71  				this.wait(timeout);
72  			} catch (InterruptedException e) {}
73  			INFO_TYPE info = (INFO_TYPE) ((list) ? servicesList : remoteObj);
74  			if (info != null) return info;
75  			if (rex != null)  throw rex;
76  			if (nbex != null) throw nbex;
77  		}
78  
79  		// RemoteResolver used will dispose itself automatically once it returns from its blocked state
80  		throw new ConnectionTimeoutException(uriObj.toString(), timeout);
81  	}
82  
83  	public void run() {
84  		try {
85  			log.info("Retrieving remote registry '" + uriObj.getHost() + ":" + uriObj.getPort() + "'...");
86  			Registry registry = LocateRegistry.getRegistry(uriObj.getHost(), uriObj.getPort(), socketFactory);
87  			log.info("Registry obtained! " + registry);
88  			log.info("Retrieving remote object '" + uriObj.toString() + "'...");
89  			RT rObj = null;
90  			String[] sList = null;
91  			if (list)
92  				sList = registry.list();
93  			else
94  				rObj = (RT) registry.lookup(uriObj.getPath().substring(1));
95  			log.info("Remote proxy object created: '" + rObj + "'. Actual object at '" + uriObj.toString() + "'");
96  			synchronized (this) {
97  				remoteObj = rObj;
98  				servicesList = sList;
99  				close();
100 			}
101 		} catch (RemoteException e) {
102 			synchronized (this) {
103 				this.rex = e;
104 				close();
105 			}
106 		} catch (NotBoundException e) {
107 			synchronized (this) {
108 				this.nbex = e;
109 				close();
110 			}
111 		}
112 	}
113 	
114 	private synchronized void close() {
115 		resolverThread = null;
116 		this.notifyAll();
117 	}
118 	
119 }
120 
121 class ConnectionTimeoutException extends Exception {
122 	
123 	public ConnectionTimeoutException(String uriStr, long timeout) {
124 		super("Timeout reached! No exception or sucessful response received from '" + uriStr + "' within " + timeout / 1000 + " seconds");
125 	}
126 }