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1   /*
2      Copyright 2007 Ivo Limmen
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  package org.limmen.crs.client.locator;
17  
18  import java.io.IOException;
19  import java.net.InetAddress;
20  import java.net.NetworkInterface;
21  import java.net.UnknownHostException;
22  import java.util.Enumeration;
23  
24  import javax.jmdns.JmDNS;
25  import javax.jmdns.ServiceInfo;
26  
27  import org.limmen.crs.Constants;
28  
29  public class MDNSServiceLocator implements ServiceLocator {
30  
31  	public MDNSServiceLocator() {
32  
33  		super();
34  	}
35  
36  	@Override
37  	public Service locate() throws ServiceLocatorException {
38  
39  		JmDNS jmdns = null;
40  		String hostname = null;
41  		int port = 0;
42  		String contextPath = null;
43  
44  		try {
45  
46     		Enumeration<NetworkInterface> addressesEnum =
47     			NetworkInterface.getNetworkInterfaces();
48  
49     		InetAddress inetAddress = addressesEnum.nextElement().getInetAddresses().nextElement();
50  
51     		while (addressesEnum.hasMoreElements()
52     				&& inetAddress.isLoopbackAddress()) {
53  
54     			inetAddress = addressesEnum.nextElement().getInetAddresses().nextElement();
55  
56     		}
57  
58  			jmdns = new JmDNS(inetAddress);
59  
60  			ServiceInfo serviceInfo = jmdns.getServiceInfo(
61  					Constants.ZERO_CONF_SERVICE_TYPE,
62  			      Constants.ZERO_CONF_SERVICE_NAME,
63  			      10000);
64  
65  			if (serviceInfo != null) {
66  
67  				hostname = serviceInfo.getHostAddress();
68  
69  				port = serviceInfo.getPort();
70  
71  				contextPath = new String(
72  						serviceInfo.getPropertyBytes(
73  								Constants.SERVICE_CONTEXTPATH_PROPERTY));
74  			}
75  			else {
76  
77  				throw new ServiceLocatorException(
78  						"CRS Service could not be located.");
79  			}
80  		}
81  		catch (UnknownHostException uhe) {
82  
83  			throw new ServiceLocatorException(uhe);
84  		}
85  		catch (IOException ioe) {
86  
87  			throw new ServiceLocatorException(ioe);
88  		}
89  		finally {
90  
91  			jmdns.close();
92  		}
93  
94  		return new Service(hostname, port, contextPath);
95  	}
96  }