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comparison src/org/dancres/jini/util/ServiceLocator.java @ 0:3dc0c5604566

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Initial checkin of blitz 2.0 fcs - no installer yet.
author Dan Creswell <dan.creswell@gmail.com>
date Sat, 21 Mar 2009 11:00:06 +0000
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1 package org.dancres.jini.util;
2
3 import net.jini.lookup.entry.Name;
4 import net.jini.core.entry.Entry;
5 import net.jini.discovery.DiscoveryListener;
6 import net.jini.discovery.DiscoveryEvent;
7 import net.jini.discovery.LookupDiscovery;
8 import net.jini.core.discovery.LookupLocator;
9 import net.jini.core.lookup.ServiceRegistrar;
10 import net.jini.core.lookup.ServiceTemplate;
11 import java.rmi.RMISecurityManager;
12 import java.rmi.RemoteException;
13
14 /**
15 * ServiceLoactor is a simple wrapper class over Jini's LookupDiscover.
16 * It which returns the first matching instance of a service either via
17 * unicast or multicast discovery
18 */
19
20 public class ServiceLocator{
21
22 static {
23 if (System.getSecurityManager() == null) {
24 System.setSecurityManager(new RMISecurityManager());
25 }
26 }
27
28 private Object _proxy;
29 private Object _lock=new Object();
30 private ServiceTemplate _template;
31
32 /**
33 * Locates a service via Unicast discovery
34 * @param lusHost The name of the host where a Jini lookup service is running
35 * @param serviceClass The class object representing the interface of the service
36 * @throws MalformedURLException
37 * @throws IOException
38 * @throws ClassNotFoundException
39 * @return The proxy to the discovered service
40 */
41 public static Object getService(String lusHost,Class serviceClass)
42 throws java.net.MalformedURLException,java.io.IOException,ClassNotFoundException{
43
44 LookupLocator loc=new LookupLocator("jini://"+lusHost);
45 ServiceRegistrar reggie=loc.getRegistrar();
46 ServiceTemplate tmpl=new ServiceTemplate(null, new Class[]{serviceClass},null);
47 return reggie.lookup(tmpl);
48
49 }
50 /**
51 *
52 * @param lusHost
53 * @param serviceClass
54 * @param serviceName
55 * @return proxy or <code>null</code>
56 * @throws java.net.MalformedURLException
57 * @throws java.io.IOException
58 * @throws ClassNotFoundException
59 */
60 public static Object getService(String lusHost,Class serviceClass,
61 String serviceName)
62 throws java.net.MalformedURLException,java.io.IOException,
63 ClassNotFoundException{
64
65 Class [] types=new Class[]{serviceClass};
66 Entry [] entry=null;
67
68 if(serviceName!=null){
69 entry=new Entry[]{new Name(serviceName)};
70 }
71
72 ServiceTemplate _template = new ServiceTemplate(null,types,entry);
73 LookupLocator loc=new LookupLocator("jini://"+lusHost);
74 ServiceRegistrar reggie=loc.getRegistrar();
75
76 return reggie.lookup(_template);
77 }
78 /**
79 * Locates the first matching service via multicast discovery
80 * @param serviceClass The class object representing the interface of the service
81 * @throws IOException
82 * @throws InterruptedException
83 * @return */
84 public static Object getService(Class serviceClass)
85 throws java.io.IOException,InterruptedException{
86
87 return getService(serviceClass,null,Long.MAX_VALUE);
88 }
89 /**
90 * Locates the first matching service via multicast discovery
91 * @param serviceClass The class object representing the interface of the service
92 * @param waitTime How to wait for the service to be discovered
93 * @throws IOException
94 * @throws InterruptedException
95 * @return */
96 public static Object getService(Class serviceClass,long waitTime)
97 throws java.io.IOException,InterruptedException{
98
99 return getService(serviceClass,null,waitTime);
100 }
101 /**
102 * Locates the first matching service via multicast discovery
103 * @param serviceClass The class object representing the interface of the service
104 * @param serviceName The Name attribute of the service
105 * @throws IOException
106 * @throws InterruptedException
107 * @return */
108 public static Object getService(Class serviceClass,String serviceName,long waitTime)
109 throws java.io.IOException,InterruptedException{
110
111 ServiceLocator sl=new ServiceLocator();
112 return sl.getServiceImpl(serviceClass,serviceName,waitTime);
113 }
114
115
116 private Object getServiceImpl(Class serviceClass,String serviceName,long waitTime)
117 throws java.io.IOException,InterruptedException{
118
119
120 Class [] types=new Class[]{serviceClass};
121 Entry [] entry=null;
122
123 if(serviceName!=null){
124 entry=new Entry[]{new Name(serviceName)};
125 }
126
127 _template=new ServiceTemplate(null,types,entry);
128
129 LookupDiscovery disco=
130 new LookupDiscovery(LookupDiscovery.ALL_GROUPS);
131
132 disco.addDiscoveryListener(new Listener());
133
134
135
136 synchronized(_lock){
137 _lock.wait(waitTime);
138 }
139
140 disco.terminate();
141 if(_proxy==null){
142 throw new InterruptedException("Service not found within wait time");
143 }
144 return _proxy;
145
146 }
147 class Listener implements DiscoveryListener {
148 //invoked when a LUS is discovered
149 public void discovered(DiscoveryEvent ev) {
150 ServiceRegistrar[] reg = ev.getRegistrars();
151 for (int i=0 ; i<reg.length && _proxy==null ; i++) {
152 findService(reg[i]);
153 }
154 }
155
156 public void discarded(DiscoveryEvent ev) {
157 }
158 }
159 private void findService(ServiceRegistrar lus) {
160
161 try {
162 synchronized(_lock){
163 _proxy=lus.lookup(_template);
164 if(_proxy!=null){
165 _lock.notifyAll();
166 }
167 }
168 }catch(RemoteException ex) {
169 ex.printStackTrace(System.err);
170 }
171 }
172 }