001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 */
017package org.apache.activemq.util.osgi;
018
019import java.io.IOException;
020import java.io.InputStream;
021import java.io.InputStreamReader;
022import java.io.BufferedReader;
023import java.util.List;
024import java.util.Properties;
025import java.util.ArrayList;
026import java.util.concurrent.ConcurrentHashMap;
027import java.util.concurrent.ConcurrentMap;
028import java.net.URL;
029
030import org.apache.activemq.Service;
031import org.apache.activemq.store.PersistenceAdapter;
032import org.apache.activemq.transport.Transport;
033import org.apache.activemq.transport.discovery.DiscoveryAgent;
034import org.apache.activemq.util.FactoryFinder;
035import org.apache.activemq.util.FactoryFinder.ObjectFactory;
036import org.slf4j.LoggerFactory;
037import org.slf4j.Logger;
038
039import org.osgi.framework.Bundle;
040import org.osgi.framework.BundleActivator;
041import org.osgi.framework.BundleContext;
042import org.osgi.framework.BundleEvent;
043import org.osgi.framework.SynchronousBundleListener;
044
045/**
046 * An OSGi bundle activator for ActiveMQ which adapts the {@link org.apache.activemq.util.FactoryFinder}
047 * to the OSGi environment.
048 *
049 */
050public class Activator implements BundleActivator, SynchronousBundleListener, ObjectFactory {
051
052    private static final Logger LOG = LoggerFactory.getLogger(Activator.class);
053
054    private final ConcurrentHashMap<String, Class> serviceCache = new ConcurrentHashMap<String, Class>();
055    private final ConcurrentMap<Long, BundleWrapper> bundleWrappers = new ConcurrentHashMap<Long, BundleWrapper>();
056    private BundleContext bundleContext;
057
058    // ================================================================
059    // BundleActivator interface impl
060    // ================================================================
061
062    public synchronized void start(BundleContext bundleContext) throws Exception {
063
064        // This is how we replace the default FactoryFinder strategy
065        // with one that is more compatible in an OSGi env.
066        FactoryFinder.setObjectFactory(this);
067
068        debug("activating");
069        this.bundleContext = bundleContext;
070        debug("checking existing bundles");
071        bundleContext.addBundleListener(this);
072        for (Bundle bundle : bundleContext.getBundles()) {
073            if (bundle.getState() == Bundle.RESOLVED || bundle.getState() == Bundle.STARTING ||
074                bundle.getState() == Bundle.ACTIVE || bundle.getState() == Bundle.STOPPING) {
075                register(bundle);
076            }
077        }
078        debug("activated");
079    }
080
081
082    public synchronized void stop(BundleContext bundleContext) throws Exception {
083        debug("deactivating");
084        bundleContext.removeBundleListener(this);
085        while (!bundleWrappers.isEmpty()) {
086            unregister(bundleWrappers.keySet().iterator().next());
087        }
088        debug("deactivated");
089        this.bundleContext = null;
090    }
091
092    // ================================================================
093    // SynchronousBundleListener interface impl
094    // ================================================================
095
096    public void bundleChanged(BundleEvent event) {
097        if (event.getType() == BundleEvent.RESOLVED) {
098            register(event.getBundle());
099        } else if (event.getType() == BundleEvent.UNRESOLVED || event.getType() == BundleEvent.UNINSTALLED) {
100            unregister(event.getBundle().getBundleId());
101        }
102    }
103
104    protected void register(final Bundle bundle) {
105        debug("checking bundle " + bundle.getBundleId());
106        if( !isImportingUs(bundle) ) {
107            debug("The bundle does not import us: "+ bundle.getBundleId());
108            return;
109        }
110        bundleWrappers.put(bundle.getBundleId(), new BundleWrapper(bundle));
111    }
112
113    /**
114     * When bundles unload.. we remove them thier cached Class entries from the
115     * serviceCache.  Future service lookups for the service will fail.
116     *
117     * TODO: consider a way to get the Broker release any references to
118     * instances of the service.
119     *
120     * @param bundleId
121     */
122    protected void unregister(long bundleId) {
123        BundleWrapper bundle = bundleWrappers.remove(bundleId);
124        if (bundle != null) {
125            for (String path : bundle.cachedServices) {
126                debug("unregistering service for key: " +path );
127                serviceCache.remove(path);
128            }
129        }
130    }
131
132    // ================================================================
133    // ObjectFactory interface impl
134    // ================================================================
135
136    public Object create(String path) throws IllegalAccessException, InstantiationException, IOException, ClassNotFoundException {
137        Class clazz = serviceCache.get(path);
138        if (clazz == null) {
139            StringBuffer warnings = new StringBuffer();
140            // We need to look for a bundle that has that class.
141            int wrrningCounter=1;
142            for (BundleWrapper wrapper : bundleWrappers.values()) {
143                URL resource = wrapper.bundle.getResource(path);
144                if( resource == null ) {
145                    continue;
146                }
147
148                Properties properties = loadProperties(resource);
149
150                String className = properties.getProperty("class");
151                if (className == null) {
152                    warnings.append("("+(wrrningCounter++)+") Invalid service file in bundle "+wrapper+": 'class' property not defined.");
153                    continue;
154                }
155
156                try {
157                    clazz = wrapper.bundle.loadClass(className);
158                } catch (ClassNotFoundException e) {
159                    warnings.append("("+(wrrningCounter++)+") Bundle "+wrapper+" could not load "+className+": "+e);
160                    continue;
161                }
162
163                // Yay.. the class was found.  Now cache it.
164                serviceCache.put(path, clazz);
165                wrapper.cachedServices.add(path);
166                break;
167            }
168
169            if( clazz == null ) {
170                // Since OSGi is such a tricky environment to work in.. lets give folks the
171                // most information we can in the error message.
172                String msg = "Service not found: '" + path + "'";
173                if (warnings.length()!= 0) {
174                    msg += ", "+warnings;
175                }
176                throw new IOException(msg);
177            }
178        }
179        return clazz.newInstance();
180    }
181
182    // ================================================================
183    // Internal Helper Methods
184    // ================================================================
185
186    private void debug(Object msg) {
187        LOG.debug(msg.toString());
188    }
189
190    private Properties loadProperties(URL resource) throws IOException {
191        InputStream in = resource.openStream();
192        try {
193            BufferedReader br = new BufferedReader(new InputStreamReader(in, "UTF-8"));
194            Properties properties = new Properties();
195            properties.load(in);
196            return properties;
197        } finally {
198            try {
199                in.close();
200            } catch (Exception e) {
201            }
202        }
203    }
204
205    private boolean isImportingUs(Bundle bundle) {
206        return isImportingClass(bundle, Service.class)
207                || isImportingClass(bundle, Transport.class)
208                || isImportingClass(bundle, DiscoveryAgent.class)
209                || isImportingClass(bundle, PersistenceAdapter.class);
210    }
211
212    private boolean isImportingClass(Bundle bundle, Class clazz) {
213        try {
214            return bundle.loadClass(clazz.getName())==clazz;
215        } catch (ClassNotFoundException e) {
216            return false;
217        }
218    }
219
220    private static class BundleWrapper {
221        private final Bundle bundle;
222        private final List<String> cachedServices = new ArrayList<String>();
223
224        public BundleWrapper(Bundle bundle) {
225            this.bundle = bundle;
226        }
227    }
228}