Improved the discovery of providers inside OSGi

core/pom.xml

@@ -41,6 +41,7 @@
     <properties>
         <jclouds.osgi.import>*</jclouds.osgi.import>
         <jclouds.osgi.export>org.jclouds*;version=${project.version};-noimport:=true</jclouds.osgi.export>
+        <jclouds.osgi.activator>org.jclouds.osgi.Activator</jclouds.osgi.activator>
     </properties>
 
     <dependencies>
@@ -106,6 +107,12 @@
             <artifactId>guava</artifactId>
             <version>12.0</version>
         </dependency>
+        <dependency>
+            <groupId>org.osgi</groupId>
+            <artifactId>org.osgi.core</artifactId>
+            <version>4.2.0</version>
+            <scope>provided</scope>
+        </dependency>
     </dependencies>
 
     <build>

core/src/main/java/org/jclouds/osgi/Activator.java

@@ -0,0 +1,71 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jclouds.osgi;
+
+import org.jclouds.providers.ProviderRegistry;
+import org.osgi.framework.BundleActivator;
+import org.osgi.framework.BundleContext;
+
+public class Activator implements BundleActivator {
+
+  ProviderBundleListener bundleListener = new ProviderBundleListener();
+
+  /**
+   * Called when this bundle is started so the Framework can perform the
+   * bundle-specific activities necessary to start this bundle. This method
+   * can be used to register services or to allocate any resources that this
+   * bundle needs.
+   * <p/>
+   * <p/>
+   * This method must complete and return to its caller in a timely manner.
+   *
+   * @param context The execution context of the bundle being started.
+   * @throws Exception If this method throws an exception, this
+   *                   bundle is marked as stopped and the Framework will remove this
+   *                   bundle's listeners, unregister all services registered by this
+   *                   bundle, and release all services used by this bundle.
+   */
+  @Override
+  public void start(BundleContext context) throws Exception {
+    context.addBundleListener(bundleListener);
+  }
+
+  /**
+   * Called when this bundle is stopped so the Framework can perform the
+   * bundle-specific activities necessary to stop the bundle. In general, this
+   * method should undo the work that the <code>BundleActivator.start</code>
+   * method started. There should be no active threads that were started by
+   * this bundle when this bundle returns. A stopped bundle must not call any
+   * Framework objects.
+   * <p/>
+   * <p/>
+   * This method must complete and return to its caller in a timely manner.
+   *
+   * @param context The execution context of the bundle being stopped.
+   * @throws Exception If this method throws an exception, the
+   *                   bundle is still marked as stopped, and the Framework will remove
+   *                   the bundle's listeners, unregister all services registered by the
+   *                   bundle, and release all services used by the bundle.
+   */
+  @Override
+  public void stop(BundleContext context) throws Exception {
+    context.removeBundleListener(bundleListener);
+    ProviderRegistry.clear();
+  }
+}

core/src/main/java/org/jclouds/osgi/ProviderBundleListener.java

@@ -0,0 +1,129 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jclouds.osgi;
+
+import org.jclouds.providers.ProviderMetadata;
+import org.jclouds.providers.ProviderRegistry;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.BundleEvent;
+import org.osgi.framework.BundleListener;
+
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * A {@link BundleListener} that listens for {@link BundleEvent} and searches for {@link org.jclouds.providers.ProviderMetadata} in newly
+ * installed Bundles. This is used as a workaround for OSGi environments where the ServiceLoader cannot cross bundle
+ * boundaries.
+ */
+public class ProviderBundleListener implements BundleListener {
+
+  private Map<Long, ProviderMetadata> bundleMetadataMap = new HashMap<Long, ProviderMetadata>();
+
+  @Override
+  public void bundleChanged(BundleEvent event) {
+    ProviderMetadata metadata;
+    switch (event.getType()) {
+      case BundleEvent.STARTED:
+        metadata = getProviderMetadata(event.getBundle());
+        if (metadata != null) {
+          ProviderRegistry.registerProvider(metadata);
+          bundleMetadataMap.put(event.getBundle().getBundleId(), metadata);
+        }
+        break;
+      case BundleEvent.STOPPING:
+      case BundleEvent.STOPPED:
+        metadata = bundleMetadataMap.get(event.getBundle().getBundleId());
+        if (metadata != null) {
+          ProviderRegistry.uRegisterProvider(metadata);
+        }
+        break;
+    }
+  }
+
+  /**
+   * Creates an instance of {@link ProviderMetadata} from the {@link Bundle}.
+   *
+   * @param bundle
+   * @return
+   */
+  public ProviderMetadata getProviderMetadata(Bundle bundle) {
+    ProviderMetadata metadata = null;
+    String className = getProviderMetadataClassName(bundle);
+    if (className != null && !className.isEmpty()) {
+      try {
+        Class<? extends ProviderMetadata> provideClass = bundle.loadClass(className);
+        metadata = provideClass.newInstance();
+      } catch (ClassNotFoundException e) {
+        // ignore
+      } catch (InstantiationException e) {
+        // ignore
+      } catch (IllegalAccessException e) {
+        // ignore
+      }
+    }
+    return metadata;
+  }
+
+  /**
+   * Retrieves the {@link ProviderMetadata} class name for the bundle if it exists.
+   *
+   * @param bundle
+   * @return
+   */
+  public String getProviderMetadataClassName(Bundle bundle) {
+    URL resource = bundle.getEntry("/META-INF/services/org.jclouds.providers.ProviderMetadata");
+    InputStream is = null;
+    InputStreamReader reader = null;
+    BufferedReader bufferedReader = null;
+    StringBuilder sb = new StringBuilder();
+
+    try {
+      is = resource.openStream();
+      reader = new InputStreamReader(is, "UTF-8");
+      bufferedReader = new BufferedReader(reader);
+      String line;
+      while ((line = bufferedReader.readLine()) != null) {
+        sb.append(line).append("\n");
+      }
+    } catch (Throwable e) {
+    } finally {
+      try {
+        if (reader != null)
+          reader.close();
+      } catch (Throwable e) {
+      }
+      try {
+        if (bufferedReader != null)
+          bufferedReader.close();
+      } catch (Throwable e) {
+      }
+      try {
+        is.close();
+      } catch (Throwable e) {
+      }
+
+    }
+    return sb.toString().trim();
+  }
+}

core/src/main/java/org/jclouds/providers/ProviderRegistry.java

@@ -0,0 +1,46 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jclouds.providers;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A registry for holding {@link org.jclouds.providers.ProviderMetadata}.
+ */
+public class ProviderRegistry {
+
+  private static final Set<ProviderMetadata> providers = new HashSet<ProviderMetadata>();
+
+  public static void registerProvider(ProviderMetadata provider) {
+    providers.add(provider);
+  }
+
+  public static void uRegisterProvider(ProviderMetadata provider) {
+    providers.remove(provider);
+  }
+
+  public static Iterable<ProviderMetadata> fromRegistry() {
+    return Iterable.class.cast(providers);
+  }
+
+  public static void clear() {
+    providers.clear();
+  }
+}

core/src/main/java/org/jclouds/providers/Providers.java

@@ -24,6 +24,7 @@ import static com.google.common.collect.Iterables.find;
 import java.util.NoSuchElementException;
 import java.util.ServiceLoader;
 
+import com.google.common.collect.Iterables;
 import org.jclouds.Context;
 import org.jclouds.View;
 import org.jclouds.apis.ApiMetadata;
@@ -82,7 +83,7 @@ public class Providers {
     * @return all available providers
     */
    public static Iterable<ProviderMetadata> all() {
-      return fromServiceLoader();
+     return Iterables.concat(fromServiceLoader(), ProviderRegistry.fromRegistry());
    }
 
    /**

project/pom.xml

@@ -560,6 +560,7 @@ pageTracker._trackPageview();
                 <configuration>
                     <obrRepository>NONE</obrRepository>
                     <instructions>
+                        <Bundle-Activator>${jclouds.osgi.activator}</Bundle-Activator>
                         <Bundle-SymbolicName>${project.artifactId}</Bundle-SymbolicName>
                         <Export-Package>${jclouds.osgi.export}</Export-Package>
                         <Import-Package>${jclouds.osgi.import}</Import-Package>