diff --git a/dependencymanager/core/src/main/java/org/apache/felix/dm/impl/dependencies/TemporalServiceDependencyImpl.java b/dependencymanager/core/src/main/java/org/apache/felix/dm/impl/dependencies/TemporalServiceDependencyImpl.java
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information
+ * regarding copyright ownership. The ASF 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.apache.felix.dependencymanager.dependencies;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+import org.apache.felix.dependencymanager.DependencyActivatorBase;
+import org.apache.felix.dependencymanager.DependencyService;
+import org.apache.felix.dependencymanager.impl.Logger;
+import org.osgi.framework.BundleContext;
+import org.osgi.framework.ServiceReference;
+
+/**
+* A Temporal Service dependency that can block the caller thread between service updates. Only
+* useful for required stateless dependencies that can be replaced transparently.
+* A Dynamic Proxy is used to wrap the actual service dependency. When the dependency goes 
+* away, an attempt is made to replace it with another one which satisfies the service dependency 
+* criteria. If no service replacement is available, then any method invocation (through the 
+* dynamic proxy) will block during a configurable timeout. On timeout, an unchecked ServiceUnavailable 
+* exception is raised (but the service is not deactivated).<p>
+* 
+* When an OSGi update takes place, we use the following locking strategy: A Read/Write lock is used
+* to synchronize the updating thread with respect to the other threads which invoke the backed service. 
+* The Updating thread uses an exclusive Write lock and service invokers uses a Read lock. This model
+* allows multiple threads to invoke the backed service concurrently, but the updating thread won't
+* update the dependency if it's currently in use.<p>
+* 
+* <b>This class only supports required dependencies, and temporal dependencies must be accessed outside
+* the Activator (OSGi) thread, because method invocations may block the caller thread when dependencies
+* are not satisfied.
+* </b>
+*
+* <p> Sample Code:<p>
+* <blockquote>
+* 
+* <pre>
+* import org.apache.felix.dependencymanager.*;
+* 
+* public class Activator extends DependencyActivatorBase {
+*   public void init(BundleContext ctx, DependencyManager dm) throws Exception {
+*     dm.add(createService()
+*            .setImplementation(MyServer.class)
+*        .add(createTemporalServiceDependency()
+*            .setService(MyDependency.class)
+*            .setTimeout(15000)));
+*   }
+* 
+*   public void destroy(BundleContext ctx, DependencyManager dm) throws Exception {
+*   }
+* }
+* 
+* class MyServer implements Runnable {
+*   MyDependency _dependency; // Auto-Injected by reflection.
+*   void start() {
+*     (new Thread(this)).start();
+*   }
+*   
+*   public void run() {
+*     try {
+*       _dependency.doWork();
+*     } catch (ServiceUnavailableException e) {
+*       t.printStackTrace();
+*     }
+*   }   
+* </pre>
+* 
+* </blockquote>
+*/
+public class TemporalServiceDependency extends ServiceDependency implements InvocationHandler {
+    // Max millis to wait for service availability.
+    private long m_timeout = 30000;
+
+    /**
+     * Creates a new Temporal Service Dependency.
+     * 
+     * @param context The bundle context of the bundle which is instantiating this dependency object
+     * @param logger the logger our Internal logger for logging events.
+     * @see DependencyActivatorBase#createTemporalServiceDependency()
+     */
+    public TemporalServiceDependency(BundleContext context, Logger logger) {
+        super(context, logger);
+        super.setRequired(true);
+    }
+
+    /**
+     * Sets the timeout for this temporal dependency. Specifying a timeout value of zero means that there is no timeout period,
+     * and an invocation on a missing service will fail immediately.
+     * 
+     * @param timeout the dependency timeout value greater or equals to 0
+     * @throws IllegalArgumentException if the timeout is negative
+     * @return this temporal dependency
+     */
+    public TemporalServiceDependency setTimeout(long timeout) {
+        if (timeout < 0) {
+            throw new IllegalArgumentException("Invalid timeout value: " + timeout);
+        }
+        m_timeout = timeout;
+        return this;
+    }
+
+    /**
+     * The ServiceTracker calls us here in order to inform about a service arrival.
+     */
+    public synchronized void addedService(ServiceReference ref, Object service) {
+        boolean makeAvailable = makeAvailable();
+        if (makeAvailable) {
+            m_serviceInstance = Proxy.newProxyInstance(m_trackedServiceName.getClassLoader(), new Class[] { m_trackedServiceName }, this);
+        }
+        Object[] services = m_services.toArray();
+        for (int i = 0; i < services.length; i++) {
+            DependencyService ds = (DependencyService) services[i];
+            if (makeAvailable) {
+                ds.dependencyAvailable(this);
+            }
+        }
+        if (!makeAvailable) {
+            notifyAll();
+        }
+    }
+
+    /**
+     * The ServiceTracker calls us here when a tracked service properties are modified.
+     */
+    public void modifiedService(ServiceReference ref, Object service) {
+        // We don't care.
+    }
+
+    /**
+     * The ServiceTracker calls us here when a tracked service is lost.
+     */
+    public synchronized void removedService(ServiceReference ref, Object service) {
+        // Unget what we got in addingService (see ServiceTracker 701.4.1)
+        m_context.ungetService(ref);
+    }
+
+    /**
+     * @returns our dependency instance. Unlike in ServiceDependency, we always returns our proxy.
+     */
+    public synchronized Object getService() {
+        return m_serviceInstance;
+    }
+
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        Object service = m_tracker.getService();
+        if (service == null) {
+            synchronized (this) {
+                long start = System.currentTimeMillis();
+                long waitTime = m_timeout;
+                while (service == null) {
+                    if (waitTime <= 0) {
+                        throw new IllegalStateException("Service unavailable: " + m_trackedServiceName.getName());
+                    }
+                    try {
+                        wait(waitTime);
+                    }
+                    catch (InterruptedException e) {
+                        throw new IllegalStateException("Service unavailable: " + m_trackedServiceName.getName());
+                    }
+                    waitTime = m_timeout - (System.currentTimeMillis() - start);
+                    service = m_tracker.getService();
+                }
+            }
+        }
+        try {
+            return method.invoke(service, args);
+        }
+        catch (IllegalAccessException iae) {
+            method.setAccessible(true);
+            return method.invoke(service, args);
+        }
+    }
+}