ipojo/core/src/main/java/org/apache/felix/ipojo/handlers/dependency/DependencyHandler.java - onos-felix - Gitiles

 /*
  * 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.ipojo.handlers.dependency;

 import java.util.Comparator;
 import java.util.Dictionary;

 import org.apache.felix.ipojo.ConfigurationException;
 import org.apache.felix.ipojo.IPojoContext;
 import org.apache.felix.ipojo.PolicyServiceContext;
 import org.apache.felix.ipojo.PrimitiveHandler;
 import org.apache.felix.ipojo.architecture.HandlerDescription;
 import org.apache.felix.ipojo.metadata.Element;
 import org.apache.felix.ipojo.parser.FieldMetadata;
 import org.apache.felix.ipojo.parser.MethodMetadata;
 import org.apache.felix.ipojo.parser.PojoMetadata;
 import org.apache.felix.ipojo.util.DependencyModel;
 import org.apache.felix.ipojo.util.DependencyStateListener;
 import org.osgi.framework.BundleContext;
 import org.osgi.framework.Filter;
 import org.osgi.framework.InvalidSyntaxException;
 import org.osgi.framework.ServiceReference;

 /**
  * The dependency handler manages a list of service dependencies.
  * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
  */
 public class DependencyHandler extends PrimitiveHandler implements DependencyStateListener {

     /**
      * List of dependencies of the component.
      */
     private Dependency[] m_dependencies = new Dependency[0];

     /**
      * Is the handler started.
      */
     private boolean m_started;

     /**
      * Add a dependency.
      * @param dep : the dependency to add
      */
     private void addDependency(Dependency dep) {
         for (int i = 0; m_dependencies != null && i < m_dependencies.length; i++) {
             if (m_dependencies[i] == dep) {
                 return;
             }
         }
         if (m_dependencies == null) {
             m_dependencies = new Dependency[] { dep };
         } else {
             Dependency[] newDep = new Dependency[m_dependencies.length + 1];
             System.arraycopy(m_dependencies, 0, newDep, 0, m_dependencies.length);
             newDep[m_dependencies.length] = dep;
             m_dependencies = newDep;
         }
     }

     /**
      * Get the list of managed dependency.
      * @return the dependency list
      */
     public Dependency[] getDependencies() {
         return m_dependencies;
     }

     /**
      * Validate method. This method is invoked by an AbstractServiceDependency when this dependency becomes RESOLVED.
      * @param dep : the dependency becoming RESOLVED.
      * @see org.apache.felix.ipojo.util.DependencyStateListener#validate(org.apache.felix.ipojo.util.DependencyModel)
      */
     public void validate(DependencyModel dep) {
         checkContext();
     }

     /**
      * Invalidate method. This method is invoked by an AbstractServiceDependency when this dependency becomes UNRESOLVED or BROKEN.
      * @param dep : the dependency becoming UNRESOLVED or BROKEN.
      * @see org.apache.felix.ipojo.util.DependencyStateListener#invalidate(org.apache.felix.ipojo.util.DependencyModel)
      */
     public void invalidate(DependencyModel dep) {
         setValidity(false);
     }

     /**
      * Check the validity of the dependencies.
      */
     protected void checkContext() {
         if (!m_started) {
             return;
         }
         synchronized (m_dependencies) {
             // Store the initial state
             boolean initialState = getValidity();

             boolean valid = true;
             for (int i = 0; i < m_dependencies.length; i++) {
                 Dependency dep = m_dependencies[i];
                 if (dep.getState() != Dependency.RESOLVED) {
                     valid = false;
                     break;
                 }
             }

             // Check the component dependencies
             if (valid) {
                 // The dependencies are valid
                 if (!initialState) {
                     // There is a state change
                     setValidity(true);
                 }
                 // Else do nothing, the component state stay VALID
             } else {
                 // The dependencies are not valid
                 if (initialState) {
                     // There is a state change
                     setValidity(false);
                 }
                 // Else do nothing, the component state stay UNRESOLVED
             }

         }
     }

     /**
      * Check if the dependency given is valid in the sense that metadata are consistent.
      * @param dep : the dependency to check
      * @param manipulation : the component-type manipulation metadata
      * @return true if the dependency is valid
      * @throws ConfigurationException : the checked dependency is not correct
      */
     private boolean checkDependency(Dependency dep, PojoMetadata manipulation) throws ConfigurationException {
         // Check the internal type of dependency
         String field = dep.getField();
         DependencyCallback[] callbacks = dep.getCallbacks();

         if (callbacks == null && field == null) {
             throw new ConfigurationException("A service requirement requires at least callbacks or a field");
         }

         for (int i = 0; callbacks != null && i < callbacks.length; i++) {
             MethodMetadata[] mets = manipulation.getMethods(callbacks[i].getMethodName());
             if (mets.length == 0) {
                 info("A requirement callback " + callbacks[i].getMethodName() + " does not exist in the implementation, try the super classes");
             } else {
                 if (mets[0].getMethodArguments().length > 2) {
                     throw new ConfigurationException("Requirement Callback : A requirement callback "
                             + callbacks[i].getMethodName()
                             + " must have 0 or 1 or 2 arguments");
                 }

                 callbacks[i].setArgument(mets[0].getMethodArguments());

                 if (mets[0].getMethodArguments().length == 1) {
                     if (!mets[0].getMethodArguments()[0].equals(ServiceReference.class.getName())) {
                         // The callback receives the service object.
                         setSpecification(dep, mets[0].getMethodArguments()[0], false); // Just warn if a mismatch is discovered.
                     }
                 } else if (mets[0].getMethodArguments().length == 2) {
                     // The callback receives service object, service reference. Check that the second argument is a service reference
                     if (!mets[0].getMethodArguments()[1].equals(ServiceReference.class.getName())) {
                         String message =
                                 "The requirement callback " + callbacks[i].getMethodName() + " must have a ServiceReference as the second argument";
                         throw new ConfigurationException(message);
                     }
                     setSpecification(dep, mets[0].getMethodArguments()[0], false); // Just warn if a mismatch is discovered.
                 }
             }

         }

         if (field != null) {
             FieldMetadata meta = manipulation.getField(field);
             if (meta == null) {
                 throw new ConfigurationException("Requirement Callback : A requirement field "
                         + field
                         + " does not exist in the implementation class");
             }
             String type = meta.getFieldType();
             if (type.endsWith("[]")) {
                 // Set the dependency to multiple
                 dep.setAggregate(true);
                 type = type.substring(0, type.length() - 2);
             } else {
                 if (dep.isAggregate()) {
                     throw new ConfigurationException("A required service is not correct : the field "
                             + meta.getFieldName()
                             + " must be an array to support aggregate injections");
                 }
             }
             setSpecification(dep, type, true); // Throw an exception if the filed type mismatch.
         }

         // Check that all required info are set
         return dep.getSpecification() != null;
     }

     /**
      * Check if we have to set the dependency specification with the given class name.
      * @param dep : dependency to check
      * @param className : class name
      * @param error : set to true to throw an error if the set dependency specification and the given specification are different.
      * @throws ConfigurationException : the specification class cannot be loaded correctly
      */
     private void setSpecification(Dependency dep, String className, boolean error) throws ConfigurationException {
         // We have to set the dependency in two cases : either the dependency as no specification, or the specification is different from the given
         // one
         if (dep.getSpecification() == null || !dep.getSpecification().getName().equals(className)) {
             if (dep.getSpecification() != null) {
                 if (error) {
                     throw new ConfigurationException("A required service is not correct : the discoevered type ["
                             + className
                             + "] and the specified (or already discovered)  service interface ["
                             + dep.getSpecification().getName()
                             + "] are not the same");
                 } else {
                     // If the specification is different, warn that we will overide it.
                     warn("[DependencyHandler on "
                             + getInstanceManager().getInstanceName()
                             + "] The field type ["
                             + className
                             + "] and the needed service interface ["
                             + dep.getSpecification()
                             + "] are not the same");
                 }
             }
             try {
                 dep.setSpecification(getInstanceManager().getContext().getBundle().loadClass(className));
             } catch (ClassNotFoundException e) {
                 throw new ConfigurationException("The required service interface cannot be loaded : " + e.getMessage());
             }
         }
     }

     /**
      * Configure the handler.
      * @param componentMetadata : the component type metadata
      * @param configuration : the instance configuration
      * @throws ConfigurationException : one dependency metadata is not correct.
      * @see org.apache.felix.ipojo.Handler#configure(org.apache.felix.ipojo.InstanceManager, org.apache.felix.ipojo.metadata.Element,
      *      java.util.Dictionary)
      */
     public void configure(Element componentMetadata, Dictionary configuration) throws ConfigurationException {
         // getPojoMetadata();
         PojoMetadata manipulation = getFactory().getPojoMetadata();
         boolean atLeastOneField = false;

         // Create the dependency according to the component metadata
         Element[] deps = componentMetadata.getElements("Requires");

         // Get instance filters.
         Dictionary filtersConfiguration = (Dictionary) configuration.get("requires.filters");

         for (int i = 0; deps != null && i < deps.length; i++) {
             // Create the dependency metadata
             String field = deps[i].getAttribute("field");
             String serviceSpecification = deps[i].getAttribute("interface");
             String filter = deps[i].getAttribute("filter");
             String opt = deps[i].getAttribute("optional");
             boolean optional = opt != null && opt.equalsIgnoreCase("true");
             String defaultImplem = deps[i].getAttribute("default-implementation");

             String agg = deps[i].getAttribute("aggregate");
             boolean aggregate = agg != null && agg.equalsIgnoreCase("true");
             String identitity = deps[i].getAttribute("id");

             String nul = deps[i].getAttribute("nullable");
             boolean nullable = nul == null || nul.equalsIgnoreCase("true");

             String scope = deps[i].getAttribute("scope");
             BundleContext context = getInstanceManager().getContext(); // Get the default bundle context.
             if (scope != null) {
                 // If we are not in a composite, the policy is set to global.
                 if (scope.equalsIgnoreCase("global") || ((((IPojoContext) getInstanceManager().getContext()).getServiceContext()) == null)) {
                     context =
                             new PolicyServiceContext(getInstanceManager().getGlobalContext(), getInstanceManager().getLocalServiceContext(),
                                     PolicyServiceContext.GLOBAL);
                 } else if (scope.equalsIgnoreCase("composite")) {
                     context =
                             new PolicyServiceContext(getInstanceManager().getGlobalContext(), getInstanceManager().getLocalServiceContext(),
                                     PolicyServiceContext.LOCAL);
                 } else if (scope.equalsIgnoreCase("composite+global")) {
                     context =
                             new PolicyServiceContext(getInstanceManager().getGlobalContext(), getInstanceManager().getLocalServiceContext(),
                                     PolicyServiceContext.LOCAL_AND_GLOBAL);
                 }
             }

             // Get instance filter if available
             if (filtersConfiguration != null && identitity != null && filtersConfiguration.get(identitity) != null) {
                 filter = (String) filtersConfiguration.get(identitity);
             }

             Filter fil = null;
             if (filter != null) {
                 try {
                     fil = getInstanceManager().getContext().createFilter(filter);
                 } catch (InvalidSyntaxException e) {
                     throw new ConfigurationException("A requirement filter is invalid : " + filter + " - " + e.getMessage());
                 }
             }

             Class spec = null;
             if (serviceSpecification != null) {
                 spec = DependencyModel.loadSpecification(serviceSpecification, getInstanceManager().getContext());
             }

             int policy = DependencyModel.getPolicy(deps[i]);
             Comparator cmp = DependencyModel.getComparator(deps[i], getInstanceManager().getGlobalContext());
             Dependency dep = new Dependency(this, field, spec, fil, optional, aggregate, nullable, identitity, context, policy, cmp, defaultImplem);

             // Look for dependency callback :
             Element[] cbs = deps[i].getElements("Callback");
             for (int j = 0; cbs != null && j < cbs.length; j++) {
                 if (!cbs[j].containsAttribute("method") && cbs[j].containsAttribute("type")) {
                     throw new ConfigurationException("Requirement Callback : a dependency callback must contain a method and a type attribute");
                 }
                 String method = cbs[j].getAttribute("method");
                 String type = cbs[j].getAttribute("type");
                 int methodType = 0;
                 if ("bind".equalsIgnoreCase(type)) {
                     methodType = DependencyCallback.BIND;
                 } else {
                     methodType = DependencyCallback.UNBIND;
                 }

                 DependencyCallback callback = new DependencyCallback(dep, method, methodType);
                 dep.addDependencyCallback(callback);
             }

             // Check the dependency :
             if (checkDependency(dep, manipulation)) {
                 addDependency(dep);
                 if (dep.getField() != null) {
                     getInstanceManager().register(manipulation.getField(dep.getField()), dep);
                     atLeastOneField = true;
                 }
             }
         }

         if (atLeastOneField) { // Does register only if we have fields
             MethodMetadata[] methods = manipulation.getMethods();
             for (int i = 0; i < methods.length; i++) {
                 for (int j = 0; j < m_dependencies.length; j++) {
                     getInstanceManager().register(methods[i], m_dependencies[j]);
                 }
             }
         }
     }

 //    /**
 //     * GetterCallback Method.
 //     * @param pojo : the pojo object on which the field is accessed
 //     * @param fieldName : the field name.
 //     * @param value : the value passed to the field (by the previous handler).
 //     * @return the object that the dependency handler want to push.
 //     * @see org.apache.felix.ipojo.Handler#onGet(Object, java.lang.String, java.lang.Object)
 //     */
 //    public Object onGet(Object pojo, String fieldName, Object value) {
 //        for (int i = 0; i < m_dependencies.length; i++) {
 //            Dependency dep = m_dependencies[i];
 //            if (fieldName.equals(dep.getField())) {
 //                // The field name is a dependency, return the get
 //                return dep.get();
 //            }
 //        }
 //        // Else return the value
 //        return value;
 //    }

     /**
      * Handler start method.
      * @see org.apache.felix.ipojo.Handler#start()
      */
     public void start() {
         // Start the dependencies
         for (int i = 0; i < m_dependencies.length; i++) {
             Dependency dep = m_dependencies[i];
             dep.start();
         }
         // Check the state
         m_started = true;
         setValidity(false);
         checkContext();
     }

     /**
      * Handler stop method.
      * @see org.apache.felix.ipojo.Handler#stop()
      */
     public void stop() {
         m_started = false;
         for (int i = 0; i < m_dependencies.length; i++) {
             m_dependencies[i].stop();
         }
     }

     /**
      * Handler createInstance method. This method is override to allow delayed callback invocation.
      * @param instance : the created object
      * @see org.apache.felix.ipojo.Handler#onCreation(java.lang.Object)
      */
     public void onCreation(Object instance) {
         for (int i = 0; i < m_dependencies.length; i++) {
             m_dependencies[i].onObjectCreation(instance);
         }
     }

     /**
      * Get the dependency handler description.
      * @return the dependency handler description.
      * @see org.apache.felix.ipojo.Handler#getDescription()
      */
     public HandlerDescription getDescription() {
         DependencyHandlerDescription dhd = new DependencyHandlerDescription(this);
         for (int j = 0; j < getDependencies().length; j++) {
             Dependency dep = getDependencies()[j];
             // Create & add the dependency description
             DependencyDescription desc =
                     new DependencyDescription(dep.getSpecification().getName(), dep.isAggregate(), dep.isOptional(), dep.getFilter(), dep.getBindingPolicy(), dep.supportsNullable(), dep.getDefaultImplementation(), dep.getComparator(), dep.isFrozen(), dep.getState());
             desc.setServiceReferences(dep.getServiceReferencesAsList());
             desc.setUsedServices(dep.getUsedServiceReferences());
             dhd.addDependency(desc);
         }
         return dhd;
     }

 }
	/*
	* 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.ipojo.handlers.dependency;

	import java.util.Comparator;
	import java.util.Dictionary;

	import org.apache.felix.ipojo.ConfigurationException;
	import org.apache.felix.ipojo.IPojoContext;
	import org.apache.felix.ipojo.PolicyServiceContext;
	import org.apache.felix.ipojo.PrimitiveHandler;
	import org.apache.felix.ipojo.architecture.HandlerDescription;
	import org.apache.felix.ipojo.metadata.Element;
	import org.apache.felix.ipojo.parser.FieldMetadata;
	import org.apache.felix.ipojo.parser.MethodMetadata;
	import org.apache.felix.ipojo.parser.PojoMetadata;
	import org.apache.felix.ipojo.util.DependencyModel;
	import org.apache.felix.ipojo.util.DependencyStateListener;
	import org.osgi.framework.BundleContext;
	import org.osgi.framework.Filter;
	import org.osgi.framework.InvalidSyntaxException;
	import org.osgi.framework.ServiceReference;

	/**
	* The dependency handler manages a list of service dependencies.
	* @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
	*/
	public class DependencyHandler extends PrimitiveHandler implements DependencyStateListener {

	/**
	* List of dependencies of the component.
	*/
	private Dependency[] m_dependencies = new Dependency[0];

	/**
	* Is the handler started.
	*/
	private boolean m_started;

	/**
	* Add a dependency.
	* @param dep : the dependency to add
	*/
	private void addDependency(Dependency dep) {
	for (int i = 0; m_dependencies != null && i < m_dependencies.length; i++) {
	if (m_dependencies[i] == dep) {
	return;
	}
	}
	if (m_dependencies == null) {
	m_dependencies = new Dependency[] { dep };
	} else {
	Dependency[] newDep = new Dependency[m_dependencies.length + 1];
	System.arraycopy(m_dependencies, 0, newDep, 0, m_dependencies.length);
	newDep[m_dependencies.length] = dep;
	m_dependencies = newDep;
	}
	}

	/**
	* Get the list of managed dependency.
	* @return the dependency list
	*/
	public Dependency[] getDependencies() {
	return m_dependencies;
	}

	/**
	* Validate method. This method is invoked by an AbstractServiceDependency when this dependency becomes RESOLVED.
	* @param dep : the dependency becoming RESOLVED.
	* @see org.apache.felix.ipojo.util.DependencyStateListener#validate(org.apache.felix.ipojo.util.DependencyModel)
	*/
	public void validate(DependencyModel dep) {
	checkContext();
	}

	/**
	* Invalidate method. This method is invoked by an AbstractServiceDependency when this dependency becomes UNRESOLVED or BROKEN.
	* @param dep : the dependency becoming UNRESOLVED or BROKEN.
	* @see org.apache.felix.ipojo.util.DependencyStateListener#invalidate(org.apache.felix.ipojo.util.DependencyModel)
	*/
	public void invalidate(DependencyModel dep) {
	setValidity(false);
	}

	/**
	* Check the validity of the dependencies.
	*/
	protected void checkContext() {
	if (!m_started) {
	return;
	}
	synchronized (m_dependencies) {
	// Store the initial state
	boolean initialState = getValidity();

	boolean valid = true;
	for (int i = 0; i < m_dependencies.length; i++) {
	Dependency dep = m_dependencies[i];
	if (dep.getState() != Dependency.RESOLVED) {
	valid = false;
	break;
	}
	}

	// Check the component dependencies
	if (valid) {
	// The dependencies are valid
	if (!initialState) {
	// There is a state change
	setValidity(true);
	}
	// Else do nothing, the component state stay VALID
	} else {
	// The dependencies are not valid
	if (initialState) {
	// There is a state change
	setValidity(false);
	}
	// Else do nothing, the component state stay UNRESOLVED
	}

	}
	}

	/**
	* Check if the dependency given is valid in the sense that metadata are consistent.
	* @param dep : the dependency to check
	* @param manipulation : the component-type manipulation metadata
	* @return true if the dependency is valid
	* @throws ConfigurationException : the checked dependency is not correct
	*/
	private boolean checkDependency(Dependency dep, PojoMetadata manipulation) throws ConfigurationException {
	// Check the internal type of dependency
	String field = dep.getField();
	DependencyCallback[] callbacks = dep.getCallbacks();

	if (callbacks == null && field == null) {
	throw new ConfigurationException("A service requirement requires at least callbacks or a field");
	}

	for (int i = 0; callbacks != null && i < callbacks.length; i++) {
	MethodMetadata[] mets = manipulation.getMethods(callbacks[i].getMethodName());
	if (mets.length == 0) {
	info("A requirement callback " + callbacks[i].getMethodName() + " does not exist in the implementation, try the super classes");
	} else {
	if (mets[0].getMethodArguments().length > 2) {
	throw new ConfigurationException("Requirement Callback : A requirement callback "
	+ callbacks[i].getMethodName()
	+ " must have 0 or 1 or 2 arguments");
	}

	callbacks[i].setArgument(mets[0].getMethodArguments());

	if (mets[0].getMethodArguments().length == 1) {
	if (!mets[0].getMethodArguments()[0].equals(ServiceReference.class.getName())) {
	// The callback receives the service object.
	setSpecification(dep, mets[0].getMethodArguments()[0], false); // Just warn if a mismatch is discovered.
	}
	} else if (mets[0].getMethodArguments().length == 2) {
	// The callback receives service object, service reference. Check that the second argument is a service reference
	if (!mets[0].getMethodArguments()[1].equals(ServiceReference.class.getName())) {
	String message =
	"The requirement callback " + callbacks[i].getMethodName() + " must have a ServiceReference as the second argument";
	throw new ConfigurationException(message);
	}
	setSpecification(dep, mets[0].getMethodArguments()[0], false); // Just warn if a mismatch is discovered.
	}
	}

	}

	if (field != null) {
	FieldMetadata meta = manipulation.getField(field);
	if (meta == null) {
	throw new ConfigurationException("Requirement Callback : A requirement field "
	+ field
	+ " does not exist in the implementation class");
	}
	String type = meta.getFieldType();
	if (type.endsWith("[]")) {
	// Set the dependency to multiple
	dep.setAggregate(true);
	type = type.substring(0, type.length() - 2);
	} else {
	if (dep.isAggregate()) {
	throw new ConfigurationException("A required service is not correct : the field "
	+ meta.getFieldName()
	+ " must be an array to support aggregate injections");
	}
	}
	setSpecification(dep, type, true); // Throw an exception if the filed type mismatch.
	}

	// Check that all required info are set
	return dep.getSpecification() != null;
	}

	/**
	* Check if we have to set the dependency specification with the given class name.
	* @param dep : dependency to check
	* @param className : class name
	* @param error : set to true to throw an error if the set dependency specification and the given specification are different.
	* @throws ConfigurationException : the specification class cannot be loaded correctly
	*/
	private void setSpecification(Dependency dep, String className, boolean error) throws ConfigurationException {
	// We have to set the dependency in two cases : either the dependency as no specification, or the specification is different from the given
	// one
	if (dep.getSpecification() == null \|\| !dep.getSpecification().getName().equals(className)) {
	if (dep.getSpecification() != null) {
	if (error) {
	throw new ConfigurationException("A required service is not correct : the discoevered type ["
	+ className
	+ "] and the specified (or already discovered) service interface ["
	+ dep.getSpecification().getName()
	+ "] are not the same");
	} else {
	// If the specification is different, warn that we will overide it.
	warn("[DependencyHandler on "
	+ getInstanceManager().getInstanceName()
	+ "] The field type ["
	+ className
	+ "] and the needed service interface ["
	+ dep.getSpecification()
	+ "] are not the same");
	}
	}
	try {
	dep.setSpecification(getInstanceManager().getContext().getBundle().loadClass(className));
	} catch (ClassNotFoundException e) {
	throw new ConfigurationException("The required service interface cannot be loaded : " + e.getMessage());
	}
	}
	}

	/**
	* Configure the handler.
	* @param componentMetadata : the component type metadata
	* @param configuration : the instance configuration
	* @throws ConfigurationException : one dependency metadata is not correct.
	* @see org.apache.felix.ipojo.Handler#configure(org.apache.felix.ipojo.InstanceManager, org.apache.felix.ipojo.metadata.Element,
	* java.util.Dictionary)
	*/
	public void configure(Element componentMetadata, Dictionary configuration) throws ConfigurationException {
	// getPojoMetadata();
	PojoMetadata manipulation = getFactory().getPojoMetadata();
	boolean atLeastOneField = false;

	// Create the dependency according to the component metadata
	Element[] deps = componentMetadata.getElements("Requires");

	// Get instance filters.
	Dictionary filtersConfiguration = (Dictionary) configuration.get("requires.filters");

	for (int i = 0; deps != null && i < deps.length; i++) {
	// Create the dependency metadata
	String field = deps[i].getAttribute("field");
	String serviceSpecification = deps[i].getAttribute("interface");
	String filter = deps[i].getAttribute("filter");
	String opt = deps[i].getAttribute("optional");
	boolean optional = opt != null && opt.equalsIgnoreCase("true");
	String defaultImplem = deps[i].getAttribute("default-implementation");

	String agg = deps[i].getAttribute("aggregate");
	boolean aggregate = agg != null && agg.equalsIgnoreCase("true");
	String identitity = deps[i].getAttribute("id");

	String nul = deps[i].getAttribute("nullable");
	boolean nullable = nul == null \|\| nul.equalsIgnoreCase("true");

	String scope = deps[i].getAttribute("scope");
	BundleContext context = getInstanceManager().getContext(); // Get the default bundle context.
	if (scope != null) {
	// If we are not in a composite, the policy is set to global.
	if (scope.equalsIgnoreCase("global") \|\| ((((IPojoContext) getInstanceManager().getContext()).getServiceContext()) == null)) {
	context =
	new PolicyServiceContext(getInstanceManager().getGlobalContext(), getInstanceManager().getLocalServiceContext(),
	PolicyServiceContext.GLOBAL);
	} else if (scope.equalsIgnoreCase("composite")) {
	context =
	new PolicyServiceContext(getInstanceManager().getGlobalContext(), getInstanceManager().getLocalServiceContext(),
	PolicyServiceContext.LOCAL);
	} else if (scope.equalsIgnoreCase("composite+global")) {
	context =
	new PolicyServiceContext(getInstanceManager().getGlobalContext(), getInstanceManager().getLocalServiceContext(),
	PolicyServiceContext.LOCAL_AND_GLOBAL);
	}
	}

	// Get instance filter if available
	if (filtersConfiguration != null && identitity != null && filtersConfiguration.get(identitity) != null) {
	filter = (String) filtersConfiguration.get(identitity);
	}

	Filter fil = null;
	if (filter != null) {
	try {
	fil = getInstanceManager().getContext().createFilter(filter);
	} catch (InvalidSyntaxException e) {
	throw new ConfigurationException("A requirement filter is invalid : " + filter + " - " + e.getMessage());
	}
	}

	Class spec = null;
	if (serviceSpecification != null) {
	spec = DependencyModel.loadSpecification(serviceSpecification, getInstanceManager().getContext());
	}

	int policy = DependencyModel.getPolicy(deps[i]);
	Comparator cmp = DependencyModel.getComparator(deps[i], getInstanceManager().getGlobalContext());
	Dependency dep = new Dependency(this, field, spec, fil, optional, aggregate, nullable, identitity, context, policy, cmp, defaultImplem);

	// Look for dependency callback :
	Element[] cbs = deps[i].getElements("Callback");
	for (int j = 0; cbs != null && j < cbs.length; j++) {
	if (!cbs[j].containsAttribute("method") && cbs[j].containsAttribute("type")) {
	throw new ConfigurationException("Requirement Callback : a dependency callback must contain a method and a type attribute");
	}
	String method = cbs[j].getAttribute("method");
	String type = cbs[j].getAttribute("type");
	int methodType = 0;
	if ("bind".equalsIgnoreCase(type)) {
	methodType = DependencyCallback.BIND;
	} else {
	methodType = DependencyCallback.UNBIND;
	}

	DependencyCallback callback = new DependencyCallback(dep, method, methodType);
	dep.addDependencyCallback(callback);
	}

	// Check the dependency :
	if (checkDependency(dep, manipulation)) {
	addDependency(dep);
	if (dep.getField() != null) {
	getInstanceManager().register(manipulation.getField(dep.getField()), dep);
	atLeastOneField = true;
	}
	}
	}

	if (atLeastOneField) { // Does register only if we have fields
	MethodMetadata[] methods = manipulation.getMethods();
	for (int i = 0; i < methods.length; i++) {
	for (int j = 0; j < m_dependencies.length; j++) {
	getInstanceManager().register(methods[i], m_dependencies[j]);
	}
	}
	}
	}

	// /**
	// * GetterCallback Method.
	// * @param pojo : the pojo object on which the field is accessed
	// * @param fieldName : the field name.
	// * @param value : the value passed to the field (by the previous handler).
	// * @return the object that the dependency handler want to push.
	// * @see org.apache.felix.ipojo.Handler#onGet(Object, java.lang.String, java.lang.Object)
	// */
	// public Object onGet(Object pojo, String fieldName, Object value) {
	// for (int i = 0; i < m_dependencies.length; i++) {
	// Dependency dep = m_dependencies[i];
	// if (fieldName.equals(dep.getField())) {
	// // The field name is a dependency, return the get
	// return dep.get();
	// }
	// }
	// // Else return the value
	// return value;
	// }

	/**
	* Handler start method.
	* @see org.apache.felix.ipojo.Handler#start()
	*/
	public void start() {
	// Start the dependencies
	for (int i = 0; i < m_dependencies.length; i++) {
	Dependency dep = m_dependencies[i];
	dep.start();
	}
	// Check the state
	m_started = true;
	setValidity(false);
	checkContext();
	}

	/**
	* Handler stop method.
	* @see org.apache.felix.ipojo.Handler#stop()
	*/
	public void stop() {
	m_started = false;
	for (int i = 0; i < m_dependencies.length; i++) {
	m_dependencies[i].stop();
	}
	}

	/**
	* Handler createInstance method. This method is override to allow delayed callback invocation.
	* @param instance : the created object
	* @see org.apache.felix.ipojo.Handler#onCreation(java.lang.Object)
	*/
	public void onCreation(Object instance) {
	for (int i = 0; i < m_dependencies.length; i++) {
	m_dependencies[i].onObjectCreation(instance);
	}
	}

	/**
	* Get the dependency handler description.
	* @return the dependency handler description.
	* @see org.apache.felix.ipojo.Handler#getDescription()
	*/
	public HandlerDescription getDescription() {
	DependencyHandlerDescription dhd = new DependencyHandlerDescription(this);
	for (int j = 0; j < getDependencies().length; j++) {
	Dependency dep = getDependencies()[j];
	// Create & add the dependency description
	DependencyDescription desc =
	new DependencyDescription(dep.getSpecification().getName(), dep.isAggregate(), dep.isOptional(), dep.getFilter(), dep.getBindingPolicy(), dep.supportsNullable(), dep.getDefaultImplementation(), dep.getComparator(), dep.isFrozen(), dep.getState());
	desc.setServiceReferences(dep.getServiceReferencesAsList());
	desc.setUsedServices(dep.getUsedServiceReferences());
	dhd.addDependency(desc);
	}
	return dhd;
	}

	}