src/main/java/org/apache/felix/dependencymanager/ConfigurationDependency.java

/*
 * 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;

/**
 * Configuration dependency that can track the availability of a (valid) configuration.
 * To use it, specify a PID for the configuration. The dependency is always required,
 * because if it is not, it does not make sense to use the dependency manager. In that
 * scenario, simply register your service as a <code>ManagedService(Factory)</code> and
 * handle everything yourself. Also, only managed services are supported, not factories.
 * There are a couple of things you need to be aware of when implementing the
 * <code>updated(Dictionary)</code> method:
 * <ul>
 * <li>Make sure it throws a <code>ConfigurationException</code> when you get a
 * configuration that is invalid. In this case, the dependency will not change:
 * if it was not available, it will still not be. If it was available, it will
 * remain available and implicitly assume you keep working with your old
 * configuration.</li>
 * <li>This method will be called before all required dependencies are available.
 * Make sure you do not depend on these to parse your settings.</li>
 * </ul>
 * 
 * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
 */
public abstract class ConfigurationDependency implements Dependency {
    /**
     * Sets a callback which will be invoked when the configuration is available.
     * The method may take in parameter a Dictionary and may also throw a 
     * ConfigurationException.
     * @param callback the callback to invoke when the configuration is available
     * @return this dependency.
     */
	public abstract ConfigurationDependency setCallback(String callback);

	/**
	 * Sets the <code>service.pid</code> of the configuration you
	 * are depending on.
	 */
	public abstract ConfigurationDependency setPid(String pid);

	/**
	 * Sets propagation of the configuration properties to the service
	 * properties. Any additional service properties specified directly
	 * are merged with these.
	 */
	public abstract ConfigurationDependency setPropagate(boolean propagate);

	public abstract boolean isAvailable();

	public abstract boolean isRequired();
}