/*
 * Copyright 2007 the original author or authors.
 * 
 * Licensed 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.wamblee.system.core;

/**
 * A component represents a part of a system that requires a 
 * number of interfaces and provides a number of interfaces.
 * 
 * The component interface provides the meta-data for a component. 
 * After calling {@link #start(Scope)}, an actual runtime representation of the
 * component can be created which is independent of this component. 
 * As a special case, the runtime representation may be identical to the 
 * component instance but in general it is not. This allows a component to be 
 * used as a factory for creating objects. 
 * 
 *
 * @author Erik Brakkee
 */
public interface Component<Type> {
	
	/**
	 * Gets the name of the subsystem.
	 * @return Subsystem name. 
	 */
	String getName();
	
	/**
	 * Prepends the context with a super context. 
	 */
	void addContext(String aContext);
	
	/**
	 * Gets the fully qualified name of the component which includes
	 * the context of the component.  
	 * This method can only be used after the component has started.
	 * @return Qualified name. 
	 */
	String getQualifiedName(); 

	/**
	 * Gets a description of the provided interfaces. 
	 * @return Provided interfaces. 
	 */
	ProvidedInterface[] getProvidedInterfaces();
	
	/**
	 * Gets a description of the required interfaces. 
	 * @return Required interfaces. 
	 */
	RequiredInterface[] getRequiredInterfaces();

	
	/**
	 * Initialises the subsystem by starting all the services that
	 * it described as provided.
	 * @param aScope Scope with external interface implementations that are available. The component 
	 *  implementation can either oublish itself in this scope or it can decide to
	 *  create a new scope with the scope passed in as a parent. 
	 * @return Gets an object representing the runtime of the component.  
	 */
	Type start(Scope aScope);
	
	/**
	 * Stops a component. 
	 * @param aRuntime THe runtime part of the component.  
	 */
	void stop(Type aRuntime); 
}