package org.wamblee.system;

/**
 * A component represents a part of a system that requires a 
 * number of interfaces and provides a number of interfaces. 
 *
 * @author Erik Brakkee
 */
public interface Component {
	
	enum Status { 
		NOT_STARTED, RUNNING, STOPPED
	}
	
	/**
	 * Gets the status of the component. 
	 * @return Status. 
	 */
	Status getStatus();
	
	/**
	 * Gets the name of the subsystem.
	 * @return Subsystem name. 
	 */
	String getName();

	/**
	 * Gets a description of the provided interfaces. 
	 * @return Provided interfaces. 
	 */
	ProvidedInterfaceDescriptor[] getProvidedServices();
	
	/**
	 * Gets a description of the required interfaces. 
	 * @return Required interfaces. 
	 */
	RequiredInterfaceDescriptor[] getRequiredServices();

	
	/**
	 * Initialises the subsytem by starting all the services that
	 * it described as provided. 
	 * @param aContext Unique name for the subsystem. 
	 * @param aRequiredServices Running services from other 
	 * subsystems that are required by this subsystem. 
	 * @return Services that are running in the subsystem. 
	 */
	Service[] start(String aContext, Service[] aRequiredServices);
	
	/**
	 * Stops a subsystem. 
	 */
	void stop(); 
	
	/**
	 * Gets the list of running services in the subsystem. 
	 * 
	 * This method may only be called after the
	 * {@link #initialize(String, Service[])} has been called. 
	 * @return
	 */
	Service[] getRunningServices();
}