EventProvider.java

/*******************************************************************************
 * Mission Control Technologies, Copyright (c) 2009-2012, United States Government
 * as represented by the Administrator of the National Aeronautics and Space 
 * Administration. All rights reserved.
 *
 * The MCT platform is 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.
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package gov.nasa.arc.mct.event.services;

import java.util.Collection;


/**
 * A service that can send events once topics have been subscribed to.
 * 
 * <p>Services that generate events without needing subscription do
 * not need to implement this interface.
 * 
 * @author mrose
 */
public interface EventProvider {
	/**
	 * This represents the prefix used for subscriptions. The subscription id follows this
	 * string and can be used to actually do the subscription. 
	 */
	public static final String TELEMETRY_TOPIC_PREFIX = "gov/nasa/arc/telemetry/id/";

	/**
	 * Attempt to subscribe to events on the given topic. Return an
	 * indication of whether the subscription succeeded.
	 * 
	 * @param topics to subscribe to
	 * @return topics subscribed to
	 */
	Collection<String> subscribeTopics(String... topic);
	
	/**
	 * Stop subscribing to events on the given topic.
	 * 
	 * @param topic the topic no longer being subscribed to
	 */
	void unsubscribeTopics(String... topic);
	
	/**
	 * Refresh the subscription.
	 */
	public void refresh();
}