Subject.java

/*******************************************************************************
 * Copyright (c) 2013 Steve Flasby
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * <ul>
 *     <li>Redistributions of source code must retain the above copyright notice,
 *         this list of conditions and the following disclaimer.</li>
 *     <li>Redistributions in binary form must reproduce the above copyright notice,
 *         this list of conditions and the following disclaimer in the documentation
 *         and/or other materials provided with the distribution.</li>
 * </ul>
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *******************************************************************************/
package org.flasby.bus;

import java.lang.reflect.ParameterizedType;
import java.util.HashSet;
import java.util.Set;

import org.flasby.bus.PageBus.MessageVolatility;
import org.flasby.bus.PageBus.Subscriber;
import org.flasby.bus.PageBus.Subscription;
import org.flasby.util.DefaultConvertor;

public class Subject<T> {
	
	private static Set<String> IDs = new HashSet<>();
	
	private final String id;

	public Subject(String id) {
		this.id = id;
		if ( ! IDs.add(id) ) {
			System.err.println("Subject error: non-unique subject ("+id+") registered - expect problems with your publishing.");
		}
	}

	public Subject(Subject<?> parent, String id) {
		this.id = parent.getId() + "." + id;
	}

	public void send(T msg) {
		send( msg, MessageVolatility.NON_VOLATILE);
	}
	public void send(T msg, MessageVolatility volatility) {
		PageBus.getGlobalInstance().publish(getId(), msg, volatility);
	}

	public String getId() {
		return id;
	}
	
	public static interface Delivery<T> {
		public void deliver(T delivery);
	}
	
	@SuppressWarnings("unchecked")
	protected T convert( Delivery<T> delivery, Object publication ) {
		Class<?> dest = (Class<?>)((ParameterizedType)delivery.getClass().getGenericInterfaces()[0]).getActualTypeArguments()[0];
		Class<?> source = publication.getClass();
		return (T)DefaultConvertor.find(source, dest).convert(publication);
	}
	
	public Subscription subscribe(final Delivery<T> delivery) {
		return PageBus.getGlobalInstance().subscribe(getId(), new Subscriber() {
			@Override
			public void receive(String sourceAddress, Object publication) {
				delivery.deliver( convert(delivery, publication) );
			}
		});
	}
}