RemoteService.java

/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2015 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   Granite Data Services is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 *   General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */
package org.granite.client.messaging;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;

import org.granite.client.messaging.channel.Channel;
import org.granite.client.messaging.channel.ResponseMessageFuture;
import org.granite.client.messaging.messages.requests.InvocationMessage;

/**
 * RemoteService allows to call a remote service using RPC style
 * Calling a service is asynchronous and won't block the thread initiating the call.
 *
 * <pre>
 * {@code
 * RemoteService remoteService = new RemoteService(remotingChannel, "myService");
 * remoteService.newInvocation("myMethod", arg1, arg2).invoke();
 * }
 * </pre>
 *
 * It is also possible to chain multiple invocations in one single call:
 *
 * <pre>
 * {@code
 * RemoteService remoteService = new RemoteService(remotingChannel, "myService");
 * remoteService.newInvocation("myMethod", arg1, arg2).appendInvocation("myMethod2", arg3).invoke();
 * }
 * </pre>
 *
 * @author Franck WOLFF
 */
public class RemoteService {

	private final Channel channel;
	private final String id;

    /**
     * Create a remote service for the specified channel and destination
     * @param channel messaging channel
     * @param id remote destination name
     */
	public RemoteService(Channel channel, String id) {
		if (channel == null || id == null)
			throw new NullPointerException("channel and id cannot be null");
		this.channel = channel;
		this.id = id;
	}

    /**
     * Remoting channel
     * @return channel
     */
	public Channel getChannel() {
		return channel;
	}

    /**
     * Destination id
     * @return destination id
     */
	public String getId() {
		return id;
	}

    /**
     * Create an invocation for this service
     * @param method remote method name
     * @param parameters arguments to send
     * @return fluent invocation object
     */
	public RemoteServiceInvocation newInvocation(String method, Object...parameters) {
		return new RemoteServiceInvocation(this, method, parameters);
	}
	
	public static interface RemoteServiceInvocationChain {

        /**
         * Append a new invocation to the current chain of invocations
         * @param method remote method name
         * @param parameters arguments to send
         * @return fluent invocation object
         */
		RemoteServiceInvocationChain appendInvocation(String method, Object...parameters);

        /**
         * Execute the chain of invocations
         * @return future that will be triggered when the chain of invocations has been processed
         */
		ResponseMessageFuture invoke();
	}
	
	public static class RemoteServiceInvocation implements RemoteServiceInvocationChain {
		
		private final RemoteService remoteService;
		private final InvocationMessage request;
		
		private long timeToLive = 0L;
		private List<ResponseListener> listeners = new ArrayList<ResponseListener>();
		
		public RemoteServiceInvocation(RemoteService remoteService, String method, Object...parameters) {
			if (remoteService == null)
				throw new NullPointerException("remoteService cannot be null");
			this.remoteService = remoteService;
			this.request = new InvocationMessage(null, remoteService.id, method, parameters);
		}

        /**
         * Register a listener for the current invocation
         * @param listener listener
         * @return fluent invocation object
         */
		public RemoteServiceInvocation addListener(ResponseListener listener) {
			if (listener != null)
				this.listeners.add(listener);
			return this;
		}

        /**
         * Registers many listeners for the current invocation
         * @param listeners array of listener
         * @return fluent invocation object
         */
		public RemoteServiceInvocation addListeners(ResponseListener...listeners) {
			if (listeners != null && listeners.length > 0)
				this.listeners.addAll(Arrays.asList(listeners));
			return this;
		}

        /**
         * Set the time to live for the current invocation
         * @param timeToLiveMillis time to live in milliseconds
         * @return fluent invocation object
         */
		public RemoteServiceInvocation setTimeToLive(long timeToLiveMillis) {
			return setTimeToLive(timeToLiveMillis, TimeUnit.MILLISECONDS);
		}

        /**
         * Set the time to live in any unit for the current invocation
         * @param timeToLive time to live value
         * @param unit time to live unit
         * @return fluent invocation object
         */
		public RemoteServiceInvocation setTimeToLive(long timeToLive, TimeUnit unit) {
			if (timeToLive < 0)
				throw new IllegalArgumentException("timeToLive cannot be negative");
			if (unit == null)
				throw new NullPointerException("unit cannot be null");
			this.timeToLive = unit.toMillis(timeToLive);
			return this;
		}

		@Override
		public RemoteServiceInvocationChain appendInvocation(String method, Object...parameters) {
			InvocationMessage message = request;
			while (message.getNext() != null)
				message = message.getNext();
			message.setNext(new InvocationMessage(null, remoteService.id, method, parameters));
			return this;
		}
		
		@Override
		public ResponseMessageFuture invoke() {
			request.setTimeToLive(timeToLive);
			return remoteService.channel.send(request, listeners.toArray(new ResponseListener[listeners.size()]));
		}
	}
}