//******************************************************************************
//
// File:    Proxy.java
// Package: edu.rit.pj.cluster
// Unit:    Class edu.rit.pj.cluster.Proxy
//
// This Java source file is copyright (C) 2006 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ 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 General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.pj.cluster;

import edu.rit.mp.Buf;
import edu.rit.mp.Channel;
import edu.rit.mp.ChannelGroup;
import edu.rit.mp.Status;

import edu.rit.mp.ObjectBuf;

import java.io.IOException;

/**
 * Class Proxy is the abstract base class for a proxy object for sending
 * messages to a PJ process.
 *
 * @author  Alan Kaminsky
 * @version 20-Nov-2006
 */
public abstract class Proxy
	{

// Hidden data members.

	private ChannelGroup myChannelGroup;
	private Channel myChannel;

// Exported constructors.

	/**
	 * Construct a new proxy. The proxy will use the given channel in the given
	 * channel group to send messages to the far end process.
	 *
	 * @param  theChannelGroup  Channel group.
	 * @param  theChannel       Channel.
	 */
	public Proxy
		(ChannelGroup theChannelGroup,
		 Channel theChannel)
		{
		myChannelGroup = theChannelGroup;
		myChannel = theChannel;
		}

// Exported operations.

	/**
	 * Send the given message to this proxy's far end process.
	 *
	 * @param  theMessage  Message.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void send
		(Message theMessage)
		throws IOException
		{
		myChannelGroup.send
			(myChannel,
			 theMessage.getTag(),
			 ObjectBuf.buffer (theMessage));
		}

	/**
	 * Send a message with the given tag and items to this proxy's far end
	 * process.
	 *
	 * @param  theTag  Message tag.
	 * @param  theSrc  Item source buffer.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void send
		(int theTag,
		 Buf theSrc)
		throws IOException
		{
		myChannelGroup.send (myChannel, theTag, theSrc);
		}

	/**
	 * Receive a message from this proxy's far end process. A message will be
	 * received from this proxy's channel in this proxy's channel group. The
	 * message must have a tag of 0. The message items are stored in the given
	 * item destination buffer.
	 * <P>
	 * The <TT>receive()</TT> method does not return until the message has been
	 * fully received.
	 *
	 * @param  theDst  Item destination buffer.
	 *
	 * @return  Status object giving the outcome of the message reception.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public Status receive
		(Buf theDst)
		throws IOException
		{
		return myChannelGroup.receive (myChannel, theDst);
		}

	/**
	 * Receive a message with the given tag from this proxy's far end process. A
	 * message will be received from this proxy's channel in this proxy's
	 * channel group. If <TT>theTag</TT> is null, a message will be received
	 * with any tag. The message items are stored in the given item destination
	 * buffer.
	 * <P>
	 * The <TT>receive()</TT> method does not return until the message has been
	 * fully received.
	 *
	 * @param  theTag  Message tag, or null to receive any tag.
	 * @param  theDst  Item destination buffer.
	 *
	 * @return  Status object giving the outcome of the message reception.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public Status receive
		(Integer theTag,
		 Buf theDst)
		throws IOException
		{
		return myChannelGroup.receive (myChannel, theTag, theDst);
		}

	/**
	 * Close communication with this proxy's far end process.
	 */
	public void close()
		{
		myChannel.close();
		}

	}