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Jinterface Java package contains java classes, which help you integrate programs written in Java with Erlang. Erlang is a programming language designed at the Ericsson Computer Science Laboratory.
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/*
 * %CopyrightBegin%
 * 
 * Copyright Ericsson AB 2000-2009. All Rights Reserved.
 * 
 * The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved online at http://www.erlang.org/.
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * %CopyrightEnd%
 */
package com.ericsson.otp.erlang;

import java.io.IOException;
import java.net.Socket;

/**
 * 
 * Maintains a connection between a Java process and a remote Erlang, Java or C
 * node. The object maintains connection state and allows data to be sent to and
 * received from the peer.
 * 
 * 
 * 
 * Once a connection is established between the local node and a remote node,
 * the connection object can be used to send and receive messages between the
 * nodes.
 * 
 * 
 * 
 * The various receive methods are all blocking and will return only when a
 * valid message has been received or an exception is raised.
 * 
 * 
 * 
 * If an exception occurs in any of the methods in this class, the connection
 * will be closed and must be reopened in order to resume communication with the
 * peer.
 * 
 * 
 * 
 * The message delivery methods in this class deliver directly to
 * {@link OtpMbox mailboxes} in the {@link OtpNode OtpNode} class.
 * 
 * 
 * 
 * It is not possible to create an instance of this class directly.
 * OtpCookedConnection objects are created as needed by the underlying mailbox
 * mechanism.
 * 
 */
public class OtpCookedConnection extends AbstractConnection {
    protected OtpNode self;

    /*
     * The connection needs to know which local pids have links that pass
     * through here, so that they can be notified in case of connection failure
     */
    protected Links links = null;

    /*
     * Accept an incoming connection from a remote node. Used by {@link
     * OtpSelf#accept() OtpSelf.accept()} to create a connection based on data
     * received when handshaking with the peer node, when the remote node is the
     * connection intitiator.
     * 
     * @exception java.io.IOException if it was not possible to connect to the
     * peer.
     * 
     * @exception OtpAuthException if handshake resulted in an authentication
     * error
     */
    // package scope
    OtpCookedConnection(final OtpNode self, final Socket s) throws IOException,
	    OtpAuthException {
	super(self, s);
	this.self = self;
	links = new Links(25);
	start();
    }

    /*
     * Intiate and open a connection to a remote node.
     * 
     * @exception java.io.IOException if it was not possible to connect to the
     * peer.
     * 
     * @exception OtpAuthException if handshake resulted in an authentication
     * error.
     */
    // package scope
    OtpCookedConnection(final OtpNode self, final OtpPeer other)
	    throws IOException, OtpAuthException {
	super(self, other);
	this.self = self;
	links = new Links(25);
	start();
    }

    // pass the error to the node
    @Override
    public void deliver(final Exception e) {
	self.deliverError(this, e);
	return;
    }

    /*
     * pass the message to the node for final delivery. Note that the connection
     * itself needs to know about links (in case of connection failure), so we
     * snoop for link/unlink too here.
     */
    @Override
    public void deliver(final OtpMsg msg) {
	final boolean delivered = self.deliver(msg);

	switch (msg.type()) {
	case OtpMsg.linkTag:
	    if (delivered) {
		links.addLink(msg.getRecipientPid(), msg.getSenderPid());
	    } else {
		try {
		    // no such pid - send exit to sender
		    super.sendExit(msg.getRecipientPid(), msg.getSenderPid(),
			    new OtpErlangAtom("noproc"));
		} catch (final IOException e) {
		}
	    }
	    break;

	case OtpMsg.unlinkTag:
	case OtpMsg.exitTag:
	    links.removeLink(msg.getRecipientPid(), msg.getSenderPid());
	    break;

	case OtpMsg.exit2Tag:
	    break;
	}

	return;
    }

    /*
     * send to pid
     */
    void send(final OtpErlangPid from, final OtpErlangPid dest,
	    final OtpErlangObject msg) throws IOException {
	// encode and send the message
	sendBuf(from, dest, new OtpOutputStream(msg));
    }

    /*
     * send to remote name dest is recipient's registered name, the nodename is
     * implied by the choice of connection.
     */
    void send(final OtpErlangPid from, final String dest,
	    final OtpErlangObject msg) throws IOException {
	// encode and send the message
	sendBuf(from, dest, new OtpOutputStream(msg));
    }

    @Override
    public void close() {
	super.close();
	breakLinks();
    }

    @Override
    protected void finalize() {
	close();
    }

    /*
     * this one called by dying/killed process
     */
    void exit(final OtpErlangPid from, final OtpErlangPid to,
	    final OtpErlangObject reason) {
	try {
	    super.sendExit(from, to, reason);
	} catch (final Exception e) {
	}
    }

    /*
     * this one called explicitely by user code => use exit2
     */
    void exit2(final OtpErlangPid from, final OtpErlangPid to,
	    final OtpErlangObject reason) {
	try {
	    super.sendExit2(from, to, reason);
	} catch (final Exception e) {
	}
    }

    /*
     * snoop for outgoing links and update own table
     */
    synchronized void link(final OtpErlangPid from, final OtpErlangPid to)
	    throws OtpErlangExit {
	try {
	    super.sendLink(from, to);
	    links.addLink(from, to);
	} catch (final IOException e) {
	    throw new OtpErlangExit("noproc", to);
	}
    }

    /*
     * snoop for outgoing unlinks and update own table
     */
    synchronized void unlink(final OtpErlangPid from, final OtpErlangPid to) {
	links.removeLink(from, to);
	try {
	    super.sendUnlink(from, to);
	} catch (final IOException e) {
	}
    }

    /*
     * When the connection fails - send exit to all local pids with links
     * through this connection
     */
    synchronized void breakLinks() {
	if (links != null) {
	    final Link[] l = links.clearLinks();

	    if (l != null) {
		final int len = l.length;

		for (int i = 0; i < len; i++) {
		    // send exit "from" remote pids to local ones
		    self.deliver(new OtpMsg(OtpMsg.exitTag, l[i].remote(), l[i]
			    .local(), new OtpErlangAtom("noconnection")));
		}
	    }
	}
    }
}