# VirtualSession.java

    /*
    ** Module   : VirtualSession.java
    ** Abstract : Session implementation for multiplexed connections between nodes
    **
    ** Copyright (c) 2004-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ------------------Description-------------------
    ** 001 ECF 20071101  @35863  Created initial version. Session
    **                           implementation for multiplexed connections
    **                           between nodes.
    ** 002 CA  20090901  @43817  Removed final modifier for preprocess method, to
    **                           be able to override it in RequesterSession. Now
    **                           the virtual sessions keep the local context ID
    **                           too, to be able to deregister from the session
    **                           manager's local maps.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
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    **     work or Appropriate Legal Notices displayed by works containing the covered
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    **
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    */

    package com.goldencode.p2j.net;

    /**
     * A concrete implementation of the {@link Session} interface, built upon
     * <code>BaseSession</code>.  This implementation is to be used for virtual,
     * multiplexed connections between network nodes.
     * <p>
     * This class implements the superclass' abstract {@link #preprocess(Message)}
     * to set the session's context ID as the message's routing key's context ID.
     * This is necessary to support the multiplexing of virtual sessions across a
     * single transport queue.
     */
    class VirtualSession
    extends BaseSession
    {
       /**
        * The context ID to which this virtual session is registered locally
        * on this side of the connection.
        */
       private int localContextID = 0;

       /**
        * Constructor.
        *
        * @param   queue
        *          Message transport.
        * @param   context
        *          Security context.  Must not be <code>null</code>.
        * @param   peerID
        *          Unique identifier for this session's peer security context on
        *          the other side of the network connection.
        * @param   contextID
        *          Unique identifier for this session's local security context on
        *          the this side of the network connection.
        */
       VirtualSession(Queue queue, Object context, int peerID, int contextID)
       {
          super(queue, context, peerID);

          this.localContextID = contextID;
       }

       /**
        * Overrides the parent class' implementation to disallow the registraction
        * of a state synchronizer.  This is necessary because a virtual session is
        * multiplexed and a state synchronizer currently supports only a one to
        * one connection.
        *
        * @param   sync
        *          The synchronizer to register or <code>null</code> if the
        *          currently registered synchronizer should be deregistered.
        *
        * @throws  UnsupportedOperationException
        *          always.
        */
       public void registerSynchronizer(StateSynchronizer sync)
       {
          throw new UnsupportedOperationException();
       }

       /**
        * Get the context ID to which the virtual session is registered on this
        * side.
        *
        * @return    the context ID to which the virtual session is registered on
        *            this side.
        */
       int getLocalContextID()
       {
          return localContextID;
       }

       /**
        * Update the security context ID of the given message to this session's
        * (peer) context ID, before it is sent.  This will the other side of the
        * connection to demultiplex the inbound message to provide the appropriate
        * security context.
        *
        * @param   message
        *          Message to process.
        */
       protected void preprocess(Message message)
       {
          RoutingKey key = message.getKey();
          int id = getContextID();
          key.setContextID(id);
       }
    }