# SessionManagerFactory.java

    /*
    ** Module   : SessionManagerFactory.java
    ** Abstract : Factory to create singleton SessionManager instance
    **
    ** Copyright (c) 2004-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- -T- --JPRM-- ----------------Description-----------------
    ** 001 ECF 20071112 ADD  @35869  Created initial version. Factory to create
    **                               singleton SessionManager instance.
    ** 002 ECF 20071121 CHG  @35938  Fixed initialization sequence. On subsequent
    **                               calls to createXxxxxNode(), the session
    **                               manager's initialize() method was not being
    **                               called.
    */
    /*
    ** 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
    **     work.  You may not remove from the covered work any author or developer
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    **
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    **
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    */

    package com.goldencode.p2j.net;

    import com.goldencode.p2j.cfg.*;

    /**
     * Factory for creating a singleton instance of the network {@link
     * SessionManager} for this process.  Either a {@link
     * #createLeafNode(BootstrapConfig) leaf} or a {@link
     * #createRouterNode(BootstrapConfig) router} session manager can be created.
     * <p>
     * This class may not be constructed.  All functionality is provided by static
     * methods.
     */
    public final class SessionManagerFactory
    {
       /**
        * Private constructor to prevent this class from being instantiated.
        */
       private SessionManagerFactory()
       {
       }

       /**
        * Create the singleton instance of the <code>SessionManager</code> used
        * for a leaf network node, or simply return this instance if it already
        * exists.
        * <p>
        * The preferred way to retrieve the existing singleton session manager,
        * once it has been created, is with {@link SessionManager#get()}.
        *
        * @param   config
        *          Bootstrap configuration for this network node.
        *
        * @return  Leaf node session manager.
        *
        * @throws  ConfigurationException
        *          if there is any configuration error during the session
        *          manager's initialization.
        */
       public static SessionManager createLeafNode(BootstrapConfig config)
       throws ConfigurationException
       {
          SessionManager sessMgr;
          synchronized (SessionManager.class)
          {
             sessMgr = SessionManager.get();
             if (sessMgr != null)
             {
                assert (sessMgr.isLeaf());
             }
             else
             {
                sessMgr = new LeafSessionManager();
             }
          }

          sessMgr.initialize(config);

          return sessMgr;
       }

       /**
        * Create the singleton instance of the <code>SessionManager</code> used
        * for a router network node, or simply return this instance if it already
        * exists.
        * <p>
        * The preferred way to retrieve the existing singleton session manager,
        * once it has been created, is with {@link SessionManager#get()}.
        *
        * @param   config
        *          Bootstrap configuration for this network node.
        *
        * @return  Router node session manager.
        *
        * @throws  ConfigurationException
        *          if there is any configuration error during the session
        *          manager's initialization.
        */
       public static SessionManager createRouterNode(BootstrapConfig config)
       throws ConfigurationException
       {
          SessionManager sessMgr;
          synchronized (SessionManager.class)
          {
             sessMgr = SessionManager.get();
             if (sessMgr != null)
             {
                assert (sessMgr.isRouter());
             }
             else
             {
                sessMgr = new RouterSessionManager();
             }
          }

          sessMgr.initialize(config);

          return sessMgr;
       }
    }