/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2006 Georgia Tech Research Corporation

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: George F. Riley<riley@ece.gatech.edu>

 */

#ifndef __APPLICATION_H__

#define __APPLICATION_H__

#include "ns3/event-id.h"

#include "ns3/nstime.h"

#include "ns3/object.h"

#include "ns3/ptr.h"

#include "ns3/node.h"

namespace ns3 {

class Node;

class RandomVariable;

/**

 * \addtogroup applications Applications

 *

 * Class ns3::Application can be used as a base class for ns3 applications.

 * Applications are associated with individual nodes.  Each node

 * holds a list of references (smart pointers) to its applications.

 * 

 * Conceptually, an application has zero or more ns3::Socket

 * objects associated with it, that are created using the Socket

 * creation API of the Kernel capability.  The Socket object

 * API is modeled after the

 * well-known BSD sockets interface, although it is somewhat 

 * simplified for use with ns3.  Further, any socket call that

 * would normally "block" in normal sockets will return immediately

 * in ns3.  A set of "upcalls" are defined that will be called when

 * the previous blocking call would normally exit.  THis is documented

 * in more detail Socket class in socket.h.

 *

 * The main purpose of the base class application public API is to  

 * provide a uniform way to start and stop applications.

 */

 /**

 * \brief The base class for all ns3 applications

 * 

 */

class Application : public Object

{

public:

  static TypeId GetTypeId (void);

  Application ();

  virtual ~Application ();

  /**

   * \brief Specify application start time

   * \param startTime Start time for this application,

   *        relative to the current simulation time.

   *

   * Applications start at various times in the simulation scenario.

   * The Start method specifies when the application should be

   * started.  The application subclasses should override the

   * private "StartApplication" method defined below, which is called at the

   * time specified, to cause the application to begin.

   */

  void Start (const Time& startTime);

  /** 

   * \brief Specify application start time.

   * \param startVariable the random variable to use to pick

   *        the real start time as a relative time, in units of

   *        seconds, relative to the current simulation time.

   */

  void Start (const RandomVariable& startVariable);

  /**

   * \brief Specify application stop time

   * \param stopTime Stop time for this application, relative to the

   *        current simulation time.

   *

   * Once an application has started, it is sometimes useful

   * to stop the application.  The Stop method specifies when an

   * application is to stop.  The application subclasses should override

   * the private StopApplication method, to be notified when that

   * time has come.

   */

  void Stop (const Time& stopTime);

  /**

   * \brief Specify application stop time

   * \param stopVariable the random variable to use to pick

   *        the real stop time, in units of seconds, 

   *        relative to the current simulation time.

   */

  void Stop (const RandomVariable& stopVariable);

  /**

   * \returns the Node to which this Application object is attached.

   */

  Ptr<Node> GetNode () const;

  /**

   * \param node the node to which this Application object is attached.

   */

  void SetNode (Ptr<Node> node);

private:

  /**

   * \brief Application specific startup code

   *

   * The StartApplication method is called at the start time specifed by Start

   * This method should be overridden by all or most application

   * subclasses.

   */

  virtual void StartApplication (void);

  /**

   * \brief Application specific shutdown code

   *

   * The StopApplication method is called at the stop time specifed by Stop

   * This method should be overridden by all or most application

   * subclasses.

   */

  virtual void StopApplication (void);

protected:

  virtual void DoDispose (void);

private:

  void ScheduleStart (const Time &time);

  void ScheduleStop (const Time &time);

  EventId         m_startEvent;

  EventId         m_stopEvent;

  Ptr<Node>       m_node;

};

} //namespace ns3

#endif