/* -*-  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__

//

// \brief The base class for all ns3 applicationes

//

// Class Application is the base class for all ns3 applications.

// Applications are associated with individual nodes, and are created

// using the AddApplication method in the ApplicationManager capability.

// 

// Conceptually, an application has zero or more 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.

// 

// There is a second application class in ns3, called "ThreadedApplication"

// that implements a true sockets interface, which should be used

// when porting existing sockets code to ns3.  The true

// sockets approach is significantly

// less memory--efficient using private stacks for each defined application,

// so that approach should be used with care.  The design and implementation

// of the ThreadedApplication are still being discussed.

#include "ns3/event-id.h"

#include "ns3/nstime.h"

#include "ns3/object.h"

namespace ns3 {

class Node;

class RandomVariable;

class Application : public Object

{

public:

  Application(Node *);

  Application(const Application&);  // Copy constructor

  Application& operator=(const Application&); // Assignment operator

  virtual ~Application();

  virtual Application* Copy() const = 0; // All applications must provide

  // \brief Specify application start 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.

  // \param Start time for this application, relative to the

  // current simulation time.

  void Start(const Time&);

  // \brief Same as above, but uses a random variable for start time

  // The random variable returns the desired start time in units of

  // Seconds.

void Start(const RandomVariable&);

  // \brief Specify application stop 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 defined below, to cause the application

  // to stop.

  // \param Stop time for this application, relative to the

  // current simulation time.

  void Stop(const Time&);

  // \brief Same as above, but uses a random variable for stop time

  // The random variable returns the desired stop time in units of

  // Seconds.

  void Stop(const RandomVariable&);

  // \brief Attaches an application to a specific node

  // Specifies which node object this application is associated with.

  // \param Node object to associate with this application.

  void SetNode(Node *);

  // \brief Returns the pointer to the attached node.

  Node* PeekNode() const;

  // Members

  Node          * m_node;      // All applications have an associated node

  RandomVariable* m_startVar;  // Random variable for start time

  RandomVariable* m_stopVar;   // Random variable for stop time

  EventId         m_startEvent;// Event identifier for start event

  EventId         m_stopEvent; // Event identifier for the stop event

  bool            m_start;     // True if start event scheduled

  bool            m_stop;      // True if stop event scheduled

protected:

  // \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();

  // \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();

  virtual void DoDispose (void);

private:

  // Helpers

  void ScheduleStart();

  void ScheduleStop();

};

} //namespace ns3

#endif