/*!

\page callbacks Using ns-3 callbacks

\anchor howtos-callbacks

\section null_callbacks Null Callbacks

<b>Question:</b> The API I am using calls for using a callback (in the 

function signature), but I do not

want to provide one.  Is there a way to provide a null callback?

<b>Answer:</b> Use the ns3::MakeNullCallback construct:

\code

template<typename R>

Callback< R, T1, T2, T3, T4, T5, T6 > ns3::MakeNullCallback (void)

\endcode

Example usage:  The ns3::Socket class uses callbacks to indicate completion

of events such as a successful TCP connect().  These callbacks are set

in the following function:

\code

  void Socket::SetConnectCallback (Callback<void, Ptr<Socket> > connectionSucceeded,

                        Callback<void, Ptr<Socket> > connectionFailed,

                        Callback<void, Ptr<Socket> > halfClose);

\endcode

But suppose you do not care about registering a callback for the 

halfClose event (but you want to register one for the 

connectionSucceeded and connectionFailed cases).  In that case, you

can pass a null callback as the third argument.  You just need to

pass a callback with the matching signature, as follows:

\code

  localSocket->SetConnectCallback (

  MakeCallback (&ConnectionSucceededCallback),

  MakeCallback (&ConnectionFailedCallback),

  MakeNullCallback<void, Ptr<Socket> > () );

\endcode

*/

/*!

\page howtos ns-3 HOWTOs

\anchor howtos-anchor

This is an organized set of frequently asked questions (FAQ) and HOWTOs

for ns-3.  This complements the following wiki pages:

- <a href="http://www.nsnam.org/wiki/index.php/User_FAQ">User FAQ</a>

- <a href="http://www.nsnam.org/wiki/index.php/Developer_FAQ">Developer FAQ</a>

Please consider contributing tips to either the wiki (yourself) or

by submitting a patch to this maintained documentation.

- \subpage callbacks

*/

/**

 * \mainpage ns-3 Documentation

 *

 * \section intro-sec Introduction

 * <a href="http://www.nsnam.org/">ns-3</a> documentation is maintained using 

 * <a href="http://www.doxygen.org">Doxygen</a>.

 * Doxygen is typically used for 

 * API documentation, and organizes such documentation across different

 * modules.   This project uses Doxygen both for building the manual around 

 * the API documentation,  and a separate GNU texinfo document is used for 

 * the manual.

 *

 * The ns-3 project documentation is organized as follows:

 *     - <b><a href="modules.html">modules</a></b>:  The "Modules" tab (above) 

 *       organizes  all of the public API and supporting manual text 

 *       along the  source code directory structure.   This forms the 

 *       "ns-3 manual", and it is available in HTML and PDF forms.

 *     - \ref howtos-anchor "HOWTOs": A set of HOWTOs and FAQs is

 *       maintained on another Doxygen "Related Page" 

 *     - <a href="http://www.nsnam.org/docs/tutorial/tutorial.html">tutorial</a>:  The ns-3 tutorial is a separate document maintained in <a href="http://www.gnu.org/software/texinfo/"> GNU Texinfo</a>. 

 *     - The <b><a href="http://www.nsnam.org/wiki/index.php/Main_Page">ns-3 wiki</a></b> 

 *       contains additional user-contributed material.  Some wiki-contributed

 *       material may migrate to and overlap with the Doxygen information.

 *

 * \section install-sec Building the Documentation

 * 

 * ns-3 requires Doxygen version 1.5.4 or greater to fully build all items,

 * although earlier versions of Doxygen will mostly work.

 * 

 * Type "./waf check" followed by "./waf --doxygen" to build the documentation.

 * There is a program that runs during "./waf check" that builds pieces of

 * the documentation through introspection.  The doc/ directory contains

 * configuration for Doxygen (doxygen.conf and main.txt).  The Doxygen 

 * build process puts html files into the doc/html/ directory, and latex 

 * filex into the doc/latex/ directory.

 * 

 * \section module-sec Module overview

 *

 * The ns-3 library is split across multiple modules:

 *     - core: located in src/core and contains a number of facilities which

 *       do not depend on any other module. Some of these facilities are

 *       OS-dependent.

 *     - simulator: located in src/simulator and contains event scheduling

 *       facilities.

 *     - common: located in src/common and contains facilities specific

 *       to network simulations but shared by pretty much every model

 *       of a network component.

 *     - node: located in src/node. Defines the abstract interfaces which 

 *       must be implemented by every node and more specifically, by ipv4 nodes.       

 *     - devices: located in src/devices. Contains a set of MAC-level models

 *

 * More detail can be found in the <b><a href="modules.html">Modules</a></b>

 * tab.

 *

 */

/**

 * \namespace ns3

 * \brief Every class exported by the ns3 library is enclosed in the

 * ns3 namespace.

 */

/**

 * @anchor modules_anchor

 *

 * @defgroup simulator Simulator

 * The "simulator" module contains: 

 *    - a time management class to hold a time and convert between various time units: ns3::Time 

 *    - a scheduler base class used to implement new simulation event schedulers:       

 *      ns3::Scheduler and ns3::SchedulerFactory 

 *    - a simulator class used to create, schedule and cancel events: ns3::Simulator

 *

 * @defgroup core Core

 * \brief The "core" module contains:

 *    - a Functor class: ns3::Callback  

 *    - an os-independent interface to get access to the elapsed wall clock time: ns3::SystemWallClockMs 

 *    - a class to register regression tests with the test manager: ns3::Test and ns3::TestManager

 *    - debugging facilities: \ref logging, \ref assert, \ref error

 *    - \ref randomvariable

 *    - \ref config

 *    - a base class for objects which need to support reference counting

 *      and QueryInterface: ns3::Object and ns3::InterfaceId 

 *    - a set of low-level trace facilities integrated in the ns3::Object system: \ref tracing

 *    - a ns3::ComponentManager which can be used to manage the creation

 *      of any object which derives from ns3::Object through an ns3::ClassId 

 *    - a smart-pointer class ns3::Ptr designed to work together with ns3::Object

 *

 * @defgroup common Common

 * The "core" module contains: 

 *    - a packet class to create and manipulate simulation packets: 

 *      ns3::Packet, ns3::Header,  and ns3::Trailer. This packet class 

 *      also supports per-packet ns3::Tag which are  globs of data 

 *      which can be attached to any packet.

 *

 * @defgroup node Node

 * The "node" module contains:

 *    - a ns3::Node base class which should be subclassed by any new type of

 *      network Node.

 *    - models which abstract the MAC-layer from the IP layer protocols:

 *      ns3::NetDevice and ns3::Channel. 

 *    - models which abstract the application-layer API: ns3::Application,

 *      ns3::Socket, ns3::SocketFactory, and, ns3::Udp

 * 

 *

 * @defgroup devices Devices

 * The "devices" module contains:

 *    - a PointToPoint MAC device: ns3::PointToPointNetDevice, ns3::PointToPointChannel,

 *      and ns3::PointToPointTopology.

 *

 * @defgroup internetNode InternetNode

 * 

 * The "internet-node" module contains a set of classes which implement the

 * APIs defined in the "node" module:

 *    - an Ipv4/Udp stack with socket support 

 *    - an ARP module

 *    - an InternetNode class which is a Node subclass.

 *    

 * @defgroup applications Applications

 *

 * @defgroup mobility Mobility

 *

 * @defgroup routing Routing

 *

 * @defgroup constants Constants

 * @brief Constants you can change

 *

 * @defgroup contrib Contrib

 */

 * \ingroup core

 * \ingroup core

 * \ingroup common

 * \ingroup core

 * \ingroup core

 * \ingroup core

 * \ingroup core

 * \ingroup core

 * \ingroup core

 * \ingroup devices

  os << "/// \\ingroup core" << std::endl;