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SocketAcceptor.h

//
// SocketAcceptor.h
//
// $Id: //poco/1.2/Net/include/Poco/Net/SocketAcceptor.h#1 $
//
// Library: Net
// Package: Reactor
// Module:  SocketAcceptor
//
// Definition of the SocketAcceptor class.
//
// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Net_SocketAcceptor_INCLUDED
#define Net_SocketAcceptor_INCLUDED


#include "Poco/Net/Net.h"
#include "Poco/Net/SocketNotification.h"
#include "Poco/Net/ServerSocket.h"
#include "Poco/Net/StreamSocket.h"
#include "Poco/Observer.h"


namespace Poco {
namespace Net {


template <class ServiceHandler>
00055 class SocketAcceptor
      /// This class implements the Acceptor part of the
      /// Acceptor-Connector design pattern.
      ///
      /// The Acceptor-Connector pattern has been described in the book
      /// "Pattern Languages of Program Design 3", edited by Robert Martin,
      /// Frank Buschmann and Dirk Riehle (Addison Wesley, 1997).
      ///
      /// The Acceptor-Connector design pattern decouples connection
      /// establishment and service initialization in a distributed system
      /// from the processing performed once a service is initialized.
      /// This decoupling is achieved with three components: Acceptors, 
      /// Connectors and Service Handlers.
      /// The SocketAcceptor passively waits for connection requests (usually
      /// from a remote Connector) and establishes a connection upon
      /// arrival of a connection requests. Also, a Service Handler is
      /// initialized to process the data arriving via the connection in
      /// an application-specific way.
      ///
      /// The SocketAcceptor sets up a ServerSocket and registers itself
      /// for a ReadableNotification, denoting an incoming connection request.
      ///
      /// When the ServerSocket becomes readable the SocketAcceptor accepts
      /// the connection request and creates a ServiceHandler to
      /// service the connection.
      ///
      /// The ServiceHandler class must provide a constructor that
      /// takes a StreamSocket and a SocketReactor as arguments,
      /// e.g.:
      ///     MyServiceHandler(const StreamSocket& socket, ServiceReactor& reactor)
      ///
      /// When the ServiceHandler is done, it must destroy itself.
      ///
      /// Subclasses can override the createServiceHandler() factory method
      /// if special steps are necessary to create a ServiceHandler object.
{
public:           
      SocketAcceptor(ServerSocket& socket):
            _socket(socket),
            _pReactor(0)
            /// Creates an SocketAcceptor, using the given ServerSocket.
      {
      }

00099       SocketAcceptor(ServerSocket& socket, SocketReactor& reactor):
            _socket(socket),
            _pReactor(0)
            /// Creates an SocketAcceptor, using the given ServerSocket.
            /// The SocketAcceptor registers itself with the given SocketReactor.
      {
            registerAcceptor(reactor);
      }

00108       virtual ~SocketAcceptor()
            /// Destroys the SocketAcceptor.
      {
            unregisterAcceptor();
      }
      
00114       virtual void registerAcceptor(SocketReactor& reactor)
            /// Registers the SocketAcceptor with a SocketReactor.
            ///
            /// A subclass can override this and, for example, also register
            /// an event handler for a timeout event.
            ///
            /// The overriding method must call the baseclass implementation first.
      {
            _pReactor = &reactor;
            _pReactor->addEventHandler(_socket, Poco::Observer<SocketAcceptor, ReadableNotification>(*this, &SocketAcceptor::onAccept));
      }
      
00126       virtual void unregisterAcceptor()
            /// Unregisters the SocketAcceptor.
            ///
            /// A subclass can override this and, for example, also unregister
            /// its event handler for a timeout event.
            ///
            /// The overriding method must call the baseclass implementation first.
      {
            if (_pReactor)
            {
                  _pReactor->removeEventHandler(_socket, Poco::Observer<SocketAcceptor, ReadableNotification>(*this, &SocketAcceptor::onAccept));
            }
      }
      
      void onAccept(ReadableNotification* pNotification)
      {
            pNotification->release();
            StreamSocket sock = _socket.acceptConnection();
            createServiceHandler(sock);
      }
      
protected:
00148       virtual ServiceHandler* createServiceHandler(StreamSocket& socket)
            /// Create and initialize a new ServiceHandler instance.
            ///
            /// Subclasses can override this method.
      {
            return new ServiceHandler(socket, *_pReactor);
      }

00156       SocketReactor* reactor()
            /// Returns a pointer to the SocketReactor where
            /// this SocketAcceptor is registered.
            ///
            /// The pointer may be null.
      {
            return _pReactor;
      }

00165       Socket& socket()
            /// Returns a reference to the SocketAcceptor's socket.
      {
            return _socket;
      }

private:
      SocketAcceptor();
      SocketAcceptor(const SocketAcceptor&);
      SocketAcceptor& operator = (const SocketAcceptor&);
      
      ServerSocket   _socket;
      SocketReactor* _pReactor;
};


} } // namespace Poco::Net


#endif // Net_SocketAcceptor_INCLUDED

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