We now have a framework for creating servers. The user needs to provide a worker thread class that is derived from CSocketServer::WorkerThread and a socket server that's derived from CSocketServer. These classes could look something like this:

class CSocketServerWorkerThread : public CSocketServer::WorkerThread
{
   public :

      CSocketServerWorkerThread(
         CIOCompletionPort &iocp);

   private :

      virtual void ReadCompleted(
         CSocketServer::Socket *pSocket,
         CIOBuffer *pBuffer);
};

class CMySocketServer : CSocketServer
{
   public :

      CMySocketServer (
         unsigned long addressToListenOn,
         unsigned short portToListenOn);

   private :

      virtual WorkerThread *CreateWorkerThread(
         CIOCompletionPort &iocp);

      virtual SOCKET CreateListeningSocket(
         unsigned long address,
         unsigned short port);

      virtual void OnConnectionEstablished(
         Socket *pSocket,
         CIOBuffer *pAddress);
};

Implementations for CreateListeningSocket() and OnConnectionEstablished() have already been presented. CreateWorkerThread() is as simple as this:

   CSocketServer::WorkerThread *CMySocketServer::CreateWorkerThread(
      CIOCompletionPort &iocp)
   {
      return new CSocketServerWorkerThread(iocp);
   }

Which leaves us with the implementation of our worker thread's ReadCompleted() method. This is where the server handles incoming data and, in the case of a simple Echo server ;) it could be as simple as this:

   void CSocketServerWorkerThread::ReadCompleted(
      CSocketServer::Socket *pSocket,
      CIOBuffer *pBuffer)
   {
      pSocket->Write(pBuffer);
   }

A complete echo server is available for download in SocketServer1.zip. The server simply echos the incoming byte stream back to the client. In addition to implementing the methods discussed above the socket server and worker thread derived classes also implement several 'notifciation' methods that the server and worker thread classes call to inform the derived class of various internal goings on. The echo server simply outputs a message to the screen (and log file) when these notifications occur but the idea behind them is that the derived class can use them to report on internal server state via performance counters or suchlike. You can test the echo server by using telnet. Simply telnet to localhost on port 5001 (the port that the sample uses by default) and type stuff and watch it get typed back at you. The server runs until a named event is set and then shuts down. The very simple Server Shutdown program, available in ServerShutdown.zip, provides an off switch for the server.