服务器端WSAAsyncSelect模型编程

WSAAsyncSelect是服务器端的六种I/O模型之一，他的主要思想是运用了windows窗口的消息机制，用函数WSAAsyncSelect()将监听端口感兴趣的网络消息注册到窗口，然后在窗口的消息过程中处理，该模型只提供异步通知，并不提供异步数据传送，只适用于系统开销不大的情况。

使用该模型编程，需要基于窗口，以下CreateServerWindow提供了创建窗口的过程。

#include <cassert>
#include <iostream>
#include "ServerWindowCreator.h"
#include "SocketUtil.h"

HWND ServerWindowCreator::CreateServerWindow(HINSTANCE hInstance, LPCTSTR wndClass, WNDPROC wndProc)
{
	assert(hInstance);
	assert(wndClass);
	assert(wndProc);
	if(!hInstance || !wndClass || !wndProc)
		return NULL;

	HWND hWnd = NULL;
	if (MyRegisterClass(hInstance, wndClass, wndProc))//注册窗口类
		hWnd = InitInstance(hInstance, wndClass);//创建窗口

	return hWnd;
}

bool ServerWindowCreator::MyRegisterClass(HINSTANCE hInstance, LPCTSTR wndClass, WNDPROC wndProc)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX);

	wcex.style			= 0;
	wcex.lpfnWndProc	= wndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInstance;
	wcex.hIcon			= NULL;
	wcex.hCursor		= NULL;
	wcex.hbrBackground	= NULL;
	wcex.lpszMenuName	= NULL;
	wcex.lpszClassName	= wndClass;
	wcex.hIconSm		= NULL;

	ATOM ret = RegisterClassEx(&wcex);
	assert(ret!=NULL || ::GetLastError()==ERROR_CLASS_ALREADY_EXISTS);
	return ret!=NULL || ::GetLastError()==ERROR_CLASS_ALREADY_EXISTS;
}

HWND ServerWindowCreator::InitInstance(HINSTANCE hInstance, LPCTSTR wndClass)
{
	HWND hWnd = CreateWindow(wndClass, NULL, WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, 0, 0, 0, NULL, NULL, hInstance, NULL);
	
	assert(hWnd);
	if(!hWnd)
	{
		DWORD dwError = GetLastError();
		std::cout<<"create server window failed"<<std::endl;
	}

	return hWnd;
}

服务器端的通信过程

#include "SocketUtil.h"
#include "ServerWindowCreator.h"
#include "ServerSourceHolder.h"
#include "ServerParamDef.h"
#include <iostream>

#pragma comment(lib, "Ws2_32.lib")

int WINAPI WinMain(HINSTANCE hInstance,
	HINSTANCE hPrevInstance, LPSTR lpCmdLine,
	int nCmdShow)
{
	ServerHolder skHoder;//该对象负责管理winsock库的初始化和清理，监听socket的释放，窗口的资源和消息管理
	if (!skHoder.Init())
		return 0;

	SOCKET skListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);//创建监听socket
	if (skListen == INVALID_SOCKET)
	{
		RecordSocketError("create listen socket failed");
		return 0;
	}
	std::cout<<"listen socket = "<<skListen<<std::endl;
	skHoder.HoldSocketFd(skListen);

	sockaddr_in addr;
	memset(&addr, NULL, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = htonl(INADDR_ANY);
	addr.sin_port = htons(SERVER_PORT);
	if (bind(skListen, (sockaddr*)&addr, sizeof(addr)))//将socket与地址绑定
	{
		RecordSocketError("bind address failed");
		return 0;
	}

	const TCHAR* WINDOW_CLASS = _T("ServerWindow");//创建窗口
	HWND hWnd = ServerWindowCreator::CreateServerWindow(hInstance, WINDOW_CLASS, 
		ServerHolder::ServerWndProc);
	if (!hWnd || !::IsWindow(hWnd))
		return 0;

	skHoder.HoldWindow(hWnd);

	if (WSAAsyncSelect(skListen, hWnd, WM_SOCKET,
		FD_ACCEPT | FD_CLOSE | FD_WRITE) != 0)//注册网络消息
	{
		RecordSocketError("set socket error");
		return 0;
	}

	if (listen(skListen, MAX_PENDING_CONN) != 0) //开始监听
	{
		RecordSocketError("listen error");
		return 0;
	}

	std::cout<<"start server ..."<<std::endl;
	ServerHolder::ServerMessageLoop();//进入窗口消息循环

	return 0;
}

WSAAsyncSelect模型的基础编程可以参考《windows网络编程第二版》，里面有比较详细的介绍。