CassiniDev源码学习

最近一个项目是将web版的程序，改为单机版。话说这个web版号称当年十几个人用了至少3个月的时间开发，后来三年还不断有修改，而现在要在1个月内由一个人完成，这简直是不可能完成的任务！直觉告诉我，重写肯定不是办法，还好有朋友用过Cassini http://cassinidev.codeplex.com （可替代IIS的单机Web Form解决方案）立即投入测试，可用；有源码，不担心出太大问题。

现在项目结束了，看了一遍CassiniDev，它的基本思路是：

1.新建socket，绑定并监听本机上一个可用的端口。

2.对新建连接（新的请求）创建新的socket。

　　　　 public void Start()
        {
            _socket = CreateSocketBindAndListen(AddressFamily.InterNetwork, _ipAddress, _port);

            //start the timer
            //DecrementRequestCount();

            ThreadPool.QueueUserWorkItem(delegate
                {
                    while (!_shutdownInProgress)
                    {
                        try
                        {
                            Socket acceptedSocket = _socket.Accept();

                            ThreadPool.QueueUserWorkItem(delegate
                                {
                                    if (!_shutdownInProgress)
                                    {
                                        Connection conn = new Connection(this, acceptedSocket);

                                        if (conn.WaitForRequestBytes() == 0)
                                        {
                                            conn.WriteErrorAndClose(400);
                                            return;
                                        }

                                        Host host = GetHost();

                                        if (host == null)
                                        {
                                            conn.WriteErrorAndClose(500);
                                            return;
                                        }

                                        //IncrementRequestCount();
                                        host.ProcessRequest(conn);
                                    }
                                });
                        }
                        catch
                        {
                            Thread.Sleep(100);
                        }
                    }
                });
        }

3.通过一个微软的内部类“System.Web.Compilation.BuildManagerHost”（未对外公布，MSDN查不到），生成Host实例。

　　　　 /// <remarks>
        /// This is Dmitry's hack to enable running outside of GAC.
        /// There are some errors being thrown when running in proc
        /// </remarks>
        private object CreateWorkerAppDomainWithHost(string virtualPath, string physicalPath, Type hostType,int port)
        {


            // create BuildManagerHost in the worker app domain
            //ApplicationManager appManager = ApplicationManager.GetApplicationManager();
            Type buildManagerHostType = typeof(HttpRuntime).Assembly.GetType("System.Web.Compilation.BuildManagerHost");
            IRegisteredObject buildManagerHost = ApplicationManager.CreateObject(_appId, buildManagerHostType, virtualPath,
                                                                          physicalPath, false);

            // call BuildManagerHost.RegisterAssembly to make Host type loadable in the worker app domain
            buildManagerHostType.InvokeMember("RegisterAssembly",
                                              BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic,
                                              null,
                                              buildManagerHost,
                                              new object[] { hostType.Assembly.FullName, hostType.Assembly.Location });

            // create Host in the worker app domain
            // FIXME: getting FileLoadException Could not load file or assembly 'WebDev.WebServer20, Version=4.0.1.6, Culture=neutral, PublicKeyToken=f7f6e0b4240c7c27' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418)
            // when running dnoa 3.4 samples - webdev is registering trust somewhere that we are not
            return ApplicationManager.CreateObject(_appId, hostType, virtualPath, physicalPath, false);
        }

4.继承“SimpleWorkerRequest”类（它是System.Web.HttpWorkerRequest 抽象类的简单实现，该抽象类可用于在 Internet 信息服务 (IIS) 应用程序之外承载ASP.NET 应用程序），写一个自己的Request类。

5.由HttpRuntime驱动所有 ASP.NET Web 处理执行。

HttpRuntime.ProcessRequest(this);

这个开源组件确实不错，好用，稳定，在winxp, vista, win7, win8都可用。但有一个性能上的不足，在创建微软内部类“System.Web.Compilation.BuildManagerHost”实例时，耗时要5-6秒的时间，机器差一点的话，要9-20秒，目前暂无改进。