你必须知道ASP.NET知识------从IIS到httpmodule(第一篇)
一、写在前面
最近有时间,顺便将这系列洗完,接着上文:IIS各个版本知识总结
这篇文章原本计划写到HttpHandler为止,但限于篇幅就写到httpmodule
本文有不足之处,求指正,希望我能将它分析透彻.
二、回顾--我们还是从IIS说起
从上文(IIS各个版本知识总结)可以很清楚地意思到经典模式和集成模式的区别:集成模式是一个伟大的改进，让IIS集成了.NET功能（不在依靠之前IIS版本的aspnet_ISPAI.DLL).
所以,对于我们所开发的ASP.NET程序而言,这些完全不必知道;但运行环境自己必须知道发生了什么情况.
所以两者的主要区别在于:从w3wp.exe初始化httpapplication这一阶段.
三、看看经典模式(包括IIS6)的过程
IIS的处理进程到w3wp这一阶段后,iis会通过com的方式创建AppManagerAppDomainFactory对象,AppManagerAppDomainFactory会
在Create方法中创建ISAPIRuntime对象.代码如下.
using System;
using System.Globalization;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.Remoting;
using System.Security.Permissions;
using System.Web.Util;
namespace System.Web.Hosting
{
[SecurityPermission(SecurityAction.LinkDemand, Unrestricted = true)]
public sealed class AppManagerAppDomainFactory : IAppManagerAppDomainFactory
{
private ApplicationManager _appManager;
public AppManagerAppDomainFactory()
{
this._appManager = ApplicationManager.GetApplicationManager();
this._appManager.Open();
}
[return: MarshalAs(UnmanagedType.Interface)]
public object Create(string appId, string appPath)
{
object result;
try
{
if (appPath[0] == '.')
{
FileInfo fileInfo = new FileInfo(appPath);
appPath = fileInfo.FullName;
}
if (!StringUtil.StringEndsWith(appPath, '\\'))
{
appPath += "\\";
}
ISAPIApplicationHost appHost = new ISAPIApplicationHost(appId, appPath, false);
ISAPIRuntime iSAPIRuntime = (ISAPIRuntime)this._appManager.CreateObjectInternal(appId, typeof(ISAPIRuntime), appHost, false, null);
iSAPIRuntime.StartProcessing();
result = new ObjectHandle(iSAPIRuntime);
}
catch (Exception)
{
throw;
}
return result;
}
public void Stop()
{
this._appManager.Close();
}
internal static string ConstructSimpleAppName(string virtPath)
{
if (virtPath.Length <= 1)
{
return "root";
}
return virtPath.Substring(1).ToLower(CultureInfo.InvariantCulture).Replace('/', '_');
}
}
}
View Code
最终将流程交由ProcessRequest处理,代码如下.接着如红色处,由HttpRuntime.ProcessRequestNoDemand(iSAPIWorkerRequest)处理
public int ProcessRequest(IntPtr ecb, int iWRType)
{
IntPtr intPtr = IntPtr.Zero;
if (iWRType == 2)
{
intPtr = ecb;
ecb = UnsafeNativeMethods.GetEcb(intPtr);
}
ISAPIWorkerRequest iSAPIWorkerRequest = null;
int result;
try
{
bool useOOP = iWRType == 1;//注:internal abstract class ISAPIWorkerRequest : HttpWorkerRequest
iSAPIWorkerRequest = ISAPIWorkerRequest.CreateWorkerRequest(ecb, useOOP);
iSAPIWorkerRequest.Initialize();
string appPathTranslated = iSAPIWorkerRequest.GetAppPathTranslated();
string appDomainAppPathInternal = HttpRuntime.AppDomainAppPathInternal;
if (appDomainAppPathInternal == null || StringUtil.EqualsIgnoreCase(appPathTranslated, appDomainAppPathInternal))
{
HttpRuntime.ProcessRequestNoDemand(iSAPIWorkerRequest);
result = 0;
}
else
{
HttpRuntime.ShutdownAppDomain(ApplicationShutdownReason.PhysicalApplicationPathChanged, SR.GetString("Hosting_Phys_Path_Changed", new object[]
{
appDomainAppPathInternal,
appPathTranslated
}));
result = 1;
}
}
catch (Exception ex)
{
//..................................
}
return result;
}
ISAPIWorkerRequest是对请求信息的一层C++封装.
四、HttpRuntime中发生的事情
接着上面 HttpRuntime.ProcessRequestNoDemand(iSAPIWorkerRequest)
internal static void ProcessRequestNoDemand(HttpWorkerRequest wr)
{
RequestQueue requestQueue = HttpRuntime._theRuntime._requestQueue;
wr.UpdateInitialCounters();
if (requestQueue != null)
{
wr = requestQueue.GetRequestToExecute(wr);
}
if (wr != null)
{
HttpRuntime.CalculateWaitTimeAndUpdatePerfCounter(wr);
wr.ResetStartTime();
HttpRuntime.ProcessRequestNow(wr);
}
}
internal static void ProcessRequestNow(HttpWorkerRequest wr)
{
HttpRuntime._theRuntime.ProcessRequestInternal(wr);
}
View Code
我们看到方法进入
rivate void ProcessRequestInternal(HttpWorkerRequest wr)
其结构如下
private void ProcessRequestInternal(HttpWorkerRequest wr)
{
Interlocked.Increment(ref this._activeRequestCount);
if (this._disposingHttpRuntime)
{
try
{
wr.SendStatus(503, "Server Too Busy");
wr.SendKnownResponseHeader(12, "text/html; charset=utf-8");
byte[] bytes = Encoding.ASCII.GetBytes("<html><body>Server Too Busy</body></html>");
wr.SendResponseFromMemory(bytes, bytes.Length);
wr.FlushResponse(true);
wr.EndOfRequest();
}
finally
{
Interlocked.Decrement(ref this._activeRequestCount);
}
return;
}
HttpContext httpContext;
try
{
httpContext = new HttpContext(wr, false);
}
catch
{
try
{
wr.SendStatus(400, "Bad Request");
wr.SendKnownResponseHeader(12, "text/html; charset=utf-8");
byte[] bytes2 = Encoding.ASCII.GetBytes("<html><body>Bad Request</body></html>");
wr.SendResponseFromMemory(bytes2, bytes2.Length);
wr.FlushResponse(true);
wr.EndOfRequest();
return;
}
finally
{
Interlocked.Decrement(ref this._activeRequestCount);
}
}
wr.SetEndOfSendNotification(this._asyncEndOfSendCallback, httpContext);
HostingEnvironment.IncrementBusyCount();
try
{
try
{
this.EnsureFirstRequestInit(httpContext);
}
catch
{
if (!httpContext.Request.IsDebuggingRequest)
{
throw;
}
}
httpContext.Response.InitResponseWriter();
IHttpHandler applicationInstance = HttpApplicationFactory.GetApplicationInstance(httpContext);
if (applicationInstance == null)
{
throw new HttpException(SR.GetString("Unable_create_app_object"));
}
if (EtwTrace.IsTraceEnabled(5, 1))
{
EtwTrace.Trace(EtwTraceType.ETW_TYPE_START_HANDLER, httpContext.WorkerRequest, applicationInstance.GetType().FullName, "Start");
}
if (applicationInstance is IHttpAsyncHandler)
{
IHttpAsyncHandler httpAsyncHandler = (IHttpAsyncHandler)applicationInstance;
httpContext.AsyncAppHandler = httpAsyncHandler;
httpAsyncHandler.BeginProcessRequest(httpContext, this._handlerCompletionCallback, httpContext);
}
else
{
applicationInstance.ProcessRequest(httpContext);
this.FinishRequest(httpContext.WorkerRequest, httpContext, null);
}
}
catch (Exception e)
{
httpContext.Response.InitResponseWriter();
this.FinishRequest(wr, httpContext, e);
}
}
View Code
传说中的HttpApplication就是在这里初始化的.
IHttpHandler applicationInstance = HttpApplicationFactory.GetApplicationInstance(httpContext);//因为HttpApplication实现了IHttpHandler接口
最终通过BuildManager.GetGlobalAsaxType()获取对应的Global.asax所告知的类型进行HttpApplication的实例化.
internal static IHttpHandler GetApplicationInstance(HttpContext context)
{
if (HttpApplicationFactory._customApplication != null)
{
return HttpApplicationFactory._customApplication;
}
if (context.Request.IsDebuggingRequest)
{
return new HttpDebugHandler();
}
HttpApplicationFactory._theApplicationFactory.EnsureInited();
HttpApplicationFactory._theApplicationFactory.EnsureAppStartCalled(context);
return HttpApplicationFactory._theApplicationFactory.GetNormalApplicationInstance(context);
}
private HttpApplication GetNormalApplicationInstance(HttpContext context)
{
HttpApplication httpApplication = null;
lock (this._freeList)
{
if (this._numFreeAppInstances > 0)
{
httpApplication = (HttpApplication)this._freeList.Pop();
this._numFreeAppInstances--;
if (this._numFreeAppInstances < this._minFreeAppInstances)
{
this._minFreeAppInstances = this._numFreeAppInstances;
}
}
}
if (httpApplication == null)
{
httpApplication = (HttpApplication)HttpRuntime.CreateNonPublicInstance(this._theApplicationType);
using (new ApplicationImpersonationContext())
{
httpApplication.InitInternal(context, this._state, this._eventHandlerMethods);//注意:这里是主战场
}
}
if (AppSettings.UseTaskFriendlySynchronizationContext)
{
httpApplication.ApplicationInstanceConsumersCounter = new CountdownTask(1);
httpApplication.ApplicationInstanceConsumersCounter.Task.ContinueWith(delegate(Task _, object o)
{
HttpApplicationFactory.RecycleApplicationInstance((HttpApplication)o);
}, httpApplication, TaskContinuationOptions.ExecuteSynchronously);
}
return httpApplication;
}
五、主战场中的发生的事情
internal void InitInternal(HttpContext context, HttpApplicationState state, MethodInfo[] handlers)
{
this._state = state;
PerfCounters.IncrementCounter(AppPerfCounter.PIPELINES);
try
{
try
{
this._initContext = context;
this._initContext.ApplicationInstance = this;
context.ConfigurationPath = context.Request.ApplicationPathObject;
using (new DisposableHttpContextWrapper(context))
{
if (HttpRuntime.UseIntegratedPipeline)
{
try
{
context.HideRequestResponse = true;
this._hideRequestResponse = true;
this.InitIntegratedModules();
goto IL_6B;
}
finally
{
context.HideRequestResponse = false;
this._hideRequestResponse = false;
}
}
this.InitModules();
IL_6B:
if (handlers != null)
{
this.HookupEventHandlersForApplicationAndModules(handlers);
}
this._context = context;
if (HttpRuntime.UseIntegratedPipeline && this._context != null)
{
this._context.HideRequestResponse = true;
}
this._hideRequestResponse = true;
try
{
this.Init();
}
catch (Exception error)
{
this.RecordError(error);
}
}
if (HttpRuntime.UseIntegratedPipeline && this._context != null)
{
this._context.HideRequestResponse = false;
}
this._hideRequestResponse = false;
this._context = null;
this._resumeStepsWaitCallback = new WaitCallback(this.ResumeStepsWaitCallback);
if (HttpRuntime.UseIntegratedPipeline)
{
this._stepManager = new HttpApplication.PipelineStepManager(this);
}
else
{
this._stepManager = new HttpApplication.ApplicationStepManager(this);
}
this._stepManager.BuildSteps(this._resumeStepsWaitCallback);
}
finally
{
this._initInternalCompleted = true;
context.ConfigurationPath = null;
this._initContext.ApplicationInstance = null;
this._initContext = null;
}
}
catch
{
throw;
}
}
待续................................
六、求关注、求推荐
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