异步HTTPHandler的实现

使用APM的方式实现

using System;
using System.Web;
using System.Threading;
 
class HelloWorldAsyncHandler : IHttpAsyncHandler
{
    public bool IsReusable { get { return false; } }
 
    public HelloWorldAsyncHandler()
    {
    }
    public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
    {
        context.Response.Write("<p>Begin IsThreadPoolThread is " + Thread.CurrentThread.IsThreadPoolThread + "</p>\r\n");
        AsynchOperation asynch = new AsynchOperation(cb, context, extraData);
        asynch.StartAsyncWork();
        return asynch;
    }
 
    public void EndProcessRequest(IAsyncResult result)
    {
    }
 
    public void ProcessRequest(HttpContext context)
    {
        throw new InvalidOperationException();
    }
}
 
class AsynchOperation : IAsyncResult
{
    private bool _completed;
    private Object _state;
    private AsyncCallback _callback;
    private HttpContext _context;
 
    bool IAsyncResult.IsCompleted { get { return _completed; } }
    WaitHandle IAsyncResult.AsyncWaitHandle { get { return null; } }
    Object IAsyncResult.AsyncState { get { return _state; } }
    bool IAsyncResult.CompletedSynchronously { get { return false; } }
 
    public AsynchOperation(AsyncCallback callback, HttpContext context, Object state)
    {
        _callback = callback;
        _context = context;
        _state = state;
        _completed = false;
    }
 
    public void StartAsyncWork()
    {
        ThreadPool.QueueUserWorkItem(new WaitCallback(StartAsyncTask), null);
    }
 
    private void StartAsyncTask(Object workItemState)
    {
 
        _context.Response.Write("<p>Completion IsThreadPoolThread is " + Thread.CurrentThread.IsThreadPoolThread + "</p>\r\n");
 
        _context.Response.Write("Hello World from Async Handler!");
        _completed = true;
        _callback(this);
    }
}

IIS 6.0 注册Handler

<configuration>
  <system.web>
<httpHandlers><add verb="*" path="*.SampleAsync" type="HelloWorldAsyncHandler"/></httpHandlers>
  </system.web>
</configuration>

IIS 7.0 注册handler 经典模式下

configuration>
  <system.web>
<httpHandlers><add verb="*" path="*.SampleAsync" type="HelloWorldAsyncHandler"/></httpHandlers>
  </system.web>
  <system.webServer>
<handlers><add  verb="*" path="*.SampleAsync"name="HelloWorldAsyncHandler"type="HelloWorldAsyncHandler"modules="IsapiModule"/>scriptProcessor="%path%\aspnet_isapi.dll"</handlers>
  </system.webServer>
</configuration>

IIS 7.0 注册handler 集成模式下

<configuration>
  <system.webServer>
<handlers><add verb="*" path="*.SampleAsync"name="HelloWorldAsyncHandler"type="HelloWorldAsyncHandler"/></handlers>
  </system.webServer>
</configuration>

使用TPM的方式实现

<%@ WebHandler Language="C#" Class="ajaxResponse" %>
 
public class ajaxResponse: System.Web.HttpTaskAsyncHandler
{
    //設定一個集合來存放結果集
    private System.Collections.Generic.List<ORM_Class> oResult;
    //泛型處理常式主要進入點
    public override async System.Threading.Tasks.Task ProcessRequestAsync(System.Web.HttpContext context)
    {
        //指定要存取的網址，壓入非同步工作中
        await PushToTask(new string[] {
            "http://date.jsontest.com", //FreeJson
            "http://date.jsontest.com", //FreeJson
            "http://date.jsontest.com"  //FreeJson
        });
        //輸出結果集之JSON
        context.Response.ContentType = "application/json; charset=utf-8";
        context.Response.Write(Newtonsoft.Json.JsonConvert.SerializeObject(oResult));
    }
 
    //非同步工作佇列處理
    private async System.Threading.Tasks.Task PushToTask(System.Collections.Generic.IList<string> oURLs)
    {
        System.Collections.Generic.List<System.Threading.Tasks.Task> oTasks = new System.Collections.Generic.List<System.Threading.Tasks.Task>();
        System.Threading.SemaphoreSlim oControl = new System.Threading.SemaphoreSlim(oURLs.Count);
        oResult = new System.Collections.Generic.List<ORM_Class>();
        foreach (var cURL in oURLs)
        {
            await oControl.WaitAsync();
            oTasks.Add(System.Threading.Tasks.Task.Run(async () =>
            {
                try
                {
                    using (System.Net.WebClient oWC = new System.Net.WebClient() { Encoding = System.Text.Encoding.UTF8 })
                    {
                        oResult.Add(Newtonsoft.Json.JsonConvert.DeserializeObject<ORM_Class>(
                            await oWC.DownloadStringTaskAsync(new System.Uri(cURL))
                        ));
                    }
                }
                catch { return; }
                finally { oControl.Release(); }
            }));
        }
        //等候所有的工作完成
        await System.Threading.Tasks.Task.WhenAll(oTasks);
    }
}
 
//預計取用的ORM類別
class ORM_Class
{
    public string time { get; set; }
    public long milliseconds_since_epoch { get; set; }
    public string date { get; set; }
}