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);
}
}

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

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>

<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; }
}

参考