如何使用PageAsyncTask与WebRequest的多个请求？ [英] How to use PageAsyncTask with WebRequest for multiple requests?

问题描述

我针对一个Web服务，接受一个字符串参数。
按计划我要火了大约100个​​电话，为从我的数据库100个值的Web服务。
为了优化过程中，我相信我需要做的WebRequest异步调用。
我已经遇到了code 示例下面对各种博客等，但无法弄清楚如何去适应它作为我的要求。
我该如何收官RegisterAsyncTask foreach循环内，通过URI进行解析类向WebRequest.Create（）这里面BeginAsyncOperation？

I'm targeting a web service that takes a single string parameter. On a schedule I want to fire off approximately 100 calls to that web service for 100 values from my database. To optimise the process I believe I need to do the WebRequest calls asynchronously. I've come across the code example below on a variety of blogs etc. but can't figure out how to adapt it for my requirement. How can I wrap up the RegisterAsyncTask inside a foreach loop, parsing through the uri for the WebRequest.Create() that's inside BeginAsyncOperation?

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Net;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;

public partial class AsyncPageTask : System.Web.UI.Page
{
    private WebRequest _request;

    protected void Page_Load(object sender, EventArgs e)
    {
        PageAsyncTask task = new PageAsyncTask(
            new BeginEventHandler(BeginAsyncOperation),
            new EndEventHandler(EndAsyncOperation),
            new EndEventHandler(TimeoutAsyncOperation),
            null
        );
        RegisterAsyncTask(task);
    }

    IAsyncResult BeginAsyncOperation(object sender, EventArgs e, 
        AsyncCallback cb, object state)
    {
        _request = WebRequest.Create("http://msdn.microsoft.com");
        return _request.BeginGetResponse(cb, state);
    }

    void EndAsyncOperation(IAsyncResult ar)
    {
        string text;
        using (WebResponse response = _request.EndGetResponse(ar))
        {
            using (StreamReader reader = 
                new StreamReader(response.GetResponseStream()))
            {
                text = reader.ReadToEnd();
            }
        }

        Output.Text = text;
    }

    void TimeoutAsyncOperation(IAsyncResult ar)
    {
        Output.Text = "Data temporarily unavailable";
    }
}

我的本意是写响应字符串返回到数据库中。鸭preciate这是一个额外的问题，但是，没有任何理由不包括EndAsyncOperation方法中插入方法调用？

My intention is to write the response string back into a database. Appreciate this is an additional question but, is there any reason not to include the insert method call within the EndAsyncOperation method ?

这<一个href=\"http://stackoverflow.com/questions/7822948/asp-net-pageasynctaks-how-to-pass-parameter-to-the-task/7823119#7823119\">Q&A对我的主要问题，但其第四个参数提示？

This Q&A hints towards my main question but which 4th argument?

推荐答案

首先，你需要添加到您的Web.config文件（默认仅有2）：

First you need to add this to your Web.config file (default is just 2):

<configuration>
    <system.net>
        <connectionManagement>
            <add address="*" maxconnection="100" />
        </connectionManagement>
    <system.net>
<configuration>

然后你需要异步指令添加到您的网页：＆LT;％@页面异步=真正的％GT;

protected void Page_Load(object sender, EventArgs e)
{
    //...first get UriStringArray from db, and then:
    foreach(string uri in UriStringArray)
    {
        var task = new PageAsyncTask(
            new BeginEventHandler(BeginAsyncOperation),
            new EndEventHandler(EndAsyncOperation),
            new EndEventHandler(TimeoutAsyncOperation),
            uri,
            true; //run in parallel
        );
        RegisterAsyncTask(task);
    }
}

IAsyncResult BeginAsyncOperation(object sender, EventArgs e, AsyncCallback cb, object state)
{
    var request = (HttpWebRequest)WebRequest.Create((string)state);
    return request.BeginGetResponse(cb, request);
}

void EndAsyncOperation(IAsyncResult ar)
{
    string text;
    var request = (HttpWebRequest)ar.State;
    using(WebResponse response = request.EndGetResponse(ar))
    {
        using(StreamReader reader = new StreamReader(response.GetResponseStream()))
            text = reader.ReadToEnd();
    }
    //yes, you can insert in db here, even as a new PageAsyncTask - but then must call ExecuteRegisteredAsyncTasks() manually...
}

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