慢WebClient.DownloadString？ [英] Slow WebClient.DownloadString?

问题描述

我的工作是与ASP.Net 3.5上运行的Web应用程序

I'm working on a web application that runs with ASP.Net 3.5

在某处的应用，我正在给外部系统调用。这一呼吁包括从特定的URL下载的字符串：

Somewhere in the application, I'm making calls to an external system. This call consists on downloading a string from a specific url :

string targetUrl = BuildMyUrl();
WebClient wc = new WebClient();
string data = wc.DownloadString(targetUrl);

此代码工作得很好用可接受的响应时间（500毫秒以下）。

This code works quite well with a acceptable response time (under 500ms).

然而，在特定情况下，这种反应时间超过15秒。我可以重现的行为，我可以清楚的看到很长一段时间是在 DownloadString 电话。

However, in specific cases this response time is over 15 seconds. I can reproduce the behavior, and I can clearly see the long time is on the DownloadString call.

的

I don't understand why this occurs in my scenario.

您会说：嘿，这是目标系统，慢行。但我不能能够重现我的应用程序之外的行为（我建立一个隔离断层代码小型控制台应用程序。从来没有得到任何问题）。

You will say : "Hey, it's the target system that is slow". But I was not able able to reproduce the behavior outside my application (I've build a small console application that isolate the faulting code. Never get any issue).

我不知道去哪里现在看明白这个问题。哪些原因会导致一个简单的下载数据进行很长

I don't know where to look now to understand the issue. What can cause a simple download data to be be lengthy ?

FYI：目标系统是一种身份验证服务。目标URL是怎么样的：

FYI: the target system is an authentication service. The target url is of kind :

HTTP 取值：// mysystem /验证票= XXXYYY

httpS://mysystem/validate?ticket=XXXYYY

也许https协议是问题。

Maybe the https protocol is the issue.

是否使用IIS下WebClient类？可以改变Web客户端的行为

Does using WebClient class under IIS can alter the behavior of the WebClient ?

我已经试过：

• 要明确设置WebClient的对象的代理属性设置为null



• 我已经换成了DownloadData通话这段代码：

• To explicitly set the Proxy property of the WebClient object to null

• I've replaced the DownloadData call by this code :

VAR REQ =（HttpWebRequest的）WebRequest.CreateDefault（新的URI（targetUrl这个））;使用
（VAR响应=（HttpWebResponse）req.GetResponse（））
{
使用（VAR SR =新的StreamReader（response.GetResponseStream（）））
{
数据= sr.ReadToEnd（）;
}
}

var req = (HttpWebRequest)WebRequest.CreateDefault(new Uri(targetUrl)); using (var response = (HttpWebResponse)req.GetResponse()) { using (var sr = new StreamReader(response.GetResponseStream())) { data= sr.ReadToEnd(); } }

本次测试没有成功。

推荐答案

的延迟是由于证书验证超时。一链中的发行者的不正确部署在客户端服务器

The latency was due to a certificate validation timeout. One of the issuer in the chain was not correctly deployed in the client server.

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