R – How many concurrent outbound HttpWebRequest calls can be made in ASP.NET / IIS7

asp.netconnectionhttpwebrequesttcpwebrequest

I'm writing an ASP.NET web application which will run on Windows Server 2008 (IIS7).

Each page's codebehind will need to make at least one synchronous web service call to an external server using HttpWebRequest and GET.

My question – is there any limit to the number of outbound HttpWebRequest calls I can make? (assume that the server I'm calling has no limit)

Is there any means to pool these connections to make the app scale better? Would a web garden configuration help?

Best Answer

By default, an HTTP/1.1 server is limited to two connection, and a HTTP/1.0 server is limited to four connections. So, your ASP.NEt app will have serious throughput problems if you are trying to issue more than two outstanding requests to an HTTP/1.1 server, for eg.

You will need to increase the connection limit, either per server, or globally.

For eg, globally:

ServicePointManager.DefaultConnectionLimit = 10; // allow 10 outstanding connections

Hope this helps.

Related Solutions

.net – How to take more control in ASP.NET

This solution will give you programmatic access to the controls in their entirety including all attributes on the controls. Also, only the text box values will appear in the URL upon submission so your GET request URL will be more "meaningful"

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="JonSkeetForm.aspx.cs" Inherits="JonSkeetForm" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Jon Skeet's Form Page</title>
</head>
<body>
    <form action="JonSkeetForm.aspx" method="get">
    <div>
        <input type="text" ID="text1" runat="server" />
        <input type="text" ID="text2" runat="server" />
        <button type="submit">Submit</button>
        <asp:Repeater ID="Repeater1" runat="server">
            <ItemTemplate>
                <div>Some text</div>
            </ItemTemplate>
        </asp:Repeater>
    </div>
    </form>
</body>
</html>

Then in your code-behind you can do everything you need on PageLoad

public partial class JonSkeetForm : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        text1.Value = Request.QueryString[text1.ClientID];
        text2.Value = Request.QueryString[text2.ClientID];
    }
}

If you don't want a form that has runat="server", then you should use HTML controls. It's easier to work with for your purposes. Just use regular HTML tags and put runat="server" and give them an ID. Then you can access them programmatically and code without a ViewState.

The only downside is that you won't have access to many of the "helpful" ASP.NET server controls like GridViews. I included a Repeater in my example because I'm assuming that you want to have the fields on the same page as the results and (to my knowledge) a Repeater is the only DataBound control that will run without a runat="server" attribute in the Form tag.

Async HttpWebRequest with no wait from within a web application

HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(myUrl);
//set up web request...
ThreadPool.QueueUserWorkItem(o=>{ myRequest.GetResponse(); });

Also known as Fire-and-Forget.

Best Answer

Related Solutions

.net – How to take more control in ASP.NET

Async HttpWebRequest with no wait from within a web application

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