getting incoming http request in asp.net C#

Question

I have an external application (written from a different company) which fires some requests to my asp.net web application when hitting a button. My application is running on https://localhost:59917/Main.aspx. If I hit the request button in the external program it says the following:

08:53:25 Requesting web page : https://localhost:59917/Main.aspx?token=mcQYVqoe7LxmBx7jgHBq6FtXXp4uPCzX0FDZStiZDFMDd4l6oB3x5CgysXJKgy2y

So this app is now requesting my web application. I now have to get the given arguments of this request (in this example I need to read the argument token). I found this thread and tried the following in my code behind (Main.aspx.cs):

protected void btnListener_Click(object sender, EventArgs e)
{
    string token = Request.QueryString["token"];
    ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "AlertToken", "alert('" + token + "');", true);
}

But this returns an empty string. Since I'm new to asp.net and web development I'm not sure if I understand the HttpRequest class correctly. Is this even the right way to get the arguments I need?

The code above should be moved presumably in the main.aspx.cs file under the Page_Load method when IsPostBack == false. — Steve, May 22 '17 at 08:47
Why in `Page_Load()` method? This method is only fired on startup, right? But the request could be fired anytime. — Therk, May 22 '17 at 08:51
Page_Load is fired everytime a request arrives to the page. So, if the external application makes a request to main.aspx passing the mentioned querystring you should receive a Page_Load event in your main.aspx.cs — Steve, May 22 '17 at 08:58
Oh, okay. I tried it and it works, I now have the requested token. I'll keep this in reminder. If you post this as an answer I'll accept it. Thank you very much :) — Therk, May 22 '17 at 09:00

score 2 · Accepted Answer · answered May 22 '17 at 09:04

If the external application makes a request to the main.aspx page then a Page_Load events occurs in the Page Lifecycle

Thus you can simply move your code in the Page_Load event handler already written for you by the designer

protected void main_Load(object sender, EventArgs e)
{
    string token = Request.QueryString["token"];
    ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "AlertToken", "alert('" + token + "');", true);
}

Actually Page_Load events are called everytime a request for the page comes trough the ASP.NET engine also when you click a button on the same page.

Before the call to the event handler for the button clicked you receive a call to the Page_Load event handler. You can discover if this is the first time that your page loads looking at the IsPostBack property (true when the load is the result of an action performed on the same page, false when the page is loaded to present its interface to the end-user)

getting incoming http request in asp.net C#

1 Answers1