In ASP.Net, How do I run code after sending page - asp.net

Question

In ASP.Net, I want to run some code (logging, other cleanup) after the page has already been sent to the user. I don't want this code to interfere with the amount of time it takes the client to receive a response. I tried placing this code in the OnUnload part of the page, but through testing (using breakpoints, or busy waiting loops) the client does not actually display the page until the code in the OnUnload is finished executing. Even though the response object is no longer available at this point, and therefore I would assume that the buffered response has been sent to the client, the client still does not display the page until the OnUnload is finished executing. The only way that seems to work at the moment is to start a new thread to do the work, and allow the OnUnload to finish immediately. However, I don't know if this is safe or not. Will the server kill the thread if it executes too long after the page is already sent out? Is there a more correct way to accomplish this?

Answer 1

Kibbee,
Try overriding the Page.Render method and flushing the response like so:
Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)
MyBase.Render(writer)
Response.Flush() ' Sends all buffered output to the client
' Run some code after user gets their content
End Sub
I think at this point the response still isn't complete, but the user will get what the page has rendered before you finish running that final code.
HTH,
Mike

Answer 2

Unload is the last part of the ASP.NET page life cycle. See link below:
http://msdn.microsoft.com/en-us/library/ms178472.aspx
Is this something you could do with javascript or AJAX?

Answer 3

How about hooking into the page.Disposed event instead of the Unload event?

Answer 4

Depending on what you need to do an ISAPI filter can be created to do stuff at the end of the response.

Answer 5

You could try this solution - Best ASP.NET Background Service Implementation
Using a windows service and communicating with it through MSMQ might be a far more reliable solution and can scale up better. This will help you separate the concerns and let asp.net front end just focus on the user while the windows service focusses on the background tasks.
If you are moving to the cloud with azure, you can simply replace the asp.net front end with a web role and the windows service with a worker role and ur solution can scale seamlessly!

Answer 6

Here's a redneck way to do it. Have a second aspx page that does all your "clean up" post-rendering logic. Call that one 'cleanup.aspx' for example. Have your clean up code run in Page_Load of cleanup.aspx:
public partial class cleanup: System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
// do logging blah blah here....
}
}
In your main aspx page, have a JavaScript function that makes an AJAX call to 'cleanup.aspx'. Make the AJAX function fire after page load. I recommend jquery, if so your code will look like this:
$(function(){
yourAJAXYFunctionName();
});
function yourAJAXYFunctionName()() {
// ajax code here
//
$.ajax({
url: "cleanup.aspx",
});
}
This way, your first page's code runs, then the page is sent to the browser. As the page renders to the client, the 2nd ASPX page is called via AJAX, which really doesn't matter to cleanup.aspx, it doesn't care how its called and its page load event is executed. Your cleanup/logging code is then ran.
Caveats: client side JavaScript is required. But really who the hell doesn't have JS running anyway? Also, your cleanup.aspx page is totally abstracted from your main page, so if you want to use any object in cleanup.aspx that originated in your first page, then you'll have to store them in session or cookies, or you can pass them as parameters in the AJAX call. That will require dynamic manipulation of the AJAX script itself, but that's not too hard.

Answer 7

Better i think try try{Response.End()}catch{} runcode();