Where to store progress information in ASP.Net web application

I'm creating a page that get uploaded text files and builds them into multiple PDFs. They are just exports from Excel. Each row in the file corresponds to a new PDF that needs to be created.

Anyway, once the files are uploaded I want to begin processing them, but I don't want the user to have to stay on the page, or even still have their session open. For example they could close the browser and come back 10 minutes later, log in, and the progress information will say like 112/200 files processed or something. It will be a lot quicker than that though.

So two questions really, how can I pass this processing job to something (Handler?Thread?) that will continue to run when the page is closed, and will return as soon as the job has started 开发者_开发百科(so the browser isn't stopped)? Secondly, where can I store this information so that when the user comes back to the page, they can see the current progress.

I realise that I can't use sessions, and since it will be processing about a file a second I don't really want to update a DB every second. Is there some way I can do this? Is it possible?

I solved this by using the link provided by astander above. I simply create an object in the HttpContext.Application to store progress variables, and then Set the method which does my processing inside a new Thread.

// Create the new progress object
BatchProgress bs = new BatchProgress(0);
if(Application["BatchProgress"] != null)
{
    // Should never happen
    Application["BatchProgress"] = bs;
}
else
{
    Application.Add("BatchProgress","bs");
}

//Set up new thread, run batch is the method that does all the processing.
ThreadStart ts = new ThreadStart(RunBatch);
Thread t = new Thread(ts);
t.Start();

It then returns after the thread starts and I can use jQuery to get the Application["BatchProgress"] object at regular intervals. At the end of my thread the BatchProgress object has its status set to "Complete", then when jQuery queries it, it sees the complete status and removes the progress object from the application.