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I am attempting to use a jQuery progress bar in my ASP.NET Web Forms application. My goal is this:

A user clicks a button, which then by ajax sends off a request which does a bunch of stuff (i.e. generating some PDFs) Since this PDF generation is a little time consuming, I would love to have a jQuery progress bar keep up to date on how many of the PDFs out of the total are completed. How would I go about starting up this process on an AJAX request and then poll the process every so often to see how it is doing? What kind of considerations do I need to take into account for multiple users using this application at one time? Sometimes I get my head all wrapped up and backwards on how the browser should talk to the server and so forth that it could be a simple solution that I am not seeing.

Any direction would be much appreciated. Thank you so much for all of your help and your time.

Justin Rassier
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  • I thought maybe I could have the process keep updating a record in a database and then my ajax query could go poll that record until it is done? I feel like there is a better way, but maybe that is a decent solution? Any thoughts? – Justin Rassier Feb 15 '11 at 18:58

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Just to keep anyone interested posted with what I did:

I used one AJAX call to start up the PDF generation process. Each step of the process I update a database record with the generation status. I then use javascript setTimeout() to call another ajax method that retrieves the record and display the current progress. Once the generation is done, the status checker ajax call is stopped.

I know this is not ideal, if this site was to get thousands of hits, that is a lot of read and writes to the DB just to do a simple progress bar. It is a solution, not even a great one in my mind, so if anyone has something they have done I would be more than willing to look into it. Thank you all for your help and thoughts on the matter.

Justin Rassier
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    An alternative would be use session. Instead of checking the database, just poll a web service that checks data in a session. This assumes that if you update a Session value, it is immediately available to other processes, which I'm not sure about. If not, then you could use a global static cache, e.g. create a static Dictionary in global.asax.cs using some id that is tied to a user session as a way to pass info between processes. – Jamie Treworgy Feb 18 '11 at 16:08
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Instead of using a jquery progressbar, you might try starting the PDF generation in a separate process, and then using an <asp:Timer> to update the page with the progress.

ChessWhiz
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  • I suppose I could look into that, I just feel that this has been done before and that there are solutions to this problem. Especially since jQuery is now part of ASP.NET projects. If there's not, then there's not, I just would like to see my options. Thank you for the input an I will start looking at that to see how it would fit into my project. – Justin Rassier Feb 15 '11 at 22:51