Re: Upload Progress Bar

I had to solve this exact problem about 6 months ago for an application that parsed uploaded files real time and fed back progress indicators to the user. There is a great description of how to do a search in progress out there by merlyn, but this situation is a bit different in that the main application window is handling the upload, and cannot be refreshed.

I did this in a mod_perl2 handler using Apache::Request, but you should be able to accomplish the same with cgi scripts. Upon the user clicking 'Upload', I used javascript to open a small status window which refreshed waiting for the presense of upload status data. Meanwhile the main window begins the upload process. An UPLOAD_HOOK (see a::r docs) subroutine measured the amount of bytes received from the client and wrote it to a status file which the monitor read.

Now, this worked very well for displaying the amount of bytes received from the user. As for determining the percentage of file uploaded, a::r provides the following useful method:

my $size = $upload->size;

However I did not find the size returned to be reliable when referenced from within the UPLOAD_HOOK subroutine. I suspect is determined once the file is fully uploaded. So I wasn't able to give the user a realistic estimation of when the file would be done uploading.

But I was able to parse the contents real-time, display the results to the user, and terminate the upload if the errors in the file exceeded a certain threshold, which got good feedback from the users. I got some flak from reviewers of the technique, but it worked very well. I was able to pass back to the user accurate information about where in the file errors were, which saved them a great deal of time.

HTH

Comment on Re: Upload Progress Bar Download Code

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Re^2: Upload Progress Bar by Anonymous Monk on Dec 26, 2004 at 02:40 UTC
Hey Red, Thanks a lot, that´s exactly what I was looking for. I´ve visited CPAN and in fact I think it will do. But, tell me, I can run this module even without mod_perl? My host's server is Apache. The one thing that still remains a mystery to me is how to manage, and by how many scripts, the signals and the processing of the file. I still don´t know if I can have the same script that processes the file upload and processing, to check $upload->size, tell the status bar (in wich page?) the new status or to get lost as the upload ends. Other thing is the javascript. I´m not very skilled in javascript. Can you send me your code, or some sample of it? I don´t have a clue of how to do it... Thank you very much! André	[reply]
Re^3: Upload Progress Bar by redhotpenguin (Deacon) on Dec 26, 2004 at 06:46 UTC
For information on javascript check here. I had the upload handler write the byte count to a session file, and the monitor process which was opened through the javascript on the "Upload" button read from the same session. CGI.pm also has an upload_hook subroutine which you can use to do this - you don't explicitly need a::r. You might also want to take a look at Apache::UploadMeter , I was using mod_perl2 so I had to roll my own.	[reply]