File upload / download progress bar



Does anyone know how a file upload / download progress bar can be made - like the one used by Yahoo Mail when using MSIE 6.something?

For you who don't know, it's a progress bar used when attaching files to an email, showing you how much it has uploaded of the total size. It has to contain some server-side and some client-side parts but have no ideea.
in php its imposible.

but you can calculate with flash speed of user internet, and make a psevdo progress bar, that will show a not real upload or download progres bar.
Oleg is correct, it's not possible with a vanilla PHP installation. There is a patch floating around somewhere that does it, but that would require you to patch the source yourself.

But if your server has Perl installed, you can use the "Mega Upload" progress indicator, which is a combination of Perl and PHP.