This may be a dumb question, but what kind of protocol a website such as: megaupload, rapidshare, yousendit is using for file upload from client to server? are they using http, ftp?
How does this actually work?
I’ve been doing some research regarding this but no luck.
They are using HTTP or HTTPS. When you’re not using AJAX, that is just a simple file upload using a form tag.
If AJAX is used, there are many possible libraries to use. Since you tagged your question with Java. You could reverse engineer the requests done to the server (for example, with browser plugins like this one) and send them using java instead of your browser. Some uploading sites also offer public APIs, like Rapidshare.com