Java EE (Java Enterprise Edition) General Discussion

hi all, I need some help if someone know how to do it.
I am making a jsp servlet mysql application and problem is canceling running upload.
I am using ajax get request to start file upload to servlet and it works fine. I am monitoring
upload progress in a msgbox.
But if client wants to stop(cancel) running upload, he push the close button, and msgbox is closing but
upload continues at servlet. How can tell servlet to cancel this upload?
If i dont do that. Servlet keep file name info, and when client starts another upload, this time servlet uses previous uploaded(canceled) file name info for new uploaded file.
How can say servlet to stop uploading and set all values to null?
Thanks all.