It seems to me that AWTDI might be to use named pipes, though I'm not sure how well supported they are with perl on Win32. But, in theory, you could just leave your application running in the background (or a small program that would launch your program upon demand), and point the browser to the named pipe and have it treat it like a normal file. Of course, this makes passing parameters to the file difficult, so maybe it wouldn't work out after all.