PHP/AJAX file upload with progress bar, part 2

I made some good progress on implementing the server side of things as outlined in my prior post on this subject, but I got lazy as usual. I simply haven’t gotten around to finishing this up, so I decided to throw the code up and make a post about it in the hopes that someone will either badger me into completing it, or find some of what is already there useful. The code as of now implements what could be a reasonably useful (python asyn* inspired) set of utility classes for writing socket applications in PHP. Not that anyone would ever want to do anything like that, of course.