I'm looking to implement a real-time collaboration on a document on the web. Is there some sort of library that enables it in PHP? Something similar to SignalR which creates 'persistent connection' by using long-polling.
update found this library for pubsubhubbub http://code.google.com/p/pubsubhubbub/source/browse/trunk/publisher_clients/php/
Searching on the library name led me to How to implement PubSubHubbub?
Checkout pubsubhubbub