Hi everybody, I have a little (maybe the answer could require a book) question about web services and server side programming.

But first, a little preamble. Recently we have seen new kind of applications & games using some kind of real-time interaction with a database, or more generally, with other users. I'm talking about shared drawing canvas, games like this , or simple chats, or the Android app "a World of Photo", where in real time you see who is online, to share your photos, etc.

Now my question: Are all these apps based on classic TCP client/server architectures or is there a way to make them in a simpler way, like a web platform like LAMP?

What I'm asking, in other words is: Can PHP+MySQL (or JSP, or RoR, or any other server language) provide a way to make online users communicate in real time and share data? Is there a way to do that without the ugly and heavy mechanism of temporary tables?

Thank you! I hope I've been clear.