Websockets what are they? Here is what wikipedia had to say on the subject http://en.wikipedia.org/wiki/WebSocket. Basically put, websockets let you do a server "push" to a client browser.
If you have ever used BlazeDs you will be familiar with this type of technology. However with BlazeDS there was a constant open connection to the server. With websockets there is no persistant open connection. This greatly reduces overall overhead for both the client and the server.
So, what can you build with websockets? Well lots of stuff, you can create the obligatory chat client. Maybe an ad system that feeds new ads to a client. Maybe even a game where 2 people can play against each other.
Well, I figured it would be better just to build something to demo its features then to just talk about it. So, with that, I made a game. It is a 2 player game that allows people to play against each other in the same fashion as Battleship.
The downloadable code is attached to this post. A couple notes about the code. To run it effectively you need to open 2 browsers, not to browser windows. Also, I didn't to an exhaustive amount of testing on the app. If you just use it as intended it should work just fine. Also, if you have a console (firebug, or Developer Tools) running you can see the messages passed back and forth. In the base.js file at the very bottom uncomment the console.log line to see the output. Take a look at the code. Use it as an example to build your own next great thing. Let me know if you have any issues, questions or comments. I will do my best to assist as much as possible.
Till Next time...