I’ve been getting back into chess recently, and my favorite online community is the Free Internet Chess Server (FICS). There are a wealth of free and open interfaces available for download, but they all have one thing in common: you have to download them. At my workplace this is a no-no, but over my lunch break it would be nice to get in a few games. If I forget my laptop then I have no way to play.
Enter Gazebo. I started this project last Friday night, so it’s only been about two days. Still, what I have right now is rather impressive for that amount of time. At face value, the current version is not very representative of the time that’s gone into the project so far, and for a very good reason.
The HTTP protocol used by web servers was not engineered around the idea that you’d establish a long-lasting connection with the server. It’s better suited for quick request-response cycles. Because of this, the PHP web service has no good way to maintain a connection to FICS.
The solution I came up with for this problem is simple, yet very involved. A daemon script (yes, written in PHP…) listens on a UNIX socket for connections from the PHP web service script. If a new FICS session is requested, it creates a new session and returns some authentication parameters to the web service. On every request to the service, another connection to the daemon is made over the UNIX socket, the session attached to with the authentication parameters, and some action taken, like “write this to the network socket” or “tell me when you get new data from the network socket” or even “close the network socket and destroy the session.” The daemon essentially acts as a super-proxy that persists the network sockets and enables access to all of them from one UNIX socket.
Yes, it’s kinda ugly. But it also works incredibly well. There is still some tuning to be done, but behold the awesomeness of what is essentially in-browser, color-coded telnet:
