GSTChannels uses php/mysql on a http-server to register servers.
every 60 secs the different 3dgs gstnet servers execute a non-blocking http request to update various properties for the appropriate server in the list with a timestamp.

the serverlist call is also an http request which execute at first a query to delete those servers where the last timestamp is older than 120 seconds (gui or non gui version).

that should work for most mp games.