Quote:Original post by @
consider MMORPG. lobby (central) server keeps all client connections mainly to prevent logging in the same account.

Of flip a flag in the database. There's no need for there to be one single server that holds every single connection. Checking for duplicate logins isn't a time-critical activity that can't afford a DB access. And you probably have to hit the DB to look up authentication/authorisation stuff anyway.

Quote:Original post by Kylotan

Quote:Original post by @
consider MMORPG. lobby (central) server keeps all client connections mainly to prevent logging in the same account.

Of flip a flag in the database. There's no need for there to be one single server that holds every single connection. Checking for duplicate logins isn't a time-critical activity that can't afford a DB access. And you probably have to hit the DB to look up authentication/authorisation stuff anyway.

looks like error-prone approach:
client authorizes in lobby, lobby marks it as online in db and redirects it to zone server, client disconnects from lobby and crashes but is still marked as online one. the same happens when client moves between zones

to prevent this a sophisticated check if client is really online is required, e.g. to check all zones if this client is really alive

alternatively, to move a client ticket to zone server on redirection so it waits for this client and marks it offline in db when client haven't connected after some time. doesn't look robust too, timeouts are always a pain

Quote:Original post by @

Quote:Original post by Kylotan

Quote:Original post by @
consider MMORPG. lobby (central) server keeps all client connections mainly to prevent logging in the same account.

Of flip a flag in the database. There's no need for there to be one single server that holds every single connection. Checking for duplicate logins isn't a time-critical activity that can't afford a DB access. And you probably have to hit the DB to look up authentication/authorisation stuff anyway.

looks like error-prone approach:
client authorizes in lobby, lobby marks it as online in db and redirects it to zone server, client disconnects from lobby and crashes but is still marked as online one. the same happens when client moves between zones

You'd still have a keepalive system, which would clear the flag in the db when it detects that the connection has been dropped. The difference is that you're not doing it all on one server, nor having to hold an extra connection open just for this purpose.

You might need a small bit of extra code to detect the situation when someone is authorised to log in but doesn't actually do so. But that's usually easily done - give out the login token, then check with the database or zone server after a short time to check that they got through. If not, clear the flag.

Quote:to prevent this a sophisticated check if client is really online is required, e.g. to check all zones if this client is really alive

Easier to have the zones tell the database which clients they have connected.