You may want to look in to "SIP". At the very least, when a client is up and running - it needs to send a special REGISTER message containing its name/id to the server. On receiving this the server would associate that name/id with the source IP address. After this the client needs to send periodic keep-alives or else the server can delete the mapping.
I recently worked on UDP and you also would like to read about "UDP punching" if your clients are going to be behind NATs. On Thu, Oct 18, 2012 at 2:43 AM, Emmanuel Lécharny <elecha...@gmail.com>wrote: > Le 10/17/12 3:04 PM, Dever, Jeffrey a écrit : > > We have a connection that is currently TCP but are changing it to UDP on >> both the client and server sides. It looks like we could just change the >> SocketConnector to a DatagramConnector and same for the Acceptor and use >> all the same IoHandler, Decoder etc classes. >> >> This does seem to work, but I don't get some of the callbacks when I >> expect them. In particular, when I build both endpoints, I don't get a >> sessionCreated() called on the server when a client connects. Only when >> the client sends data does that function get called from the IoHandler. In >> my case the client will never send data, only the server does, but the >> server can't send data since I don't have a session objects. >> >> Advice would be helpful. >> > Hi Jeffrey, > > there is no way for the server to 'know' that the client connects. The > connection is just used to store the IP in order to check that the incoming > messages are to be handled or not (you can perfectly receive some messages > you don't wnat to get, for instance when some broadcast messages are sent). > > In other word, it's plain normal that your server does not call the > SessionCreated event. The only way to do that is to send a message, which > will trigger the session creation, session that will remain active as soon > as some other messages are being received before it becomes idle - and get > discarded. > > The way the UDP server handles session is somehow really different in UDP > compared to TCP. It's also du to he fact that UDP is a connectionless > protocol, when TCP is connected. > > I don't see any simple way to send a direct message from the server to the > client when you don't have the client IP address... > > May be it would be a good extension to MINA to add a way to send a message > to a session which does not -yet- exist, assuming that there is no real > difference between a client and a server when it comes to UDP protocol > handling ? > > -- > Regards, > Cordialement, > Emmanuel Lécharny > www.iktek.com > >
