Let me resurrect this old thread to point to this URL: http://www.gnugk.org/keepalive.html
Using the information on that site, I managed to change the keepalive timer of my system so that my application can detect (IOException) the disconnection of, say, a mobile device within seconds of its occurrence. It's far from ideal, since this configuration affects all of the system, but this way you don't have to implement a heartbeat protocol to detect "almost immediate" disconnection. Zigor. On 7 Jul 2010, at 16:55, Alexander Christian wrote: > > Hi, > > > On Wed, 07 Jul 2010 14:16:25 +0200, Emmanuel Lecharny > <[email protected]> > wrote: >> There is no way to detect a connection failure. The connection is opened > >> or closed, but you will know only after having successfully sent >> something to the client. > > What about TCP KeepAlive? That IS checking the connection automatically. > The only problem with this is: > You don't know WHEN the OS will send a keep-alive-message to check the > connection. It can be within seconds (unlikely), several minutes (more > likely) or even hours ... (or maybe never?) > It is possible to change the keep-alive interval, but this then counts for > all socket connections the OS manages ... :-( > > A maybe useful hint: > > http://mindprod.com/jgloss/socket.html#DISCONNECT > > I don't use transactions. But I also wanted to know asap when the > connection dies. > > So I created my own keepl-alive check: > > * As long as client and server and sending data to each other, the check > happens when sending this data. If sending fails, the connection is broken > * If client and server fall into IDLE (mina's session idle thing), then my > communicationlayer on top of MINA sends ping-pong packages: If a pong has > not been received xx sec after a ping is sent, the connection is broken. > > For me this has the positive sideeffect, that a "blocking" remote > (dealocked?!) is detected as well. > > br, > Alex
