Keeping socket connections alive

[Mariano Capezzani]

Hi all, I have a server application awaiting incoming connections through a series of sockets set in "listen" mode. I have a number of client applications in remote locations that communicate via tcp/ip, opening the corresponding socket connection to the server and transmitting data. The problem I have is that the client-to-server socket connections seem to die out after a while, specially in locations where internet is intermittent. When this happens, the connection does not terminate, rather it stays in "connected" state, but data transfer is lost in the web. Even though the winsock.state = sckConnected, the data is not received. In order to solve this, I implemented a refresh timer, that closes and reopens all sockets in the server once every n seconds. It works, but it's terribly unelegant. I have found no other way of doing this, keeping the connections alive. Anybody could please give me a suggestion on how this can be done properly? How can I determine if a connection is alive or dead, regardless of what .state says? Thanks, Regards.

[rprateek]

are you using win sock . I had the similar problem before using win sock where i lost data even the client was connected with the server. But later i used dart sock and it helped me you can get the trial version of these from www.dart.com and try it out, hope this would help you.

Blog for Programmers

[Mariano Capezzani]

Yes, I use winsock. Thanks for the tip!!, but I think I might have solved temporally in a rather clumsy way. I set up each client to "ping" the server every second. The server "pongs" to each "ping". I there is no "pong", the connection is down and a reconnect is issued. This check is performed at both sides. Unelegant, but it works, and it´s free... Has anybody implemented a different type of "keep alive" mecanism? Regards,