Socket problem - C# / C Sharp

Jason Hurder

Hi folks,

I am writing a small network application that uses TCP sockets. My
application is the accepts connections via the AcceptConnectio n function
of a server socket and creates a client socket from it. My question is,
if someone disconnects from my server, how can I detect this? Checking
the Connected property of the System.Net.Sock et object does not seem to
solve the problem. Thank you!

Jason

Nov 16 '05 #1

Subscribe Reply

2249

Angel J. Hernández

Hi there...

The Connected property will return the latest known state of the Socket.
There's no way the server detects a client has gone offline... unless you
program it. A couple of months ago I had to develop this app (based on
TCP/IP) and I had the same question as you do. My solution was to implement
some sort of "keep alive" message send from the server to the client in a
time based frequency (it's a parameter in my app's config file). I suppose
that you had to define the protocol that is gonna be used throughout your
application, well consider having this "pinging" message. It's worked
excellent to me.

As a matter of fact, if you issue the netstat command at the prompt having
the client disconnected you still see "the connection" it's a funny thing
but it's true. Have a nice day.

Hope this might help you,

Regards,
--
Angel J. Hernández M.
MCSD

"Jason Hurder" <jhurder@spam_m e_not.fastpicsy stems.com> escribió en el
mensaje news:Oy******** ******@TK2MSFTN GP10.phx.gbl...

Hi folks,

I am writing a small network application that uses TCP sockets. My
application is the accepts connections via the AcceptConnectio n function
of a server socket and creates a client socket from it. My question is, if
someone disconnects from my server, how can I detect this? Checking the
Connected property of the System.Net.Sock et object does not seem to solve
the problem. Thank you!

Jason

Nov 16 '05 #2

Jason Hurder

Hi Angel,

I have seen this behavior after disconnecting the client and using
"netstat -aon" (usually the state will be TIME_WAIT or FIN_WAIT_2 or
CLOSE_WAIT). I'm not really sure what these states are for other than to
alert the OS that those ports can't be used just yet (read that
somewhere on MS's site). I wonder how chat clients do it, they know when
a user logs out.

I guess I could just send a ping message to the client to see if the
client disconnected or not, though it seems to me that this
functionality should already be a part of the API.

Thank you for your help,

Jason
Angel J. Hernández wrote:

Hi there...

The Connected property will return the latest known state of the Socket.
There's no way the server detects a client has gone offline... unless you
program it. A couple of months ago I had to develop this app (based on
TCP/IP) and I had the same question as you do. My solution was to implement
some sort of "keep alive" message send from the server to the client in a
time based frequency (it's a parameter in my app's config file). I suppose
that you had to define the protocol that is gonna be used throughout your
application, well consider having this "pinging" message. It's worked
excellent to me.

As a matter of fact, if you issue the netstat command at the prompt having
the client disconnected you still see "the connection" it's a funny thing
but it's true. Have a nice day.

Hope this might help you,

Regards,

Nov 16 '05 #3

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