Hi James,
TCP std does specify about connection closing, called
"four-way close connection".
Here, side X sends a FIN, to indicate that he has
nothing to send. The other guy Y receives this FIN and
sends an ACK. X sends an ACK on receiving Y's ACK.
Thats when the connection actually closes
TCP provides the ability for one end of the connection
to terminate its output, while still recving data from
the other end. This is called a half-close.
In case of client-server scenario, if client sends
FIN, and server still has data to be sent, then server
sends an ACK and continues to send the data. After
server is done with transmitting data, it sends a FIN
and waits for ACK. When client sends the ACK,
connection is closed.
Client Server
| |
|-----FIN------>|
| |
|<----ACK-------|
| |
| |
|<----DATA------|
| |
| |
|<----FIN-------|
| |
|-----ACK------>|
| |
In case, server wants to close, it sends FIN and waits
for ACK. Since client has nothing else to do, it
replies an ACK, sends FIN and waits for the ACK. Upon
client receiving ACK, connection is finally closed.
So now the SIP programming interface must provide a
way for the appln to say "I am done sending data,so
sending FIN to the other end. But I still want to recv
data from the other end, until it sends me FIN".
Regards,
Prithi.
--- James Ford <[EMAIL PROTECTED]> wrote:
> Hi,
> Does the SIP standard specify who is responsible for
> closing tcp connections
> (client/server)?
> To be more specific if a server transaction closes
> its TCP connection before
> termination it will be
> impossible to keep a persistent connection open to
> an outbound proxy for
> example.
> Thanks,
> James.
>
>
>
>
>
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