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Well I can't answer to how jabber detects outages,
but I can comment on the SO_KEEPALIVE. You can program it to be any length of
time (it's an ioctl).
Chuck Wegrzyn
----- Original Message -----
Sent: Friday, April 06, 2001 12:58
PM
Subject: [JDEV] Detecting client/server
disconnect?
How does the Jabber protocol deal with the unexpected
disconnection of a client or server? I'm referring not to a process crash, but
to unlikely situations like kernel panic or power failure, as well as more
likely ones like network failure (modem hangs up, PacBell's DSL network horks,
laptop moves out of 802.11 range, baby yanks out Ethernet plug,
etc.)
According to R. Stevens' Unix Network Programming, vol. 1
(pp.185-186), this situation is not detectable unless the SO_KEEPALIVE socket
option is set. (But libjabber doesn't set this option.) And even keepalive
only detects it after two hours, which is rather too long for a real-time
presence protocol.
Some other presence protocols solve this by
requiring the client to send a "noop" or "ping" command every few minutes,
which the server must respond to. Jabber doesn't seem to have anything
equivalent. Am I missing or misunderstanding something, or is this an issue
with the current Jabber protocol?
�Jens
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