Hi,
On Oct 5, 2008, at 2:07 PM, Pavel Simerda wrote:
Please look into real world, not idealistic.
Servers have sometimes long timeouts (nobody says they can't), don't
do
any sort of pings (nobody says they must) and many people have
unstable
connections, even on ADSL, but much more on wireless, especially when
moving aroud.
IMHO, "pings" are awful. I would much rather have session-reconnect
and link-level acks for stanzas. The pair should provide an even more
resiliant network than "pings" will ever do.
Pings assert only one thing: A stanza reached the server, and another
was able to get back. You cannot extrapolate any assurances of quality
what so ever from this.
Having said that, a link level keep-alive is useful for silent network
losses, and pings have its place on my toolbox to kick-start S2S
connections. If I want to send stanzas to a certain domain and I don't
know if they have a S2S connection available on my server, I delay the
send until I get back some sort of ping response.
It's a common things to loose messages on Jabber for people with bad
connectins. The good thing is that when one comes back, the old
resource is kicked (with reason: reconnected) and the user is
notified... and after some time, users learn that after other party's
"reconnect", they must re-send what they have posted.
Yes, as I said above, pings are great to kickstart S2S connections.
Although I think servers should keep S2S connections open while there
is an active session with a roster item from the remote domain....
If this is not the case, users become confused and will start to think
Jabber is unreliable. And what more, they will rightly do so.
I agree that reliability is still a problem with the larger XMPP
network, specially small servers.
But unwinding the conversation, using the same resource as a session-
resume/takeover tool is the wrong way to go about it.
Even if you reconnect 10 seconds after you lost the first connection,
you can still loose messages and other stanzas. You need a proper
session-resume service to deal with that.
Everything else is like using a sieve to block out the sun: half-
measures.
Best regards,
--
Pedro Melo
Blog: http://www.simplicidade.org/notes/
XMPP ID: [EMAIL PROTECTED]
Use XMPP!
