Thanks Patrick for the reply.
On Tue, Jul 10, 2012 at 11:38 AM, Patrick Oppenlander < pattyo.li...@gmail.com> wrote: > > > > On Tue, Jul 10, 2012 at 4:55 AM, Patrick Oppenlander < > pattyo.li...@gmail.com> wrote: > >> On 05/07/12 20:19, Ajay Garg wrote: >> >> Hi all. >> >> I ran into a issue, as described at >> https://bugs.freedesktop.org/show_bug.cgi?id=51501 >> >> >> This behaviour is not a bug. It's a side-effect of how MDNS is >> (intentionally) designed. >> >> Your bug report states that the callback is not called. It will in fact >> be called, it just takes a long time. >> > > > Yes, I think it would. > But the callback is not called after 120 seconds. May be after 75 > minutes.. but I haven't waited that long enough :) > > Also, as per > https://tools.ietf.org/html/draft-cheshire-dnsext-multicastdns-15#section-10, > the standard says that the timeout is expected to be 120 seconds. > > > I think you're misunderstanding how the TTLs are used. the 120 seconds > refers to host specific records -- i.e. records that are available after a > resolve. A client application is not notified when these records expire as > they are transient. > > The 75 minute TTL is for everything else, including PTR records, which is > what you are interested in. > > I've never used Telepathy so I can't really offer suggestions on how to > proceed with your issue, but keep in mind that DNS-SD was never designed to > provide an iron-clad guarantee that a service is available. The only way to > determine that a service is genuinely available is to first resolve it, and > if the resolve succeeds attempt to connect. > Yes, that's right. But the use-case we need to handle (getting to know when a client has disconnected from the telepathy-salut network) wouldn't be solved by this. Therein, we need to have a mechanism by which the dis-connectivity may be known. Unfortunately, polling (or pseudo-polling) is the only ultimate way (since the going-disconnected-buddy doesn't give the "goodbye" signal, since no network-medium is available). So, perhaps a client notification *should* get notified, once the transient-resolved-records expire??!! Just my 2 cents :) Thanks and Regards, Ajay > Patrick > > > _______________________________________________ > avahi mailing list > avahi@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/avahi > >
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