[Standards] Inconsistent Subscriptions in XMPP

Philipp Hancke fippo at goodadvice.pages.de
Tue Jun 2 20:00:25 UTC 2009


Peter Saint-Andre wrote:
[snip]
> Yes, I did:
>
> "If the contact does not approve or deny the subscription request within
> some configurable amount of time, the user's server SHOULD resend the
> subscription request to the contact based on an implementation-specific
> algorithm (e.g., whenever a new resource becomes available for the user,
> or after a certain amount of time has elapsed); this helps to recover
> from transient, silent errors that might have occurred in relation to
> the original subscription request."

What if the contact is "polite" and never replies to the request?

While the subsequent subscription requests will not be delivered
to the contact (state is pending_in), the user's server has no way
to determine that the request has been processed by the contact's
server. So it will continue to resend the request which is silently
dropped by the contact's server. I don't think you want that ;-)

Solution: replace presence subscriptions with <iq/> on s2s.

philipp



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