(dropping [email protected]) So I'd like to close this, so I'll summarize and propose an action:
Question: max-interval expires, is it permitted for a notifier to generate an empty notify? Position: This is NOT desirable behaviour. A notifier has advance warning that it needs to generate state and can do so. I don't actually see a need to support empty notifications once the subscription is established and the notifier is providing state. It's only going to lead to unexplained holes. Text: (for loc-filters, no change to rate-control) OLD: If complete state is not immediately available, then an empty NOTIFY is sent immediately and subsequently a separate NOTIFY containing location is generated some time between the time included in 'min- interval' and the time in 'max-interval'. An important use case for NEW: Immediately after the creation of a subscription, if complete state is not immediately available, then an empty NOTIFY is sent immediately. A separate NOTIFY containing location is subsequently generated some time between the time included in 'min- interval' and the time in 'max-interval'. An important use case for I think that this addresses the problem. Whether or not this was the original intent of the authors, we didn't really discuss this particular wrinkle. --Martin > -----Original Message----- > From: Ben Campbell [mailto:[email protected]] > Sent: Sunday, 21 March 2010 4:09 PM > To: Thomson, Martin > Cc: Tschofenig, Hannes (NSN - FI/Espoo); [email protected]; > [email protected]; [email protected] Loreto; Cullen > Jennings; Rohan Mahy; IETF-Discussion list; General Area Review Team; > Hannes Tschofenig; [email protected]; Adam Roach > Subject: Re: Gen-ART LC/Tekechat Review of draft-ietf-geopriv-loc- > filters-10 > > > On Mar 21, 2010, at 3:49 PM, Thomson, Martin wrote: > > > So, the rate control does recognize that the first notify message can > be empty or might not contain all state: > > > > $3.2: Thus, the first notification might be empty, or certain > values might be absent. > > > > The text that was originally quoted, that we're discussing is this: > > > > A compliant notifier MUST generate notifications whenever the time > > since the most recent notification exceeds the value in the "max- > > interval" parameter. Depending on the event package and subscriber > > preferences indicated in the SUBSCRIBE request, the NOTIFY request > > MUST contain either the current full state or the partial state > > showing the difference between the current state and the last > > successfully communicated state. > > > > The second sentence, taken out of context might be interpreted as Ben > did - a blanket prohibition on empty notify messages. Reading through > again, with complete context, I'm not sure that I agree with this > assessment. If the rate-control editors are amenable to a > clarification in this section, it would be nice, but I don't see it as > necessary. > > > > i did not take it to be blanket prohibition on empty NOTIFY requests. I > took it to be a prohibition against empty NOTIFY requests sent as a > result of the expiration of a max-interval parameter. The language I > objected to in the location filter draft seemed to explicitly suggest > empty notifies as a result of max-interval parameter. > > Here's the language I refer to, in section 3.6, last sentence of > paragraph 1 and first sentence of 2: > > > [...] Whenever the time since the > > most recent notification exceeds the value in the "max-interval" > > parameter, the current state would be sent in its entirety, just > like > > after a subscription refresh. > > > > If complete state is not immediately available, then an empty > NOTIFY > > is sent immediately and subsequently a separate NOTIFY containing > > location is generated some time between the time included in 'min- > > interval' and the time in 'max-interval'. An important use case > for > > location based applications focuses on the behavior of the initial > > NOTIFY message(s) and the information it returns, for example in > case > > of emergency call routing. When an initial NOTIFY is transmitted > it > > might not include complete state. > > Although the last couple of sentences talk about, I read the first part > as suggesting that if state is not available when a max-interval > expires, you should send an empty NOTIFY. > > > > > > > _______________________________________________ Gen-art mailing list [email protected] https://www.ietf.org/mailman/listinfo/gen-art
