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.
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