Hi Ben,
Thanks for your detailed review. Please find my response inline.
An updated version of the draft will be submitted in the next few days.
-----Original Message-----
From: ietf-bounces(_at_)ietf(_dot_)org
[mailto:ietf-bounces(_at_)ietf(_dot_)org] On
Behalf Of ext Ben Campbell
Sent: 09 March, 2010 18:00
To: Rohan Mahy; Brian Rosen; Hannes Tschofenig; General Area
Review Team
Cc: Cullen Jennings; IETF-Discussion list
Subject: Gen-ART LC/Tekechat Review of
draft-ietf-geopriv-loc-filters-10
I have been selected as the General Area Review Team (Gen-ART)
reviewer for this draft (for background on Gen-ART, please see
http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).
Please wait for direction from your document shepherd or AD
before posting a new version of the draft.
Document: draft-ietf-geopriv-loc-filters-10
Reviewer: Ben Campbell
Review Date: 9 March 2010
IESG Telechat date: 11 March 2010
Note: Since the IETF LC end-date and the telechat are only a
day apart, I intend for this review to serve for both purposes.
Summary:
This draft is almost ready for publication as a proposed
standard, but there are issues that should be addressed first.
Major issues:
-- section 3.6, general:
As far as I can tell, this section creates a profile of the
rate-control draft. You basically say use pieces of it, but
make minor modifications to the normative requirements. Can
you motivate why rate-control does not work as-is? And if it
can't, perhaps this draft and that one should be harmonized
prior to publication?
I don't believe that we introduce modifications to rate-control.
-- section 3.6, 2nd paragraph:
The empty notify language seems to conflict with the MUST
level normative statement in rate-control that says:
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.
Is it your intent to update rate-control to change this
requirement? If so, it would be good to do so prior to
publication of that draft. (see previous comment)
I tried to clarify the sentence. In the use cases we consider it is
quite likely that location information is not available at the time the
subscription request was received and then the returned state
corresponds to an empty notification.
Minor issues:
-- general:
Some of the filter mechanisms in this draft require a lot of
calculations for every candidate update to determine if it
matches a filter. It would be useful to have some discussion
of the scalability impacts of this.
I agree with you that some of the filtering operations require a fair
amount of calculations and location determination to happen in order to
have real-time access to location information.
We did not address scalability considerations in the document and we
would rather like to postpone detailed investigations once we gain some
implementation and deployment experience. If such scalability concerns
indeed arise we are happy to fix them with an update to the document but
we believe that it will take a fair amount of time to reach maturity
before we can make good measurements.
The approach is a bit similar to what you see other groups doing in the
IETF with the work on presence scalability. There, the specifications
got implemented and deploymend and only some time later investigations
are made regarding scalability with the available deployment experience.
-- Section 1, paragraph 1, last sentence:
I assume their persistence ends when the associated
subscription ends, right?
Correct. I extended the sentence.
-- Section 3.2, first paragraph after figure 2:
It looks you've effectively declared the example as normative,
and skipped over normative text that needs to be here. I find
the "No other variant..." language confusing in context, as it's
not clear to me what restriction in the example is
constraining on <ns-binding>. I think you're better off
treating the examples as informative, and fully defining the
normative requirements in words. (Note that this applies for
several instances where you say something to the effect of "an
implementation MUST do FOO according to Figure X".)
Changed the text according to your suggestion.
-- section 3.6, first paragraph:
Why is average-rate left out? If you are going to suggest
using just part of a previously defined mechanism, it would be
nice to show motivation for the parts left out.
We don't think that there is anything wrong with implementing rate
control but we could not find a use case for the average-rate feature
for our application domain.
-- section 3.6, last paragraph:
I think you need more motivation for this use case. I _think_
you are referring to situations where, for example, a location
service can give you increasing precision over time, and you
want to say "give me the best you can in X seconds." But I'm
afraid this could be misused in situations where the notifier
requires some period of time to get _any_ information.
I have added a pointer to Section 6.1 of the HELD specification
referring to the fucntionality of the responseTime parameter where this
functionality came from.
It would be helpful to have some comment on how filters
interact with rate-control for location. For example, what
happens if I have a max-interval that expires before a filter
has been met? A trigger that fires before the min-interval
expires? (I think the answer is that rate-control wins, but
some text would be helpful.)
I believe that these aspects should be explained in rate control because
it is not specific to this document.
Nits/editorial comments:
-- General:
I find the organization of this draft confusing. It would be
helpful to have a clearer distinction between text that
creates new mechanism or normative requirements, and text that
describes how you can use existing mechanism. I think it would
be easier to read if you separated new mechanism and usage of
existing mechanisms into separate sections.
Interesting comment. I actually thought that an implementer would not
care about this distinction but would rather be interested in how to
accomplish the functionality overall. I had written the document
intentionally with such a focus.
-- section 1, paragraph 1:
Please expand PIDF-LO on first mention. The expansion in the
abstract doesn't count--the document should stand alone
without the abstract.
OK.
s/technical/technically
"...alternative signaling approach..." - Alternative to what?
This wording makes it sound like sip-events is an alternative
to 4119, which I don't think is what you mean to say.
Clarified.
-- Section 1, paragraph 2:
Do you mean to say "[the subscriber] not having to receive...",
or "without the notifier having to issue..."?
Fixed.
-- section 1, numbered list and preceding paragraph:
The list does not seem to follow from the preceding paragraph.
That paragraph leads me to expect a list of mechanisms, and I
think what I see is a list of problems to be solved.
OK. Fixed.
-- section 3.6, first paragraph:
Please clarify--do you mean "the implementation of only two
attributes is required", i.e. you must not implement more than
the two attributes, or "only the implementation of two
attributes is required", meaning you don't have to implement
more than the two attributes.
Fixed.
Ciao
Hannes
--idnits reports the following:
Checking boilerplate required by RFC 5378 and the IETF Trust (see
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== You're using the IETF Trust Provisions' Section 6.b
License Notice from
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Checking nits according to
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No issues found here.
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No issues found here.
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== The document seems to lack a disclaimer for pre-RFC5378
work, but was
first submitted before 10 November 2008. Should you
add the disclaimer?
(See the Legal Provisions document at
http://trustee.ietf.org/license-info for more
information.) -- however,
there's a paragraph with a matching beginning.
Boilerplate error?
Checking references for intended status: Proposed Standard
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(See RFCs 3967 and 4897 for information about using
normative references
to lower-maturity documents in RFCs)
== Unused Reference: 'GML' is defined on line 690, but no explicit
reference was found in the text
== Unused Reference: 'RFC3023' is defined on line 719, but
no explicit
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== Unused Reference: 'RFC4288' is defined on line 731, but
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== Unused Reference:
'I-D.ietf-geopriv-http-location-delivery' is defined
on line 746, but no explicit reference was found in the text
-- Possible downref: Non-RFC (?) normative reference: ref. 'GML'
** Downref: Normative reference to an Informational draft:
draft-ietf-geopriv-arch (ref. 'I-D.ietf-geopriv-arch')
== Outdated reference: A later version (-08) exists of
draft-singh-geopriv-pidf-lo-dynamic-07
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