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[minutes] POI WG 19 January Minutes

From: Matt Womer <mdw@w3.org>
Date: Mon, 24 Jan 2011 11:36:30 -0500
Message-Id: <3F8FFC95-0FEE-49CD-9EA5-45FF91BCB12A@w3.org>
To: public-poiwg W3C <public-poiwg@w3.org>
Hi all,

The minutes for last week's meeting are available here:
	http://www.w3.org/2011/01/19-poiwg-minutes.html

And as text below.

-M

   [1]W3C

      [1] http://www.w3.org/

                               - DRAFT -

            Points of Interest Working Group Teleconference

19 Jan 2011

   [2]Agenda

      [2] http://lists.w3.org/Archives/Member/member-poiwg/2011Jan/0013.html

   See also: [3]IRC log

      [3] http://www.w3.org/2011/01/19-poiwg-irc

Attendees

   Present
          cperey, alexh, jacques, Luca, Raj

   Regrets
          Gary, Karl, Ronald, Jens

   Chair
          Matt

   Scribe
          Matt

Contents

     * [4]Topics
         1. [5]Discussion of id Primitive
         2. [6]Discussion of time Primitive
         3. [7]F2F
     * [8]Summary of Action Items
     _________________________________________________________

   <trackbot> Date: 19 January 2011

   <cperey> Hi

   -> [9]http://www.w3.org/2010/POI/wiki/Drafts WG drafts

      [9] http://www.w3.org/2010/POI/wiki/Drafts

Discussion of id Primitive

   -> [10]http://www.w3.org/2010/POI/wiki/Core/Draft POI Core Draft

     [10] http://www.w3.org/2010/POI/wiki/Core/Draft

   <cperey> I'll be signing off at half past

   <scribe> scribe: Matt

   matt: The ID we mentioned at the F2F only had to be unique to a
   particular system, not globally unique. I thought a URI would work
   here to get both, but there was a pushback.

   alexh: I'd rather figure out what that means before I try to comment
   on it.
   ... I'm thinking like in XML where you can have an ID but it's not
   required.

   <cperey> so the question is if an ID is REQUIRED or not?

   <cperey>
   [11]http://en.wikipedia.org/wiki/Uniform_Resource_Identifier

     [11] http://en.wikipedia.org/wiki/Uniform_Resource_Identifier

   alexh: So, you aren't required to have an ID but it isn't required
   unless there is a reference to it.

   matt: URIs give us a globally unique method of assigning IDs.

   cperey: The wikipedia entry has a diagram that shows URIs above URLs
   and URNs.
   ... But we're not always talking about a Web environment.
   ... Is there still debate about whether an ID is required?
   ... Is it required or not?

   alexh: I am interested in that too. I don't think that's an obvious
   need.
   ... And if we decide it is required, whether it's a URI or at a
   document level.
   ... I need to hear justification as to why each POI needs these
   things.

   cperey: We have insufficient people to answer that question

   <cperey> geopriv

   cperey: If we had Henning here he would convince you

   -> [12]http://tools.ietf.org/wg/geopriv/ Geopriv docs

     [12] http://tools.ietf.org/wg/geopriv/

   cperey: He would say all information needs to have an embedded
   classifier.
   ... Whether it's a POI or any other piece of information. It's one
   school of thought, but not the only one that advocates for these
   ids.
   ... And the Semantic Web is like that.

   matt: Yep. And one thing to say is that the URI doesn't have to be
   http.

   rsingh2: OGCs opinion would be that we need a unique ID too. I
   relate it to the IRS tax id.

   cperey: Same philosophy at Geopriv.
   ... Have to be classified in some way.

   alexh: One of the motivations for this is that some of these
   standards don't have IDs, and we consider that relieves a certain
   burden on generating the data.

   cperey: If you do require it, then which system is it that we're all
   going to abide by.

   rsingh2: Seems simple to me.

   cperey: What classification system would you espouse?

   rsingh2: At the most relaxed, just a string.
   ... Since it's generated by, or maybe the generators id plus a
   unique key for it.

   cperey: That's about provenance, really.

   rsingh2: No one wants to go to a central registry to get globally
   unique IDs. Combine own URI with some unique string.

   matt: And that URI doesn't have to be dereferencable, just has to be
   unique.

   cperey: Example: I've got a cup, I want to put it in a database and
   it contains coffee. When I generate that reference in the database
   something creates a unique identifier.
   ... It's stored in the database, and now the next time my sensor
   detects that object, then a pretty picture appears on the cup.
   ... Now, Alex's put the same cup in at the trade show. It gets a
   different unique identifier or different?

   alexh: For me, in the AR context, if somebody describes that there
   is a cup out there, I expect to have some information on how to
   identify it uniquely. Perhaps a visual signature that the system may
   recognize.
   ... Once I find it, it's important for me to dereference it to get
   more information about it, but to find it, I don't need the unique
   ID.
   ... There was discussion about how to find these, the name, etc.
   ... So maybe information came along with it, and how to describe it,
   but it doesn't have an ID yet.

   rsingh2: Any identifying information about this POI can change,
   except for the ID. A name, could have a spelling error you found it,
   but then someone wants to access that again and the name has
   changed.

   alexh: What about this situation: two different databases are giving
   me a POI that everyone agrees is a POI, then I'll get two different
   IDs for the same POI.

   rsingh2: I'd love to be stricter to say that we have a global id
   with a central registry.

   alexh: So you're saying that the ID works within the domain of that
   ID system.

   rsingh2: We're not saying globally unique yet, but just a unique ID
   in a system.
   ... It would be great to update in one place.

   alexh: There's no unique marker on a coffee cup to distinguish it
   from yours.

   cperey: Or we don't say anything about it, that the creator says
   information about it.

   alexh: There may be two POIs, a picture of your dog and my dog that
   is on these coffee cups. Then it comes down to the descriptor of the
   object.

   cperey: Seems to me that in a physical plane, the lat/lng/alt is the
   unique id for those that are fixed in space.

   jacques_: No.

   cperey: There may be other things at that lat/lng/alt?

   rsingh2: The unique id is the thing you know will never change.

   cperey: In a perfect fixed world, things that are fixed always have
   the same lat/lng/alt.
   ... So, the question then is why? How is this burden of adding the
   unique id and who do we get it from? Where does it come from? What
   is the benefit?

   alexh: If the way you are identifying it shifts, then you need a way
   to track it, a unique ID to refer to it.
   ... I wanted to be sure this was the same POI, that was spelled
   differently, then I need a unique ID, until then, I don't.

   cperey: I think we've got the benefit: disambiguation. But it's not
   necessary in all cases.

   <Luca> Thanks Matt

   rsingh2: If you want something, what's the burden on developers?
   Anyone serving out POIs has a database of them, and they have an
   internal way of tracking them. They'll be maintaining an ID, and
   it's not a big burden for them to include that information.
   ... It's hard to imagine it being a big burden for POI database
   people to do this.

   alexh: So a POI gets created, and I introduce it, say it now exists.
   Now I have the burden of creating an ID.
   ... In some sense, I might use this datastructure to describe the
   POI, but I won't be providing an ID.

   cperey: I've got to go, good discussion!

   <cperey> and great scribbing!

   alexh: It's clear to me the discussion, it's straight forward, we
   can use URIs, web address plus some sort of generated scheme. But
   I'm up in the air as to whether it's something to force.
   ... We need some guidance between the must and the can.
   ... I don't have an argument with requiring it, but I'm on the side
   of the fence that there is precedence for exchange systems that
   don't require it.

   jacques_: If you use the ID of the guy who creates the POI, say a
   foaf ID, and you're using the dataformat with a local ID, then the
   guy who creates the POI and the POI id together, you have a likely
   global ID.
   ... We use some foaf elements, we identify who made the POI, and use
   the local ID for a unique POI ID.

   alexh: That's perfectly reasonable to me, just whether it's required
   or not.
   ... Maybe we should table this.

   rsingh2: Sounds like you're asking for a use case for a unique ID.

   matt: action item?

   alexh: Either Gary or Karl had to have this, so let's wait until we
   get them on the line and have another round on this.

   matt: I'll email him privately about it.

Discussion of time Primitive

   alexh: Looking at Google Earth, they timestamp things in KML. We had
   discussion that if there was no timestamp that it is permanent.

   jacques_: Perhaps a bit more than a timestamp, but a start and end
   time?

   alexh: If you know that information.
   ... A beginning and an end for historical things. For things that
   currently exist when it came into existence is useful.

   matt: I think we could have more rich time stamps, that could apply
   to anything on the POI, not just it's existence.

   alexh: To me, it's existence is what the timestamp is for. The rest
   is extensible data.

   jacques_: I agree.

   matt: But not built on the same primitive?

   alexh: Looking at something like the Battle of 1826. You assign the
   start and end time to when that event happened.
   ... Nobody cares that it's put into the POI database on 7 Jan 2011.
   ... In that sense the timestamp is when it's valid.
   ... The timestamp could be 6-7pm every week.

   matt: I guess I was getting at: should this be richer than just a
   begin/end rather than a simple timestamp.

   rsingh2: Is this the same as the ID discussion?
   ... If you have a timestamp that isn't metadata, it becomes a way to
   identify the item. Combine the timestamp with the company ID you
   have the unique ID.

   <jacques_> a timestamp for the browser to know if this POI has to be
   shown

   alexh: What guarantee do you have that the timestamp will have
   granularity to guarantee it's unique.

   rsingh2: Our specification would identify it.

   alexh: I think that this is getting into an area where we as people
   trying to decide what a POI needs, can agree that it needs some rich
   timestamping, e.g. happy hours on Friday, but specifying that seems
   out of our purview. Somewhere out there there is a format that
   defines time.

   <jacques_> a tmestamp for validity of the POI is different for
   timestamp related to the content of the pOI

   rsingh2: ISO has a great definition of time, but I think we're
   hearing that we have great use cases, but none are mandatory.

   alexh: Agree it wouldn't be mandatory. If it's completely metadata,
   then we have no standard to describe it.
   ... We probably do want to make some sort of element that may have
   different interpretations, but we at least have a way of describing
   time data.

   <jacques_> no timestamp means the the browser will always show the
   POI

   matt: I'm nervous to say we have different interpretations. I think
   we can agree we need to describe the basic building block though.

   alexh: We have lots of things it could mean, creation, open hours,
   etc.

   matt: I'm thinking the time building block could be applied to other
   primitives, e.g. the circus is here in July and here in January.

   alexh: Good point, people are going to want to associate times with
   locations. At some point they have to decide whether it's two
   different POIs, or whether it's a change in database tracking.
   ... Looking at KML they have location with series of times. The
   other option is to make multiple POIs.
   ... Regardless, we do need that.

   <jacques_> agree

   alexh: For example if the POI is me, then someone might want to know
   how long Alex has been at his desk, when did he arrive there, etc.
   ... If you look on Foursquare I might be at a bar. If you look at
   the timestamp, you could say that's probably not where he is.
   ... Do we need two time stamps, or a time stamp associated with
   location.
   ... I would argue for it associated with location.

   <jacques_> or a serie of time stamps?

   alexh: But perhaps this gets to be a slippery slope: what if someone
   changes the name? Is there a timestamp for that? That's something
   I'm resistant to as well.

   rsingh2: Me too.

   matt: Why?

   alexh: I expect the world is going to be full of this kind of data,
   that every nuance is going to be recorded and stored somewhere.
   ... By saying that I'm resistant to it, I'm not denying it, but I'm
   concerned if you start building it into a POI then it might become
   unwieldly.

   rsingh2: It's a burden on developers without a clear advantage.

   alexh: Something like tracks, it could be accumulated and make it
   available.

   matt: How would you make it available?
   ... Separate POIs?

   alexh: There is some precedence of people creating separate data
   elements that encapsulates the reference to the POI we're talking
   about and a time relation pairs. You can use that to create a path.
   ... It's data about the POI but not data within the POI.

   matt: I guess I'm advocating for it to be available, but not
   required. I think the information is valuable to have access to in a
   standardized way, but doesn't have to be on every POI.

   alexh: I can't argue against that.

F2F

   matt: So far it looks like everyone is available on the 29-31 March
   dates. We're narrowing in on a location in Amsterdam.

Summary of Action Items

   [End of minutes]
     _________________________________________________________


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