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Re: Clarification required: BP6 "use HTTP URIs for spatial things"

From: Jeremy Tandy <jeremy.tandy@gmail.com>
Date: Thu, 01 Sep 2016 22:03:05 +0000
Message-ID: <CADtUq_0K2LrJ+K2RRSKt8U9wz+4MUqCZU2Ru55B9on2WFJ_6tw@mail.gmail.com>
To: janowicz@ucsb.edu, Joshua Lieberman <jlieberman@tumblingwalls.com>
Cc: Frans Knibbe <frans.knibbe@geodan.nl>, SDW WG Public List <public-sdw-wg@w3.org>
> There is some fantastic (and recent) work on how this impacts geo-data
interoperability

Given time pressures I can't read all the base material. Are there any
crucial points in these works that need to be surfaced in the BP doc?

On Thu, 1 Sep 2016 at 22:51 Krzysztof Janowicz <janowicz@ucsb.edu> wrote:

>
> Feature discernment is a real cognitive process that precedes
> representation in data
>
>
> You mean the perceptual and cognitive process of cutting out discrete
> objects from our sensory fields? Yes, absolutely. In fact, this is among
> the key issues underlying the so called symbol grounding problem; see
> Harnad's work. There is some fantastic (and recent) work on how this
> impacts geo-data interoperability:
>
> Scheider, S. (2012). Grounding geographic information in perceptual
> operations (Vol. 244). IOS Press.
>
>
> Krzysztof
>
>
>
>
>
>
> On 08/31/2016 10:09 AM, Joshua Lieberman wrote:
>
>
> On Aug 31, 2016, at 12:22 PM, Jeremy Tandy <jeremy.tandy@gmail.com> wrote:
>
> @josh
>
> > Is the triangle spatial data or a graphic with drawing instructions
> that assumes a certain technology? If 100 people print out the SVG, there
> is really nothing to indicate that the underlying entity is the same on
> each piece of paper, just that the same instructions were used, unless we
> want to get into trademark issues.
>
> This seems to be getting away from the main topic. Unless you object, can
> I pull us back?
>
>
> My point is only that if we are dealing with spatial data as feature data
> (referencing real world space whether geospatial or not), then the indirect
> identification of real world features is on solid theoretical ground.
> Otherwise we’re back in the “I know it when I see it” of general Web
> content.
>
>
> @Krzysztof
>
> Apologies if my terminology is confusing.
>
> I was trying to say that <owl:sameAs> indicates that two identifiers
> (URIs, in this case <http://example.com/sar/features/vo/EDY> and <
> http://example.org/maritime/navaid/2650253>) refer to the same entity
> (Eddystone Lighthouse). You said it much better than me.
>
> The term "representation" was drawn from @josh's email text; in which he
> meant "Eddystone Lighthouse seen as a vertical obstruction" and
> "Eddystone Lighthouse seen as a maritime navigation aid".
>
> > there is no need for such a class [whose members are both vertical
> obstructions and maritime navigation aids] (which you can define if you
> really want to, but it could lead to a combinatorial explosion)
>
> I agree. This is what I've seen with Linked Data implementations - which
> means that "sameRealWorldEntityAs" is not required.
>
> Hmmm. I hope I'm not confusing myself and everyone else.
>
>
> Feature discernment is a real cognitive process that precedes
> representation in data. It’s a subtle concept, however, and if it’s so
> difficult to convey, one might as well deal with the fallout of the
> uncommon occasions where it leads to dissonance, rather than addressing it
> up front.
>
> Josh
>
>
> Jeremy
>
> On Wed, 31 Aug 2016 at 17:02 Joshua Lieberman <
> jlieberman@tumblingwalls.com> wrote:
>
>> On Aug 31, 2016, at 10:20 AM, Frans Knibbe <frans.knibbe@geodan.nl>
>> wrote:
>>
>>
>>
>> On 31 August 2016 at 13:42, Joshua Lieberman <
>> jlieberman@tumblingwalls.com> wrote:
>>
>>> If we are asserting that spatial data on the Web is "always" feature
>>> data that represents a real world entity, then yes, we don't have the
>>> general Web "is it or isn't it physical" ambiguity and can assume that a
>>> feature data identifier also and indirectly identifies the feature.
>>>
>>
>> I hope we can broaden that assumption, that the assertion still holds
>> even if we are not talking about feature data representing real world
>> entities.
>>
>> Let's look at a border case: I am drawing a triangle in Inkscape and I
>> save it as a *.svg file. I publish the file on the web, so it has a URI.
>> Now I would say the triangle is a spatial thing (not sure if it counts as a
>> real world entity, but I hope we can leave the idea of 'real world' out of
>> definitions anyway). The SVG object in the file is the geometry describing
>> the spatial thing. I think that only if we understand the SVG file to be
>> the spatial thing we get into trouble. I might want to state that the file
>> has a certain size and that the triangle has a certain area. It would be
>> funny if I used the same URI for both statements. So I would need to have a
>> different URI for my triangle. Could that be all?
>>
>>
>> Is the triangle spatial data or a graphic with drawing instructions that
>> assumes a certain technology? If 100 people print out the SVG, there is
>> really nothing to indicate that the underlying entity is the same on each
>> piece of paper, just that the same instructions were used, unless we want
>> to get into trademark issues.
>>
>>
>>
>>> That still leaves a gap in expressing whether two feature data entities
>>> represent the same real world entity. Perhaps we need a "sameFeatureAs"
>>> predicate to address this.
>>>
>>
>> Yes, that is what the Subject equality
>> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#SubjectEquality>
>> requirement is about. So the BP document is expected to say something about
>> that.
>>
>> Regards,
>> Frans
>>
>>
>>> Josh
>>>
>>> Joshua Lieberman, Ph.D.
>>> Principal, Tumbling Walls Consultancy
>>> Tel/Direct: +1 617-431-6431 <%2B1%20617-431-6431>
>>> jlieberman@tumblingwalls.com
>>>
>>> On Aug 31, 2016, at 07:29, Frans Knibbe <frans.knibbe@geodan.nl> wrote:
>>>
>>> Hello,
>>>
>>> As stated before, I don't think the httpRange-14 problem exists in our
>>> domain of discourse. I think (and hope) that confusion can only occur when
>>> the things that are described are digital things, or things that can be
>>> transmitted over a computer network, like web pages or mail boxes. It seems
>>> to me that spatial things are never that type of thing. Therefore there is
>>> no reason to take precautions against possible confusion.
>>>
>>> That probably means +1.
>>>
>>> Greetings,
>>> Frans
>>>
>>>
>>>
>>> On 31 August 2016 at 09:50, Jeremy Tandy <jeremy.tandy@gmail.com> wrote:
>>>
>>>> Thanks Rob & Clemens ...
>>>>
>>>> On Wed, 31 Aug 2016 at 08:30, Clemens Portele <
>>>> portele@interactive-instruments.de> wrote:
>>>>
>>>>> +1
>>>>>
>>>>>
>>>>> On 30 August 2016 at 10:10:26, Jeremy Tandy (jeremy.tandy@gmail.com)
>>>>> wrote:
>>>>>
>>>>> Hi. It would be good to close this issue out & include our collective
>>>>> recommendation in the BP doc working draft.
>>>>>
>>>>> PROPOSAL: SDW working group recommends use of "indirect identifiers"
>>>>> for spatial things
>>>>>
>>>>> ... I'll start the voting.
>>>>>
>>>>> +1
>>>>>
>>>>> Jeremy
>>>>>
>>>>> (BTW, to make sense of the PROPOSAL you'll need to read the email
>>>>> thread)
>>>>>
>>>>> On Fri, 26 Aug 2016 at 10:12 Linda van den Brink <
>>>>> l.vandenbrink@geonovum.nl> wrote:
>>>>>
>>>>>> So… do we agree we can recommend indirect identifiers, or do we try
>>>>>> to fix the issue with getting the correct identifier as Rob describes?
>>>>>>
>>>>>>
>>>>>> While waiting for this I’ve updated the issue and the text referring
>>>>>> to the issue in BP6.
>>>>>>
>>>>>>
>>>>>> *Van:* Rob Atkinson [mailto:rob@metalinkage.com.au]
>>>>>> *Verzonden:* woensdag 24 augustus 2016 13:56
>>>>>> *Aan:* Jeremy Tandy; Phil Archer; Linda van den Brink; Bill Roberts
>>>>>>
>>>>>>
>>>>>> *CC:* SDW WG Public List
>>>>>>
>>>>>> *Onderwerp:* Re: Clarification required: BP6 "use HTTP URIs for
>>>>>> spatial things"
>>>>>>
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>>
>>>>>> Agree this is a real concern - people cant be blamed for doing the
>>>>>> obvious, if dumb, thing..
>>>>>>
>>>>>>
>>>>>> I think we should take note of best practice in the HTML world -
>>>>>> which is often to include a citable link to a resource in the rendered
>>>>>> view.  Or a "share" or something similar. We can also put fairly explicit
>>>>>> annotation in machine-readable code - stating that the resource is about
>>>>>> the URI - and even notes saying when citing this resource use the URI....
>>>>>>
>>>>>>
>>>>>> I'd also like to see browsers evolve to offer you the original link
>>>>>> or the redirected when cutting and pasting - how hard can it be!
>>>>>>
>>>>>>
>>>>>> Maybe we can get Ed to ask around Google Chrome team for suggestions
>>>>>> on how best to handle this :-)
>>>>>>
>>>>>>
>>>>>> Rob
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wed, 24 Aug 2016 at 18:27 Jeremy Tandy <jeremy.tandy@gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>> Yes, I think so ... And we should do so if we are recommending
>>>>>> "indirect identification".
>>>>>>
>>>>>> Jeremy
>>>>>>
>>>>>> On Wed, 24 Aug 2016 at 09:24, Phil Archer <phila@w3.org> wrote:
>>>>>>
>>>>>> Bill's comments also made me think about some of the classic
>>>>>> arguments,
>>>>>> such as that a lake doesn't have a last updated date and isn't 435KB
>>>>>> big. Which are true, however, that kind of metadata generally comes
>>>>>> from
>>>>>> the server, i.e. the HTTP layer. That's an over simplification but the
>>>>>> point is that it is relatively easy to avoid deliberately creating
>>>>>> misleading metadata - metadata about the doc rather than the thing it
>>>>>> describes - and it's also generally easy to avoid looking for that
>>>>>> metadata.
>>>>>>
>>>>>> Is there scope for some BP advice there?
>>>>>>
>>>>>> Phil.
>>>>>>
>>>>>> On 24/08/2016 08:25, Jeremy Tandy wrote:
>>>>>> > Thanks Linda. More clear examples where being "correct" (in terms of
>>>>>> > avoiding uri collisions by using two distinct uris) is making
>>>>>> things worse
>>>>>> > because users take the wrong one!
>>>>>> >
>>>>>> > So, as a WG, are we content to recommend this "indirect
>>>>>> identification"
>>>>>> > pattern where thing & info resource identifiers are conflated?
>>>>>> >
>>>>>> > Bill has added some good points about how to avoid impacts of uri
>>>>>> > collision- by using the (dataset) metadata to talk about licenses
>>>>>> and
>>>>>> > creators for the information ...
>>>>>> > On Wed, 24 Aug 2016 at 07:52, Linda van den Brink <
>>>>>> l.vandenbrink@geonovum.nl>
>>>>>> > wrote:
>>>>>> >
>>>>>> >> Experience from the Netherlands: we have the id/doc pattern in our
>>>>>> URI
>>>>>> >> strategy, based on the Cool URIs note [8] and the ISA study on
>>>>>> persistent
>>>>>> >> identifiers [9].
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> That being said, same as Bill I also notice data users getting
>>>>>> confused
>>>>>> >> and generally using the /doc/  URI as that is the one they can
>>>>>> copy from
>>>>>> >> their browser address bar. This is not only casual confusion but
>>>>>> also ends
>>>>>> >> up in published information resources.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> You see this, for example, all over the CB-NL which is a
>>>>>> vocabulary for
>>>>>> >> the building sector and contains links to other Dutch standards
>>>>>> such as
>>>>>> >> IMGeo, an information model and vocabulary for large scale
>>>>>> topography. E.g.
>>>>>> >> the CB-NL concept of ‘Gebouw’ (Building) [10]  links to two IMGeo
>>>>>> concepts
>>>>>> >> ‘Pand’ (building part) and ‘Overig Bouwwerk’ (other construction)
>>>>>> using
>>>>>> >> their /doc/ URIs. If you click on Pand (which doesn’t have its own
>>>>>> landing
>>>>>> >> page in CB-NL so I can’t include the link) you will see it
>>>>>> includes the
>>>>>> >> /doc/  URI as the identifier of Pand.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> This is an example where it occurs in vocabularies, but I also see
>>>>>> it
>>>>>> >> happen with identifiers for data instances.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> [8]: https://www.w3.org/TR/cooluris/
>>>>>> >>
>>>>>> >> [9]:
>>>>>> >>
>>>>>> https://joinup.ec.europa.eu/sites/default/files/D7.1.3%20-%20Study%20on%20persistent%20URIs_0.pdf
>>>>>> >> 10: http://ont.cbnl.org/cb/def/Gebouw
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> Linda
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> *Van:* Jeremy Tandy [mailto:jeremy.tandy@gmail.com]
>>>>>> >> *Verzonden:* dinsdag 23 augustus 2016 20:57
>>>>>> >> *Aan:* Bill Roberts
>>>>>> >> *CC:* SDW WG Public List
>>>>>> >> *Onderwerp:* Re: Clarification required: BP6 "use HTTP URIs for
>>>>>> spatial
>>>>>> >> things"
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> Thanks Bill. Sounds very coherent ... I hoped for some responses
>>>>>> such as
>>>>>> >> this based on practical experience. Jeremy
>>>>>> >>
>>>>>> >> On Tue, 23 Aug 2016 at 19:41, Bill Roberts <bill@swirrl.com>
>>>>>> wrote:
>>>>>> >>
>>>>>> >> ah Jeremy, you are a brave man to poke the sleeping beast of
>>>>>> httpRange-14.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> But I'll get my thoughts in early, then I can tune out of the
>>>>>> ensuing mail
>>>>>> >> avalanche :-)
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> When publishing Linked Data about places we (at Swirrl) generally
>>>>>> do the
>>>>>> >> id/doc fandango, but to be honest I think data users either don't
>>>>>> notice,
>>>>>> >> or they get confused by it.  In the applications we are working
>>>>>> with (and I
>>>>>> >> acknowledge that others may have different applications and
>>>>>> different
>>>>>> >> experiences), it wouldn't cause any problems to have a single URI,
>>>>>> the 'id'
>>>>>> >> URI if you like.  We just don't find a need to say anything about
>>>>>> the /doc/
>>>>>> >> URI.  If we were starting again, I'd probably ditch the /doc/ and
>>>>>> the 303
>>>>>> >> and rely on context and a little bit of documentation to make it
>>>>>> clear what
>>>>>> >> we mean.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> The place where we find a need to talk about creators and licences
>>>>>> and
>>>>>> >> modified dates is in metadata about datasets where a dataset might
>>>>>> be a
>>>>>> >> collection of information about a bunch of places - and we treat
>>>>>> datasets
>>>>>> >> as an 'information resource'. If someone requests a dataset URI we
>>>>>> return a
>>>>>> >> status code of 200 and the dataset metadata as the response.  That
>>>>>> metadata
>>>>>> >> includes info on where to get all the contents of the dataset if
>>>>>> you want
>>>>>> >> that.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> By the way, though it's sensible and consistent, I find that the
>>>>>> implied
>>>>>> >> and parallel property stuff makes it more rather than less
>>>>>> complicated.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> Bill
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> On 23 August 2016 at 17:37, Jeremy Tandy <jeremy.tandy@gmail.com>
>>>>>> wrote:
>>>>>> >>
>>>>>> >> All-
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> Linda has done a great job of consolidating the best practices are
>>>>>> use of
>>>>>> >> identifiers. We have just one [1] now.
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> Reading though just now, it occurred to me that there's still an
>>>>>> open
>>>>>> >> issue about identifier assignment ...
>>>>>> >>
>>>>>> >>
>>>>>> >>
>>>>>> >> W3C's Architecture of the World Wide Web constraint "URIs identify
>>>>>> a
>>>>>> >> single resource" [2] asserts "Assign distinct URIs to distinct
>>>>>> resources"
>>>>>> >> in order to avoid URI collisions [2a] which "often imposes a cost
>>>>>> in
>>>>>> >> communication due to the effort required to resolve ambiguities".
>>>>>> >> Discussions from earlier years in UK Gov Linked Data working group
>>>>>> (and
>>>>>> >> elsewhere) concluded that
>>>>>>
>>>>>>
Received on Thursday, 1 September 2016 22:03:49 UTC

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