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
>
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> 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 the "real world thing" and "information resource
>> that describes the real world thing" are separate resources. I think this
>> is based on a (purist?) view when working with RDF of needing to be totally
>> clear on "what's the subject" of each triple ... the thing or the document.
>> This manifests as URIs with `id` or `doc` included somewhere to distinguish
>> between the resources and some RDF triples to clarify that the doc resource
>> is talking about the thing resource etc..
>>
>> (dangerously close to "httpRange-14" [3] here ... let's avoid that bear
>> trap)
>>
>> Jeni Tennison's "URLs in Data Primer" draft TAG note captures this
>> practice in §5.3 "Publishing data" [4]:
>>
>> ```
>> Publishers can help enable more accurate merging of data from different
>> sites if they support URLs for each entity
>> <https://www.w3.org/TR/urls-in-data/#dfn-entity> they or other sites may
>> wish to describe, separate from the landing pages
>> <https://www.w3.org/TR/urls-in-data/#dfn-landing-page> or records
>> <https://www.w3.org/TR/urls-in-data/#dfn-record> that they publish.
>> ```
>>
>> Yet Architecture of the World Wide Web §2.2.3 "Indirect identification"
>> [5] notes that:
>>
>> ```
>> To say that the URI "mailto:nadia@example.com" identifies both an
>> Internet mailbox and Nadia, the person, introduces a URI collision.
>> However, we can use the URI to indirectly identify Nadia. Identifiers are
>> commonly used in this way.
>> ```
>>
>> This is consistent with what I recall TimBL saying at TPAC-2015 in
>> regards to Vcard; come the finish, no one really cares to distinguish
>> between the thing and its associated information resource.
>>
>> ... And in most cases, one can use context to determine whether a
>> statement concerns the thing or the information resource. In those cases
>> where you can't, "URLs in Data Primer" suggests some mechanisms to mitigate
>> such confusion [6][7].
>>
>> I think that in our SDW WG discussion we have concluded that we _are_
>> content to use "indirect identification" - e.g. that we use URIs that
>> conflate the thing and document resource.
>>
>> Please can we confirm this? Assuming that indirect identification is
>> "approved" as best practice, then it seems prudent to add a note to the BP
>> document saying "don't worry about distinguishing between thing and
>> resource; indirect identification is fine" (etc.)
>>
>> Thanks, Jeremy
>>
>> [1]: http://w3c.github.io/sdw/bp/#globally-unique-ids
>> [2]: https://www.w3.org/TR/webarch/#pr-uri-collision
>> [2a]: https://www.w3.org/TR/webarch/#URI-collision
>> [3]: https://www.w3.org/2001/tag/group/track/issues/14
>> [4]: https://www.w3.org/TR/urls-in-data/#publishing-data
>> [5]: https://www.w3.org/TR/webarch/#indirect-identification
>> [6]: https://www.w3.org/TR/urls-in-data/#documenting-properties
>> [7]: https://www.w3.org/TR/urls-in-data/#authoring-specifications
>>
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