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Re: [Moderator Action] Re: Webby Data

From: Phil Archer <phila@w3.org>
Date: Sat, 10 Oct 2015 10:41:29 +0100
To: Jeremy Tandy <jeremy.tandy@gmail.com>, Erik Wilde <dret@berkeley.edu>, public-dwbp-comments@w3.org
Message-ID: <5618DD49.1030600@w3.org>
Moving this to the public comments list so Jeremy doesn't get blocked.

On 10/10/2015 10:13, Jeremy Tandy wrote:
> Phil- thanks for drafting this update. It makes sense to me.
> There are 3 minor changes I would suggest ... and then there's Eric's
> concerns that 'webby data' is necessary but not sufficient for hypermedia.
> Starting with the three things:
> 1) your reference to the CSVW on the web method of assigning URIs to things
> that within a dataset only have locally scoped identifiers; would suggest
> you point folks directly to URI Template Properties [1] and the 'aboutUrl'
> [2]
> 2) you talk about 'confirming the versioning policy' ... a bit thorny this
> one. In my opinion, only information resources can be versioned. Real-world
> resources can't be. For example, if I replace my car with another that is
> just like it, it this a new version of my car? No, it's a different car
> with a different identifier. Using version numbers in URIs means that you
> can only create durable links to that specific version ... and when a new
> version is released, your links are broken. That said, you might want to
> refer to a specific version of a document (or other information resource)
> as the basis of an analysis. I'm guessing that your need a section on the
> merits of when and where to use versioned URIs over and above what is
> already stated in http://www.w3.org/TR/dwbp/#dataVersioning (BTW, I agree
> that if you are going to use versioning, you should provide a version
> history, and that datasets, as information resources, are great candidates
> to be versioned). By way of example, please refer to the Linked Data
> Registry [3] that makes a distinction between versioned and non-versioned
> things [4]. You can see this in a live example [5]; the concept
> 'AGRICULTURE - SITE DRAINAGE' [6] is not versioned but the register item
> [7] that binds that concept into a controlled list (the register) is
> versioned (each version of a register item refers to a graph of information
> about the registered concept, so that the information held about the
> concept can be updated). Furthermore, we use a syntax (add a suffix `:n`
> where n is the version number) to allow people to access specific versions
> (see example [8] - although not very interesting as it only has one version
> ... in other examples you can traverse the version history). In the UI of
> the Linked Data Registry you can find the versions by clicking on the
> 'History' link.
> 3) in the 'How to test' section you say "Check that the URIs are
> resolvable". Now, IMHO, it's certainly best practice to have these URIs for
> data points resolve (I suppose even if it is only to the description of the
> dataset within which they're defined?), but there are cases where it's
> equally valid to use them just as (globally scoped) identifiers rather than
> URLs. This still adds value when you're trying to merge information from
> disparate datasets that you have downloaded and are working with, say, in a
> local triple store.
> ----
> Now, Eric's point [9] is that there is a "difference between 'web data
> only' and the 'web of hypermedia-driven services'" and that "'webby data'
> is a necessary but not sufficient condition to have hypermedia. [which
> requires providing navigational affordances to get things done with that
> data."
> I see that in the vast majority of cases, the data is accessed via a
> service end-point ... even if it is a trivial HTTP Get. But there are cases
> where (as I said in point #3 above) that you simply want to use URIs as
> identifiers. This clearly is not hypermedia. I wonder if there are two
> levels of requirements here? At this point, I'm unable to unpick this
> distinction further, but I'm sure it will be relevant in the Spatial Data
> on the Web WG.
> More thinking required.
> Jeremy
> [1]: http://www.w3.org/TR/tabular-metadata/#uri-template-properties
> [2]: http://www.w3.org/TR/tabular-metadata/#cell-aboutUrl
> [3]: https://github.com/UKGovLD/registry-core
> [4]:
> https://github.com/UKGovLD/registry-core/wiki/Principles-and-concepts#versioned-types
> [5]: http://environment.data.gov.uk/registry/
> [6]:
> http://environment.data.gov.uk/registry/def/water-quality/sampling_point_types/AE
> [7]:
> http://environment.data.gov.uk/registry/def/water-quality/sampling_point_types/_AE
> [8]:
> http://environment.data.gov.uk/registry/def/water-quality/sampling_point_types/_AE:1
> [9]: https://lists.w3.org/Archives/Public/public-dwbp-wg/2015Oct/0026.html
> On Sat, 10 Oct 2015 at 08:53 Tandy, Jeremy <jeremy.tandy@metoffice.gov.uk>
> wrote:
>> -----Original Message-----
>> From: Phil Archer [mailto:phila@w3.org]
>> Sent: 09 October 2015 22:29
>> To: Public DWBP WG
>> Cc: Erik Wilde; Tandy, Jeremy
>> Subject: Webby Data
>> Dear all,
>> As the WG is well aware, Erik has been flying the flag for Webby
>> data/hypermedia.
>> It took me a while to work out just what Erik was getting at, mainly
>> because I have been somewhat word blind. When you've seen a document as
>> much as we've seen the BP doc, you think things are there that aren't and
>> vice versa.
>> It was Jeremy Tandy (SDW and CSV WG) pointed out to me last week what was
>> missing - which is what I think Erik has been saying for a while.
>> Erik says it differently but I dare to hope that what I've suggested as a
>> new BP addresses his issue.
>> We had a BP that said "use persistent URIs as identifiers". And then  it
>> said *Datasets* must be identified by persistent URIs. What it didn't say
>> was that data points within the data should also be URIs where possible.
>> I've drafted a BP to cover this, see
>> http://philarcher1.github.io/dwbp/bp.html#identifiersWithinDatasets
>> For those who were there, this is the short form of my over-long talk in
>> Sao Paulo the other day ;-)
>> The BP emphasises the importance of links between things that are
>> identified. It does this with reference to the Web in general and then
>> cites *both* 5 stars of linked data and Erik's words on hypermedia as
>> examples of what this means.
>> @Erik - is that doc going to stay on GitHub? Any chance it might find a
>> more stable/permanent home? I really don't like linking to GH in a W3C Rec
>> track document.
>> I very much doubt this BP will go through unchanged, but I've had a go at
>> drafting it and have created the pull request. I hope the WG will discuss
>> it and not just merge it.
>> HTH
>> Phil.
>> --
>> Phil Archer
>> W3C Data Activity Lead
>> http://www.w3.org/2013/data/
>> http://philarcher.org
>> +44 (0)7887 767755
>> @philarcher1


Phil Archer
W3C Data Activity Lead

+44 (0)7887 767755
Received on Saturday, 10 October 2015 09:41:35 UTC

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