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Re: Webby Data

From: Jeremy Tandy <jeremy.tandy@gmail.com>
Date: Sat, 10 Oct 2015 11:10:33 +0000
Message-ID: <CADtUq_38c2q-0vMkvBS3wdgCw30qV=fS_qgposo4osM_-obc2Q@mail.gmail.com>
To: Phil Archer <phila@w3.org>, Erik Wilde <dret@berkeley.edu>, public-dwbp-comments@w3.org
Phil-

those changes look fine. Happy to help with the subject of versioning; Dave
Reynolds and I spent some time working through the strategy implemented in
the Linked Data Registry. It works in all the cases I have found so far.

Regards, Jeremy

On Sat, 10 Oct 2015 at 11:43 Phil Archer <phila@w3.org> wrote:

>
>
> On 10/10/2015 10:12, 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]
>
> Done at
> http://philarcher1.github.io/dwbp/bp.html#identifiersWithinDatasets
>
> It now says:
> URIs can be long. In a dataset of even moderate size, storing each URI
> is likely to be repetitive and obviously wasteful. Instead, define
> locally unique identifiers for each element and provide data that allows
> them to be converted to globally unique URIs programmatically. The
> Metadata Vocabulary for Tabular Data [tabular-metadata] provides
> mechanisms for doing this within tabular data such as CSV files, in
> particular using URI template properties such as the about URL property.
>
>
> >
> > 2) you talk about 'confirming the versioning policy' ... a bit thorny
> this
> > one.
>
> Indeed. I've removed that bullet point, lazily copied from LD-BP.
>
>
> 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.
>
> That's really helpful info. The editors are struggling a little with the
> issue of versioning so this should help us make progress. I'll need to
> look at it too to see if it should be in this particular BP or elsewhere
> in the doc.
>
>
> >
> > 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.
>
> Fixed. It now says:
>
> Check that within the dataset, references to things that don't change or
> that change slowly, such as countries, regions, organizations and
> people, as referred to by URIs or by short identifiers that can be
> appended to a URI stub. Ideally the URIs should resolve, however, they
> have value as globally scoped variables whether they resolve or not.
>
>
>
> >
> > ----
> >
> > 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.
>
> I've given my first pass answer to Erik - let's see how it goes.
>
> Thanks for the review - much appreciated.
>
> Phil.
>
>
> >
> > 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
> http://www.w3.org/2013/data/
>
> http://philarcher.org
> +44 (0)7887 767755
> @philarcher1
>
Received on Saturday, 10 October 2015 11:11:12 UTC

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