- From: Dan Brickley <danbri@google.com>
- Date: Thu, 31 Dec 2015 11:09:08 +0000
- To: Clemens Portele <portele@interactive-instruments.de>, Rob Atkinson <rob@metalinkage.com.au>
- Cc: Phil Archer <phila@w3.org>, Simon Cox <Simon.Cox@csiro.au>, amgreiner@lbl.gov, ericphb@gmail.com, jeremy.tandy@metoffice.gov.uk, koubarak@di.uoa.gr, public-dwbp-comments@w3.org, public-sdw-comments@w3.org
- Message-ID: <CAK-qy=5BkqrORAWuWxb8mFmW3-dd9Pucyjc3f-ZOy=0uF-gWDw@mail.gmail.com>
Isn't a "subset" just a query result, or which there are effectively an unlimited number? Storing a query so it can be re-run against evolving data has value. Having a URI for that, perhaps less so. Dan On Thu, 31 Dec 2015, 08:14 Clemens Portele < portele@interactive-instruments.de> wrote: > Rob, > > what you describe seems to apply to the dataset (resource) the same way it > would apply to any subset resource. I.e. are you discussing a more general > question, not the subsetting question? > > Phil, > > a (probably often unproblematic) restriction to the temperature/uk/london > or stations/manchester approach is that there is only one path, so you end > up with limitations on the subsets. If you want to support multiple > subsets, e.g. also stations where high speed trains stop, stations that > have a ticket shop, etc. then there are several issues with a > /{dataset}/{subset}/…/{subset}/{object} approach. These include an unclear > URI scheme ("manchester" and "eurostar" would be on the same path level), > potential name collisions of subset names of different subsetting > categories, and multiple URIs for the same feature/object. > > Best regards, > Clemens > > > On 31 Dec 2015, at 03:07, Rob Atkinson <rob@metalinkage.com.au> wrote: > > I'm not a strong set-theoretician - but it strikes me there are some > tensions here: > > Does the identifier of a set mean that the members of that set are > constant, known in advance and always retrievable? Is a query endpoint a > resource (does either URI or URL have meaning against a query that delivers > real time data - including the use case of "at this point in time we think > these things are members of this set?" ) > > If the subset is the result of a query - and you care that it is the same > subset another time you look at it - are you actually assigning an > identifier to the artefact - which is the query response, whose properties > include the original query, where it was made, and the time it was made? > > Can you define an ontology for terms like subset, query, response that you > all agree on? > > I share Phil's implicit concern that subsetting by type with URI patterns > may not be universally applicable - IMHO that equates to a "sub-register" > pattern, where a set has its members defined by some identifiable process > (indepent of any query functions available) - which may include explicit > subsets - for example by object type, or delegated registration processes. > That probably fits the UK implementation better than a query-defined > subset. > > If subsets have some prior meaning - and a query is used to access then > from a service endpint - then the query is a URL that needs to be bound to > the object URI. AFAICT thats a very different thing to saying an arbitrary > query result defines a subset of data. > > I think you may, in general, assign an ID to the artefact which is the > result of a query at a given time, and if you want to make that into > something with more semantics then you need make it into a new type of > object which can be described in terms of what it means. I think currently > the conversation is conflating these two perspectives of "subset". > > Cheers, and farewell to 2015. > Rob Atkinson. > > > > > On Thu, 31 Dec 2015 at 08:26 <Simon.Cox@csiro.au> wrote: > >> Another way of looking at it is that a query, encoded as a URI pattern, >> defines an implicit set of potential URIs, each of which denotes a subset. >> >> Simon J D Cox >> Environmental Informatics >> CSIRO Land and Water >> >> E simon.cox@csiro.au T +61 3 9545 2365 M +61 403 302 672 >> Physical: Central Reception, Bayview Avenue, Clayton, Vic 3168 >> Deliveries: Gate 3, Normanby Road, Clayton, Vic 3168 >> Postal: Private Bag 10, Clayton South, Vic 3169 >> http://people.csiro.au/Simon-Cox >> http://orcid.org/0000-0002-3884-3420 >> http://researchgate.net/profile/Simon_Cox3 >> >> ------------------------------ >> *From:* Phil Archer >> *Sent:* Wednesday, 30 December 2015 6:31:16 PM >> *To:* Manolis Koubarakis; 'public-sdw-comments@w3.org'; Annette Greiner; >> Eric Stephan; Tandy, Jeremy; public-dwbp-comments@w3.org >> *Subject:* Subsetting data >> >> At various times in recent months I have promised to look into the topic >> of persistent identifiers for subsets of data. This came up at the SDW >> F2F in Sapporo but has also been raised by Annette in DWBP. In between >> festive activities I've been giving this some thought and have tried to >> begin to commit some ideas to a page [1]. >> >> During the CEO-LD meeting, Jeremy pointed to OpenSearch as a possible >> way forward, including its geo-temporal extensions defined by the OGC. >> There is also the Linked Data API as a means of doing this, and what >> they both have in common is that they offer an intermediate layer that >> turns a URL into a query. >> >> How do you define a persistent identifier for a subset of a dataset? IMO >> you mint a URI and say "this identifies a subset of a dataset" - and >> then provide a means of programmatically going from the URI to a query >> that returns the subset. As long as you can replace the intermediate >> layer with another one that also returns the same subset, we're done. >> >> The UK Government Linked Data examples tend to be along the lines of: >> >> http://transport.data.gov.uk/id/stations >> returns a list of all stations in Britain. >> >> http://transport.data.gov.uk/id/stations/Manchester >> returns a list of stations in Manchester >> >> http://transport.data.gov.uk/id/stations/Manchester/Piccadilly >> identifies Manchester Piccadilly station. >> >> All of that data of course comes from a single dataset. >> >> Does this work in the real worlds of meteorology and UBL/PNNL? >> >> Phil. >> >> >> >> >> [1] https://github.com/w3c/sdw/blob/gh-pages/subsetting/index.md >> >> >> >> >> -- >> >> >> Phil Archer >> W3C Data Activity Lead >> http://www.w3.org/2013/data/ >> >> http://philarcher.org >> +44 (0)7887 767755 >> @philarcher1 >> >> >
Received on Thursday, 31 December 2015 11:09:46 UTC