Re: Re-write of use case 48

I think "cascading profiles" does need more discussion.  In one sense its a
mechanism for meeting requirements, and lives in the solution space. We
should not deny requirements because at this stage we havent collectively
agreed on a solution in advance.

The underlying requirements IMHO are:

1)  to be able to define what is common and what is different between two
2) to be able to easily extend an existing profile to add additional
3) to be able to declare conformance to multiple profiles, including those
baseline profiles derived from/extended.
4) to be able to detect change to the original profile so that the intent
to extend and remain conformant with it as a baseline can be managed
5) to be able to inherit additional validation rules and other supporting
resources from a profile into derived profiles

Whilst its hard to point at existing distributed systems based on HTTP
services to evidence these as requirements, we see every modern
closed-system where components interact ( e.g. programming language)
supporting them, and we see major scalability issues in catalogs of web
 based data and services where these requirements are not supported. We see
inheritance emerging in non-machine-readable profiles already, so the idea
of using machine readability to support tools to help us is actually a way
to simplify the end-user interaction.  An analysis of such challenges
around infrastructure for supporting citizen science (i.e. a Use Case)
undertaken by the OGC [1] [2] has identified that both hierarchy and
polymorphism (i.e. multiple inheritance) is a direct requirement to realise
distributed system interoperability given the underlying governance
constraints on the stakeholders involved.

I suspect that inheritance will prove by far the easiest solution to meet
these requirements. however, other approaches such as provision of
infrastructure services to perform comparisons may be tractable, and even
pushing it to the client to do all the hard work is possible - but only if
we end up with very, very tight and comprehensive standards for describing
all the aspects of each resource that a client will need to be able to
interpret to infer the underlying inheritance patterns from a corpus of
"flattened" descriptions. Maybe there is some other pattern that can be
demonstrated to work?


On Wed, 23 Aug 2017 at 13:40 Karen Coyle <> wrote:

> Thanks, Rob. Note below under 1)
> On 8/22/17 6:44 PM, Rob Atkinson wrote:
> > Hi Karen
> >
> > That's now formed as a Use Case :-)  We might need to think about the
> > specific implementations as examples, rather than solutions.
> >
> > a few points to consider:
> >
> > 1) it is unlikely that a dataset conforms to "a profile" - rather it
> > conforms to 0-N profiles - and these are sometime "hierarchical"
> > specialisations - take for example NetCDF convention - CF extends COARDS
> [1]
> This came up at the f2f, and probably needs more discussion. In general,
> my understanding is that the group was not comfortable with "cascading
> profiles" due to considerations like: having a profile fragment change
> could mean it no longer describes your (static) dataset. However, it was
> agreed that there would be "copying" of profiles or profile fragments
> into new profiles that would be based on them.
> Discussion is at
> use case 37.
> This probably also relates to #4, below. I know that SHACL is developing
> re-usable common patterns, but I haven't looked into how one is expected
> to integrate those. In general, I think that SHACL (and ShEx) work fine
> as atomistic rules, and I am hoping that profiles will provide a
> coherent view of a usable set of data. The purposes are different.
> (p.s. I referred to SHACL because it came up in discussion, and I had
> the impression that some folks see it as a key aspect of profiles due to
> the validation-like functions. I'm happy to not include it in this use
> case.)
> kc
> > 2) distributions also conform to profiles - both for content and
> > potentially service behaviours
> > 3) SHACL is an RDF technology, but I dont see any reason why it cannot
> > be applied to any structure if the mapping to RDF is predictable.
> > 4) multiple SHACL rules can co-exist and be re-used across different
> > profiles - i would expect a profile to bind a set of appropriate SHACL
> > rules - rather than be a large complex monolithic artefact
> > 5) there is no reason to restrict validation rules to SHACL - some rules
> > may be better expressed other ways - thus a profile is a collection of
> > rules, and each rule should be associated with explanatory text.
> > 6) rules should have identity and if two different languages are used to
> > express the same rules this should be easily detectable
> > 7) rules may span multiple requirements from the profile - may be
> > inconvenient or inefficient to test related requirements separately
> > 8) The minimum case is a single text document describing the
> > convention/profile (cf the NetDCF conventions and DCAT-AP profiles) -
> > these still have useful semantics of declaring conformance with the
> > profile via a machine-readable identifier.
> > 9) SHACL is a potential solution - i dont see a strong requirement for
> > it as a specific choice yet
> >
> > Please do a sanity check on this reasoning, if you disagree lets discuss
> > the specific issue, and if I've missed anything lets capture it. Then
> > perhaps review the wording against the constraints, and I will undertake
> > to ensure the first-draft of the requirements are properly expressed to
> > capture the intent.
> >
> > [1]
> >
> > On Wed, 23 Aug 2017 at 09:24 Karen Coyle <
> > <>> wrote:
> >
> >     (Just the description portion)
> >
> >     Project X has decided to make its datasets available as open access,
> >     downloadable. They do not know who will find the datasets useful but
> >     assume that some potential users are outside of Project X's immediate
> >     community. They need a way to describe their metadata and its usage
> such
> >     that anyone can work with the datasets, and they hope to do this
> with a
> >     profile that is machine-readable, human-understandable, and that
> defines
> >     the criteria for valid data.
> >
> >     Some of their datasets are in RDF and Project X could potentially
> >     provide a SHACL document that fulfills the functions above, either
> >     instead of or in addition to a profile. However, they also have many
> >     datasets that are in metadata schemas for which there is no standard
> >     validation language. For those datasets, the profile will need to
> >     suffice.
> >
> >     Note that there is also a question about the RDF datasets and SHACL.
> If
> >     one expects users of the datasets to be fully conversant in SHACL
> and to
> >     have SHACL tools, then it isn't clear if a profile will provide any
> >     additional information to a SHACL validation document. There may,
> >     however, be users who wish to work with Project X's RDF data but who
> are
> >     not (yet) using SHACL. There could be both a profile for that RDF
> data
> >     as well as a SHACL document, but the programmers at Project X are
> wary
> >     of having two entirely separate definitions of the data, since it
> may be
> >     difficult to guarantee that they are 100% equivalent.
> >
> >
> >     --
> >     Karen Coyle
> > <>
> >     m: 1-510-435-8234 (Signal)
> >     skype: kcoylenet/+1-510-984-3600 <+1%20510-984-3600>
> <tel:+1%20510-984-3600>
> >
> --
> Karen Coyle
> m: 1-510-435-8234 (Signal)
> skype: kcoylenet/+1-510-984-3600 <+1%20510-984-3600>

Received on Wednesday, 23 August 2017 04:17:44 UTC