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Re: Vocabulary 'tutorial'?

From: Harry Halpin <hhalpin@w3.org>
Date: Mon, 23 Mar 2015 15:07:17 +0100
Message-ID: <55101E15.1010008@w3.org>
To: ☮ elf Pavlik ☮ <perpetual-tripper@wwelves.org>, Erik Wilde <dret@berkeley.edu>, "Bassetti, Ann" <ann.bassetti@boeing.com>, Social Web Working Group <public-socialweb@w3.org>, Social Interest Group <public-social-interest@w3.org>
CC: "Martin, Julie" <julie.martin@boeing.com>, "Donovan, Andrew R" <andrew.r.donovan@boeing.com>
Hash: SHA1


It's JSON-LD based but we are accepting the reality of the situation
that 99% of the programmers are not currently using RDF  or any
semantic tooling, especially inference and will glaze over any
RDF-heavy parts of the spec. That's why any sub-class/sub-type
relationships have to be coded as such in the spec.

Thus, most AS2.0 will likely forget @context, not follow any JSON-LD
processing, etc. Thus, we'll have a implicit context in the media type.

However, we want the minority of RDF-enabled developers to take
advantage of their toolsets.  ince it *will* feature URI-based
extensibility, the vocabularies will use URIs.

 We could for vocabularies just use lists of URIs. I see no harm done
in allowing these vocabularies to use RDF(S) since the communities
that care about extensibility may end up using RDF more than others.
However, again, tooling for RDF vocabulary creation is, 15 years into
RDF, still seemingly rather undeveloped.

If we mandated full RDF processing, probably at least half of the
Working Group would walk away (i.e. the IndieWeb folks). If we
mandated no extensibility, we'd repeat the mistake of AS1.0 and we'd
have to redesign AS3.0 pretty soon.

So JSON-LD is a compromise. If in the future RDF takes off, more
people can use it. If it fails, then we'll just treat AS2.0 as
ordinary JSON. It's a win-win situation and it seems any objections
(i.e. mandating inference, etc.) are effectively edge-cases that
ignore the reality of modern web development.


On 03/23/2015 11:28 AM, ☮ elf Pavlik ☮ wrote:
> On 03/23/2015 10:23 AM, Erik Wilde wrote:
>> hello elf.
>> On 2015-03-23 10:07, ☮ elf Pavlik ☮ wrote:
>>> On 03/23/2015 09:56 AM, Erik Wilde wrote:
>>>> i am wondering if/why semantic tooling would even be
>>>> required. if we say that AS2 is JSON-based, then there's no
>>>> requirement to define new vocabularies with RDF, correct?
>>>> semantic tooling would be necessary for those who *want* to
>>>> use it, but that would be outside of AS's scope.
>>> If we design RDF Ontologies, those who want to use them as
>>> still JSON can do that thanks to JSON-LD. It comes with certain
>>> limitations but we can consider it a Lite mode which will not
>>> provide all the robust features. If we don't keep RDF in mind
>>> while designing, it may not work very well if someone wants to
>>> use more powerful features and treat it as Linked Data.
>> that's the point i've been trying to make, and decision we've
>> been dancing around for a couple of months. is AS2 JSON-based, or
>> is it RDF-based. saying that it's "JSON-LD based" really doesn't
>> solve the problem, it simply provides rhetoric to justify our
>> inability to decide.
>>>> the approach follows the idea of
>>>> https://github.com/dret/sedola, which has the same idea of
>>>> providing a basic documentation harness (in the case of
>>>> sedola it's used for for media types, HTTP link headers and
>>>> link relation types), without forcing people to subscribe to
>>>> a single modeling framework that's required to formally
>>>> describe these things.
>>> Could you please give an example of how those who want to treat
>>> it as Link Data can simply do so? Once again, we can not just
>>> say "we don't mind if you try to use it as Linked Data", but if
>>> we want to make it possible we must keep it in mind when we
>>> design things.
>> it all comes down to how things are defined. if we *require* all 
>> identifiers to be dereferencable, then we (probably) require
>> people to publish RDF at those URIs. if one the other hand we
>> treat identifiers as identifiers, then it is outside of the scope
>> of AS2 if people decide to publish RDF at those URIs. if they do,
>> they're welcome to do so, but if they don't, that's fine, too.
>> conflating the concepts of identifiers and links can be risky. if
>> AS2 says that concepts such as activity types and object
>> properties are identifiers, then everything works just fine. if
>> otoh AS2 says that those concepts must be treated as links,
>> that's a very different design.
> Personally I often start with using HTTP URIs which return 404,
> still at any time in the future I can simply 'fix' it and return
> some meaningful description for those who dereference it. We could
> recommend using identifiers for vocabulary terms in such order: 1)
> Use URIs 2) Use HTTP URIs 3) Provide useful information about term
> you define for those who dereference its HTTP URI. You may consider
> using RDFS and OWL but even plain text or HTML (from .md) gives a
> good start!
> I would also consider that we recommend
> 2.5) Publish shared vocabularies under https://w3id.org/ namespace
> to ensure longevity of URI other used it their data.
> Those who know what they do can simply ignore such recommendations
> :)
> BTW Jason Hagg (xAPI/adlnet.gov) applied to join IG and will bring
> to the table very concrete requirements for extending 'verbs' /
> verb types.
> Cheers!
>> practically speaking, many linked data implementations treat
>> core concepts as identifiers anyway, because otherwise the web
>> would melt down under the constant load of implementations
>> pulling in all interlinked concepts every time they encounter
>> them, to check if they may have changed.
>>>> as an experiment, i have created sedola documentation for
>>>> many W3C and IETF specs, and despite the fact that these are
>>>> using different (and often no) formalisms, this still results
>>>> in a useful list of the concepts that matter: *
>>>> https://github.com/dret/sedola/blob/master/MD/mediatypes.md *
>>>> https://github.com/dret/sedola/blob/master/MD/headers.md *
>>>> https://github.com/dret/sedola/blob/master/MD/linkrels.md
>>> Looks cool! I guess meant for human consumption and not for
>>> machine processing?
>> so far i'm just publishing MD because it's easy and it's good to
>> look at. it would be trivial to transform it into other
>> metamodels, such as JSON, XML, or RDF.
>> wrt to human consumption vs machine consumption: machines can
>> understand the concepts that have been defined somewhere, so
>> that's already pretty useful. and that's really all there
>> practically is, because the vast majority of meaningful concepts
>> on the internet and the web today have only textual descriptions,
>> so there's nothing to consume for machines other than a distilled
>> list of the concepts defined in those specs.
>> cheers,
>> dret.
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Received on Monday, 23 March 2015 14:07:30 UTC

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