shex/Lobby

Shape Expressions

Eric Prud'hommeaux

@ericprud

@nishad , @gkellogg is the maintainer of the rub ShEx gem

andrawaag

@andrawaag

FYI: https://www.wikidata.org/wiki/Wikidata:Events#Wikidata_bug_triage_hour

danbri

@danbri:matrix.org

[m]

So if we had the triples for some shape definitions, how would we easily create ShexJ files with the right syntax structure? (Reposting from chat with eric)

trying to avoid having custom code that cares about syntax, or volatile dependencies

(And prefer Python...)

Sorry to be picky! But they could be really interesting shape definitions...

Eric Prud'hommeaux

@ericprud

@gkellogg , have you taken a stab at framing to ShExJ with the latest framing impls?

@hsolbrig , have you got a ShExR recognizer? I think danbri's crew is living in python-land

danbri

@danbri:matrix.org

[m]

Yup, crew is Google

Eric Prud'hommeaux

@ericprud

don't they sell ads or something like that?

danbri

@danbri:matrix.org

[m]

I really should get around to watching Mad Men

If there’s straightforward code in another language maybe we could port it to py?

Eric Prud'hommeaux

@ericprud

i have a not-so-straighforward way to do it in my code.

Sameroom

@sameroom-bot

[Harold Solbrig] I don't have a ShExR recognizer, but could build one pretty quickly if you need it

[Harold Solbrig] Basically we need to add framing information to shex.context.jsonld

Eric Prud'hommeaux

@ericprud

i validate it against ShExR.shex and use the proof to construct the schema object which i can save as JSON

go with harold's approach

Sameroom

@sameroom-bot

[Harold Solbrig] The way we go from ShEx(J) to ShExR is via json-ld anyway

[Harold Solbrig] Harold Solbrig what is the deal with the apostrophe 'd'?

[Eric Prud'hommeaux] i corrected it in gitter but sameroom didn't transcribe it here

danbri

@danbri:matrix.org

[m]

So to go from shex triples to shexJ, is that even possible in python today?

Sameroom

@sameroom-bot

[Jose Emilio Labra Gayo] One possibility is to invoke a web service

[Jose Emilio Labra Gayo] rdfshape does that already but you would need to invoke it as a web service

1 reply

Eric Prud'hommeaux

@ericprud

I think Ima write a ShEx-driven RDF parser generator that will compile the equivalent of a recursive descent parser that operates against some API (RDFJS, in my case, but can be made to work over python's RDFLib with clever tools like sed

Sameroom

@sameroom-bot

[Harold Solbrig] I'm sorry, can you restate that in English?

[Harold Solbrig] Harold Solbrig wonders what language IS he speaking?

[Harold Solbrig] FWIW - if you were to wrap rdflib triple (which is what we do in in some of the PyShEx implementations, you could simply record the queries that went through. The problem, however, is that you wouldn't follow all paths, eh?

Eric Prud'hommeaux

@ericprud

if i walk through https://github.com/shexSpec/shexTest/blob/master/doc/ShExR.shex , i can build something that populates a data structure with the values from that schema. that data structure, when expressed in JSON, should basically be ShExJ

1 reply

and if i'm wrong, i'd like to know that

danbri

@danbri:matrix.org

[m]

Or tell us ShexR (with some tweaks to use collections) is a legit alternative to shexJ?

Eric Prud'hommeaux

@ericprud

yeah, it's very well defined by the @context

but all of the tooling uses ShExJ because it's basically the compiled form of ShEx (i.e. an AST)

which means those tools will ultimately need to recognize said RDF and parse it to be ShExJ

(at least, all of the current tools that i know of use ShExJ)

danbri

@danbri:matrix.org

[m]

If we can get stuff out of Google in some stable shex variant, that would be a great milestone

Currently it is easy to dump shacl triples, and a bit “it’s complicated!” wrt shex

Eric Prud'hommeaux

@ericprud

right. ok, let's fix this

i assume that by dump, you mean dump in Turtle

(vs. json-ld)

danbri

@danbri:matrix.org

[m]

could be

they both have their issues!

but if it is in github a Github Action could run and maintain other flavours maybe

Eric Prud'hommeaux

@ericprud

'cause the JSON-LD is an RDF representation; it's just that it takes a JSON-LD processesor, and they're heavier-weight and less common than Turtle parsers

my pref, if someone's gone to the effort of creating a JSON-LD representation, is usually LD 'cause it offers the mythic dual access

Eric Prud'hommeaux

@ericprud

re the change to the (ordered) collection of shape expressions in a schema, that's a one-line change to https://www.w3.org/ns/shex.jsonld:

    "shapes": {
      "@id": "shex:shapes",
      "@type": "@id"
    }

needs "@container": "@list", but that also needs some quick discussion in the CG

Eric Prud'hommeaux

@ericprud

btw, that change takes the RDF output from https://tinyurl.com/26tfanhr to https://tinyurl.com/vdvu84mv

prettier in Turtle:

PREFIX shex: <http://www.w3.org/ns/shex#>

[] a shex:Schema ;
  shex:shapes ( <http://a.example/S1> <http://a.example/S2> ) .

<http://a.example/S1> a shex:Shape ;
  shex:expression [
    a shex:TripleConstraint ;
    shex:predicate <http://a.example/p1>
  ] .

<http://a.example/S2> a shex:Shape ;
  shex:expression [
    a shex:TripleConstraint ;
    shex:predicate <http://a.example/p2>
  ] .

danbri

@danbri:matrix.org

[m]

You think we should publish turtle then?

https://twitter.com/kuzeko/status/1374325885856256002?s=21 looks interesting btw

Gregg Kellogg

@gkellogg

@ericprud Haven't done anything with framing ShEx recently. Main thing would be @included support and id/type maps that might be useful. You can play around in json-ld.org/playground and send me a link of what you're working with.

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