Hi David et al. The use case at hand is pretty clear. And I think we also did our analysis… The issues that arise have to do with unnecessary complexity en use of OWA where people really want/need CWA. Furthermore we see people use modelling styles with RDFS/OWL (involving ‘objectification’) where they want to put meta-data at properties and relationships introducing their own meta-concept like xxx:hasProperty, xxx:hasValue, … etc.
Triple stores explode because of this and people unfairly blame LD for this in favour of relational etc. They start using both (or more) and introduce multiple transformations (both syntax and semantics) being another big source of trouble. So we decided to define a good compromise between modelling power and simplicity. Ie not throwing away the baby but trying to keep the baby simple. We want to do this by: - define a minimum language stack (as below) in CWA fashion - define a simple modelling style making the optimal use of this stack (not use it for meta-modelling your own language) It’s is clear that this way some things cannot be done (esp. in the meta-modelling area) but these things might be compromised to go one granularity level higher. More specifically on inverses: We see people enrich both ontologies and datasets with inverse structure/data for performance reasons (partly because of all the above…). Maybe you have you views here… Gr Michel Dr. ir. H.M. (Michel) Böhms Senior Data Scientist T +31888663107 M +31630381220 E [email protected]<mailto:[email protected]> Location<https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=!3m1!4b1!4m5!3m4!1s0x47c5b58c52869997:0x56681566be3b8c88!8m2!3d52.000788!4d4.376707> [cid:[email protected]]<http://www.tno.nl/> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages. From: [email protected] <[email protected]> On Behalf Of David Price Sent: vrijdag 6 juli 2018 12:17 To: [email protected] Subject: Re: [topbraid-users] SHACL usage On 6 Jul 2018, at 02:41, Holger Knublauch <[email protected]<mailto:[email protected]>> wrote: On 6/07/2018 4:41, Bohms, H.M. (Michel) wrote: Thanks Richard, Irene, David & Holger for all your advice here! For our modelling guide I now start with: Serialisation: Turtle CMO (advice on any more generic variants welcome) * cmo:hasDirectPart * cmo:isDirectPartOf * ! currently using in here owl:inverseOf, guess I better use shacl here too (?) My personal opinion is to avoid inverse properties and owl:inverseOf in particular. The problem is redundancy: you need two distinct triples for the same information. RDF triples can be walked both ways - from subject to object or from object to subject and languages like SPARQL make this easy. So there is no real reason to have two properties for both directions, and in fact they can make working with such data harder. That’s strictly true for RDF and SPARQL. However, many user interfaces that support a UI-only search or mapping capability, only support handling a forward reference. That is why we have customers now that use OWL inverses extensively. Otherwise, it’s very hard for the end user to get from Instance1 to Instance2 and also from Instance2 to Instance1 in the UI navigation. We have no idea if such a UI will be required in the user community, and that raises a meta-level concern for me as follows: It’s not clear what the usage scenarios or use cases are, who the actual customers are, etc. Everyone has different perspectives on this topic (e.g. Holger prefers only SHACL and I prefer having every tool available in my modelling tool box) and so IMO trying to select precisely what subset of RDFS, OWL, and SHACL should be in a modelling guide is not a sensible thing to do via a forum like this with so little understanding of the actual problem. If I’m a typical SemWeb/Linked Data modeler today, got involved in Michel's project and was told to throw away most of what I’ve ever used I’d really wonder how that guide was developed and upon what deep understanding of the problem it was based. Michel does not have a good response to that since there was no deep analysis done. Also - seems like this all may just be the result of a vast over-reaction to the limited set of problems wrt OWA, for which there are nice solutions available in a layer of SHACL, and Michel may be throwing away a lot of baby with the bath water. Michel - IMO something like this should really be a more like a 3 day workshop with your ontologists and SMEs to understand what you need and *only then* provide such detailed advice. Cheers, David In SHACL you could replace cmo:isDirectPartOf with XY sh:property [ sh:path [ sh:inversePath cmo:hasDirectPart ] ; sh:name "is direct part of" ; ... ] and form generators and features like GraphQL would still understand what you mean, and would present information accordingly. * CDT * QuantityKinds as rdfs:Datatype from https://ci.mines-stetienne.fr/lindt/v2/custom_datatypes.html#mass * Turtle: https://ci.mines-stetienne.fr/lindt/v2/custom_datatypes.ttl * Units in WKT-string from http://unitsofmeasure.org/ucum.html SHACL (full) OWL * owl:Ontology (@holger: guess this one is the only second owl construct needed) Yeah, sometimes we use this to identify the graph itself, but it's technically not really necessary. No harm though. * * owl:imports * maybe owl:versionInfo (but proab. Not need when already in URI strategy…) RDFS * rdfs:Class * rdfs:Datatype (@holger: I need this one for use of CDT quantityKinds) * rdfs:subClassOf * rdfs:label * rdfs:comment RDF * rdf:Property * rdf:type XSD * xsd:string * xsd:float * xsd:integer * xsd:Boolean Looks good (except xsd:boolean is lower-case and I typically use xsd:decimal over xsd:float because of unlimited precision that xsd:decimal offers). Holger * Comments still very welcome! Michel Dr. ir. H.M. (Michel) Böhms Senior Data Scientist T +31888663107 M +31630381220 E [email protected]<mailto:[email protected]> Location<https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=%213m1%214b1%214m5%213m4%211s0x47c5b58c52869997:0x56681566be3b8c88%218m2%213d52.000788%214d4.376707> [cid:[email protected]]<http://www.tno.nl/> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages. From: [email protected]<mailto:[email protected]> <[email protected]><mailto:[email protected]> On Behalf Of Holger Knublauch Sent: donderdag 5 juli 2018 01:07 To: [email protected]<mailto:[email protected]> Subject: Re: [topbraid-users] SHACL usage In my own work, I no longer use anything from the OWL namespace except owl:imports. However, some people start they class hierarchies at owl:Thing basically to distinguish "domain" classes from "system" classes. But that's an arbitrary distinction and thus problematic too. owl:DatatypeProperty and owl:ObjectProperty are not really needed and don't add value except hypothetical backwards compatibility with tools that only understand OWL and not RDF. Your list below on selected resources from RDF/S namespaces is what I use as well. rdfs:subClassOf is very important and is even used officially in the SHACL spec. rdfs:label and comment are well-established. I am typically not using rdfs:subPropertyOf because this takes us on a slippery slope of requiring inferences (walking the subclass hierarchy is simply unavoidable, while putting subproperties into a hierarchy is often over-used to categorize properties, and for that there are better alternatives). In general, SHACL has no notion of properties as stand-alone entities, i.e. you don't even need to define an rdf:type for the properties. Holger On 5/07/2018 7:22, Bohms, H.M. (Michel) wrote: Hi Irene Ok , but would there be any extra benefit (beyond just rdf:property) when not OWL-inferencing? Ie why would I introduce only those from owl when cwa/shacl modelling? (just playing devils advocate) Thx michel Dr. ir. H.M. (Michel) Böhms Senior Data Scientist T +31888663107 M +31630381220 E [email protected]<mailto:[email protected]> Location<https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=%213m1%214b1%214m5%213m4%211s0x47c5b58c52869997:0x56681566be3b8c88%218m2%213d52.000788%214d4.376707> [cid:[email protected]]<http://www.tno.nl/> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages. From: [email protected]<mailto:[email protected]> <[email protected]><mailto:[email protected]> On Behalf Of Irene Polikoff Sent: woensdag 4 juli 2018 18:10 To: [email protected]<mailto:[email protected]> Subject: Re: [topbraid-users] SHACL usage I do not see much harm in having owl:DatatypeProperty and owl:ObjectProperty. Most modeling languages differentiate between attributes and relationships. Of course, with SHACL this is not really needed, but may be useful as an annotation. Sent from my iPhone On Jul 4, 2018, at 11:40 AM, Bohms, H.M. (Michel) <[email protected]<mailto:[email protected]>> wrote: Hi David, Some background (vcon/interlink – like). We have a use case where data is exchanged between a client (infra asset manager) and a contractor say about a road section or bridge. They have to use the same ontology in the middle but both parties might have more detailed restrictions to which they want to validate. So we have both data sharing and data validation. (note there will be a n x m relationship between client & contractors). We have to convince them linked data is feasible (beyond relational) so we have to keep things as simple as possible at least as CWA as possible. They are scary about OWA… With the below I was investigating how simple I can go. Seems like in the middle (sharing): RDFS - rdfs:Class - rdfs:Datatype - rdfs:subClassOf - rdfs:label / rdfs:comment RDF - rdf:Property - rdf:Datatype - rdf:type XSD - xsd:string - xsd:float - xsd:integer - xsd:boolean And on the sides (validation): full shacl. In the middle we then define/agree things like Bridge, TrafficBarrier etc as rdfs classes and designLifeExpectancy as rdf properties (ie no complex ‘objectfications). We only add in facilities for: - decomposition (hasDirectpartOf), that can be constrained (CWA) on class level, and - quantities & unit (CDT units) where quantities (better: quantityKinds) are modelled as datatypes and the units in WKT like “230 mm” That’s seems a nice compromise between power and simplicty in this case….(especially the transformations that is format translators and semantics convertors to and from their native applications (typically relational) stay simple enough too… (round trip data client <> contractor involving syntax/semantics via some middle takes 8 transformations now…so in parallel we will promote sharing iso conversion…..). Gr michel Dr. ir. H.M. (Michel) Böhms Senior Data Scientist T +31888663107 M +31630381220 E [email protected]<mailto:[email protected]> Location<https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=%213m1%214b1%214m5%213m4%211s0x47c5b58c52869997:0x56681566be3b8c88%218m2%213d52.000788%214d4.376707> <image001.gif><http://www.tno.nl/> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages. From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> On Behalf Of David Price Sent: woensdag 4 juli 2018 17:18 To: [email protected]<mailto:[email protected]> Subject: Re: [topbraid-users] SHACL usage Hi Michel I would say you’ve not given enough background for a clear answer. Background items like these could change the answer : Are you sharing with others? If so, what tools do they have? Are you implementing an app? If not what or who is the customer? Are you defining something to be taken and extended by others? Where is source of any data? Does it have a data model? Is it a fixed or growing set of data, or does it not exist yet? For example, if your data is fully specified wrt data type and type and is complete and a good existing app generates it and you are just harvesting it for linking, for example, then OWA concerns are less important. Just a few thoughts to consider. Cheers, David On 4 Jul 2018, at 11:54, Bohms, H.M. (Michel) <[email protected]<mailto:[email protected]>> wrote: Thx! So, to be sure (100-harmless), I could use even a subset of RDFS (“RDFS-“) without domain & range for sharing the vocabulary. Domain and range can come in at SHACL. ‘RDFS-‘ would then be simply: - rdfs:Class - rdfs:Property - rdfs:Datatype - rdfs:subClassOf - rdfs:subPropertyOf - meta-stuff like: rdfs:label / rdfs:comment /rdfs:seeAlso / rdfs:isDefinedBy Dr. ir. H.M. (Michel) Böhms Senior Data Scientist T +31888663107 M +31630381220 E [email protected]<mailto:[email protected]> Location<https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=%213m1%214b1%214m5%213m4%211s0x47c5b58c52869997:0x56681566be3b8c88%218m2%213d52.000788%214d4.376707> <image001.gif><http://www.tno.nl/> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages. From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> On Behalf Of Richard Cyganiak Sent: woensdag 4 juli 2018 12:14 To: [email protected]<mailto:[email protected]> Subject: Re: [topbraid-users] SHACL usage My subjective answer: RDFS has OWA semantics, but RDFS has so little expressivity that it’s OW-ness doesn’t really become a problem. So I would consider the inclusion of RDFS definitions “mostly harmless”. Especially rdfs:subClassOf is fine. I find rdfs:domain and rdfs:range more problematic, but that’s not because of OWA per se, but because their semantics is not what most people expect. Richard On 4 Jul 2018, at 08:01, Bohms, H.M. (Michel) <[email protected]<mailto:[email protected]>> wrote: In case the purpose of modelling is really ‘data validation’ would it be better to go for SHACL-only (ie CWA-only) or still combine SHACL with RDFS? (like in http://spinrdf.org/shacl-and-owl.html). Would there be a downside of a SHACL-only approach. Like always having to specify properties in the context of a shape? In case of validation AND data sharing would it still work or would it be better to use ‘RDFS + SHACL’ where the SHACL is separately used at say 2 validation sides (importing the RDFS) and RDFS-only for the sharing spec? But then introducing some potential OWA/inference in the middle (that doesn’t HAVE to be utilized). Or is all THAT inference harmless wrt OWA/CWA discussion (ie inferencing rdfs superclass instantiation). Thx for your views here, Michel Dr. ir. H.M. 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