Re: SV: SV: FW: [plcs-dex] Unique constraints -> identification and versioning

[David Price <david.price@eurostep.com>]

As I've said in my emails, I don't think this approach works. It's based on a 
misunderstanding of how OWL and the ontologies making up the reference data 
need to work together.

Cheers,
David

On Tuesday 19 December 2006 18:23, Peter Bergström wrote:
> For some reason, I'm unable to post to the list...
>
>
>
> Dave, consider the following:
>
>
>
> I have a part. The ID assignment (@2 below) is classified as 'Peters_id'
> and found in 'urn:plcs:rdl:mycompany:peter'. That RDL has in the owl file a
> reference to 'urn:plcs:rdl:std', and 'peters_id' is defined as a subclass
> of 'Part_number', which is defined in 'urn:plcs:rdl:std'.
>
>
>
> I also have a class assigned (@21) to the Part, 'Engine', located in
> 'urn:plcs:rdl:std'.
>
>
>
> Do you have any problem if I do the following:
>
>
>
>
>
>
>
> I have here references to two RDLs (of which one specializes the other).
> Remember, all RDLs that are used together with PLCS are required to use the
> OWL-representation of AP239 entities. When the RDL in OASIS has become
> stable and agreed upon, there will be one OWL file that all other RDLs must
> specialize from (called in the examples urn:plcs:rdl:std).
>
>
>
> This is how all examples in DEXlib are built up to illustrate how to use
> reference data, in all templates. If you are not OK with this, then we need
> to sort out quickly what the problem is and how to solve it...
>
>
>
> Peter
>
>
>
>
>
>
>
> -----Original Message-----
> From: David Price [mailto:david.price@eurostep.com]
> Sent: den 19 december 2006 17:30
> To: plcs-dex@lists.oasis-open.org
> Subject: Re: SV: SV: FW: [plcs-dex] Unique constraints -> identification
> and versioning
>
>
>
> Hi Mats, See below for two replies. Cheers, David
>
> On Tuesday 19 December 2006 09:38, mats.nilsson@fmv.se wrote:
> > Hi David,
> >
> >
> >
> > This is one of your examples of a "class.id URI";
> >
> > >> urn:iso:std:iso:ts:10303:-1017:ed-1:tech-taxonomy:Part
> >
> > If I understand you correctly, you suggests to include both the URI for
> > the
> >
> > RDL ("urn:iso:std:iso:ts:10303:-1017:ed-1:tech-taxonomy") as well as the
> >
> > class identifier ("Part") in the 'external_class.id' (the 'id' attribute
> > in
> >
> > the 'external_class' entity).
> >
> >
> >
> > I thought (see the last of my three slides) 'external_class_library.id'
> > was
> >
> > going to be used for the URI of the RDL, and that the identifier within
> > the
> >
> > RDL (i.e. 'external_class.id') only should contain the actual
> >
> > "classification" or "term" identifier, in your example "Part".
>
> I don't think that works because of the other issues I mentioned (i.e.
> there
>
> are multiple ontologies involved and one ontology has to be identified as
> the
>
> context ontology). The context ontology is the most organization-specific
>
> ontology that uses the more general and standard ontologies.
>
> External_class_library is really the only entity type in PLCS that makes
>
> sense for that requirement and so I think there should be one instance of
> it
>
> that all the External_class entity instances point to (actually I don't
> think
>
> it's a big problem if there are multiple instances of
> External_class_library
>
> as long as they all refer to the same URI. So, if you've followed and
> agreed
>
> with the logic of requiring a context ontology then I think it's clear that
>
> the External_class.id needs to be the full URI.
>
>
>
> For what it's worth, I think people have been assuming that
> "urn:oasis:plcs"
>
> was "the reference data library", when in fact in real-world usage that is
>
> unlikely to be the case. The RDL that is the context for an exchange is
>
> actually the ontology developed by the using organization with its
> extensions
>
> to the PLCS standard classes which is imported in read-only mode. Because
> of
>
> the flexibility enabled by the use of the OWL language, it's important to
>
> have that context ontology named in the exchange file. If you look at some
> of
>
> the OWL APIs you'll see that they often force you to supply an ontology
> when
>
> you'd think only a class is required as input. That's because the same
> class
>
> can have different subclasses *and* superclasses (not to mention
> properties)
>
> depending on how it is extended in using ontologies.
>
> > Please help me understand if I've got things wrong! If someone else has
> > an
> >
> > opinion, please help David help me...
> >
> >
> >
> >
> >
> > Now over to your question David. In my not so organized world (I call it
> >
> > FMV...) people use more than one term for the same concept
> > (concept=class).
> >
> > OWL has the 'rdfs:label' element, which makes it possible to assign more
> >
> > than one term for each class. This is useful for me because the guys who
> >
> > drive helocopters and those who drive boats often have different
> >
> > terminology, and I can use this functionality to make them understand
> > each
> >
> > other and the data they send. There is also this need to be
> > "interoperable"
> >
> > within e.g. the EU Battle Groups or NATO joint operations, and then we
> >
> > swedes meet people that uses the word "lubricate" for what we call
> >
> > "smörja"...
> >
> >
> >
> > To accompish this I'd like to use a "meaningless" identifier for the
> >
> > 'external_class.id' field, e.g. "rd000453" (or with versioning
> >
> > "rd000453v1"), and then use the 'external_class.name' field for the
> >
> > readable classification (i.e. one of the available 'rdfs:label's in the
> >
> > RDL/OWL-file).
> >
> >
> >
> > This was what I meant by the question;
> >
> > >> David: How do you suggest the label used for
> > >>
> > >> classification should be identified in case there are multiple labels
> > >>
> > >> for the same class/RD?
> >
> > If I have both "lubricate" and "smörja" in the same class (that is a
> >
> > subclass of 'activity'/'task') with some unique id, I need to specify
> > which
> >
> > one is used.
> >
> >
> >
> > Clearer? Or don't you see this scenario with synonyms and multiple
> >
> > languages (used for the same class/concept)?
>
> I understand the question now. From what I've seen on the Semantic Web, the
>
> best practice is to use a (somewhat) human-interpretable name for the
>
> identifiers of classes in an ontology (within the limitations of what you
> can
>
> use in a URL or URI).  I agree that the use of rdfs:label is the proper way
>
> to specify the "name" of the class for use in browsers and GUI
> applications.
>
> However, I don't see any advantage in not following the Semantic Web
>
> practices. I've never really understood why anyone would want classes with
>
> ids like rd0049404 when they can have SerialNumber. The only rationale I've
>
> heard that made any sense to me was related to handling the uniqueness of
> ids
>
> but since we're engineering the reference data I don't think the cost in
>
> human understandability is outweighed by the small benefit of slightly
> easier
>
> uniqueness. That said, I also think that the PLCS RD should be broken up
> into
>
> sub-ontologies on a domain-by-domain basis for manageability, subsetting
> and
>
> to help with the overloading of terms.
>
>
>
> All that said, I'm not sure that the External_class.name is really useful
> for
>
> transfering rdfs:label values. I'm not sure of the business need for that
> for
>
> a start. If the External_class.id is the full URI then that's sufficient
> for
>
> an application to process. If for some reason the rdfs:label is needed then
> I
>
> think name_assignment is the only way to handle the fact that a class may
>
> have multiple rdfs:label values for different languages. However, it seems
> to
>
> me it's better to keep all the labels in the ontology itself rather than
>
> duplicating them in the exchange file.
>
> > Regards,
> >
> >   Mats
> >
> >
> >
> >
> >
> >
> >
> > -----Ursprungligt meddelande-----
> >
> > Från: David Price [mailto:david.price@eurostep.com]
> >
> > Skickat: den 18 december 2006 18:05
> >
> > Till: plcs-dex@lists.oasis-open.org
> >
> > Ämne: Re: SV: FW: [plcs-dex] Unique constraints -> identification and
> >
> > versioning
> >
> >
> >
> > Hi Mats, a few replies follow (although I'm confused by one question.
> >
> > On Monday 18 December 2006 07:51, mats.nilsson@fmv.se wrote:
> > > Questions below...
> > >
> > > Happy for opinions!
> > >
> > >
> > >
> > > Regards,
> > >
> > >   Mats
> > >
> > > >> David: Could you please give an example of what an (external)
> > > >> class.id
> > > >>
> > > >> URI could look like?
> >
> > It would be a URN or a URL depending on what organization defines it the
> >
> > class and the approach they happen to have adopted. It would be the
> > compete
> >
> > URI for the class though it's technically only the identifier and so may
> >
> > not be sufficient for location (e.g. if it's a URN then some other means
> >
> > would have to be established for an application/user to find more info
> >
> > about the class ... for example, an organization might have to buy an ISO
> >
> > standard). Examples could be:
> >
> >
> >
> > urn:iso:std:iso:ts:10303:-1017:ed-1:tech-taxonomy:Part
> >
> >
> >
> > http://schema.omg.org/spec/UML/2.1/ParameterDirectionKind
> >
> >
> >
> > http://www.madeupdod.mil/ActivityOntology#Training
> >
> > > >> David: How do you suggest the label used for
> > > >>
> > > >> classification should be identified in case there are multiple
> > > >> labels
> > > >>
> > > >> for the same class/RD?
> >
> > I don't understand what "the label used for classification" means. Can
> > you
> >
> > rephrase the question or explain that phrase?
> >
> >
> >
> > Cheers,
> >
> > David

-- 
Mobile +44 7788 561308
UK +44 2072217307
Skype +1 336 283 0606