[Tdwg-tag] UML limitations for our uses?
Phillip C. Dibner
pcd at ecosystem.com
Mon Apr 17 21:34:47 CEST 2006
I forwarded Roger's message from a few weeks ago to Simon Cox, and am
taking the liberty of copying Simon's reply to the group. It appears
that the differences between UML and OWL may be surmountable in terms
of our requirements.
It is my impression that we've substantially embraced the notion of
an information model / architecture that can be expressed using
(appropriate subsets / profiles of) a variety of technologies.
However, we have not yet really addressed the question of which tools
to choose for a given application, or the nature of profiles that
will allow us to swap model definitions among different encodings.
Begin forwarded message:
> From: <Simon.Cox at csiro.au>
> Date: April 13, 2006 6:05:37 AM PDT
> To: <pcd at ecosystem.com>
> Subject: RE: [Tdwg-tag] UML limitations for our uses?
> That's interesting stuff.
> The idea of determining class membership on the basis of property
> values is not very different from the classic UML classifier - its
> just that UML encourages "strong-typing" - the class membership
> determines the set of properties that must be populated - while the
> inferred-class approach is more "weak-typed", or (as Roger points
> out) "multi-typed" depending on the ontology you choose to apply to
> the (set of) observations. (Look - observations appear again! -
> thats because the Observation viewpoint makes the property-type a
> primary property, while the type of the feature-of-interest is more
> In the web article I take issue with many of the points in the
> section headed "Differences between OWL properties and UML
> associations/attributes". For example:
> 1. UML associations always have direction. It can be "unpsecified",
> "source->target", "target->source" or "bi-directional"
> 2. binary relations are a subset of general associations. In many
> (most?) UML models only this subset is used.
> i.e. in both of these cases UML is actually richer, but can always
> be "profiled" to look like OWL.
> 3. I would phrase this more like "UML association and role names
> are contextual - the same word may be used in different places to
> mean different thing, but is scoped by its context so the complete
> designator is effectively the scoped-name" so they end up being
> unique anyway ...
> Roger's comment "If we want to assure that we can swap between two
> or more modeling languages then we can't use all the feature of any
> of them but have to come up with a subset" is important. This is
> also why in the UML-GML world we use a subset/profile of UML (no
> operations, mandatory rolenames, single inheritance) to yield a
> subset of XML (no XML attributes, no mixed-content, very sparing
> use of <choice>, some cardinality restrictions).
> Rather than imagine that one-solution-suits-all, we should rather
> focus on criteria on how to select which tool to use when.
On Apr 3, 2006, at 5:03 AM, Roger Hyam wrote:
> There is an interesting article here:
> That discusses the differences between OWL and UML.
> One of the features of OWL that I like is the notion of a necessary
> and sufficient properties but alas this is lacking in UML.
> Sufficient conditions allow you to determine if an instance is a
> member of a class when it in not explicitly stated. You can
> therefore receive and object and work out what it is according to
> an ontology of your choice - which seems pretty useful to me. It is
> a mechanism, I believed, could enable us to integrate a simple core
> ontology with more complex specialist ontologies that some network
> participants may choose to use. It is not available in UML but
> could be used to reason about a UML ontology expressed in OWL or RDFS.
> OWL doesn't do qualified cardinality restrictions as well as UML -
> but there are work rounds and proposals and I am not sure how
> important this is.
> There is also a good quote in the article on data modeling versus
> building ontologies:
> "A data model is a model of the information in some restricted well-
> delimited application domain, whereas an ontology is intended to
> provide a set of shared concepts for multiple users and
> applications. To put it simply: data models live in a relatively
> small closed world; ontologies are meant for an open, distributed
> world (hence their importance for the Web)."
> I think we are sometime confusing the two in our discussions.
> Bottom line is:
> You can't express everything in UML or OWL.
> If we want to assure that we can swap between two or more modeling
> languages then we can't use all the feature of any of them but have
> to come up with a subset.
> The answer never includes a single TLA. <- apart from this answer!
> My personal feeling is that anything that is defined centrally by
> TDWG should use the lowest common denominator of features anyhow.
> As usual I am grateful for you comments/thoughts.
> Roger Hyam
> Technical Architect
> Taxonomic Databases Working Group
> roger at tdwg.org
> +44 1578 722782
> Tdwg-tag mailing list
> Tdwg-tag at lists.tdwg.org
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