[Tdwg-tag] Primary Objects as XML Structures or OWL Classes

Roger Hyam roger at tdwg.org
Mon Feb 20 14:10:28 CET 2006

Hi Bob,

> I'm rushing off to the GISIN meeting at AGADIR and might not have much 
> time to respond more before midweek, or maybe even until I get back 
> next week, but:
> 0.  I _wish_ this discussion were taking place in a wiki, with RSS or 
> email notification,  so it is easier to follow if you cannot keep up 
> with the email
The way I was planning on running the TAG discussions was to have 
'discussions' on the mailing list and summarize them to the wiki. The 
motivation behind this is to work towards the wiki being a readable 
document for the uninitiated. It should not be necessary for some one 
coming new to a field to have to read all the discussions that have 
taken place to reach a conclusion. These discussions should be available 
but it is the job of an editor/facilitator to create a readable 
narrative from possibly wandering dialog.

The wiki is here: http://www.tdwg.hyam.net/twiki/bin/view/TAG

The URL will change at some point in the next few months but I will make 
sure all URLs forward to the appropriate place on the new server. There 
is no RSS feed on it at present I'll see about setting one up either now 
or when we move it to the main server.

The mailing list archive is here: 
http://lists.tdwg.org/pipermail/tdwg-tag_lists.tdwg.org/ so any thread 
can be followed and resurrected at any time.

I take on board what you are saying though and will try and create links 
between the wiki and list archive.
> 1.  I don't think specifications of high level things like "objects" 
> should be done in a serlization constraint languge such as RDF or XML 
> Schema. Instead, it should have something more general as the 
> normative definition and have _representation_ in one or more of such 
> constraint languages. This is the mechanism of W3C usually. Many 
> (Most?) W3C standards have a normative BNF definition, and one or more 
> representations to allow implementers to actually do business.  OMG 
> favors UML for this, etc.There is nothing inherently normative about, 
> say RDF or XML Schema, for, say TaxonConcepts. If you take the 
> serialization language as the normative language, then in the future 
> you just end up having to support several serialization languages when 
> you find you want to extend your specification with something for 
> which the chosen one is insufficiently expressive. This, in fact, is 
> what is going on now with the cries for RDF over XML Schema. Put 
> another way, if you choose language L as the normative language, you 
> are not building a specification, but rather a set of constraints on 
> applications written in L. Such things do not have as long a life as 
> actual specifications do and mature standards bodies do not seem to 
> use serialization languages as the root specification language, as far 
> as I can tell.  My conclusion is that specifications should not be in 
> anything like RDF or XML Schema, but in something else---BNF is 
> probably adequate for most TDWG standards---with working subgroups 
> responsible for publishing a serialization definition implementing the 
> standard in languages useful for one or another purpose, e.g. LSID 
> resolution.
Yes I think you are right. We should be specifying our objects in a high 
level 'language' like UML (not so sure about BNF but I am not so 
familiar with it) . There has been talk about OWL Lite as a subset of 
UML. This was actually the next topic I was going to suggest and I'll 
kick of  a thread on it soon if no one else does.

Can I take it from your reply that you think:

   1. There should be commonality between all TDWG 'objects' and that
      that commonality should be their specification in UML/BNF/Other
      technology? (Yes to my question 1).
   2. Their should be alternative ways to serialize these objects. Some
      of the serialization may support different aspects of the objects
      (Yes to my question 2).
   3. XML Schema or RDF/S are not appropriate ways to define such objects

Have I read this correctly?


> Bob
> On 2/17/06, *Roger Hyam* <roger at tdwg.org <mailto:roger at tdwg.org>> wrote:
>     Hi All,
>     In a previous post I suggested definitions for Resolving,
>     Searching and Querying from the point of view of the TAG. There
>     has been a muted response which I take as meaning there aren't any
>     strong objections to these definitions. We can come back to them
>     later if need be. You can read the post here if you missed it:
>     http://lists.tdwg.org/pipermail/tdwg-tag_lists.tdwg.org/2006-February/000009.html
>     <http://lists.tdwg.org/pipermail/tdwg-tag_lists.tdwg.org/2006-February/000009.html>
>     I'd like to look at the implications of the first two definitions:
>        1. *Resolving.* This means to convert a pointer into a data object. 
>           Examples would be to resolve an LSID and get back either data or
>           metadata or resolve a url and get back a web page in html.
>        2. *Searching.* This means to select a set of objects (or their
>           proxies) on the basis of the values of their properties. The
>           objects are  predefined (implicitly part of the call) and we are
>           simply looking for them. An example would be finding pages on Google.
>     Both these definitions imply the existence of data 'Objects' or
>     'Structures' that are understood by the clients when they are
>     received. The kinds of objects that jump to mind are Specimens,
>     TaxonNames, TaxonConcepts, NaturalCollections, Collectors,
>     Publications, People,  Expeditions etc etc. A piece of client
>     software should be able to know what to do with an object when it
>     gets - how to display it to the user or map it to a db etc.
>     My two leading questions are:
>        1. *Should there be commonality to all the objects?* If yes -
>           what should it be? XML Schema location or OWL Class or
>           something else? If no - then how should clients handle new
>           objects dynamically - or shouldn't they be doing that kind
>           of thing.
>        2. *Should we have multiple ways of representing the SAME
>           objects?* e.g. Should there be only one way to encode a
>           Specimen or should it be possible to have several encodings
>           running in parallel. If there is only one way how do we
>           handle upgrades (where we have to run two types of encoding
>           together during the roll out of the new one) AND how do we
>           reach consensus on the 'perfect' way of encoding each and
>           every object in our domain?
>     The answers I have for my leading questions are:
>        1. Yes - We should have some commonality between objects or it
>           will be really difficult to write client code - but what
>           that commonality is has to be decided.
>        2. Yes - The architecture has to handle multiple versions/ways
>           of encoding any particular object type because any one
>           version is not likely to be ideal for everyone forever.
>     Are the two conclusions I come to here reasonable? Is this too
>     high level and not making any sense?
>     I'd be grateful for your thoughts on this,
>     Roger
>     -- 
>     -------------------------------------
>      Roger Hyam
>      Technical Architect
>      Taxonomic Databases Working Group
>     -------------------------------------
>     http://www.tdwg.org
>      roger at tdwg.org <mailto:roger at tdwg.org>
>      +44 1578 722782
>     -------------------------------------
>     _______________________________________________
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>     Tdwg-tag at lists.tdwg.org <mailto:Tdwg-tag at lists.tdwg.org>
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 Roger Hyam
 Technical Architect
 Taxonomic Databases Working Group
 roger at tdwg.org
 +44 1578 722782

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