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Re: [ontolog-forum] Ontology-based database integration

To: edbark@xxxxxxxx, "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Mike Bergman <mike@xxxxxxxxxxxxx>
Date: Tue, 06 Oct 2009 17:22:31 -0500
Message-id: <4ACBC327.9080108@xxxxxxxxxxxxx>
Hi Ed,    (01)

Really excellent post and thank you tremendously for the early 
references.  I will be a sponge if you care to provide more 
specifics. ;)    (02)

Mike    (03)

Ed Barkmeyer wrote:
> Len Yabloko wrote:
>> As I said - OntoBase is designed to simplify data integration and database 
>application development by taking advantage of ontology-based semantic 
>modeling. Part of the method used in OntoBase is semi-automatic generation of 
>ontology guided by the user, who *is* the main source of semantics. Database 
>metadata is used to ensure consistency of the end result and , at the same 
>time, to provide automatic translation of the application activity into 
>database transactions. None of these goals was ever set or accomplished by the 
>above mentioned Semantic Web initiatives. 
> They were, however, the objective of several "semantic database 
> integration" and "semantics-based federation of distributed databases" 
> projects of the 1980s.  As I remember, there was an entire issue of the 
> ACM Journal devoted to such projects, long about 1988.  Of course, the 
> integrating ontology wasn't called an "ontology" in that time; it was 
> called a "semantic data model", with such languages as SDM and OSAM*.  
> (Sudha Ram of U. Arizona published a compendium of "semantic data 
> modeling concepts" in 1990, with a bibliography of the tower of Babel of 
> that time.  I rather shamelessly plagiarized her concepts list for my 
> presentation of "OWL as a Data Modeling Language".)  NIST built similar 
> tooling back then, and we later used a commercial tool called ORION that 
> was a spinoff of some DARPA project (brainchild of Amit Sheth and some 
> other famous names).  (More lore from the ancient world before PDF, but 
> not nearly so interesting as the Dead Sea Scrolls.)
> The major difference in using OWL as the language for the integrating 
> model is that it is a standard language that is well-defined and comes 
> with a variety of supporting tools for validating the ontology itself.  
> In addition, it offers the possibility of extension to additional 
> information bases by linking to additional ontologies, assuming that the 
> "integrating ontology" is one, and is not just the OWL version of a 
> purpose-built SDM model.  (And it is easy to make tools with much nicer 
> GUIs now.)  Unfortunately, many/most databases are treated as having 
> inherent "closed world" semantics, which may make it difficult to get a 
> "semantic web language" to support some important semantics of the 
> databases.
> Ian's point is well-taken:
>>> I spent years mapping legacy data into "semantically richer" formats ...,   
>and it always comes down
>>> to the data, not the data model. You can guarantee the data modeller got it
>>> wrong when they built the system, and the users have been working against
>>> rather than with the model for years. Unless you have a good sniff around in
>>> the data, you'll never get a real picture of the true semantics (i.e. what
>>> the data is actually referring to in the real world). ...
> The data modeler needn't have got it wrong, initially.  The problem is 
> that the databases are, for various reasons, rigid, and are not easily 
> evolved when the business practices or business environments change.  
> So, over time, the schema becomes gradually more and more out of sync 
> with the reality of the business, and some bits no longer have any 
> vestige of their original intent. (I am reminded of the executive who 
> told me: "I know that is what the DB document says, but what my staff 
> puts in that field is X, and we are the only ones who still use that 
> field."  Unfortunately, he was wrong about the last.)
> Len wrote:
>> The project I do for DoD calls this process Semantic Model Discovery. 
>Actually, there are many models some times used in turns, and they all are 
> Yes.  That agrees with my experience.  In a big enough organization, 
> there is more than one (mis-)use of certain DB elements, and over time 
> some will no longer be used and others will appear.  But the schema will 
> live on.
>> They main goal of data integration should be maintaining consistent mapping 
>between different semantic models. The main challenge is to define what 
>"consistent" means. 
> Uh, yeah.  The statement of the task strikes me as an oxymoron.  I would 
> have thought that your OntoBase was about linking multiple data 
> organizations and representations to a common semantics, rather than the 
> other way around.  Perhaps I misunderstand...
>> This where Chris Partridge's work first opened my eyes on true mature of 
>semantics, as opposed to mathematical notion of 1st order logic some times 
>confused with semantics (I know this statement will provoke discussion)
> I have seen a lot of things confused with "semantics", because the 
> interpretation of "semantics" is usually "what this means for _my_ level 
> of abstraction, purpose, and domain of interest", and it often makes the 
> assumption that "my" is synonymous with "our common" or "everyone's".  
> But anyone who confuses formal logic with semantics understands neither. 
> Formal logic is a means of expression, in which the basic elements of 
> the language have well-defined meanings and a set of well-defined 
> manipulations retain those meanings, and nothing more.  As to whether 
> the snark actually is a boojum, classical formal logic offers only two 
> possible interpretations:  it is either true or it is false, and it 
> cannot be both.  And if you make a set of statements that allow the 
> well-defined manipulations to produce a result of "true", then it does.  
> That's all there is; there ain't no more.  Formal logic is about "how to 
> think"; it is not about what you think about.
> -Ed
> P.S. Ian:
>>> I never had a formal method for re-engineering data in those days. In recent
>>> years I've been using Chris Partridge's BORO Method. It seems to work pretty
>>> well as far as I can tell. Don't tell him I said that though.
> Since Chris is a frequent contributor to this exploder, your secret is 
> out...
>     (04)

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