Dave, William, and Ed, (01)
JFS
>> E-R diagrams were introduced in 1976. Even earlier, there were
>> Bachman diagrams, type hierarchies, and Petri nets. Versions
>> of all those diagrams were combined in UML, (02)
DCH
> No. UML was developed specifically to support object-oriented program
> design, and had only minimal relationship to the earlier E/R notations. (03)
I agree that the "Three Amigos" who joined forces to develop UML
and its diagrams had a specific kind of methodology intended
for a specific style of programming. (04)
WF
> First of all, object-oriented program design was developed specifically
> to support creating programs that ***were*** models of the world, just
> as E/R models were intended to do. And, just as o-o was subverted into
> models of software for software's sake by most but not all, so too,
> whatever the originators said, E/R was USED by developers as a way
> to diagram relational databases, not to model the world, except by
> a few wierdos, (yours truly included.) And, those same wierdos used
> UML in the same way, the first day it was delivered. (05)
Yes. I think of UML diagrams as a kind of graphic notation for various
subsets of logic with various built-in ontologies associated with each
diagram type. (06)
DCH
> There are no constraints as to what constitutes a "class". It might
> be a class of things in the world ("person", "project", etc.), or
> a class of things to be manipulated by the computer... (07)
WF
> Good, from this it follows that one is free to put whatever constraints
> one wants on what is going to constitute a class. That's the way I like it.
> Let our languages be under-specified, so we can use them as need be. (08)
I agree. Adding axioms makes it possible to do more detailed reasoning.
But it also creates the danger of inconsistency. I like the slogan
for dealing with leftovers in the refrigerator: (09)
"When in doubt, throw it out." (010)
DCH
> ... in my latest patterns book, Enterprise Model Patterns: Describing
> the World, I decided to use UML instead of my favorite notation.
> By addressing the premises I just mentioned, it turns out I could use
> a modified form of the UML class notation to create semantic models. (011)
That approach is consistent with William's suggestion: throw out the
unwanted or unneeded details associated with the UML methodology.
Then you get an underspecified version you can tailor to your needs. (012)
EB
> David has been arguing for 15 years that UML cannot be used to do E-R
> modeling, while many of us, including Jim Rumbaugh, Jim Odell, and
> apparently William Frank, not to mention Ed Barkmeyer, have been doing
> just that for all or most of that same time period. Admittedly, we had
> to ignore what UML v1.4 said some of the constructs meant, but that has
> not been true since the advent of UML v2... (013)
Each of the UML diagram types combines a special-purpose subset of
logic with some built-in ontology. When they're applied to a new domain,
some adjustment may be necessary. But a lot of people are using UML
diagrams for ontology. Just type "UML ontology" to Google. (014)
John (015)
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