Re: Transformation of object modells to relational structures

From: Jack L. Swayze Sr. <keystrk_at_feist.com>
Date: 1996/06/06
Message-ID: <4p5bcp$bhj_at_wormer.fn.net>#1/1


answers_at_ix.netcom.com(Steve Long) wrote:

>Or is it that you do not understand ERDs?

Umm, well. I have been earning my income as a Data Moder (or Data Analyst, or Data Administrator) for almost 11 years now. I was ERD data modling before CASE tools were even heard of (which was before I was being paid for it). I have been exposed to at least 10 different ERD modeling representations (some of which, I must admit, I now forget). And (if the above isn't enough) I participated in the USAF contract that extedned the IDEF-1 modeling paradigm into IDEF-1X (which is what ERWin uses as its default diagrammatic technique).

>Can you substantiate your statement? Provide an object model that is
>not equivalent to an ERD with an extention of adding methods as a
>counter example and your statement will have more merit than mere
>opinion.

Sure, the one that made me realize the difference was the Fusion modeling paradigm (as created by the firm: Object Space). I even had one of the representitives of that firm tell me to my face that representing data requirements based on existence is diametrically opposed to the Object modeling approach which represents data requirements based on common (or different) 'responsibilities' (meaning functional responsibility).

In other words: if you can imagine someone totally ignoring the data requirements, designing their system to be Highly modular, then determining that the best data structures is to have one and only one data structure for each and every process module, then 'encapsulating' that data structure so that the only way to get to the data structure is through that module you have designed - that is what the Smalltalk-like OO model is similar (but not identical) to.

>Steve
>804-262-6332

you didn't really want me to call you, did you? (if so, can I reverse the charges?)
>--------------------


'Keystroke'
KeystrkTX_at_AOL.COM Received on Thu Jun 06 1996 - 00:00:00 CEST

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