Re: Searching OO Associations with RDBMS Persistence Models

Dmitry A. Kazakov wrote:
On 28 May 2006 12:17:33 -0700, topmind wrote:

Dmitry A. Kazakov wrote:
On 27 May 2006 23:39:45 -0700, topmind wrote:

Dmitry A. Kazakov wrote:

Which is completely irrelevant to A and B. Those are *requirements*. As for
design, no, you won't get that contract, just because of B, which reads:
"quality of service gradually influences the value of." If the system isn't
24-hours available you won't get a penny for it.

Centralization and reliability are not necessarily at odds. One can
have mirrored drives, realtime DB replication, etc.

Bingo! How are you going to replicate something without distribution? What
is the meaning of "replication"?

Perhaps we need to make a distinction here between distributed backups
and "live" distributed.

LOL! Whatever it might be, it is *distributed*.

In a loose sense. But most contexts appear to mean that there are
multiple active processes running in multiple locations doing "live"
work.

You don't need any expertise, that's the point. If RM's decomposition
worked, you would just show how the problem relied on communication could
be decomposed and leave implementation to others. In other words, you would
identify "communication" component of the problem and describe it in the
solution space. This works with ADTs, it does not in your RM. Each time you
refer to predefined types, operations, stored procedures etc, it is an
*ADT* decomposition!

Please clarify. I am not sure what you are getting at here.

Take the distribution example. RM decomposition is based on tables. So let
"live process" be table 1, other processes be table 2,

It is bad form to make a different table for each "sub-type" of
something. A lot of OO fanatics try to do such of late and it makes a
mess.

communication, hmm,
is table 3. Care to continue? (:-))

You mean like pipes?

Well, the default is not your position either. I don't see anywhere
where relational *must* be connected to types. Other than requiring at
least one "adaptor" to deliver boolean answers, relational does not
have to care what is in the "cells" of the tables. It mostly just
passes them along as-is or via the "domain math" operating on a real or
virtual row.

That's generic programming. A generic container does not care about the
types of its elements. This does not mean that the container itself can be
untyped. You have to specify which objects can be passed as-is. That
constitutes a type. Is a table of that type? In your RM it is obviously
not. So you have at least two types. q.e.d.

Perhaps. I agree that at the "root" level that a base set of
fundimental types may indeed be needed. However, to automatically
extrapolate this to "types everywhere" is bad reasoning.

It is not. It is the only one possible reasoning.

Wow. Bold claim there. One-size-fits-all, eh? I don't dispute that one
*can* model everything as types, just like everything can be written in
assembler. But I do question the practicality of it.

You can argue that in
your application domain of cooking, concentrated solely on can opening,
there is only one type of food (as found in cans). Though I doubt that.

If you can model food cleanly as "types" be my guest....

Just make sure you don't repeat the mistakes learned in centuries of
taxonomy/classification philosophy.

You asked for a trivial demonstration. Then whatever I would take, you
could always answer that it is either non-trivial, non-biz or has no
practical use. Write an XML parser, invert matrix, make histogram of an
image, search kd-tree...

University lab toys are often not good tests for real-world utility.
It is not too much to ask for practical utility of something. And, I am
not familiar enough with systems software to make recommendations about
what is useful and what isn't. Thus, I am not sure what you are
complaining about.

I am not complaining, I am trying explain why your arguments will never be
seriously considered by anybody.

And yours will?

One cannot argument outside any logical
system. Reasoning is a part of logic. "Show me a practical example where
the Earth isn't flat", that wouldn't impress anybody to give you a contract
for mining cheese on the Moon. Even if you said that you'd use balloons,
because rockets are so dangerously impractical...

I am missing your point. I can evaluate use cases from the domain of
custom biz software, but not other domains well. That is all I am
saying. If that means you don't wish to communicate further with me,
then so be it.


As far as the Librarian Paradox, that seems like a problem with
conflicting/bad requirements. If your boss or users asks for something
contradictory, then you ask for clarification or a decision about which
of multiple paths to take.

And how do you know if a requirement contradictory?

Generally that is the job of the analyst. If the analyst does not catch
it, then sometimes it shows up in bad reports, etc. It would be nice if
we could plug all the biz rules into math-like logic and simply always
get the right answers, but it does not always work that way. For one
thing, many of the rules appear to be capricous and arbitrary. For
example, the tax law is filled with all kinds of goofy, paper-wasting
rules and exceptions because of all the political wrangling that goes
into the final tax laws.

Perhaps more formal approaches work better when working with natural
rules such as physics, chemistry, etc.

If the tax law writers were all mathemeticians, then perhaps it would
also work well.


--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

-T-

.

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