Re: WWW/Internet 2009: 2nd CFP until 21 September


"paul c" <toledobythesea@xxxxxxxx> wrote in message
news:ooZfm.38508$Db2.36932@xxxxxxxxxxx
Walter Mitty wrote:
"paul c" <toledobythesea@xxxxxxxx> wrote in message
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Walter Mitty wrote:
...
The relational view of data as regards data in transit over a network
extends the scope of discussion of the relational model beyond the
scope contemplated in 1970. The discussion in 1970 and for many years
afterwards focussed on the application of the relational model to the
organization of data banks for large scale sharing of data. Large
scale sharing of data is increasingly being carried out by shipping
data over the network from one system to another. Any databases
involved are in the background.
...
In the 1960's, let alone the 1970's, "large scale sharing of data" by
people was already a given requirement, no matter whether the vehicle
was hierarchies or graph designs. The more urgent problem, recognized
even by the Codasyl people, was sharing of data by applications..

First, I've always taken the word "user" in the 1970 paper to apply to an
application program, or to a fairly transparent command and print
utility, or to a human using the database as mediated by either an
application of a utility program. My reading might not have been careful
enough.

Second, as to whether sharing was a given requirement or not, I'd have
to say that it depended on who you talked to. A large part of my career
from 1985 through 1999 consisted not only in enabling people to share
data, but in convincing people of the merits of doing so. In almost
every client company there was a large faction that stood to lose, or
thought so, if data sharing prevailed. Even today, I'd say that over
half of the databases being built in SQL server are planned for use only
by a single application inside which the database is to be embedded. ...


No doubt, but I think Codd was emphasizing that even an individual
application becomes more clear to the user, or observer if you prefer, if
it uses his few simple universal manipulators.


You maight be right. Or you and I might each be over analyzing the 1970
paper. What's clear to me is there has been a steady stream of object
oriented programmers who have come into c.d.t. over the last five years,
and ask why we think the relational model has merit when, to them, it looks
like a return to procedural programming of the 1970s.

In almost every one of those conversations, the OO person has stated or
intimated that he's the only one who will have to understand his own code,
and or the data structure of the data stored in the database. In some
cases, I may be reading too much between the lines. In other cases, they've
made it crystal clear that this is what they think.

Now it's a fact that people are born naive. If you look up the origin of
the word "naive", it's almost by definition. It seems to be the case that
most people are still quite naive when they enter the workforce, regardless
of their level of education. What's shocking to me is the number of people
with ten or more years of professional experience under their belt who
remain almost completely naive.



I think he would have said that political territory and not-invented-here
attiitudes don't change that advantage.


This reminds me of the years I used to teach database courses. Sooner or
later, a little over halfway through the course, students would begin asking
why there was so much politics around the databases back at their work site.
I learned to answer them thus:

Knowledge is power. So said Francis Bacon.
Data is like knowledge in this regard.
When a database is successful, data gets shared.
When data gets shared, power gets shared.
When power gets shared, that's politics!


Any use of the data by other
applications, or even by general purpose report generators or OLAP
environments is to be done through the app's API.

The fact that such a view is monstrously naive doesn't prevent it from
being the majority view. Add to that the marketing plan that says that
the client has no choice but to return to us for access to their own
data, and you have the road to hell, well paved.

Speaking of apps being 'users', I remember an airline that invented an api
with fourteen verbs so that the flight control system could notify cargo
process control at various destinations. Nobody thought to include a verb
that would handle the re-routing of a plane after it had taken off, eg.,
because of bad weather at the destination. The funny thing was that only
four smallish tables were involved and they were more or less duplicated
at each end of a flight. It would have been simpler to send every insert,
delete or update of those tables to the destination computers, echo the
tables at both ends and let each applicatiion decide whether it should
ignore or reflect the message, eg., four tables and three message types.
Supplier said that couldn't be done!

I'm reminded of another thing fro my teaching days. I had an example I
would use from a hypothetical airline reservation system where the
transaction control didn't have ACID.
I would then show how it was impossible for such a system to prevent
overbooking. At the end of the example, I would always tell students that
lack of transaction control wasn't really the reason reservation systems
overbooked.

Then, one time, I had a student who had worked on the original SAABRE, or
one like it. He corrected me. He said they had spent months trying to
figure out how to detect overbooking, until finally the marketing people had
decided that overbooking was a feature, and not a bug! They had not used
relational, or even CODASYL databases in their work. And they had rolled
their own transaction control.



.

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