On Oct 4, Tom Cook quoth:
> [EMAIL PROTECTED] writes:
> > On Oct 3, Tom Cook quoth:
> [snip]
> > If you only have one database installation which contains all your data
> > and everything you are running is in one box in one location in one hard
> > drive without the need to operate in a degraded state or have graceful
> > failover then, yes, then you are correct, there is no need for a
> > distributed unique id generation system.
> >
> > In fact, it would be silly in such circumstances to try and reduce the
> > amount of interdependence between your database vendor's proprietary
> > implementation of key generation and your portable, write once, run
> > anyhere, database-issues-are-the-containers-problem Enterprise Java Beans.
> >
> > I don't know what I was thinking. I stand corrected.
>
> Sheesh, calm down already.
My apologies, but you quoted one paragraph of my response and ignored the
part half a screen down which read "Reduce system interdependency, don't
add." Specifically, and contrary to this you responded with a proposition
that for no other reason than because your beans depend upon the database
for storage, it is acceptable for your application to depend upon the
database for another completely unrelated feature. I found this to be so
full of assumptions I felt it necessary to point out just how many of
these assumptions would have to be true in order for this to be the case.
> It just seems to me (and I am no expert in the field) that it makes
> sense to have your database tightly linked to the key generator for
> that database.
Your assertion here (and correct me if this isn't what the above sentence
says), databases & their key generators should be tightly linked. I'm
interpreting this to mean "makes sense to have your [EJBs] tightly linked
to the key generator for [the] database [they are stored in]".
> While EJBs are a nice abstraction, what you have
> underneath is still a database,
Without addressing the notion of "nice abstraction" I agree that there is
in fact a database behind EJBs.
> and it seems sensible for the database
> to be responsible for the consistency of the data in it.
Fact. (Consistency is one of the ACID requirements)
> Of course
> having one database generate keys for another is not sensible since,
> as you point out, if your key generator goes down then your other
> databases are stuffed.
Agreed, however your Container is the transaction engine and therefore
ultimately responsible for the behavior of both. Recall that your
proposal was for the database to be the key generator for the container
which the beans would call upon for new keys.
> You may well argue that we want to be able to move this to any
> database backend;
Corrollary: flexibility to deal with unforseen future requirements is a
good thing. Agreed 100% and I would argue that except in the most trivial
of applications this is essential.
> in my experience of deploying
> enterprise applications (which is a bit more extensive than my
> experience of designing them), the deployment architecture is well and
> truly fixed early on.
Generally true but if they weren't liable and even likely to move, then
why would things like SQL92, jdbc, IIOP and J2EE exist?
> Enterprise applications are not the sort of thing you want to be able
> to install on everyone's desktop;
(Very) generally agreed, but that has little or nothing to do with your
assertion.
> that's the point of it being an enterprise application.
Disgree. The "point" of being an enterprise application is that it
supports a core aspect of a company's business process. Not where it is
installed or how it runs.
> It's very likely that it will be deployed to one place on earth, and
> not moved.
STRONGLY disagree. Most especially, in this age of fast moving companies
with product development being concurrent with product implementation,
and mergers happening left and right, it is more than likely that an
enterprise application, once deployed is A) going to be modified, and B)
going to change it's operating environment. If this weren't true then the
need for things like J2EE wouldn't be there and everyone could just write
their application in JCL and COBOL happy knowing that "it will be deployed
to one place on earth, and not moved."
Regardless, even if it were true that an enterprise application would "be
depoyed ... and not moved", what if your application is a product to be
sold to others, would they not have a say in which database system is used
in the deployment environment? It is for these reasons the "[EJB]
architecture defines six distinct roles in the application development and
deployment life cycle." [EJB1.1, s.3.1]
> Just my two bits worth...
As you can see, we agree on nearly many things but not a thing that you
said has anytyhing to do with your assertion that databases & their key
generators should be tightly linked.
You have said, in a public forum for *EJB development*, that it is an
acceptable (if not desirable) practice to have your beans use the
underlying database to generate primary keys. I argue that is contrary to
the spirit and intent of Enterprise Java. All I ask is that you either
support that statement with an argument addressing it, or retract it as
nothing more than an usupported opinion.
Some people see this forum as a source of useful and relevant information.
I find your advice to be not only wrong but Bad Advice liable to lead the
unwary into building unecessarily complex or deficient applications. While
I don't consider you to be anything other than a consummate professional,
you have touched a sore spot of mine by advocating that a Bad Idea be used
simply because it's there and without looking at what it's implications
are. Someone who uses database key sources and EJB at the same time is
hobbling their project in a way that is entirely contrary to the notions
of Enterprise Java and flexible computing at any scale.
If you are going to take a position such as that, defend it. Otherwise
admit you have no basis for this opinion. I am willing to be convinced,
but I need an argument and so far you have done nothing more than state a
position.
> "We rarely find that people have good sense unless they agree
> with us."
> - Francois, Duc de la Rochefoucauld
I couldn't agree with you more.
C=)
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Some people mistake the positions I take with the beliefs that I hold.
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Caskey <caskey*technocage.com> /// TechnoCage Inc.
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Oh no! Space monkeys are attacking! -- eddie izzard
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