Hi!
From: "Schaefer, Andreas" <[EMAIL PROTECTED]>
> There is a conceptual issue I like to raise here. From my
> point of view the "Unique Key" is part of the DB and therefore
> under the ownership of the DB. The idea I saw there would
> work under some assumptions:
> - DB belongs only to the application
I don't see what you mean. Could you elaborate please?
> - There is no interaction with the DB except through the EJBs
hmmm not strictly but you have a point. A java client could use this
generator, but it's true that you would have to go through java code and
have an ejb server running.
> - DB is only the persistence tool
>
> If you want to add data to the DB through the DB directly
> like an import or through a backup.
Yes, I agree that you would not be able to use some database tools to import
data.
But the goal of this UID Generator is to offer an "enterprise-ready"
solution as Scott Ambler puts it. This involves a wider range of
applications than the typical web/ejb/db solution and at a larger scale.
To summarise the arguments against surrogate keys (database generated keys
fall into that category) :
- First, your applications become plateform dependant.
- Second, the strategies typically break down in multi-database scenarios,
especially when the databases are from different vendors.
- Third, obtaining the key value causes a dip in performance each time,
especially if you need to bring the value back across the network.
- As a last argument (impact of which I must admit I am not really familiar
with), surrogate keys generated solely by databases are predicated on the
concept of your applications actually being in communication with your
database, a requirement that is difficult to fulfill if your application
needs to support mobile, disconnected users.
That's it! Further opinions: please open fire! :)
Emmanuel
> Have fun - Andy
>
> > -----Original Message-----
> > From: Sean Neville [mailto:[EMAIL PROTECTED]]
> > Sent: Tuesday, April 10, 2001 11:01 AM
> > To: '[EMAIL PROTECTED]'
> > Subject: RE: [JBoss-dev] Object Unique Id Generator
> >
> >
> > There are a series of key generation patterns available on
> > The Server Side,
> > at least one of which requires no databases and no singletons, and is
> > therefore quite portable:
> >
> > http://www2.theserverside.com/patterns/index.jsp
> >
> >
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]]On Behalf Of
> > Schaefer, Andreas
> > Sent: Tuesday, April 10, 2001 1:22 PM
> > To: '[EMAIL PROTECTED]'
> > Subject: RE: [JBoss-dev] Object Unique Id Generator
> >
> >
> > Hi Geeks
> >
> > The "FOR UPDATE" is not always necessary as like in Oracle you
> > have a sequence generator delivering you an unique ID.
> >
> > For the other DBs it is maybe better to use a DB procedure or
> > function to generate an unique ID than use a SQL Statement.
> >
> > Have fun - Andy
> >
> > > -----Original Message-----
> > > From: Emmanuel Sciara [mailto:[EMAIL PROTECTED]]
> > > Sent: Tuesday, April 10, 2001 9:28 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: [JBoss-dev] Object Unique Id Generator
> > >
> > >
> > > Hi guys,
> > >
> > > I have written an advanced key generator for ejbs
> > > (http://ejbutils.sourceforge.net/). I would like to possibly have it
> > > blundled with JBoss. For this however, I need a database that
> > > supports "FOR
> > > UPDATE" sql clauses or transactions with serializable
> > isolation level.
> > >
> > > >From what I know, Hypersonic does not provide that and I
> > > moved away from
> > > InstantDB early in the process because I had problems with
> > > it, so I don't
> > > know.
> > >
> > > So I guess, my question is two fold:
> > > - Does JBoss have such database?
> > > - If yes, do you think it would be worth blundling this stuff
> > > with JBoss.
> > >
> > > Note: the source is a bit out of date on sourceforge but I am
> > > working on it.
> > > I have a fully JBoss-deployable version if you are interested.
> > >
> > > Emmanuel
> > >
> > > > From: "marc fleury" <[EMAIL PROTECTED]>
> > > > > post this to jboss-dev, I remember there is a key
> > > generator somewhere
> > > but
> > > > > yours might be more advanced. if you generate some
> > > interest there, you
> > > > are
> > > > > on
> > > > >
> > > > > marc
> > > > >
> > > > >
> > > > > |-----Original Message-----
> > > > > |From: Emmanuel Sciara [mailto:[EMAIL PROTECTED]]
> > > > > |Sent: Friday, April 06, 2001 10:31 AM
> > > > > |To: marc fleury
> > > > > |Subject: Re: Thanks
> > > > > |
> > > > > |
> > > > > |Hey!
> > > > > |
> > > > > |Cool Idea! I am interested for sure. Just tell me where
> > > to find the
> > > right
> > > > > |sample code and I am of! (if you can do that easily
> > > enough, that would
> > > > save
> > > > > |me some time)
> > > > > |
> > > > > |Just need to modify my sql so it does not use "For
> > > Update", which is
> > > not
> > > > > |supported by Hypersonic. I would like to write some doc
> > > too. But I
> > > guess
> > > > > |that can wait if I send some explanation mail to the list.
> > > > > |
> > > > > |Any other suggestion you would have?
> > > > > |
> > > > > |Emmanuel
> > > > > |
> > > > > |----- Original Message -----
> > > > > |From: "marc fleury" <[EMAIL PROTECTED]>
> > > > > |To: "Emmanuel Sciara" <[EMAIL PROTECTED]>
> > > > > |Sent: Thursday, April 05, 2001 6:28 PM
> > > > > |Subject: Thanks
> > > > > |
> > > > > |
> > > > > |> for removing the documentation from the website,
> > > > > |>
> > > > > |> also did you think about implementing the high/low
> > pattern and
> > > > > |putting it
> > > > > |> as an MBean (or Bean) in JBoss?
> > > > > |>
> > > > > |> let me know if interested let the list know and see if
> > > they want it.
> > > > > |>
> > > > > |> marc
> > > > > |>
> > > > > |>
> > > > > |> _________________
> > > > > |> Marc Fleury, Ph.D
> > > > > |> [EMAIL PROTECTED]
> > > > > |> _________________
> > > > > |
> > > >
> > > >
> > >
> > >
> > >
> > > _______________________________________________
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> > >
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