Ah, but what's the standard way for replacing the EJB's CMP engine? Where,
precisely, in the 2.0 specification (the first place the idea of a
replaceable PersistenceManager) , does a bean indicate the kind of
Persistence Manager it was intending to use?
Ted Neward
{.NET || Java} Course Author & Instructor, DevelopMentor
(http://www.develop.com)
http://www.javageeks.com/tneward
----- Original Message -----
From: "Ara Abrahamian" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, January 15, 2002 9:56 AM
Subject: Re: [EJB-INT] As a Person Looking into EJB...
> > Take concurrency conrol for an example. By default, SQLServer works
> in
> > optimistic concurrency control. You happily write your application
> not
> > worrying about lock conflicts until commit time. When you port such
> an
> > application to DB2, you realize you have to handle lock conflicts much
> > sooner (at the time when you perform "update"). You have to add some
> UI
> > to
> > notify the user of the possible conflict. In fact, DB2 does not even
> tell
> > you that it's waiting on a lock. It appears that the application has
> > simply
> > hung.
> >
> > In order to cancel out of this blocked situation, you have to cancel
> the
> > operation, which typically means you have to do this in a separate
> thread
> > (unpleasant task).
> >
> > Some little differences will make you spend a long time. Data type
> > conversions always annoying and could be time-consuming. For example,
> > Oracle has 'NUMBER' keyword for a numeric column, DB2 does not. You
> have
> > to
> > search and replace NUMBER with DECIMAL. Oracle lets you specify a
> > primary-key column without 'NOT NULL' keywords. DB2 does not (each PK
> > column must have NOT NULL).
>
> [snip]
>
> And that's why you use CMP, cmp engine handles it...
> and if the app server's cmp engine is dumb then use something like
> MVCSoft's persistence manager which is cheap and works on many app
> servers.
>
> Ara.
>
>
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>
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