Ari Suutari wrote:
>
> Hi,
>
> I'm just starting to dig in EJB so my points might not be valid
> but anyway:
>
> Imagine a company that developes and sells various EJB beans,
> say "customer" bean and "car" bean. One of their customers might
> buy the "custmer" bean and an other one would by the "car" bean,
> maybe someone would buy them both. So I guess that it would
> make sense to put those beans in separate jars.
In addition to Rickard's response to this point, remember that Bean
Provider and Application Assembler are two distinct J2EE roles: just
because a one provider gives me a Customer bean and another an Order
bean doesn't mean I don't assemble them into one jar.
>
> Also same thing for internal business: If you maintain
> a system with many different beans, woudn't it be a little
> bit hard to re-build a huge jar every time you update your code ?
> However, building several jars is not good if parts (ie. remote interfaces)
> must be deployed by putting multiple copies of them in different
> jars.
Generally a developer (Bean Provider) would go through modify-test-debug
cycles in a test environment where they'd deploy the one bean they're
working on. From there it would move to an integration test environment
where it would be packaged into the full application jar (actually it
really ought to be an ejbjar in a .war file). The roll into integration
test is probably an automated weekly build.
Organizations that have been building large systems with large teams for
any length of time will have automated the build and roll into
integratioin test long ago: EJB just adds a few wrinkles (well, a lot of
wrinkles, since some vendors haven't implemented command line deployment
tools, which makes a scripted deploy a wee bit difficult)
danch
>
> Ari S.
>
> ----- Original Message -----
> From: "danch" <[EMAIL PROTECTED]>
> To: "jBoss" <[EMAIL PROTECTED]>
> Sent: 21. hein�kuuta 2000 7:14
> Subject: Re: [jBoss-User] Using jboss.xml to add to the classpath
>
> > Is the 'One bean per jar' habit from the book perhaps a result of EJB
> > 1.0 legacy?
> >
> > Vaughn Vernon wrote:
> > >
> > > Hi,
> > >
> > > Rickard �berg wrote:
> > > > I think you need to move your understanding of a jar from the
> practical
> > > > towards the intention of a jar.
> > > > ...
> > > > So, the first question is: why have you put two interrelated
> components
> > > > in two jars instead of one?
> > >
> > > I think the answer is in Ken Jenk's post:
> > > >> I'm still trying to get the examples from Monson-Haefel's "Enterprise
> > > >> JavaBeans" (2nd Edition) to run in jBoss.
> > >
> > > That book has taught probably tens of thousands of programmers to divide
> the
> > > app up into separate jar files. Just a brief glance through some of the
> > > chapters shows this; the build script shows no less than six jars. In
> > > principle I agree that an app should house all classes it needs in a
> single
> > > jar, if only things were that simple.
> > >
> > > > The second is: if there are indeed good reasons for having two jars,
> you
> > > > must make it possible for them to "know the face" of each other...
> > > > by placing the interfaces of one bean in anothers jar
> > >
> > > In reality I believe that will be impossible. For instance, what if a
> new
> > > ejb app is supposed to use another ejb app or set of components (in
> effect
> > > becoming a client to the older app)? Can the app builder be expected to
> > > extract interfaces from the older jar to place in their new jar? Or can
> the
> > > app builder be expected to place their new classes in the older jar?
> Pardon
> > > me if I am off base here, but aren't we talking about the same thing as
> Ken
> > > first discussed -- making TravelAgent see Cabin?
> > >
> > > I think Ken will be able to get his app to work the way you stated, but
> it
> > > is not the way the book author intended for it to work. There are not
> only a
> > > bunch of books out there, but the author has the app working on several
> > > servers, including j2ee ri, with little or no changes.
> > >
> > > So what if Monson-Haefel asked: "How do we get TravelAgent to see
> Cabin?"
> > > :-)
> > >
> > > Vaughn
> > >
> > > --
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