> >We deploy everything on Linux. Having differnet
> >processes running the different layers is a good thing, as
> >you can naturally cluster onto different machines when you
> >need to.
> >
I'm curious--have you actually done this, and how well has it scaled?
Ted Neward
{.NET || Java} Course Author & Instructor, DevelopMentor
(http://www.develop.com)
http://www.javageeks.com/tneward
----- Original Message -----
From: "Atong Appa" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, January 14, 2002 3:34 PM
Subject: Re: [EJB-INT] As a Person Looking into EJB...
> Robert:
>
> Thanks for you reply. In your case, what specific value-adds do you find
in
> EJB? That is, why would you recommend inserting the EJB layer between
your
> application logic and database? Is it for easier persistence management
> (are you using BMP or CMP)? Is it for transaction management (this one
I'm
> curious about--EJB xtn model seems overly complex to me). Or, is it
> portability? Or, something else?
>
> Thank you.
>
>
> Atong
>
>
> >From: Robert Schulz <[EMAIL PROTECTED]>
> >To: 'Atong Appa' <[EMAIL PROTECTED]>
> >Subject: RE: As a Person Looking into EJB...
> >Date: Tue, 15 Jan 2002 10:00:25 +1100
> >
> >Hi Atong,
> >
> >We do built "real" stuff - contact / matter / document
> >management. 50 screens, 20 domain objects.
> >
> >It's fully thin client with the following layers
> >
> >Browser / HTML+JavaScript (IE or Mozilla)
> >Web Server / for static content / SSL (Apache)
> >Servlet Engine / html rendering and application logic (Resin / Tomcat
> >whatever)
> > (you probably need an app framework for this layer)
> >EJB Server / business objects / facade beans (JBoss)
> >Database / persistence (Postgres / Oracle / whatever)
> >
> >We deploy everything on Linux. Having differnet
> >processes running the different layers is a good thing, as
> >you can naturally cluster onto different machines when you
> >need to.
> >
> >Hope this helps.
> >Cheers,
> >
> >Robert.
> >
> >
> > > -----Original Message-----
> > > From: Atong Appa [mailto:[EMAIL PROTECTED]]
> > > Sent: Tuesday, January 15, 2002 6:24 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: As a Person Looking into EJB...
> > >
> > >
> > > I have been asked to look at EJB by my company. After some
> > > research, I have
> > > some questions which I hoped people on this mailing list
> > > could help out.
> > >
> > > First all, all indications are remote entity beans are not to
> > > be used for
> > > small-grain objects. The reason for this is because it
> > > incurs too much
> > > network traffic. Makes sense...
> > >
> > > This seems to suggest that one should use session bean
> > > facades with entity
> > > beans working in the EJB server, using perhaps 2.0's local
> > > entity beans. I
> > > even read upon a "design-pattern" for this.
> > >
> > > Now, suppose I would like my application to run as an
> > > HTMP/JSP/XML app,
> > > where the user is using a browser. The client is talking to
> > > my servlet.
> > > The question is then whether I should have this servlet make
> > > EJB client
> > > calls.
> > >
> > > If I do, I end up with 4-tier architecture where: the client uses the
> > > browser. The HTML req comes to the servlet. Servlet makes EJB client
> > > calls, EJB client makes calls into EJB server. EJB server
> > > makes database
> > > calls.
> > >
> > > I end up with 4 processes (1 for CLIENT, 1 for SERVLET + EJB
> > > CLIENT, 1 for
> > > EJB SERVER, and 1 for DATABASE). This seems a bit excessive.
> > > I then must
> > > ask whether EJB is adding real value here. If I (for network
> > > performance
> > > reasons) have to make my session bean facades coarse-grain
> > > and have all
> > > interesting business logic happen inside EJB SERVER, what
> > > value does EJB add
> > > other than a glorified RPC and the supposed promise of portability?
> > >
> > > Wouldn't it make more sense for me to call "what would've
> > > been the session
> > > bean implementation in EJB SERVER" directly from my SERVLET?
> > >
> > > I'm not convinced at all about this promise of portability.
> > > Porting an
> > > application written for SQLServer to DB2 was bad enough (both
> > > supposedly
> > > conforming to the SQL standard). In fact, the database
> > > access language part
> > > of the porting effort (which is where the two systems shared
> > > the greatest
> > > degree of commonality due to the standard) was the easiest
> > > and simplest
> > > part. 90% of effort was on wrestling with "little"
> > > idiosyncracies of the
> > > two systems. Given the fact that each of them has to competitively
> > > differentiate itself, the most interesting part of their
> > > system was all
> > > outside the realm of the standard.
> > >
> > > I'm afraid the same is true with EJB. In fact, seeing how the spec is
> > > evolving and chaning all the time, I'm afraid it's even worse.
> > >
> > > If someone actually did real life, big app development using
> > > servlet and
> > > EJB, could you chime in and shed some light on this
> > > architecture issue?
> > >
> > > No offense, but I'm not much interested in evangelist howling or some
> > > theoretic empty-talk. I'm looking for practical advices based on real
> > > experience.
> > >
> > > Thank you.
> > >
> > >
> > > _________________________________________________________________
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