Oo, looks like the makings of a good debate. :-) OK, maybe it's been done
before, but for the benefit of the current audience (yours truly included),
can we hear the arguments again?
Scott just wrote: "One question is why are you separating the EJB and
Servlet engine on the same machine? For testing purposes? The
communication between Servlet and EJB will be much faster if they are in the
same JVM, so I am just wondering why separate them out?"
Yes Celeste asked Friday "why you are using an EJB design on the same
physical server? I had always understood that the purpose of using an EJB
design is to communicate across different physical server/system boundaries
and/or platforms. Otherwise, the overhead and performance "hit" of using an
EJB design would not be justifiable."
Ah, two sides of the same coin, and an issue about which I'm sure many often
wonder as they get started. Can we open the floor?
I've felt, too, that the discussion of EJB's seemed to make more sense when
the client talking to the EJB was on a different machine (either
client-to-server, or jsp/servlet-to-EJB container on another machine).
Like Celeste, I've wondered if those advantages were as apparent in the
latter case (JSP/servlet-to-EJB container) when those are on the same
machine (indeed, when they're in the same container--JRun-as they are for
many of us).
Indeed, it hit me one day that much of the initial excitement about EJB's
may have come from writers whose perspective was that of client developers:
those building applets that were talking to enterprise databases. Sure, for
them, the benefit of talking to an EJB instead made imminently more sense
over putting a bunch of DB code in the client.
But when all code is on the server side, is there still clear benefit?
I suppose one could make an argument that putting "all that DB code" in a
JSP/servlet is just as bad, but then others will counter that they solve
that problem with regular beans. One rarely hears this approach debated over
EJBs. Of course, it's often clarified in EJB books that "EJB's ARE NOT THE
SAME as regular JavaBeans", but again I think when they say that they're
talking to client developers for whom beans are different in concept
(indeed, many trying to learn about beans themselves are thrown off by books
that discuss beans only in the context of "gui development" tools.) They
rarely go on to say when beans on the server may make sense over ejbs.
Indeed, when one looks even more closely at EJB's, one is left wondering
what the difference would be between a bean-managed (BMP) entity bean (where
the developer is responsible for all the db/transaction coding) and a
regular javabean (where, again, the developer is responsible for all the
db/transaction coding). Is it just a matter of roles (who's doing the
work), then?
Of course, if one is leveraging container-managed persistence (CMP) in an
entity bean, then indeed it's less work than a developer creating a javabean
of their own to do that work.
But if they eschew CMP for BMP, then is there still a benefit of a BMP
entity bean over a javabean doing equivalent work?
/charlie
-----Original Message-----
From: Scott Stirling [mailto:[EMAIL PROTECTED]]
Sent: Monday, August 06, 2001 9:58 AM
To: JRun-Talk
Subject: RE: Ist it possible to seperate EJB and Servlet Server?
Vijay mentions some good things to check. It might also help to set the
classServer host in local.properties to the real IP of the machine, rather
than 127.0.0.1. You set this on the EJB server, not the Servlet server.
The Servlet engine server should have the EJB and JMS services disabled, and
your Servlets must have the ejipt_client.jar or ejipt.jar in their classpath
so they can load Ejipt's JNDI Context factory. Also make sure you are not
overriding settings in local.properties by setting them again in
deploy.properties.
One question is why are you separating the EJB and Servlet engine on the
same machine? For testing purposes? The communication between Servlet and
EJB will be much faster if they are in the same JVM, so I am just wondering
why separate them out?
Scott Stirling
JRun QA
Macromedia
> -----Original Message-----
> From: Vijay Menon [mailto:[EMAIL PROTECTED]]
> Sent: Friday, August 03, 2001 3:08 AM
> To: JRun-Talk
> Subject: Re: Ist it possible to seperate EJB and Servlet Server?
>
>
> When u set up servers in JRun, each server is completely
> independent. It
> looks like the servlet is trying to locate the ejbs by
> looking on the same
> port as itself. Check which port the servlet is using to
> connect to the ejb
> server because that would be the most likely reason
>
> Also, if the site is protected by a firewall, check that the
> port is open
> for the second server but of course, in that case, a naming
> exception will
> not be thrown.
>
> Vijay
>
> ----- Original Message -----
> From: "Alexander Sommer" <[EMAIL PROTECTED]>
> To: "JRun-Talk" <[EMAIL PROTECTED]>
> Sent: Friday, August 03, 2001 4:39 PM
> Subject: AW: Ist it possible to seperate EJB and Servlet Server?
>
>
> > Yes, I have two server in the server directory of jrun. One is
> > configured as servlet/jsp server with no ejb-service enabled in
> > the local.properties. The other one is the ejb server with no
> > web-app enabled, so it hosts only the ejb's. The are deployed
> > on that server and all loaded (the event-log) says that.
> > But when I call an servlet on the servlet server, I get an
> > naming exception. I think thats because the two server do not
> > have the same jndi-context! But the question is how to go around
> > that?
> >
> > Alex
> >
> > -----Urspr�ngliche Nachricht-----
> > Von: Vijay Menon [mailto:[EMAIL PROTECTED]]
> > Gesendet: Freitag, 03. August 2001 08:26
> > An: JRun-Talk
> > Betreff: Re: Ist it possible to seperate EJB and Servlet Server?
> >
> >
> > If I get it right, u r trying to set up 1 server jvm
> process listening on
> > port A trying to talk to another server process on a
> different port B?
> What
> > error is it throwing? is it a javax.naming exception or
> what? Maybe the
> 2nd
> > server is not actually hosting the ejbs, so to speak?
> >
> > ----- Original Message -----
> > From: "Alexander Sommer" <[EMAIL PROTECTED]>
> > To: "JRun-Talk" <[EMAIL PROTECTED]>
> > Sent: Friday, August 03, 2001 4:04 PM
> > Subject: AW: Ist it possible to seperate EJB and Servlet Server?
> >
> >
> > > Yes, I want to have the two servers on the same machine! So as I
> > understand,
> > > I don't need to change anything, because I turned off at
> one machine the
> > > EJB-Engine so the call to 127.0.0.1:2323 goes to the
> second VM. But
> > > it doesn't work for me!
> > >
> > > Alex
> > >
> > > -----Urspr�ngliche Nachricht-----
> > > Von: Mark Phelps [mailto:[EMAIL PROTECTED]]
> > > Gesendet: Donnerstag, 02. August 2001 19:25
> > > An: JRun-Talk
> > > Betreff: RE: Ist it possible to seperate EJB and Servlet Server?
> > >
> > >
> > > Are you talking about having the two servers separate but
> on the same
> > > machine or do you mean two JRun servers running on
> different machines.
> > >
> > > It should be simple to have JRun on one machine running
> the JSPs while a
> > > second machine hosts the EJBs. You would just have to
> make sure that
> the
> > > code that looks up the EJBs uses the right URL.
> > >
> > > -----Original Message-----
> > > From: Alexander Sommer [mailto:[EMAIL PROTECTED]]
> > > Sent: Thursday, August 02, 2001 9:42 AM
> > > To: JRun-Talk
> > > Subject: Ist it possible to seperate EJB and Servlet Server?
> > >
> > >
> > > Hi,
> > >
> > > Is it possible to seperate the ejb and servlet server?
> > > I want to create two server instances, one for servlets and
> > > jsp and one for the ejb's. At the moment all works if i use
> > > one server, but if I seperate the ejb's, the EJB-server doesn't
> > > find the ejb's!
> > >
> > > thanks,
> > >
> > > Alex
> > >
> > > Dipl. Ing. Alexander Sommer
> > > Software Development Manager
> > >
> > > TIScover - Travel Information Systems
> > > http://www.TIScover.com - the travel network
> > >
> > > Softwarepark Hagenberg, Hauptstr. 99
> > > A-4232 Hagenberg/Austria
> > > +43(7236)3343-777 (phone)
> > > +43(7236)3343-782 (fax)
> > > e-mail: [EMAIL PROTECTED]
> > >
> >
>
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