What are EJB

[Alexandre Bouchard <ro...@mac.com>]

I've got a simple question: What are Enterprise Java Beans. I mean, what's
the difference between EJB and the beans I develop with JDK and run with
Tomcat?

Thx

Re: What are EJB

[Luba Powell <lu...@bellatlantic.net>]

putting Tomcat in your message was smart.  this way we won't get in
trouble with our colleagues.

>From were I stand the only thing that EJB and JavaBeans have in
common is the presence of bean work in the name.

I am sure that you know what is the advantage of JavaBeans since
you wrote some.  EJB is normally used in e-commerce applications
that remotely communicate with enterprise databases and maintain
sessions across many machines.  Again, from where I stand - they
are perfect for some e-commerce apps, but it is not the greatest fit
of engineering.

There is a way to include EJBs in Tomcat4.  Haven't tried it yet.

r/luba


----- Original Message -----
From: "Alexandre Bouchard" <ro...@mac.com>
To: <to...@jakarta.apache.org>
Sent: Sunday, June 17, 2001 1:07 PM
Subject: What are EJB


> I've got a simple question: What are Enterprise Java Beans. I mean, what's
> the difference between EJB and the beans I develop with JDK and run with
> Tomcat?
>
> Thx
>
>

Re: What are EJB

[Luba Powell <lu...@bellatlantic.net>]

thank you - no rush.  can wait until next week.
r/luba
----- Original Message -----
From: "Sam Newman" <sa...@stamplets.com>
To: <to...@jakarta.apache.org>
Sent: Monday, June 18, 2001 4:54 PM
Subject: Re: What are EJB


> Hmm...I can certainly send you the config files Orcas uses to work with
> Tomcat. I'll try and dig them out (off site at the moment - back next
week).
> One way to communicate with an EJB container without any config problems
at
> all, is to use RMI.You bind an RMI object at your EJB container's machine,
> which will act as a proxy to the EJB (mine is in fact called
> CentralServerProxy). Your servlets then act as an RMI client. All you have
> to do to get this to work is run tomcat with a security manager (so you'll
> need java 2, and you have to uncomment the relevent line out of your
> server.xml), start an RMI security manager before retrieving the reference
> to the object, and tailor your tomcat.policy file to allow access (I ended
> up granting everything full permissions because I couldn't be bothered to
do
> it properly :-) ). The beauty of this approach is that:
> 1.)Tomcat doesn't have to be on the same machine as your EJB container as
> the communication is RMI (wouldn't be that secure though). It could even
> work over the web (RMI is simply a Java specific layer on Corba).
> 2.) You abstract the underlying EJB container. Different containers might
> require different configuration's for tomcat and the container itself to
get
> communication to work.
> I can go into more detail if you want (I have the code here). It doesn't
> take too long to setup, and you can easily protoype the system without an
> EJB container behind your Proxy RMI object - you could equally just use
JDBC
> to connect to MySql or something. Using servlets as an RMI client is
> outlines in the Servlet Programming book, in the odds and ends chapter I
> think (left my copy at the office!).
> Obviously you could use other communication mechanisms to abstract the
> communication - we also use 1024 bit encrypted secure pipes to communicate
> over the web between out central EJB server and client processes.
>
> sam
> ----- Original Message -----
> From: "Luba Powell" <lu...@bellatlantic.net>
> To: <to...@jakarta.apache.org>
> Sent: Monday, June 18, 2001 5:31 PM
> Subject: Re: What are EJB
>
>
> > You think so?  I will give in another chance.
> > Can you send to me configurations for Tomcat/EJB?
> >
> > thank you.
>
>

Re: What are EJB

[Sam Newman <sa...@stamplets.com>]

Hmm...I can certainly send you the config files Orcas uses to work with
Tomcat. I'll try and dig them out (off site at the moment - back next week).
One way to communicate with an EJB container without any config problems at
all, is to use RMI.You bind an RMI object at your EJB container's machine,
which will act as a proxy to the EJB (mine is in fact called
CentralServerProxy). Your servlets then act as an RMI client. All you have
to do to get this to work is run tomcat with a security manager (so you'll
need java 2, and you have to uncomment the relevent line out of your
server.xml), start an RMI security manager before retrieving the reference
to the object, and tailor your tomcat.policy file to allow access (I ended
up granting everything full permissions because I couldn't be bothered to do
it properly :-) ). The beauty of this approach is that:
1.)Tomcat doesn't have to be on the same machine as your EJB container as
the communication is RMI (wouldn't be that secure though). It could even
work over the web (RMI is simply a Java specific layer on Corba).
2.) You abstract the underlying EJB container. Different containers might
require different configuration's for tomcat and the container itself to get
communication to work.
I can go into more detail if you want (I have the code here). It doesn't
take too long to setup, and you can easily protoype the system without an
EJB container behind your Proxy RMI object - you could equally just use JDBC
to connect to MySql or something. Using servlets as an RMI client is
outlines in the Servlet Programming book, in the odds and ends chapter I
think (left my copy at the office!).
Obviously you could use other communication mechanisms to abstract the
communication - we also use 1024 bit encrypted secure pipes to communicate
over the web between out central EJB server and client processes.

sam
----- Original Message -----
From: "Luba Powell" <lu...@bellatlantic.net>
To: <to...@jakarta.apache.org>
Sent: Monday, June 18, 2001 5:31 PM
Subject: Re: What are EJB


> You think so?  I will give in another chance.
> Can you send to me configurations for Tomcat/EJB?
>
> thank you.

Re: What are EJB

[Luba Powell <lu...@bellatlantic.net>]

You think so?  I will give in another chance.
Can you send to me configurations for Tomcat/EJB?

thank you.
----- Original Message -----
From: "Sam Newman" <sa...@stamplets.com>
To: <to...@jakarta.apache.org>
Sent: Monday, June 18, 2001 12:14 PM
Subject: Re: What are EJB


> Problem is all the containers we've used up till now have had real
problems
> with bean managed persistance...as a result we had to avoid it. They seem
> better now, but its a bit late for us. The single biggest headache I've
had
> developing/designing EJB's is trying to make the OO centric java (e.g.
> encapsulation of data and process) work with the non-OO databases without
> sacrificing too many of the advantages of the two (databases speed, Javas
> flexibility).
> I'm looking forward to the new message beans which are in the new EJB 2.0
> spec. Would of made my current project a whole lot easier... Sending
> messages/setting state of beans via JMS could be very cool - if it works
:-)
>
> sam
>
> ----- Original Message -----
> From: "Luba Powell" <lu...@bellatlantic.net>
> To: <to...@jakarta.apache.org>
> Sent: Monday, June 18, 2001 4:38 PM
> Subject: Re: What are EJB
>
>
> > << but a real mess of a database....>>
> >
> > You are right here.  Because of it I stopped using Entity beans all
> > together...
> >
> >
> > ----- Original Message -----
> > From: "Sam Newman" <sa...@stamplets.com>
> > To: <to...@jakarta.apache.org>
> > Sent: Monday, June 18, 2001 9:26 AM
> > Subject: Re: What are EJB
> >
> >
> > > The only real similarity between EJB's and normal JavaBeans is that
they
> > are
> > > both based on component models. EJB's provide a java representation of
> > some
> > > data in a database - e.g. 1 EJB will equal 1 row in the table, 1 EJB
> class
> > > is tied to one table. XML is used to tie an EJB and its data to a
> > database.
> > > There is a bit of a problem with this approach, in that a typical OO
> > design
> > > for such a system can result in a good OO system on the surface, but a
> > real
> > > mess of a database....
> > >
> > > EJB's need a compliant EJB server, and a database. There are a few
free
> > > versions around - try JBoss. They work fine with Servlets/Tomcat given
> > that
> > > they are also part of the j2ee. I personally use Cape Connect
(previosly
> > > Orcas) with tomcat without too many problems (there are a couple of
> class
> > > loader issues in some circumstances however). Orcas actually bundles
> > Tomcat
> > > with it, and they pre-configure it to work with their ejb container.
> > >
> > > sam
> > > ----- Original Message -----
> > > From: "Alexandre Bouchard" <ro...@mac.com>
> > > To: <to...@jakarta.apache.org>
> > > Sent: Sunday, June 17, 2001 6:07 PM
> > > Subject: What are EJB
> > >
> > >
> > > > I've got a simple question: What are Enterprise Java Beans. I mean,
> > what's
> > > > the difference between EJB and the beans I develop with JDK and run
> with
> > > > Tomcat?
> > > >
> > > > Thx
> > > >
> > >
> >
>

Re: What are EJB

[Sam Newman <sa...@stamplets.com>]

Problem is all the containers we've used up till now have had real problems
with bean managed persistance...as a result we had to avoid it. They seem
better now, but its a bit late for us. The single biggest headache I've had
developing/designing EJB's is trying to make the OO centric java (e.g.
encapsulation of data and process) work with the non-OO databases without
sacrificing too many of the advantages of the two (databases speed, Javas
flexibility).
I'm looking forward to the new message beans which are in the new EJB 2.0
spec. Would of made my current project a whole lot easier... Sending
messages/setting state of beans via JMS could be very cool - if it works :-)

sam

----- Original Message -----
From: "Luba Powell" <lu...@bellatlantic.net>
To: <to...@jakarta.apache.org>
Sent: Monday, June 18, 2001 4:38 PM
Subject: Re: What are EJB


> << but a real mess of a database....>>
>
> You are right here.  Because of it I stopped using Entity beans all
> together...
>
>
> ----- Original Message -----
> From: "Sam Newman" <sa...@stamplets.com>
> To: <to...@jakarta.apache.org>
> Sent: Monday, June 18, 2001 9:26 AM
> Subject: Re: What are EJB
>
>
> > The only real similarity between EJB's and normal JavaBeans is that they
> are
> > both based on component models. EJB's provide a java representation of
> some
> > data in a database - e.g. 1 EJB will equal 1 row in the table, 1 EJB
class
> > is tied to one table. XML is used to tie an EJB and its data to a
> database.
> > There is a bit of a problem with this approach, in that a typical OO
> design
> > for such a system can result in a good OO system on the surface, but a
> real
> > mess of a database....
> >
> > EJB's need a compliant EJB server, and a database. There are a few free
> > versions around - try JBoss. They work fine with Servlets/Tomcat given
> that
> > they are also part of the j2ee. I personally use Cape Connect (previosly
> > Orcas) with tomcat without too many problems (there are a couple of
class
> > loader issues in some circumstances however). Orcas actually bundles
> Tomcat
> > with it, and they pre-configure it to work with their ejb container.
> >
> > sam
> > ----- Original Message -----
> > From: "Alexandre Bouchard" <ro...@mac.com>
> > To: <to...@jakarta.apache.org>
> > Sent: Sunday, June 17, 2001 6:07 PM
> > Subject: What are EJB
> >
> >
> > > I've got a simple question: What are Enterprise Java Beans. I mean,
> what's
> > > the difference between EJB and the beans I develop with JDK and run
with
> > > Tomcat?
> > >
> > > Thx
> > >
> >
>

Re: What are EJB

[Luba Powell <lu...@bellatlantic.net>]

<< but a real mess of a database....>>

You are right here.  Because of it I stopped using Entity beans all
together...


----- Original Message -----
From: "Sam Newman" <sa...@stamplets.com>
To: <to...@jakarta.apache.org>
Sent: Monday, June 18, 2001 9:26 AM
Subject: Re: What are EJB


> The only real similarity between EJB's and normal JavaBeans is that they
are
> both based on component models. EJB's provide a java representation of
some
> data in a database - e.g. 1 EJB will equal 1 row in the table, 1 EJB class
> is tied to one table. XML is used to tie an EJB and its data to a
database.
> There is a bit of a problem with this approach, in that a typical OO
design
> for such a system can result in a good OO system on the surface, but a
real
> mess of a database....
>
> EJB's need a compliant EJB server, and a database. There are a few free
> versions around - try JBoss. They work fine with Servlets/Tomcat given
that
> they are also part of the j2ee. I personally use Cape Connect (previosly
> Orcas) with tomcat without too many problems (there are a couple of class
> loader issues in some circumstances however). Orcas actually bundles
Tomcat
> with it, and they pre-configure it to work with their ejb container.
>
> sam
> ----- Original Message -----
> From: "Alexandre Bouchard" <ro...@mac.com>
> To: <to...@jakarta.apache.org>
> Sent: Sunday, June 17, 2001 6:07 PM
> Subject: What are EJB
>
>
> > I've got a simple question: What are Enterprise Java Beans. I mean,
what's
> > the difference between EJB and the beans I develop with JDK and run with
> > Tomcat?
> >
> > Thx
> >
>

Re: What are EJB

[Sam Newman <sa...@stamplets.com>]

The only real similarity between EJB's and normal JavaBeans is that they are
both based on component models. EJB's provide a java representation of some
data in a database - e.g. 1 EJB will equal 1 row in the table, 1 EJB class
is tied to one table. XML is used to tie an EJB and its data to a database.
There is a bit of a problem with this approach, in that a typical OO  design
for such a system can result in a good OO system on the surface, but a real
mess of a database....

EJB's need a compliant EJB server, and a database. There are a few free
versions around - try JBoss. They work fine with Servlets/Tomcat given that
they are also part of the j2ee. I personally use Cape Connect (previosly
Orcas) with tomcat without too many problems (there are a couple of class
loader issues in some circumstances however). Orcas actually bundles Tomcat
with it, and they pre-configure it to work with their ejb container.

sam
----- Original Message -----
From: "Alexandre Bouchard" <ro...@mac.com>
To: <to...@jakarta.apache.org>
Sent: Sunday, June 17, 2001 6:07 PM
Subject: What are EJB


> I've got a simple question: What are Enterprise Java Beans. I mean, what's
> the difference between EJB and the beans I develop with JDK and run with
> Tomcat?
>
> Thx
>