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Hi
Sorry
for the confusion. If you have a statefull session bean (SSB) you just store the
reference to the bean in http session, not the bean itself (At least with remote
beans). The reference has approximately fixed size, and the shopping cart
does not. If you don't store the reference then you would't have to create
the bean on every request, and that would give you a blank SSB
every time. The http session is used to fake state in a protocol that are
stateless.
So, as
an answere to your last question, you need to store the SSB reference somewhere,
and that somewhere could be http session. As far as I know the http client can't
store a bean, and if it could i shouldn't be allowed to do it. That would give
the client user ability to modify it, and possibly do harm to your
system.
Shortly. When not
using ejb's, all client state is stored in http session. When using SSB,
reference to klient state is stored in http session and the "real" state in the
SSB.
As an
alternative you could use a session id (or something like that) as a
lookup key to get the SSB each request, but then you would need some other
mechanism to hold the references. Or you could use the session id to query a
database through a stateless session bean.
I'm
still not sure if I would recommend SSB used like this since I really don't know
how it performs, and of cource it depends on the spesification of the overall
system.
Oystein
Thanks Oystein,
just to clear things up, does this mean that if
you're using a web tier (eg jsps) to contact an ejb tier containing a stateful
session bean, then the stateful session bean doesn't have to be put in the
HttpSession object? I'm getting quite confused unfortunately :-(
My understanding is:
1) when not using ejb, the HttpSession object is
used to store client state between requests (possibly by writing cookies to
the client under the hood?)
2) when using ejb, a stateful session bean is
used to store client state between requests (possibly by writing cookies to
the client under the hood?).
If this is the case, why do we put stateful
session beans in the HttpSession object? If we have a direct reference to the
stateful session bean in the web client isn't this enough?
thanks very much,
Brian
----- Original Message -----
Sent: Tuesday, January 07, 2003 3:02
PM
Subject: SV: [Xdoclet-user] xPetStore
v2.1 released
I
haven't seen the example code in question, but there is a significant
difference between a plain java object and a session bean. The plain object
has to be stored fully in the http session. The session bean could be stored
somwhere in a cluster environment whitch could handle load balansing and
probably persistence. ( If the shopping cart contains much information the
memory requirement could be crutial. I've heard a lot of warnings about
storing this kind of information in the session object, but then again I've
also heard general warnings about using statefull session beans at all
because of memory requirements :) I don't now if this is still the
case.
Oystein
Hmm, this gets to the root of my question.
All the educational material
seems to show a shopping cart as the perfect
use for a stateful session
bean. However, if it's just put in the
HttpSession object in the web tier anyway,
could someone please tell me what is the purpose/advantage of using a
stateful session
bean?
Someone at work suggested that it might be
used to handle sessions between a
java app client and server. Is this
valid?
thanks,
Brian
----- Original Message -----
Sent: Monday, January 06, 2003
10:37 PM
Subject: RE: [Xdoclet-user]
xPetStore v2.1 released
Honestly, in real-world app, I would have used plain
Java Object stored in
HttpSession instead of
SFSB.
This was used more for educational purpose
:-)
-----Original Message-----
From:
Brian McSweeney [mailto:[EMAIL PROTECTED]]
Sent: 06 January 2003 09:11
To:
Herve Tchepannou; xdoclet
Subject: Re:
[Xdoclet-user] xPetStore v2.1 released
Hi all,
excellent project Herve.
I have a real basic question to do with ejbs
though. You use a stateful session bean for the shopping
cart implementation. When the struts actions use the
shopping cart they
store it in the HttpSession
object. The thing I don't understand is, how
does a stateful session bean offer you more than just a plain
java object?
If it is just being stored in the
HttpSession object anyway, what extra does
it
offer you? Hope this isn't too off the xdoclet topic.
thanks very much
Brian
----- Original Message -----
From: "Herve Tchepannou" <[EMAIL PROTECTED]>
To: "xdoclet"
<[EMAIL PROTECTED]>; "jboss"
<[EMAIL PROTECTED]>
Sent:
Sunday, January 05, 2003 7:17 AM
Subject:
[Xdoclet-user] xPetStore v2.1 released
> I'm Proud to annouce a new release of xPetStore
v2.1
>
> xPetStore
is a WODRA (Write Once, Deploy and Run Anyware) implementation
> of Sun
> PetStore
application based on the following opensource tools/frameworks:
> - xDoclet
> -
Struts
> - Sitemesh
>
> xPetStore has been successfully
deployed and tested on the following
>
application servers:
> - JBoss
> - WebLogic
>
> You can download the lattest version of xPetStore
at
> http://sourceforge.net/projects/xpetstore
>
> -----------
> This release has the following changes:
> - Integration with JUnitEE
> - Simplify the installation process highly simplify
> - Spilt build.xml to reduce the complexity of the
build process
> - Mailing list created at
sourceforge net
> - Bug fixes
> --
>
> Herve Tchepannou
> mailto:[EMAIL PROTECTED]
>
>
>
>
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>
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