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 Posted: Wed Feb 07, 2007 11:14 pm Post subject: Question about EJB 3.0 |
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Just to understand better...I'm studying EBJ 3.0, session beans,
entities and JBoss to write web and distribuited applications for my
University coruse of Web Architecture. I'm studying a lot of
documentation and as a reference I'm reading the book "Mastering EJB
4th Edition". The problem is I can't understand the goal of
entities...I mean...am I supposed to use them always in the same VM
that is hosting the sessions beans, my jsp pages and servlets? Because
if I want to develop a client application that use the session beans
in order to interact with the server I need to let the entities
serializable and I have to give the .class files of the entities to
the client too! And this is not very good because if I change these
entities I'm supposed to deploy the new .class files to all the
clients...
I hope I made myself clear
Thanks in advance for your help
Cold |
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Per Newgro
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Guest
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| Posted: Thu Feb 08, 2007 8:10 am Post subject: Re: Question about EJB 3.0 |
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Still it doesn't answer to my question...I understand that an entity
bean can be shared beetween different clients, but if I have to change
something in the database (and reflecting the changes on some
entities) I need to recompile these entitites and to deploy them to
all the users...this can be very annoying, don't you think? I mean,
maybe a better scenario is when I have a web application where all the
stuff is deployed in the same application server (therefore in the
same VM as well). Or am I not grabbing something about this
technology? Is that true that I have to deploy all the entities .class
files to all the clients every time I need to change something on my
data?
Thank you for your help
Cold |
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Per Newgro
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| Posted: Thu Feb 08, 2007 3:55 pm Post subject: Re: Question about EJB 3.0 |
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Hallo cold80 (AT) libero (DOT) it,
| Quote: | Still it doesn't answer to my question...I understand that an entity
bean can be shared beetween different clients, but if I have to change
something in the database (and reflecting the changes on some
entities) I need to recompile these entitites and to deploy them to
all the users...this can be very annoying, don't you think? I mean,
maybe a better scenario is when I have a web application where all the
stuff is deployed in the same application server (therefore in the
same VM as well). Or am I not grabbing something about this
technology? Is that true that I have to deploy all the entities .class
files to all the clients every time I need to change something on my
data?
It depends. If your bean don't care about the datamodel (is generic) it's |
not required. But normally yes (in bean for BMT or in deployment descriptor
for CMT). Do you change your data model periodically often? Otherwise if
you change it maybe 2 times a year the delivery of a new version seems not
a big problem to be for me.
There is a feature called hot deployment. This manages the new deployments
on customer side. So normally its enough to build a good installer without
restarting the server.
Cheers
Per |
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