EJB newbie question

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vk02720 - 22 Jan 2006 23:23 GMT

If I have a legacy architecture for client server app where the client
connects to server ( or a group of servers seperated by their
functionality ) using message based mechanisms ( sockets, MQSeries ).
For example - there could be servers S1, S2, S3 .. and messages M1, M2,
M3 ...
How does this scenario translate into an EJB based design ? Would the
servers be designed as session beans or would it be the messages .... ?

Also, is there a good website where I can start learning about EJB ?
Any open source container I can download for Linux platform and start
writing some simple stuff.

Appreciate any help.

TIA

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Raymond DeCampo - 23 Jan 2006 01:40 GMT

> If I have a legacy architecture for client server app where the client
> connects to server ( or a group of servers seperated by their
[quoted text clipped - 3 lines]
> How does this scenario translate into an EJB based design ? Would the
> servers be designed as session beans or would it be the messages .... ?

Direct socket connections do not have an analogous technology in EJB.
J2EE is not very well suited to be used in a general client/server
architecture. Potential work-arounds include accessing the EJBs as an
application client via RMI, using web services, accessing a servlet via
HTTP, etc.

Messaging on the other hand, corresponds to JMS which a J2EE application
server must provide. One type of EJB is a message-driven bean (MDB)
which will consume messages. Look for an application server that
interoperates with the MOM you are already using.

> Also, is there a good website where I can start learning about EJB ?
> Any open source container I can download for Linux platform and start
> writing some simple stuff.

JBoss and Jonas are open source EJB containers. The J2EE tutorial on
Sun's site is a good place to start.

HTH,
Ray

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vk02720 - 23 Jan 2006 17:29 GMT

Thanks. I am going to look into the J2EE tutorial.

About the design question - I did not mean that I *have* to use
message-oriented design. I was lookin for a component -based design
solution. I mean could the "server" in the old design map to a session
bean and all the messages a specific server be represented by the
methods of the bean ?
Or some such alternatve.

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Raymond DeCampo - 29 Jan 2006 14:40 GMT

> Thanks. I am going to look into the J2EE tutorial.
>
[quoted text clipped - 4 lines]
> methods of the bean ?
> Or some such alternatve.

Yes, this is one way to do it; no reason it shouldn't work out.

Ray

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vk02720 - 30 Jan 2006 21:59 GMT

> > Thanks. I am going to look into the J2EE tutorial.
> >
[quoted text clipped - 8 lines]
>
> Ray

Thanks.

What kind of "transaction support" is provided by the J2EE
infrastructure as far as EJB objects are concerned ? I mean something
which is not available or could not be done in traditional
client/server architecture ?

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EJB newbie question

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