Samuel: Why do you think EJB is far away from Independency/Seperation of concerns?
Becasue you are a student and normally students have hard time with tutors I will be as explicit as possible.
EJB is far away because
-1 it wasn't the purpose in the first place. I mean they have as objective server application and as purpose to alllow players to use Java components in a standard way (given the wide and fast acceptance of tje Java platform ... also little bittery agains Microsoft ... why not ... the time was 1999)
- 2 EJB are just for server side applications (metro - ok avalon - not even mention that)
- 3 EJB classify the components so tightly that you are out of the game if you dont learn them by heart or have other considerations ... Metro has no idea about social classes :O)
- EJB categorizes in layers ... metro would wander ... what is that? and then would spell out a wide laugher ,,. with good reasons ... before, there wasn't WS EJB ... now we have :O) ... and hurry up, because soon we will have Metro EJBs :O)
- Entity EJBs "connected to databases" ... and the JDO society screaming on one side ... as far as I know the concept of relational theory is not that poor ... result? now they have to update EJB QL ... and watch it again ... JDO community won't give up
if you look at the definition of "Separation of concern" and "Inversion of control" you will answer your question right away.
briefly:
Separation of concerns: The container focuses on the tasks it needs to do, no special attention to the nature of components ... just what they do.
Inversion of control: When using a component I tell you when and how to get it... get your hands off ... just do with it what you need to do.
A good example of a similar platform is Quest3D ... BEAUTYFUL!!! ...Metro could be used to implement such a powerful concept.
Well ... I hope this explains something to you ... now go and impress your tailor :O) ...
Saludos Maquina
From: "El Quijote" <[EMAIL PROTECTED]> Reply-To: "Avalon framework users" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Subject: Avalon and EJB Date: Wed, 24 Nov 2004 18:20:29 +0000
Hi again!
Thank you very much for all the quick answers to my question about "context".
I will have to do one lecture about the avalon-framework at my university and today my tutor asked me: "So what is so especial about the avalon-framework?". I would like to pass this question on to you guys:
Is all said by "Seperation of Concers" and "Inversion Of Control"? Can I not achieve exchangeability simply by encapsulating Java-Objects and using well defined interfaces? How does Avalon compare to the EJB-concept? Is it comparable at all?
Samuel: Why do you think EJB is far away from Independency/Seperation of concerns?
One practical question to get me started with the avalon-tutorials:
It seems I need "Ant" and the "Magic antlib" to compile them. How do I install "Magic antlib"?
Do I have to check out all the dpml-stuff and compile Magic? I already compiled the corresponding merlin-tutorials with maven. Unfortunaly the simple-web example never worked. Is there any hope the ant-built version will work?
Many Greetings...
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