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What is the significance of EJB

 
Nick Delauney
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Im a newbie to the board. To my understanding EJB's keep the state of information that may be transported from web pages. I'm not sure where else they come into play. Anyone telling of there expierience would be appreciated. Also I'm trying to get the free book java ranch is giving away
 
Ashoke Bhowmick
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Hi,
JavaBeans are sufficient to keep the state of information that may be transported from web pages , you don't require EJB for that.
EJBs are useful when you want to develop an enterprise level distributed application , since the middleware services like connection pooling , transactions , instance pooling , persistence etc are provided by the J2EE compliant application server and the application developer needs to focus on the business logic.
Regards,
Ashoke
 
Rajesh Pathak
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EJB is one of the various technologies provided in J2EE. Usually EJB does not work in isolation, and is assited by other J2EE technologies like Jsp,Servlet,JNDI,JDBC etc. The main reason for opting for EJB in enterprise development are:

1.Faster solutions delivery time. EJB uses "containers" to simplify development. J2EE containers provide for the separation of business logic from resource and lifecycle management, which means that developers can focus on writing business logic rather than writing enterprise infrastructure.
2. Freedom of choice. The support components/ tools are based on a standard APIs and at the same time compete vary in implementations. Hence there is freedon of choice for a developer to choose application vendor.
3. Simplified connectivity. J2EE technology makes it easier to connect the applications and systems you already have and bring those capabilities to the web, to cell phones, and to devices.
4. Security. The applications built on EJB are highly secure.
5.Reliable and robust. Due to its architecture, the applications have this feature.
6. Future proof. New features can be added easily to applications built on EJB.
 
Nick Delauney
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Thank you both.
What you say makes sense. It seems enterprise java beans may be another learning curver after java. I am practicing the langauge. Is EJB something I can do at home with my tomcat installation? Are they just class files that I could add for the connection pool and the like ... ?
Perhaps a link to this information can serve me better. You both seem to have a grasp on it and are a little advanced for me.
 
Tauqueer Ali
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hi Nick
You have to look at the bigger picture to understand the importance of EJBs as mentioned by Rajesh. A good place to start is by looking at the pet store sample application on sun home page. It gives a complete picture of a J2EE application and where exactly EJB fits into it.
link
http://developer.java.sun.com/developer/releases/petstore/

hope that helps :roll:
 
Lasse Koskela
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Originally posted by Tauqueer Ali:
... good place to start is by looking at the pet store sample application on sun home page. It gives a complete picture of a J2EE application and where exactly EJB fits into it...

I wouldn't suggest starting with the Petstore if you're new to J2EE/EJB. I would prefer first reading up on the EJB concepts from some book (check theserverside.com for an excellent free book about EJBs), and after that dive into the Petstore code.
Astronauts don't start their training by launching into space right away, do they?
 
Douglas Kent
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I concur with Taq*; Petstore architecture discussion is an excellent source of illustrative discussions of each type of EJB (entity, session, and message-driven). Also Blueprints book, found at Designing Enterprise Applications
 
Nick Delauney
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Thank you all. You have been very helpful.
 
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