Enterprise java beans(ejb)

Enterprise Java Beans(EJB) With EJBs, you can develop building blocks ‘ejb components ’ – that u and someone else can assemble and reassemble into different applications. For example , you might create a customer bean that represents a customer in database. You can use that Customer bean in an accouting program, an e-commerce shopping cart and a tech support application. One beauty of EJBs is that you take code reuse to a whole new level, instead of just code it reuses whole functionality and allows you modify that way bean behaves at runtime with touching its java code. 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Enterprise Java Beans: What really EJBs gives you ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

How does it all works? ,[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Type of Beans ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Session Bean can be stateless or stateful ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

FIVE THING YOU DO TO BUILD A BEAN ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Write the Bean Class ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

AdviceGuy Bean ,[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

BEAN CLASS ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],You need this package These four methos are from SessionBean interface, so you have to put them here,for now worry about what these are for! You must have an ejbCreate() method. Its an ejb rule we’ll learn about later. But it doesn’t come from SessionBean interface. You must implemet one of three bean type interfaces: 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Write two interfaces for the Bean ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],It must extend either the EJBObject or EJBLocalObject. This is the actual business method. It MUST correspond to a method in the bean class. 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Home Interface ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],The create() method must return your component interface type!! The home must extend either the EJBHome interface or EJBLocalHome 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Create an XML DD ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Specify home interface name Remote interface 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Put the Bean, the interface and the DD into ejb-jar file META-INF EJB-JAR.XML MYPACKAGE AdvcieBean.class AdviceHome.class Advice.class MYEJB.JAR ejb-jar.xml must be in a directory named META-INF 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Deploy the bean into the server,using the tools provided by the server vendor 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

How to call a bean from Client Side? ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

The Client Code(AdviceClient.java) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Finally we get to the actual business methods. Lookup the AdviseBean using the JNDI name we gave during deployment. Initialcontext is our entrypoint into JNDI directory 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

EJB ARCHITECTURE 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

EJB uses RMI 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

How EJB uses RMI 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

EJB uses RMI ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

*** ,[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

*** ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Tricky Questions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

How EJB really Works? 06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

The Bean Home ,[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Architectural Overview: Session Beans ,[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Architectural Overview: Entity Bean ,[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Architectural Overview: Session Beans ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Stateless session beans are more scalable ,[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Tricky Questions ,[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

JNDI ,[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Rules for the home interface ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

EJBHome interface ,[object Object],[object Object],[object Object],[object Object],[object Object],Get reflection like information about the bean. You can use to get more specific class information about the bean. 06/23/10 JavaTruths.com:A Portal for all java related stuff!!! Serialize the home so that you can get the home again later, without having to go through JNDI.

EJBHome interface ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!! When u are done with session bean,you can tell the home by calling remove() and passing the EJB object’s handle. Tell the home to remove an entity bean. You can’t call remove(Object primarykey) method on session bean it will throw RemoveException.

Rules for the component interface ,[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

EJBObject methods ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!! Get the primary key of an entity bean This doesn’t apply to session bean and throws RemoteException.

EJBObject methods ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!! Get the bean’s home object. Save a reference to the EJBObject so that you can get back to your original EJB object. Tell the bean you are done with it. Container removes the resources held by the session bean. Compare the EJB object references to see if they reference the same bean.

The Handle ,[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

isIdentical? ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Session Bean life cycle ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Container Callbacks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

ejbCreate method? ,[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Container callbacks invocation 06/23/10 JavaTruths.com:A Portal for all java related stuff!!! Does not Exist Method ready Passivated setSessionContext() ejbCreate() ejbPassivate() ejbActivate() ejbRemove() or timeout Bean throw system exception timeout

Bean’s Context ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!! get EJBHome() getEJBLocalHome() getEJBObject() getEJBLocalObject() getCallerPrincipal() isCallerInRole(String s) setRollbackOnly(bollean b ) getRollbackOnly() getUserTransaction()

How to use setSessionContext(Sessioncontext sc) ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

How to use ejbCreate()? ,[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Use sessioncontext for 06/23/10 JavaTruths.com:A Portal for all java related stuff!!! setSessionContext() ejbCreate() Within business method Use your SessionContext for: Get a reference to your home Get a reference to home Get a reference to home Get a reference to your EJB Object Get a reference to your EJB Object Get security info about the client Get security info about the client Get a transaction reference and call methods on it(BMT Beans) For a transaction to rollback(CMT beans) Find out if the transaction has already been set to rollback(CMT beans) Get a transaction reference and call methods on it (BMT beans) Access : Your special JNDI Environment Your special JNDI Env. Your special JNDI Env. Another beans methods Another beans methods A resource manager(like a DB) A resource manager(like a DB)

Removing a stateful bean ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],06/23/10 JavaTruths.com:A Portal for all java related stuff!!!

Enterprise java beans(ejb)

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