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JEE Programming

INFORMATICS ENGINEERING – UNIVERSITY OF BRAWIJAYA. Introduction to EJB. JEE Programming. Eriq Muhammad Adams J eriq.adams@ub.ac.id. Agenda. What is EJB ? EJB3 Simplified Development Model Distributed Computing Model The EJB Component Model Core Features of EJB Application Server

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JEE Programming

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  1. INFORMATICS ENGINEERING – UNIVERSITY OF BRAWIJAYA Introduction to EJB JEE Programming Eriq Muhammad Adams J eriq.adams@ub.ac.id

  2. Agenda • What is EJB ? • EJB3 Simplified Development Model • Distributed Computing Model • The EJB Component Model • Core Features of EJB • Application Server • Typical EJB 3 Application Architecture • How to use EJB within Glassfish ?

  3. What is EJB 3? • EJB 3 defined by JSR 220 • History • EJB 1.0 EJB 1.1 EJB 2.0 EJB 2.1 EJB 3 • EJB 3 Simplified Development Model • Distributed Computing Model

  4. EJB3 Simplified Development Model • XML and Annotations – free to choose between XML configuration or annotation. • Dependency Injection – inject dependency at runtime with annotation or XML. • Interceptors: Callback Method – support aspect oriented programming • POJO Implementation. • Intellegent use of defaults – configure explicitly when we need non-default configuration.

  5. Distributed Computing Model • EJB Roles – we can give privelleges. • Enterprise Bean Provider – responsible for defining and implementing the business logic and structure of an enterprise bean. • The Application Assembler - combines EJBs into EJB modules and entities into persistence archives, and then combines these modules together with other Java EE modules to produce an application. • The Deployer – deploys it to a particular EJB container.

  6. The EJB Component Model • We build three object types : • Session Beans perform business service operations and orchestrate transaction and access control behavior. • Message Driven Beans (MDBs) invoked asynchronously in response to external events, through association with a messaging queue or topic. • Entities objects that have unique identities and represent persistent business data.

  7. Core Features of EJB 3 Declarative Metadata - annotations vs XML Configuration by Exception -implicit default configuration Scalability - pooling, cache, optimistic locking strategy, avoid concurrency locking Transactionality- distributed transactions Multiuser Security - declarative method access control Portability - deployable to any application servers Reusability - loosely coupled components Persistence - POJO

  8. Application Server • Is a EJB container. • Host EJB Module or application. • Real implementation of EJB provide by application server. • Many open-source or propietary application server available for market, such as IBM Websphere, Oracle Application Server, BEA Weblogic, Oracle Glassfish. • We used Oracle Glassfish v3 in this class.

  9. Typical EJB 3 Application Architecture Web Server Web Browser Mobile Client EJB Container or JEE Application Server Database Desktop Client

  10. References EJB In Action, Manning Beginning EJB 3 Application Development, Apress

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