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EJB Overview

EJB Overview. Celsina Bignoli bignolic@smccd.net. Distributed Business Applications. Client. Client. Client. Client. Server. Server. DB. DB. DB. DB. Server. Remote method invocation Load balancing Transparent fail-over Back-end integration Transactions Clustering

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EJB Overview

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  1. EJB Overview Celsina Bignoli bignolic@smccd.net

  2. Distributed Business Applications Client Client Client Client Server Server DB DB DB DB Server

  3. Remote method invocation Load balancing Transparent fail-over Back-end integration Transactions Clustering Dynamic redeployment Clean shutdown Distributed Systems – Issues

  4. Logging an auditing System management Threading Message-oriented middleware Object life cycle Resource pooling Security Caching Distributed Systems – Issues(2)

  5. Each issue correspond to a service that needs to be addressed in serious server-side computing (middleware) A company can build its own middleware Complicated to build and maintain Requires expert-level knowledge Completely orthogonal to most companies’ core business A company can buy an application server They implement the middleware layer Allow developer to focus on the code specific to the vertical industry Middleware

  6. Component Architecture • Agreement or set of interfaces between application servers and components • Allows any component to run within any application server without changing code or even recompiling it

  7. Enterprise JavaBeans (EJB) • Standard for building server-side components in Java • Defines a contract between components and applications servers, agreed upon by the industry • Focus on vertical, rapid business development rather than middleware development • Designed to support portability, scalability and reusability across any vendor’s middleware services

  8. EJB as Business Tier • Enterprise Beans are server-side components • Perform complex computations to code business logic • Access databases • Access other systems • Must run in a fault-tolerant, transactional, multi-user, secure environment • Enterprise Beans are NOT presentation components • Sit BEHIND the presentation layer (and do the hard work)

  9. EJB Ecosystem Supply Tools Tool Provider (Eclipse JDeveloper NetBeans Sun’s Java Studio) Build Application Deploy System Construct Enterprise Beans Application Assembler Supply EJB Container Deployer System Administrator Bean Provider EJB Container/ Server Provider (BEA WebLogic jBoss, WebSphere, … )

  10. J2EE Architecture J2EE Server Browser Servlet JSP Page Database Application Client Web Container Enterprise Bean Enterprise Bean Client EJB Container

  11. J2EE Technologies • Enterprise JavaBeans (EJB) • Java API for XML RPC (JAX-RPC) • Java Remote Method Invocation (RMI-IIOP) • Java Naming and Directory Service (JNDI) • Java Database Connectivity (JDBC) • Java Transaction Service (JTS)

  12. J2EE Technologies • Java Messaging System (JMS) • Java Servlets • JavaServer Pages (JSP) • Java IDL (CORBA) • JavaMail • Java API for XML Parsing (JASP) • Java Authentication and Authorization Service (JAAS)

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