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Entity Java Beans

Entity Java Beans. Jorg Janke http://www.compiere.org Open Source ERP & CRM. Objectives. Know J2EE & EJB Buzzwords Understanding of J2EE Architecture Understanding of EJB Architecture Know next steps to explore J2EE & EJB. Java Application Tiers. Java Application Tiers (Detail). J2SE.

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Entity Java Beans

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  1. Entity Java Beans Jorg Janke http://www.compiere.org Open Source ERP & CRM

  2. Objectives • Know J2EE & EJB Buzzwords • Understanding of J2EE Architecture • Understanding of EJB Architecture • Know next steps to explore J2EE & EJB

  3. Java Application Tiers

  4. Java Application Tiers (Detail)

  5. J2SE

  6. EJB Types • Session Beans • Stateless • Stateful • Entity Bean • Bean Managed Persistency • Container Managed Persistency (CMP) • Message Bean

  7. Stateless Session Bean

  8. Stateful Session Bean

  9. Entity Bean

  10. Message Bean

  11. EJB Source Code • Home Interface (extends EJBHome) • Create - Find (for Entity) • Factory Pattern • Remote Interface (EJBObject) • “Business Methods” • Proxy Pattern • Bean Class (EntityBean/SessionBean) • Deployment descriptor (ejb-jar.xml)

  12. EJB Runtime • Home (“create”, “find”) • Home Object Stub • Home Object • EJB (“business methods”) • EJB Object Stub • EJB Object • Bean (“the entity”) • Enterprise Bean Object

  13. EJB Container - Client JNDI Client Container Home Object Home Stub Home Stub RMI-IIOP Enterprise Bean Object EJB Object Object Stub Object Stub

  14. EJB Use • Context ctx = new InitialContext(); • JNDI to LDAP or other Directory Service • BeanHome home = ctx.lookup(“myBean"); • Container finds/creates Factory • BeanRemote bean = home.create(); • Container creates EJB Object -> myBean • Bean.doSomething(); • Business Method “Proxy”

  15. Getting started • The hard way • Download, Install & Implement the J2EE Reference Implementation (Cloudscape) • The easy way • Select a IDE • J2EE support often in “Enterprise Edition” • Free: Forte / NetBeans

  16. Now you have your IDE … • Check what Containers are supported (or included) • Download & Install the Container • E.g. JBoss includes Tomcat • IDEs provide • Wizards / Templates • Packaging & Deployment

  17. For a live demo … visit me

  18. JBuilder New …

  19. New Module (multiple Beans)

  20. New Session Bean

  21. Stateless Session Bean

  22. Session Bean Properties

  23. Home Interface

  24. Remote Interface

  25. Bean Class

  26. Deployment Descriptor

  27. Add additional methods …

  28. Create Test Client

  29. Client 1 – Lookup

  30. Client 1 - Create

  31. Client 1 – Business Methods

  32. Entity Bean

  33. Home Interface

  34. Remote Interface

  35. Bean Class

  36. Client 2

  37. Client 2 – Lookup / Create

  38. Client 2 – Business Methods

  39. Java Application Tiers

  40. How do EJBs “fit in” • Application Server • Business Objects • Coarse Grained Objects • Fine Grained Objects (not suited) • Local Interface

  41. Server providing Web Services Servlet, JSP JNDI, RMI, JDBC EJB Services EJB with CMP JMS, JTA, JAAS Compliance Test Version 1.2, 1.3, … License Application using One of the technologies Servlet or RMI & JDBC will do What is J2EE compliant

  42. When to use EJBs • You need a EJB project for your CV • Highly shared, long lived objects • Entity Beans • Container Managed Persistency (CMP) • Data Access Object • Receiving Messages (JMS) • (Simple) Transaction Support (outside JDBC) • Security Support

  43. Compiere & J2EE • Compiere does not use EJBs • EJB Container (candidate: JBoss) • Additional Installation effort • Additional Operation effort • Plus: Could be installed automatically • Compiere’s Business Objects (Invoice,..) dynamically are generated • Based on Data Dictionary • Business Objects & Behavior are “personalized”

  44. Intro Resources • http://java.sun.com/j2ee/ • Deployathon • http://java.sun.com/blueprints • http://java.sun.com/j2ee/tutorial • J2EE “community” sites • http://www.theserverside.com • http://www.middleware-company.com/ • http://www.onjava.com (O’Reilly)

  45. Thanks • You can download the presentation • http://www.compiere.org/download • My contact: • http://www.compiere.com/consulting.html • jorg.janke@compiere.org

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