Entity Java Beans

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Entity Java Beans

• Jorg Janke
• http//www.compiere.org
• Open Source ERP CRM

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Objectives

• Know J2EE EJB Buzzwords
• Understanding of J2EE Architecture
• Understanding of EJB Architecture
• Know next steps to explore J2EE EJB

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Java Application Tiers
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Java Application Tiers (Detail)
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J2SE
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EJB Types

• Session Beans
• Stateless
• Stateful
• Entity Bean
• Bean Managed Persistency
• Container Managed Persistency (CMP)
• Message Bean

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Stateless Session Bean
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Stateful Session Bean
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Entity Bean
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Message Bean
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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)

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EJB Runtime

• Home (create, find)
• Home Object Stub
• Home Object
• EJB (business methods)
• EJB Object Stub
• EJB Object
• Bean (the entity)
• Enterprise Bean Object

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EJB Container - Client
JNDI
Client
Container
Home Object
Home Stub
Home Stub
RMI-IIOP
Enterprise Bean Object
EJB Object
Object Stub
Object Stub
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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 -gt myBean
• Bean.doSomething()
• Business Method Proxy

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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

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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

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For a live demo visit me
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JBuilder New
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New Module (multiple Beans)
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New Session Bean
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Stateless Session Bean
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Session Bean Properties
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Home Interface
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Remote Interface
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Bean Class
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Deployment Descriptor
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Add additional methods
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Create Test Client
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Client 1 Lookup
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Client 1 - Create
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Client 1 Business Methods
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Entity Bean
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Home Interface
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Remote Interface
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Bean Class
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Client 2
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Client 2 Lookup / Create
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Client 2 Business Methods
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Java Application Tiers
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How do EJBs fit in

• Application Server
• Business Objects
• Coarse Grained Objects
• Fine Grained Objects (not suited)
• Local Interface

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What is J2EE compliant

• 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

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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

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Compiere J2EE

• Compiere does not use EJBs
• EJB Container (candidate JBoss)
• Additional Installation effort
• Additional Operation effort
• Plus Could be installed automatically
• Compieres Business Objects (Invoice,..)
  dynamically are generated
• Based on Data Dictionary
• Business Objects Behavior are personalized

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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 (OReilly)

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Thanks

• You can download the presentation
• http//www.compiere.org/download
• My contact
• http//www.compiere.com/consulting.html
• jorg.janke_at_compiere.org