Entity Java Beans

Jorg Janke

http://www.compiere.orgOpen 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

EJB Types

Session Beans Stateless Stateful

Entity Bean Bean Managed Persistency Container Managed Persistency (CMP)

Message Bean

Stateless Session Bean

Stateful Session Bean

Entity Bean

Message Bean

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)

EJB Runtime Home (“create”, “find”)

Home Object Stub Home Object

EJB (“business methods”) EJB Object Stub EJB Object

Bean (“the entity”) Enterprise Bean Object

EJB Container - Client

Client Container

Home Stub Home Stub

Object Stub Object Stub

RMI-IIOP

Home Object

EJB Object

Enterprise Bean Object

JNDI

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”

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

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

For a live demo … visit me

JBuilder New …

New Module (multiple Beans)

New Session Bean

Stateless Session Bean

Session Bean Properties

Home Interface

Remote Interface

Bean Class

Deployment Descriptor

Add additional methods …

Create Test Client

Client 1 – Lookup

Client 1 - Create

Client 1 – Business Methods

Entity Bean

Home Interface

Remote Interface

Bean Class

Client 2

Client 2 – Lookup / Create

Client 2 – Business Methods

Java Application Tiers

How do EJBs “fit in”

Application Server Business Objects Coarse Grained Objects Fine Grained Objects (not suited)

Local Interface

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

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

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”

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)

Thanks

You can download the presentation http://www.compiere.org/download

My contact: http://www.compiere.com/consulting.

html jorg.janke@compiere.org