SEAMA GLASSFISH PERSPECTIVE

DAN ALLENJBOSS, A DIVISION OF RED HAT

JSF EJB 3

SEAM BRINGS JAVA EE TOGETHER

SEAM'S MISSION

“To provide a fully integrated development platform for building rich Internet applications based upon the Java EE environment.” - Gavin King

http://in.relation.to/Bloggers/Seam3

WHAT SEAM PROVIDES

“Glue”– Contextual component model

– Dependency injection framework

– Enhanced EL

Simplify Java EE trouble spots

Manage Java Persistence correctly

Modules to integrate third-party libraries

Rapid development environment– Project generator, CRUD framework, hot deploy

SEAM TODAY

JavaServer Faces (JSF)

Facelets

Java Persistence API (JPA)

Enterprise JavaBeans 3 (EJB 3)

Java Transaction API (JTA)

JAX-RS (RESTeasy)

jBPM

JavaMail

iText (PDF)

JExcelApi (Excel)

YARFRAW (RSS)

Java Authentication and Authorization Service (JAAS)

Hibernate search

Drools

JavaScript / Ajax

Quartz

Wicket

GWT

Spring framework

JBoss Cache

...and more

SEAM EJB COMPONENT

EJB Local Reference in web.xml

<ejb-local-ref> <ejb-ref-name>vehiclesee/VehicleTradeBean/local</ejb-ref-name> <ejb-ref-type>Session</ejb-ref-type> <local>org.example.vehicles.action.VehicleTrade</local></ejb-local-ref>

EJB Local Interface and Seam SFSB component

@Localpublic interface VehicleTrade { void trade(); void remove();}

@Stateful@Name("vehicleTrade")public class VehicleTradeBean implements VehicleTrade { public void trade() { ... } @Remove public void remove() {}}

How does Seam make the connection?

RESOLVING AN EJB IN SEAM

A shared concern

First option: @JndiName

Second option: Resolve JNDI from pattern– #{ejbName}

● Value of name attribute on @Stateful/@Stateless● Unqualified class name of component● Value of <ejb-name> in ejb-jar.xml or web.xml

– Plug into Seam's jndiPattern

SFSB reference stored in Seam context– Default is conversation context

INVOKING AN EJB FROM JSF

It's not a crime!

<h:form>

...

<h:commandButton value="Trade"

action="#{vehicleTrade.trade}"/>

</h:form>

@Stateful@Name("vehicleTrade")public class VehicleTradeBean implements VehicleTrade{

public void trade() { ... }

@Remove public void remove() {}

}

CLIENT SERVER

JAVA PERSISTENCE

PERSISTENCE MANAGER

JPA EntityManager or Hibernate Session

Manages object representations of database records

Key services– First-level cache

– Transparent database reads/writes

Aligns well with use case– Seam terms this a “conversation”

CONVERSATION = UNIT OF WORK

The task at hand

Often involves more than one request

Requires state management

EXTENDING THE PERSISTENCE CONTEXT

Not expensive or dangerous!– “Just a HashMap”

Challenging to do in Java EE– No good place to store it

– Complex propagation rules

We turn over this task to Seam

TWO STYLES OF MANAGEMENT

Seam (bi)jection

@InEntityManager entityManager;

Standard Java EE injection

@PersistenceContextEntityManager entityManager;

EXTENDING THE TRANSACTION

Simulate a long transaction– Transcends many database/system transactions

Manual flushing of persistence context– You control when write occurs

– Rollback without involving database

– Persistence context can be read-only

– Only Hibernate provides this extension

Need to replace JPA provider in GlassFish– Seam provides access to Hibernate extensions

– Seam works agreeably with any JPA provider

Conversation (flushMode = MANUAL)

Request RequestResponse Response

load flush

Transaction Transaction...

APPLICATION TRANSACTION

EMBEDDED JAVA EE TESTING

SeamTest– Based on TestNG

Test application “as is”– Full JSF life cycle

– JTA, EJB 3, EL

Currently uses Embedded JBoss– Has baggage

Look forward to EJB 3.1

SEAMA GLASSFISH PERSPECTIVE

DAN ALLENJBOSS, A DIVISION OF RED HAT