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EJB and SOAP WS

Par Romain Roc��s
pour le Montr��al JUG

About me
Romain Roc��s

Teacher at Supinfo Montreal

Blue belt on BlackBelt Factory

romain.roces@gmail.com

Romain Roc��s

Concept
EJB regroups several concepts

Provides different services (Session Bean),
communicates with another application (Message Bean),
saves information (Entity Bean).

Just like a brain, EJB is the
center of the application.
It proposes many functions.

Version 3

The previous version (2.1) was too complex
The version 3.0 tends to simplification :
Less steps, less classes, less configuration
Improvements from Java EE 5
Annotations
Generics
Java Persistance API
Concepts remain the same, but Sun integrated many ideas
from popular open-source projects like Spring or Hibernate.

Application servers

WebLogic, by BEA

Oracle Application Server, by Oracle

JBoss, by RedHat

GlassFish, by Sun MicroSystems

EJB session

Singleton, Stateless, Stateful

Facade pattern

The Session Bean acts as a ��facade��.
It's the client's interlocutor

Client access
Different clients can call the Session Bean methods if they
possess its interface

Desktop application

Interface
Implementation

Session Bean deployed on a server
Web application

EJB et WS (Montreal JUG - 12 mai 2011)

Session Bean Local
Set @Local on the interface (not mandatory)
Used when the client is deployed in the same virtual
machine
Example :
A Web application deployed in the same server as the
Session Bean
Advantage :
Resource-friendly
More secure
Disadvantage :
Local scope

Session Bean Local

Local interfaces are not mandatory

@Stateless
public class HelloServiceBean {
public String sayHello(){
return "Hello World";
}
}

Session Bean Remote
Set @Remote on the interface
Used when the client is located in a different virtual
machine
Example :
A web application deployed in a different server than the
Session Bean
A rich-client
Advantage :
Open on the network
Disadvantage :
Consumes more resources (uses RMI)
Security

Session Bean Remote
Interface
@Remote
public interface HelloService {
public String sayHello();
}

Implementation
@Stateless
public class HelloServiceBean implements HelloService{
public String sayHello(){
return "Hello World";
}
}

Stateless mode
A Stateless Bean is not bound to any client

Exemples :
Retrieve a list of
products
HelloService
getPlaces() getPlaces()
Advantage : getTrips()
Resource-friendly

Stateless mode

@Stateless
public class HelloWorld {
public String sayHelloTo(String name){
return "Hello " + name;
}
}

Stateful mode
A Statefull Bean is bound to a client

Exemples :
Cart
OrderService getPlaces()
getPlaces()
Advantage : getTrips()
Impact on server
performance

Stateful mode

@Stateful
public class OrderService {
public void setName(String name){��};
public void setAddress(String address){��};
public void buyDog(){��};
��
}

Singleton mode
One Singleton Bean per JVM

Exemples :
Counter
Cache

Advantage :
Resource-friendly
One instance

Disadvantage :
One instance

Singleton mode

@Singleton
public class Counter {
private int i = 0;
public int getCount(){
return ++i;
}
}

Asynchronous calls

How to have asynchronous call in EJBs ?

Threads don't integrate well

@Asynchronous

Method returns void or java.util.concurrent.Future<T>

Asynchronous calls
@Stateless
public class HelloWorld {
@EJB MailManager mailManager;
public String sayHelloTo(String name){
mailManager.sendMail();
return "Hello " + name;
}
}

@Stateless
public class MailManager {
@Asynchronous
public void sendMail(){
...
}
}

Timer Service

Programmatic and Calendar based scheduling
? Last day of the month ?
? Every five minutes on Monday and Friday ?

Cron-like syntax
second [0..59], minute[0..59], hour[0..23], year
DayOfMonth[1..31]
dayOfWeek[0..7] or [sun, mon, tue..]
Month[0..12] or [jan,feb..]

Timer Service

@Stateless
public class WakeUpBean {
@Schedule(dayOfWeek=��Mon-Fri��, hour=��9��)
void wakeUp() {
...
}
}

JUnit

Not in EJB context

@Test
public void myTest(){
StatelessBean statelessBean = new StatelessBean();
statelessBean.getCounter();
}

JUnit

With EJB context : embedded glassfish

@Test
public void myTest() throws NamingException{
EJBContainer createEJBContainer =
EJBContainer.createEJBContainer();
StatelessBean statelessBean =
(StatelessBean)container.getContext()
.lookup("java:global/classes/StatelessBean");
statelessBean.getCounter();
container.close();
}

Unit Test

Cactus is a simple test framework for
unit testing server-side java code
(Servlets, EJBs, Tag Libs, Filters, ...).

The Ejb3Unit project automates Entity and Session
bean testing outside the container for the EJB 3.0
specification.

Client connection

lookup & @EJB

EJB connection with lookup
The client needs the JNDI context to connect to the server.
The client also needs the Session Bean interface
Retrieve the Session Bean with a lookup()
Then it's possible to call methods from the Bean

Context context = new InitialContext();
HelloService hello = (HelloService)
context.lookup(HelloService.class.getName());
System.out.println(hello.sayHello());

The Session Bean will send you a message !

EJB connection with lookup
jndi.properties file example

GlassFish parameters
java.naming.factory.initial=com.sun.enterprise.naming.SerialInitContextFactory
java.naming.factory.url.pkgs=com.sun.enterprise.naming
java.naming.factory.state=com.sun.corba.ee.impl.presentation.rmi.JNDIStateFactoryImpl

JBoss Parameters
java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory
java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces
java.naming.provider.url = 127.0.0.1:1099

EJB injection

In the same JVM, it's not necessary to do a lookup()

Obtain a Session Bean with resource injection

Used in other EJBs, web applications

public class ClientServiceBean
implements ClientService {
@EJB
private OrderService orderService;
...
}

Soap WS in EJB module
Add @WebService and @Stateless annotation on a class
It run !
@WebService
@Stateless
public class MyBeanPublic {

@WebMethod
public String helloWorld() {
return null;
}
}
Default WSDL address : http://localhost:
8080/MyBeanPublicService/MyBeanPublic?wsdl

Now, we use our EJB @stateless in our SOAP WS.

@WebService
@Stateless
public class MyBeanPublic {

@EJB
private MyBeanLocal ejbRef;

@WebMethod
public String helloWorld() {
return ejbRef.helloWorld();
}
}

Exemple with NetBeans 7

Persistence Unit
The persistence unit makes the link between your application
and a DataSource

Persistence Unit

Different providers

Hibernate (use by default in JBoss)

TopLink (use by default in Glassfish v2)

EclipseLink (use by default in Glassfish v3)

Persistence Unit

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" ...>
<persistence-unit name="montrealjugPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>

<jta-data-source>jdbc/firone</jta-data-source>

<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="eclipselink.ddl-generation" value="create-tables"/>
</properties>
</persistence-unit>
</persistence>

Persistence Unit

glassfish-resources.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE resources PUBLIC "-//GlassFish.org//DTD GlassFish Application Server 3.1
Resource Definitions//EN" "http://glassfish.org/dtds/glassfish-resources_1_5.dtd">
<resources>
<jdbc-connection-pool ...>
<property name="serverName" value="localhost"/>
<property name="portNumber" value="1527"/>
<property name="databaseName" value="firone"/>
<property name="User" value="firone"/>
<property name="Password" value="firone"/>
<property name="URL" value="jdbc:derby://localhost:1527/firone"/>
<property name="driverClass" value="org.apache.derby.jdbc.ClientDriver"/>
</jdbc-connection-pool>
<jdbc-resource enabled="true" jndi-name="jdbc/firone" object-type="user" pool-name="
derby_net_firone_fironePool"/>
</resources>

EntityManager in EJB

Obtain an EntityManager with injection

@Stateless
public class DAO {

@PersistenceContext(unitName="montrealjugPU")
protected EntityManager em;

public void createCat(Cat cat){
em.persist(cat);
}
}

EJB message

Java Message Service

JMS presentation

The same since 2002
Used when some information should be exchanged
between
Two applications : point-to-point model
Several applications : publish and subscribe model

Asynchronous system : messages are received when the
client request them

Similar to a mail system

Messages

There are three different types of messages
TextMessage to send simple text
ObjectMessage for a serialized object
MapMessage contains a map with strings as keys and
objects as values

Send a message

In order to send a message, we have to:
Reclaim required objects via JNDI
A ConnectionFactory (service provider)
A Destination (Queue or Topic)
Create a Connection using the factory
Open a Session using the connection
Create a MessageProducer
Send the message

Send a message

Context ctx = new InitialContext();
ConnectionFactory connectionFactory = (ConnectionFactory) ctx
.lookup("ConnectionFactory");
Destination destination = (Destination) ctx.lookup("queue/StockValue");

Connection cnx = connectionFactory.createConnection();

Session session = cnx.createSession(false, Session.AUTO_ACKNOWLEDGE);
MessageProducer producer = session.createProducer(destination);

TextMessage message = session.createTextMessage();
message.setText("Your'microsoft' stock has been sold !");
producer.send(message);
cnx.close();

Receive a message

Two ways to receive a message
Blocking, waiting for a message
Non-blocking, using a message listener

A message listener is similar to an event listener : it
"subscribes" to a particular destination and receives
messages each time there's a new one

Receive a message

Blocking mode
MessageConsumer consumer = session.createConsumer
(destination);
// Retrieve a single message
Message receivedMessage = consumer.receive();

Non-blocking mode, using a listener
MessageConsumer consumer = session.createConsumer(destination);
// Set the listener
consumer.setMessageListener(new MessageListener() {
public void onMessage(Message message) {
// Will be called each time a message is received
}
});

Receive a message : Message Driven Bean

A Message Driven Bean is a specific component for
receiving messages

Annotation used is @MessageDriven

Destination name and type are declared in the annotation

Implements javax.jms.MessageListener
Method public void onMessage(Message m)
Called at the moment of receipt

Receive a message : Message Driven Bean

@MessageDriven(
mappedName="queue/StockValue",
activationConfig = {
@ActivationConfigProperty(
propertyName = "destinationType",
propertyValue = "javax.jms.Queue")})
class MyDrivenBean implements MessageListener {

public void onMessage(Message message) {
TextMessage textMessage = (TextMessage) message;
System.out.println(textMessage.getText());
}
}

Sources

Supinfo : www.supinfo.com

ParisJUG : www.parisjug.org

License

http://creativecommons.org/licenses/by-nc-sa/2.0/fr/

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EJB et WS (Montreal JUG - 12 mai 2011)

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