Refactoring to Seam Web Beans

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Refactoring to Seam (Web Beans)

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Brian Leonard Java Technology Evangelist Sun
Microsystems, Inc.

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Overall Presentation Goal

• Learn enough about Seam to begin using it
  tomorrow

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Speakers Qualifications

• Brian Leonard began working with enterprise Java
  in 1997 at NetDynamics. Today he's a Java
  Technology Evangelist at Sun Microsystems

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Question

• Are Java Server Faces, which are now part of the
  Java EE specification, EJB aware?

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Agenda

• (Brief) Introduction to Java EE 5
• JSF 1.2
• EJB 3.0
• JPA
• Interceptors
• Introduction to Seam
• Refactor to use the Seam Framework
• Seam Portability
• Summary and Resources

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Agenda

• (Brief) Introduction to Java EE 5
• JSF 1.2
• EJB 3.0
• JPA
• Interceptors
• Introduction to Seam
• Refactor to use the Seam Framework
• Seam Portability
• Summary and Resources

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Java EE 5 Goal

• Make it easier to develop Java EE applications
• Especially when first getting started with Java EE

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How Was It Made Easier?

• Then
• Deployment descriptors
• Required container interfaces
• JNDI Lookups
• Configuration files and command line options
• No supported UI framework

• Now
• Java language annotations
• Plain Old Java Objects (POJOs)
• Dependency injection
• More and better defaults
• Java Server Faces (JSF)

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Question

• Are Java Server Faces, which are now part of the
  Java EE specification, EJB aware?

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How Much Easier Is It?
1 Source Raghu Kodali, Oracle
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Annotations Everywhere

• For defining and using web services
• _at_WebService
• To greatly simplify EJB development
• _at_Stateless, _at_Stateful, _at_MessageDriven
• To map Java classes to databases
• _at_Entity, _at_Table, _at_Column
• To specify external dependencies
• _at_Resource
• Reduces need for deployment descriptors and JNDI
  lookups

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For Example - J2EE 1.4 Web Service
? j2ee' version'1.1'

HelloService
WEB-INF/wsdl/HelloService.wsdlsdl-file
WEB-INF/HelloService-mapping.xml
xmlnswsdl-port_ns'urnHelloService/wsdl'
HelloServicename wsdl-port_nsHelloServiceSE
IPort e endpoint.HelloServiceSEInt-interface
WSServlet_HelloService
bservices encoding'UTF-8' ? xmlns'http//java.sun.com/xml/ns/jax-rpc/ri/confi
g' targetNamespace'urnHelloService/wsdl'
typeNamespace'urnHelloService/types'
packageName'endpoint' name'endpoint.HelloServiceSEI'
servantName'endpoint.HelloServiceImpl'

package endpoint import java.rmi. public
class HelloServiceImpl implements
HelloServiceSEI public String sayHello(String
param) throws java.rmi.RemoteException
return Hello param package
endpoint import java.rmi. public interface
HelloServiceSEI extends java.rmi.Remote
public String sayHello(String param) throws
java.rmi.RemoteException
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Java EE 5 Web Service
package endpoint import javax.jws.WebService _at_
WebService public class Hello public String
sayHello(String param) return Hello
param
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Java EE 5 Programming Model
Registration Application
Entity Class
Managed Bean
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DEMO
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Java EE 5 Programming Model
Registration Application
Entity Class
Managed Bean
DB
User
RegisterActionBean
ManagedBean
JSF Components
Action Class
JSF Context
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register.jsp JSF In Action
Username id"userName"
value"user.username"
required"true" minimum"5"
maximum"15"/ Real Name
value"user.name"
required"true" Password
value"user.password"
required"true" minimum"5"
maximum"15"/ id"registerCommand"
type"submit" value"Register"
action"user.register"/
A JSF Validator
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register.jsp BackingBean

• ...
• Username
• id"userName"
• value"user.username"
• ...
• Real Name
• id"name"
• value"user.name"
• ...
• Password
• id"password"
• value"user.password"
• ...
• id"registerCommand"
• type"submit" value"Register"

user
ManagedBean username name password register
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Managed Beans Configuration

• id"userName"
• value"user.username"

faces-config.xml

• ...
• user
• org.examples.jsf.ManagedBean
• requestscope
• ...

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Managed Bean
public class ManagedBean private
String username private String name
private String password public String
getUsername() return username Public
String setUsernaame(String username)
this.usernameusername ... private
RegisterActionLocal registerActionBean
private InitialContext ctx try
ctx new InitialContext()
registerActionBean (RegisterActionLocal)
ctx.lookup("registration/RegisterAc
tionBean/local") catch
(NamingException ex)
ex.printStackTrace()
public String register() return
registerActionBean.register(username, name,
password)
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EJB 3.0

• Dramatic simplification of all bean types
• Regular Java classes (POJO)
• _at_Stateless, _at_Stateful, _at_MessageDriven annotations
• Use standard interface inheritance
• Dependency injection
• Instead of using JNDI API to location components
  and resources, let the container fetch them for
  you.
• Interceptors
• Entity Beans (CMP) replaced with JPA

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Java Persistence API (JPA)

• Single persistence API for Java EE AND Java SE
• Much simpler than EJB CMP
• At least three implementations (all open source)
• Oracle GlassFish/TopLink Essentials
• JBoss Hibernate
• BEA Kodo/OpenJPA
• Configured via persistence.xml
• Feedback is overwhelmingly positive

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JPA Object Relational Mapping

• Developer works with objects
• Database queries return objects
• Object changes persist to the database
• Data transformation is handled by the persistence
  provider (TopLink, Hibernate, etc.)
• Annotations define how to map objects to tables
• _at_Entity marks a regular Java class as an entity.
• Class attributes map to table columns. Can be
  customized with _at_Column.
• Manage relationships _at_OneToMany, ...

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Our Entity Bean

• _at_Entity
• _at_Table(name"users")
• public class User implements Serializable
• _at_Id private String username
• private String password
• private String name
• public User(String name, String password,
• String username)
• this.name name
• this.password password
• this.username username
• //getters and setters...

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JPA Entity Manager

• EntityManager stores/retrieves data
• Inject EntityManager
• _at_PersistenceContext private EntityManager em
• Create an instance of the entity
• User u new User(params)
• Use EntityManager methods to persist data
• em.persist(u) em.merge(u) em.delete(u)
• Query using EJB QL or SQL
• User u em.find(User.class, param)

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Our Action Bean

• _at_Stateless
• public class RegisterAction implements Register
  
• _at_PersistenceContext
• private EntityManager em
• public String register(String username, String
  name, String
  password)
• List existing em.createQuery("select
  username
• from User where usernameusername")
• .setParameter("username",username)
• .getResultList()
• if (existing.size()0) // Create a new
  user
• User user new User(username, name,
  password)
• em.persist(user)
• return "success"
• else
• FacesContext facesContext
  FacesContext.getCurrentInstan
  ce()
• FacesMessage message new
  FacesMessage(username "
  already exists")
• facesContext.addMessage(null, message)
• return null

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Agenda

• (Brief) Introduction to Java EE 5
• JSF 1.2
• EJB 3.0
• JPA
• Interceptors
• Introduction to Seam
• Refactor to use the Seam Framework
• Seam Portability
• Summary and Resources

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JBoss Seam

• RAD programming model for data-driven
  applications without sacrificing the full power
  of Java EE 5
• Framework for integrating JSF and EJB3 component
  models.
• Bridge web-tier and EJB tier session contexts
• Enable EJB 3.0 components to be used as JSF
  managed beans.
• Prototype for JSR 299 Web Beans

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JBoss Seam
Some Key Concepts...

• Eliminate the ManagedBean bind directly to our
  entity and action classes.
• Enhanced context model
• Conversation
• Business process
• Depend less on xml (faces-config) use
  annotations instead
• Bijection for stateful components - dynamic,
  contextual, bidirectional
• Constraints specified on the model, not in the
  view.

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Agenda

• (Brief) Introduction to Java EE 5
• JSF 1.2
• EJB 3.0
• JPA
• Interceptors
• Introduction to Seam
• Refactor to use the Seam Framework
• Seam Portability
• Summary and Resources

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Seam Registration Application
Entity Class
DB
User
Seam Framework
RegisterActionBean
JSF Components
Action Class
JSF Context
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Integrating The Seam Framework
Additions...

• EJB Module (Jar)
• Include jboss-seam.jar
• seam.properties
• Web Module (war)
• faces-config.xml
• SeamPhaseListener
• web.xml
• JndiPattern
• SeamListener

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DEMO
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Eliminating Your ManagedBean
1.
_at_Name("use r") _at_Scope(ScopeType.EVENT)
_at_Name("register")
2.
RegisterActionBean
User
user em
username name password
register
getters setters
" ... ster"/ ...
faces-config.xml useraged-bean-classorg.ex...
4.
ManagedBean
userName name password
register
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DEMO
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User.java (1 of 2)

• _at_Entity
• _at_Name("user")
• _at_Scope(ScopeType.Event)
• _at_Table(name"users")
• public class User implements Serializable
• private String username
• private String password
• private String name
• public User(String name, String password,
• String username)
• this.name name
• this.password password
• this.username username
• ...

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User.java (2 of 2)

• public User()
• _at_Length(min5, max15)
• public String getPassword()
• return password
• public String getName()
• return name
• _at_Length(min5, max15)
• public String getUsername()
• return username

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RegisterAction.java

• _at_Stateless
• _at_Name("register")
• public class RegisterAction implements Register
• _at_In
• private User user
• _at_PersistenceContext
• private EntityManager em
• public String register()
• List existing em.createQuery("select
  username
• from User where usernameusername")
• .setParameter("username",user.getUsername
  ())
• .getResultList()
• if (existing.size()0)
• em.persist(user)
• return "success"
• else
• FacesMessages.instance().add("User
• user.username already exists")

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Agenda

• (Brief) Introduction to Java EE 5
• JSF 1.2
• EJB 3.0
• JPA
• Interceptors
• Introduction to Seam
• Refactor to use the Seam Framework
• Seam Portability
• Summary and Resources

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Seam on GlassFish

• Add missing JBoss Libraries
• hibernate-all.jar
• thirdparty-all.jar
• Change Persistence Unit to TopLink
• Update web.xml
• JndiPattern javacomp/env/
• Delete MyFaces context listener
• RegisterActionEJB reference

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DEMO
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Agenda

• (Brief) Introduction to Java EE 5
• JSF 1.2
• EJB 3.0
• JPA
• Interceptors
• Introduction to Seam
• Refactor to use the Seam Framework
• Seam Portability
• Summary and Resources

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Summary

• Hopefully you've learned how to start using the
  Seam framework in your existing JSF / EJB 3.0
  applications.
• There's much more to Seam, I've just touched the
  surface.

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• Repeat these demos yourself by visiting my blog
  at http//weblogs.java.net/blog/bleonard

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QA
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• Thank you for your attention!