Page scope of the Seam component

[msx]

Hi all,

Can anyone, please, explain me the following new-made registration example:

User.java

//$Id: User.java,v 1.9 2005/09/10 19:08:01 gavin Exp $
package org.jboss.seam.example.registration;

import static org.jboss.seam.ScopeType.SESSION;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

import org.hibernate.validator.Length;
import org.hibernate.validator.NotNull;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Scope;

@Entity
@Name("user")
@Scope(SESSION)
@Table(name = "users")
public class User implements Serializable {
 private static final long serialVersionUID = 1881413500711441951L;

 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;
 }

 public User() {
 }

 @NotNull
 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }

 @NotNull
 @Length(min = 5, max = 15)
 public String getPassword() {
 return password;
 }

 public void setPassword(String password) {
 this.password = password;
 }

 @Id
 @NotNull
 @Length(min = 5, max = 15)
 public String getUsername() {
 return username;
 }

 public void setUsername(String username) {
 this.username = username;
 }

 public String toString() {
 return "User(" + username + ")";
 }
}

Message.java

package org.jboss.seam.example.registration;

import static org.jboss.seam.ScopeType.PAGE;

import java.io.Serializable;

import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Scope;

@Name("customMessage")
@Scope(PAGE)
public class Message implements Serializable {

 private static final long serialVersionUID = -2763236998519280798L;

 private static final String DEFAULT_MESSAGE = "Hello World";

 private String message = DEFAULT_MESSAGE;
 private String description = DEFAULT_MESSAGE;

 public Message() {
 }

 public Message(String message, String description) {
 this.message = message;
 this.description = description;
 }

 public String getDescription() {
 return description;
 }

 public void setDescription(String description) {
 this.description = description;
 }

 public String getMessage() {
 return message;
 }

 public void setMessage(String message) {
 this.message = message;
 }

}

Register.java

//$Id: Register.java,v 1.2 2005/09/10 18:29:46 gavin Exp $
package org.jboss.seam.example.registration;

import javax.ejb.Local;

@Local
public interface Register {
 String register();
}

//$Id: RegisterAction.java,v 1.11 2006/06/11 19:54:33 gavin Exp $
package org.jboss.seam.example.registration;

import java.util.List;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.hibernate.validator.Valid;
import org.jboss.seam.annotations.In;
import org.jboss.seam.annotations.Logger;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Out;
import org.jboss.seam.contexts.Contexts;
import org.jboss.seam.core.FacesMessages;
import org.jboss.seam.log.Log;

@Stateless
@Name("register")
public class RegisterAction implements Register {

 @In
 @Valid
 private User user;
 
 @In(value = "customMessage", create = true) @Out
 private Message myMessage;

 @PersistenceContext
 private EntityManager em;

 @Logger
 private Log log;

 public String register() {
 List existing = em.createQuery("select username from User where username=:username")
 .setParameter("username", user.getUsername()).getResultList();
 
 myMessage.setMessage("New message");

 log.info(myMessage == Contexts.getPageContext().get("customMessage"));

 if (existing.size() == 0) {
 em.persist(user);
 log.info("Registered new user #{user.username}");
 return null; //"/registered.jsp";
 } else {
 FacesMessages.instance().add("User #{user.username} already exists");
 return null;
 }
 }

}

register.jsp

<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="http://jboss.com/products/seam/taglib" prefix="s" %>

<html>
 <head>
 <title>Register New User</title>
 </head>
 <body>
 <f:view>
 <h:form>
 <table border="0">
 <s:validateAll>
 <tr>
 <td>Username</td>
 <td><h:inputText value="#{user.username}" required="true"/></td>
 </tr>
 <tr>
 <td>Real Name</td>
 <td><h:inputText value="#{user.name}" required="true"/></td>
 </tr>
 <tr>
 <td>Password</td>
 <td><h:inputSecret value="#{user.password}" required="true"/></td>
 </tr>
 </s:validateAll>
 </table>
 <h:messages/>
 <h:commandButton type="submit" value="Register" action="#{register.register}"/>
 </h:form>
 
 Custom message: <b><h:outputText value="#{customMessage.message}"/></b><br/>
 My message: <b><h:outputText value="#{myMessage.message}"/></b><br/>

 </f:view>
 </body>
</html>

The question is about RegisterAction and register.jsp. Why are customMessage and myMessage different on the register.jsp, but in the RegisterAction the are the same?
If I set any other scope (except ScopeType.PAGE) of the Message component then customMessage and myMessage are the same.