When are interceptors and decorato...

Why is the constructor invoked twi...

The @Model annotation does to things:

• it makes the bean request-scoped (instead of dependent, the default)
• it gives the bean an EL name

Creating a request-scoped and named bean is typically accomplished by apply the annotations @RequestScoped and @Named to the class, respectively. Since the combination of these annotations is so common in web applications, the built-in stereotype annotation @Model is provided by CDI as a shorthand.

Here's an example:

@Model
public class SampleBean
{
   private String value;
   public String getValue() { return value; }
   public String setValue(String value) { this.value = value; }
}

This bean can now be bound to an input field in a JSF view:

<h:inputText value="#{sampleBean.value}"/>

If you need to access a bean directly by EL name in a JSF page, you probably need to give it a scope other than @Dependent. Otherwise, any value that gets set to the bean by a JSF input will be lost immediately. That's why CDI features the @Model stereotype; it lets you give a bean a name, and set its scope to @RequestScoped in one stroke. If you need to access a bean that really has to have the scope @Dependent from a JSF page, inject it into a different bean, and expose it to EL via a getter method.

A stereotype is an annotation that aggregates other annotations. @Model is one of the built-in stereotype in CDI and is defined as follows:

@Named 
@RequestScoped 
@Stereotype 
@Target({TYPE, METHOD}) 
@Retention(RUNTIME) 
public @interface Model {}

The @Model stereotype annotation is expected to be used frequently in web applications.