All seam components need a name. We can assign a name to a component using the @Name annotation:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
...
}
This name is the
seam component name
and is not related to any other name defined by the EJB specification. However, seam component names work just like JSF managed bean names and you can think of the two concepts as identical.
@Name is not the only way to define a component name, but we always need to specify the name
somewhere
. If we don't, then none of the other Seam annotations will function.
Just like in JSF, a seam component instance is usually bound to a context variable with the same name as the component name. So, for example, we would access the LoginAction using Contexts.getStatelessContext().get("loginAction"). In particular, whenever Seam itself instantiates a component, it binds the new instance to a variable with the component name. However, again like JSF, it is possible for the application to bind a component to some other context variable by programmatic API call. This is only useful if a particular component serves more than one role in the system. For example, the currently logged in User might be bound to the currentUser session context variable, while a User that is the subject of some administration functionality might be bound to the user conversation context variable.
For very large applications, and for built-in seam components, qualified names are often used.
@Name("com.jboss.myapp.loginAction")
@Stateless
@Interceptors(SeamInterceptor.class)
public class LoginAction implements Login {
...
}
We may use the qualified component name both in Java code and in JSF's expression language:
<h:commandButton type="submit" value="Login"
action="#{com.jboss.myapp.loginAction.login}"/>
Since this is noisy, Seam also provides a means of aliasing a qualified name to a simple name. Add a line like this to the components.xml file:
<factory name="loginAction" scope="STATELESS" value="#{com.jboss.myapp.loginAction}"/>
All of the built-in Seam components have qualified names, but most of them are aliased to a simple name by the components.xml file included in the Seam jar.
