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5.2.7. Component names
All Seam components require names. Assign a name with the
@Name annotation:
@Name("loginAction")
@Stateless
public class LoginAction implements Login { ... }
@Name("loginAction")
@Stateless
public class LoginAction implements Login { ... }
This is the Seam component name, and does not relate to any other name defined by the EJB specification. However, Seam component names work like JSF managed bean names, and can be thought of in identical terms.
@Name is not the only way to define a component name, but the name must always be specified. No other Seam annotation will function if a name is not defined.
When Seam instantiates a component, it binds the new instance to a variable matching the component name in the component's configured scope. This is identical to JSF managed bean behavior, except that Seam lets you configure this mapping with annotations rather than XML. You can also programmatically bind a component to a context variable. This is useful if a particular component serves multiple roles within the system. For example, the current
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. Take care when binding programmatically, because it is possible to overwrite context variables that reference Seam components.
For very large applications, and for built-in Seam components, qualified component names are often used to avoid naming conflicts.
@Name("com.jboss.myapp.loginAction")
@Stateless
public class LoginAction implements Login { ... }
@Name("com.jboss.myapp.loginAction")
@Stateless
public class LoginAction implements Login { ... }
The qualified component name can be used both in Java code and in JSF's expression language:
<h:commandButton type="submit" value="Login"
action="#{com.jboss.myapp.loginAction.login}"/>
<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}"/>
<factory name="loginAction" scope="STATELESS"
value="#{com.jboss.myapp.loginAction}"/>
All built-in Seam components have qualified names, but can be accessed through their unqualified names with Seam's namespace-import feature. The
components.xml file included in the Seam JAR defines the following namespaces:
When attempting to resolve an unqualified name, Seam will check each of these namespaces, in order. Additional application-specific namespaces can be included in your application's
components.xml file.
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