Navigation takes place when the user clicks a h:commandButton or other similar component.

In a JSF page these components have the following form:

     <h:commandButton value="label-expression" action="outcome-expression"/>
      

• Its value is called an outcome, which can be either static or dynamic.
• An outcome is eventually translated into a view id, which identifies the JSF page that is displayed after the button is clicked.

Part of the translation involves expanding the outcome string into a path.

• If the outcome string does not begin with a forward slash ("/") then the path for the folder containing the current JSF page is added at the beginning of the outcome string.
• If the outcome string does not have a filename suffix then the suffix for the current JSF page is added at the end of the outcome string.

	<h:commandButton value="Login" action="welcome"/>
	

Since "welcome" does not begin with "/", welcome.xhtml is assumed to reside where index.xhtml resides.

• Logical outcomes are specified in navigation rules
• Navigation rules are placed in the faces-config.xml file
• Navigation rules specify how logical outcomes are translated to view ids
• The javaquiz application is an example

• Determination of the next page does not depend on the state of the application's beans
• The outcome expression is just a string literal

	<h:commandButton value="Login" action="welcome"/>
	

It returns an outcome string to direct the navigation to the next page.

An action method is needed when either or both of the following are true.

• The desired next page is dependent on the state of a bean.

• There are multiple command buttons and each needs to modify the state of a bean in a different way before navigating to the next page.

  • When this is true the action method needs at least one parameter for modifying the bean state.
  • It must return an outcome string even if if the desired outcome is independent of the bean state.

A JSF page that uses action methods typically contains a tag like the following.

     <h:commandButton value="button-label" action="#{bean-name.method-name(argument-list)}"/>

If the method has no arguments the parentheses can be omitted.

For example, suppose that the login application has a loginController bean with a method called verifyUser that needs to be run when the user attempts to login:

     <h:commandButton label="Login" action="#{loginController.verifyUser}"/>
	  

The appropriate bean class for bean-name should contain the following declaration.

     public String method-name(parameter-declarations) {
         implementation-code
         return "outcome";
     }

The outcome should be the name of the next JSF page or a logical outcome.

For example, here is how the loginController bean's verifyUser method might look:

     String verifyUser() {
        if (...)
           return "success";
        else
           return "failure";
     }