Page navigation in your JSF application is handled by providing navigation rules in a configuration file. The navigation can specify which web component initiates the request, which web component handles the response, and which value causes navigation to follow the flow. So far, you have seen only navigation based on the hard-coded string value of an action attribute. You can also control navigation by using value-binding expressions and method-binding expressions. Navigation then depends on the value of the expression.

Static and Dynamic Navigation

When you control navigation through string values of the action attribute, the path of navigation is known when the application is deployed. We call this static navigation, because the flow is statically determined and does not change. It is the same for every request. When using static navigation, you explicitly code a value into the action attribute of a JSF custom tag. You then define navigation rules in a configuration file. The rule specifies navigation flow when the <from-outcome> of a page matches the value of the action attribute. When that occurs, navigation flows to the specified <to-view-id>. These elements are part of a navigation rule element in a configuration file, such as faces-config.xml.

When you control navigation through value-binding expressions or method-binding expressions, the path of navigation is not known when the application is deployed. In fact, navigation flow can vary from request to request depending on the value of the expression. We call this dynamic navigation.

For dynamic navigation, you use a value-binding expression or method-binding expression as the value of the action attribute. With value-binding expressions, the value of the property must be of type String. With method-binding expressions, the method must take no parameters and return a value of type String: 

public String search();

The String value returned by the method is compared to the value specified in the navigation rule to determine where control flow should go.

2007-09-18

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