JSF for Nonbelievers: The JSF Application Lifecycle

By Rick Hightower
2005-05-05


Phase 1: Restore View
In the first phase of the JSF lifecycle -- restore view -- a request comes through the FacesServlet controller. The controller examines the request and extracts the view ID, which is determined by the name of the JSP page.

The JSF framework controller uses the view ID to look up the components for the current view. If the view doesn't already exist, the JSF controller creates it. If the view already exists, the JSF controller uses it. The view contains all the GUI components.

This phase of the lifecycle presents three view instances: new view, initial view, and postback, with each one being handled differently. In the case of a new view, JSF builds the view of the Faces page and wires the event handlers and validators to the components. The view is saved in a FacesContext object.

The FacesContext object contains all the state information JSF needs to manage the GUI component's state for the current request in the current session. The FacesContext stores the view in its viewRoot property; viewRoot contains all the JSF components for the current view ID.

In the case of an initial view (the first time a page is loaded), JSF creates an empty view. The empty view will be populated as the user causes events to occur. From an initial view, JSF advances directly to the render response phase.

In the case of a postback (the user returns to a page she has previously accessed), the view corresponding to the page already exists, so it needs only to be restored. In this case, JSF uses the existing view's state information to reconstruct its state. The next phase after a postback is apply request values.

Tutorial Pages:
» Walk Through the 6 Phases of JSF's Request Processing Lifecycle
» The JSF Lifecycle: an Overview
» Phase 1: Restore View
» Phase 2: Apply Request Values
» Phase 3: Process Validation
» Phase 4: Update Model Values
» Phase 5: Invoke application
» Phase 6: Render Response
» A Working Example
» Let's Code it
» Use Case 1: Add a New CD
» Use Case 2: Edit a CD
» Use Case 3: Sort CDs
» Immediate Event Handling
» Conclusion
» Resources


First published by IBM DeveloperWorks

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