The Java EE 5 Tutorial (PDF) - Oracle Software Downloads

The Life Cycle of a JavaServer Faces Page
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The JavaServer Faces implementation performs all these tasks as a series of steps in the
JavaServer Faces request-response life cycle. Figure 10–3 illustrates these steps.
FIGURE 10–3 JavaServer Faces Standard Request-Response Life Cycle
Faces
Request
Faces
Response
Restore
View
Render
Response
Render
Response
Apply
Requests
Response
Complete
Process
Events
Response
Complete
Process
Events
Invoke
Application
Conversion Errors/
Render Response
Process
Validations
Response
Complete
Process
Events
Response
Complete
Process
Events
Update
Model
Values
Validation/
Conversion Errors/
Render Response
The life cycle handles both kinds of requests: initial requests and postbacks. When a user makes
an initial request for a page, he or she is requesting the page for the first time. When a user
executes a postback, he or she submits the form contained on a page that was previously loaded
into the browser as a result of executing an initial request. When the life cycle handles an initial
request, it only executes the restore view and render response phases because there is no user
input or actions to process. Conversely, when the life cycle handles a postback, it executes all of
the phases.
Usually, the first request for a JavaServer Faces pages comes in as a result of clicking a hyperlink
on an HTML page that links to the JavaServer Faces page. To render a response that is another
JavaServer Faces page, the application creates a new view and stores it in the FacesContext
instance, which represents all of the contextual information associated with processing an
incoming request and creating a response. The application then acquires object references
needed by the view and calls FacesContext.renderResponse, which forces immediate
rendering of the view by skipping to the “Render Response Phase” on page 316 of the life cycle,
as is shown by the arrows labelled Render Response in the diagram.
Sometimes, an application might need to redirect to a different web application resource, such
as a web service, or generate a response that does not contain JavaServer Faces components. In
these situations, the developer must skip the rendering phase (“Render Response Phase” on
The Java EE 5Tutorial • June 2010