JSF Life Cycle
The life cycle of a JavaServer Faces page is similar to that of a JSP: The client makes an HTTP request for the page, and the server responds with the page translated to HTML. However, because of the extra features that JavaServer Faces technology offers, the life cycle provides some additional services to process a page.
A JavaServer Faces page is represented by a tree of UI components, called a view. This tree is a run-time representation of a JSF page. Each UI component tag in a page corresponds to a UI component instance in the tree.
The FacesServlet object manages the request processing life cycle in JSF applications. FacesServlet creates an object called FacesContext, which contains the information necessary for request processing, and invokes an object that executes the life cycle.
When a client makes a request for the page, the life cycle starts. During the life cycle, the JSF implementation must build the view while considering the state saved from the previous postback. When the client performs a postback of the page, the JavaServer Faces implementation performs several tasks, such as validating the data input of components in the view and converting input data to types specified on the server side. The JSF implementation performs all of these tasks as a series of steps in the life cycle.