JSF

JSF Life Cycle

         

JSF life cycle is consist of 6 phases.

1.    Restore View

2.    Apply Request Values

3.    Process Validations

4.    Update Model Values

5.    Invoke application

6.    Render Response

Restore View:

A request comes through the Faces Controller. A controller examine the request and get the view ID.

JSF framework uses the view id to get all components. If the view doesn't exist JSF create new view otherwise it used existing view.

View is 3 types

·         new view

·         initial view

·         post back

-->For new view JSF builds the view for the faces page and event handlers and validator to the components.

-->In case of initial view (first time page is loaded)JSF create empty view and assign all components with blank values. From the initial view JSF directly call the render response phase

-->In case of post-back (the user returned to the page he has accessed previously), the view corresponding to the page is already exist so it needs to be store. The next phase of post-back is apply request values.

Apply request values:

The purpose of this phase is for each component to receive it's state. The components must first be retrieved or created from the Faces context object. Components values typically retrieved from the request and cookies and session.

--> the component immediate="false", and component is bounded with integer then value is converted to integer if any conversion fail then system adds the validation message to the Faces Context and these message will be displayed in render response phase

--> The component immediate="true" all the values converted to proper types and validated. The conversion value stored in the component if fails it should store message in faces context object.

Process Validations:

The first event handling takes place after the apply request value phase. In this phase each component is having its values, validated against to the application rules. This validation rules can be predefined or mentioned by developer. If any component fails the validation then message is added to the faces context and component is marked as invalid. If any component is marked as invalid then JSF call the render response phase.

Update model values:

This phase updates the all the model values. This phase is executed after process validations, we can say that all the values are validated.

Invoke application:

JSF controller invokes the application to handle form submissions. In this phase all the values are validated, updated so we can execute our business logic.

Render response:

This phase displays all the components with current state.