Difference between Immediate and Deferred Evaluation in JSF

Immediate and deferred evaluation are two ways JSF processes EL expressions.

Immediate Evaluation

Immediate evaluation evaluates EL expressions during the Apply Request Values phase of the JSF lifecycle. It is useful for UI components that require immediate processing, like buttons for validation or navigation.

Deferred Evaluation

Deferred evaluation evaluates EL expressions during the Render Response phase of the JSF lifecycle. It is useful for UI components that do not require immediate processing, like displaying data in tables or forms.

Overall, the key difference is the timing of when the EL expressions are evaluated, with immediate evaluation happening earlier in the lifecycle compared to deferred evaluation.