Often a page or a region within a page needs information from somewhere else on the page or from a different region. While you can pass parameters to obtain that information, doing so makes sense only when the parameters are well known and the inputs are EL-accessible to the page. Parameters are also useful when a task flow may need to be restarted if the parameter value changes.
However, suppose you have a task flow with multiple page fragments that contain various interesting values that could be used as input on one of the pages in the flow. If you were to use parameters to pass the value, the task flow would need to surface output parameters for the union of each of the interesting values on each and every fragment. Instead, for each fragment that contains the needed information, you can define a contextual event that will be raised when the page is submitted. The page or fragment that requires the information can then subscribe to the various events and receive the information through the event.
Contextual Events is an Oracle ADF feature that enables developers to implement view-to-region, region-to-view, and region-to-region communication. Among the options for passing information to and from regions, Contextual Events is the most powerful and the option that does not make regions refresh or require the referenced bounded task flow to restart.
Posted Date:- 2021-09-27 22:13:17