I don’t know about you.. I was for quite some time not quite getting the hang on “requestScope” and “viewScope” variables.
I did understand the “sessionScope” and the “applicationScope” variables.
after a few weeks of playing around with xPages, getting quite deep into JSF framework etc, I had today finally (maybe only to me) a stupid revelation:
why a requestScope and a viewScope variable is called this way, and thus understand properly how it works
requestScope
Say you have a webpage open and you now click a button (ie. to save a document). The page (or parts of it) are sent back to the server (mostly via post, sometimes via a get HTTP request). When you in this button now set a requestScope variable you can actually use this value in the next page to be opened. I personally will use this to detect which view is most likely to be opened after a document has been submitted.
There is a little tweek to be made to get this working properly, see my other post.
viewScope
the viewScope is only valid as long as you stay on the same page! and if you know that an xPage is essentially (in JSF terms) a “view” you now also know the reason why it’s called a “viewScope” variable.
Use case why I would use viewScope variable I don’t really have, but you could use it example to track how many times a user has refreshed the current webpage, say to switch between tabs etc. This could help you to track down bottlenecks in your layout.