Q:

Mixing JSF1.2 and JSF2

The legacy web app is using JSF1.2 with facelets.  Due to the size of the app, upgrading it to JSF2 would take extensive effort.  Is it possible to mix JSF1.2 and JSF2 in the same web app during the transition period?
I read this post: Mixing JSP and XHTML (Facelets) in JSF2 Project - possible?
but it seems to be related more to converting a JSP app to JSF2?
Thanks for any help.

A:

Is it possible to mix JSF1.2 and JSF2 in the same web app during the transition period?

No.
You can mix JSP and Facelets in one web application, but you can definitely not mix different JSF impls/versions in the same web application. It would only result in class loading conflicts in all colors because multiple different versions of the very same classes are then present in the runtime classpath.
See also:

Migrating from JSF 1.2 to JSF 2.0

