While learning JSF, at some locations in Google, I found that Oracle is the implementer while at other Apache and JBoss. Can someone please suggest whether there are multiple implementors of JSF techonology ? If yes, then how should we decide which one to choose for JSF enabled project ? If there are multiple implementer, there are high chances of one providing more feature than other. Which one is considered best from most functionality perspective ? As web application runs on application server, is there any recommendation that which implementer's JSF should be used with which application server ? Do all of these use same function names and signature for same operation or different ?
JSF comes in core and add-on packages. You always need the core. Add-ons are optional.
The definitive core release is the Sun (Oracle) Reference Implementation. The Apache foundation also implemented the core JSF spec in MyFaces. Anyone can implement the JSF specification, actually. When done properly, they're all functionally interchangeable.
The Apache MyFaces Tomahawk, JBoss, Primefaces, IceFaces and other third-party extensions are optional and which one you use (if any) is up to you.
An IDE is no substitute for an Intelligent Developer.