posted 9 years ago
Have you tried typing "http://xmlns.jcp.org/jsf/core" into your web browser?
The URIs do not control what tag libraries are used. They control what XML schemas are used to validate the XML that they are referenced from. That's ALL they're used for. They don't locate any software components, they only guide the compilation process of the View Template in a simple binary fashion - "pass" or "fail". If the View Template (.xhtml) file contains elements or attributes not defined by one of the schemas provided, the entire XML will be rejected. Likewise, the XML will be rejected if you don't provide all the elements and/or attributes a schema demands. You can see this in action by ripping out one of the namespace references such as "http://xmlns.jcp.org/jsf/html". The page will no longer be processable even though the actual tag libraries are still present.
If you reference a schema that doesn't accurately represent the tag libraries, then things may go wrong at runtime, because the XML will have been digested into a DOM that doesn't match what the tag libraries expect.
I'm not sure about the switch from the sun domain to the jcp domain. Ordinarily, I'd say that jcp would be only applicable to pre-release implementations, but Oracle may be getting less involved in the standard and thus backing away from the sun domain name. What matters isn't the namespace name, however, it's how well that particular schema maps to the JSF tag libraries that you are actually using. If you code JSF2.2 schemas into an app and only use JSF2.0 features, you'd have no problems if your webapp server is based on JSF2.0 tag libraries. But if you code JSF2.2 XML into your View Templates, that won't magically upgrade the underlying tag libraries. They'll remain at 2.0.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.