This class allows the Faces API to be unaware of the nature of its containing application environment. 

FacesContext contains all of the per-request state information related to the processing of a single JavaServer Faces request, and the rendering of the corresponding response. 

FacesContextFactory is a factory object that creates (if needed) and returns new FacesContext instances, initialized for the processing of the specified request and response objects. 

ResponseStream is an interface describing an adapter to an underlying output mechanism for binary output.

ResponseWriter is an abstract class describing an adapter to an underlying output mechanism for character-based output. 

Provides a simple implementation of ResponseWriter that can be subclassed by developers wishing to provide specialized behavior to an existing ResponseWriter instance.