ExceptionHandler is the central point for handling unexpected Exceptions that are thrown during the Faces lifecycle. 

ExceptionHandlerFactory is a factory object that creates (if needed) and returns a new ExceptionHandler instance.

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

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

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

There must be one ExternalContextFactory instance per web application that is utilizing JavaServer Faces. 

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

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. 

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

The Flash concept is taken from Ruby on Rails and provides a way to pass temporary objects between the user views generated by the faces lifecycle. 

PartialViewContext contains methods and properties that pertain to partial request processing and partial response rendering on a view.

The PartialViewContext instance is used to determine if the current request indicates the requirement to perform partial processing and/or partial rendering. 

PartialViewContextFactory is a factory object that creates (if needed) and returns new PartialViewContext instances.

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

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. 

PartialResponseWriter decorates an existing ResponseWriter to support the generation of a partial response suitable for Ajax operations.