Represents a unique page within the application. Pages are part of the
internal structure of a Tapestry application; end developers who refer to "page" are really referring to the {@link #getRootComponent() rootcomponent} of the actual page.
One of the most important aspects of a Page is that it
does not have to be coded in a thread-safe manner. Pages are always accessed within a single thread, associated with a single incoming request.
The Page object is never visible to end-user code. The page also exists to provide a kind of service to components embedded (directly or indirectly) within the page.