An application service or data object is an entity that is either an
instance of a specific application service or a specific data object.
The identity of the object persists over time and is not tied to the
end system hosting the service or data. Examples are SIP services
or web pages. An application is reachable to clients at its points of
application attachment. They are located at the ASI and are comparable
to standard TCP/IP sockets in the Berkeley API. A bearer,
the upper-level connectivity abstraction described in Section 2,
connects two points of application attachment with one another.