A conceptual, or abstract, representation of this system looks
like:
Notes:
The flow of actual data is from one WWW
application (eg, the server), down the "stack", across the network
and back up to the other WWW application.
The apparent flow of data in the upper layers
is peer to peer across the network: the two WWW
apps talk "to one another" in HTTP, whilst the two "Transport
Service Modules" (TCP) talk to one another by the exchange of
segments.
The internal operation of each of the layers is independent of
those above and/or below: each layer has a particular function
which it must carry out, but it doesn't, in general, concern itself
with the operation of other layers -- hence a
communications architecture.
