Suppose you are announcing a new www service, which is running on a
machine mydesk.cs.nowhere.edu . People used to announce the service as
http://mydesk.cs.nowhere.edu/ .
This has the recognized problem that you may someday wish to use a
different machine. So the convention has developed of creating a DNS
alias or pointer. Thus you might announce http://www.cs.nowhere.edu/ .
But a related problem is NOT addressed by this solution:
It is not posible to transparently move two services,
begun on different servers, to a single server.
For service identity is being uniquely determined by the DNS name,
as a server receiving a connection does not know the name(s) which
the client resolved to find the server's IP address.
Adding service identity to the "path" addresses this problem.
One might announce http://www.cs.nowhere.edu/www-cs/ .
This allows you to later, transparently, let the server providing
http://www.nowhere.edu/nowhere/ to also provide your service.
And lets you run take over the experimental
http://mumble-www.cs.nowhere.edu/mumble/ .
Mitchell