1. In some transports the server cannot know the adressing scheme of
the client and so cannot form an adress that makes sense for the client. A
URI is meant to be Universal (hence the name) - even if a server can form a
URI that makes sense in the addressing scheme of the original client, what
happens if this is forwarded to another client? Example - in a 1284
connected environment what should the URI look like (ipp:/lpt1/jobx ?), how
does the server know which lpt port number to use.
2. I cannot forward an IPP packet containing a URI to another system
that is not part of the same homogeneous address space as the original
client and server. I have to crack every packet , find all the URIs and
change them. However I do not know HOW to change them because we have
avoided making rules about the formation of URI (they are supposed to be
implementation specific), without the knowledge of which bits mean what in
the URI I cannot know how to change them from one transport to another