Re: [art] [dispatch] [Uri-review] Internet-Draft: Using URIs With Multiple Transport Stacks

[Dave Thaler <[e-mail]>]

Adam Roach wrote:
> I think you stopped quoting the paragraph before it got to something highly relevant for CoAP: 
> "...there are serious drawbacks to naming the same resource with more than one URI..."  I do 
> see that the TCP draft as submitted for consideration tries to deal with this by making making 
> the TCP-only schemes use a different namespace than the original schemes, but this looks like
> a sleight of hand: in practice, it seems highly likely that servers will need to make resources
> available to both TCP-only clients and UDP-only clients, which makes this kind of aliasing inevitable.
>
> I do not believe the "tactical versus strategic" distinction you're trying to draw here has any bearing
> on that aspect of URL use.

OCF defines a higher layer URI which is the same regardless of which transport you use (COAP over
UDP, COAP over TCP, HTTP, whatever else) for the reasons you allude to, but that URI is at the 
layer that apps should use (which I take it is what Carsten calls "strategic").   But that has to be resolved
to a set of transport endpoints, and in some cases the transport endpoints are already expressed
via URIs (e.g., a websocket).   That's the layer that I think Carsten is calling "tactical".   A different
terminology might be id vs locator, where URIs are also used for locators in that sense.   That's
what the COAP-TCP draft is doing... defining schemes usable for locators underneath ids.   One point
in my doc is that there can be multiple layers not just two (id vs locator) and so using URIs at each 
layer allows such chaining/stacking.

Dave