Re: [core] CoAP requirements and HTTP iwf

> Regarding HTTP specifically: due to its proliferation, I cannot see how we can avoid putting emphasis on mapping to it, so I actually
> think what we are doing now is right, i.e. providing a mapping to HTTP as mandatory and making mappings to other protocols optional and
> in separate documents.

Agree.

Due to HTTP ubiquity, a good CoAP-HTTP mapping looks one of the key requirement for CoAP success. Other mappings are optional and not necessarily within this WG.

Adriano

-----Original Message-----
From: Robert Cragie [mailto:robert.cragie@gridmerge.com] 
Sent: venerdì 26 marzo 2010 15.52
To: d.sturek@att.net
Cc: Adriano Pezzuto (apezzuto); core@ietf.org
Subject: Re: [core] CoAP requirements and HTTP iwf

I guess there are two approaches:
1. Do a clean-room protocol design specification based on the specific requirements for CoAP
2. Analyse existing relevant protocols, i.e. HTTP and others (such as those listed by Adrian) and distil the essence of them into the design specification
You could summarise these approaches as (1) purist and (2) practical approach.

The main issue with (1) is that we could end up with a protocol which doesn't map cleanly to anything. This in itself may not be a problem if mapping essentially always means proxying at an application gateway.
The main issue with (2) is what Don says below, i.e. it may be a compromise which doesn't meet the primary requirements. On the other hand, if done correctly, it could provide the optimum protocol for mapping onto a few key existing protocols.

One advantage of the RESTful style is that it does provide constraints on a protocol usage, so any existing protocol which can be used RESTfully is probably going to end up mapping at least fairly cleanly to whatever is developed for CoAP.

Regarding HTTP specifically: due to its proliferation, I cannot see how we can avoid putting emphasis on mapping to it, so I actually think what we are doing now is right, i.e. providing a mapping to HTTP as mandatory and making mappings to other protocols optional and in separate documents.

Robert
Robert Cragie (Pacific Gas & Electric)
Gridmerge Ltd.
89 Greenfield Crescent,
Wakefield, WF4 4WA, UK
+44 (0) 1924 910888
http://www.gridmerge.com

-----Original Message-----
On 26/03/2010 6:47 AM, Don Sturek wrote: 
If I recall, the CoRE charter removed the mapping devices (CoGII is what I
think they were back in the original CoAP charter).  I think CoRE only
focused on development of a RESTful architecture implementation over
transports that are not constrained to be TCP (ie, UDP is supported).

I think we will make a mistake by having a discussion on mapping to HTTP
since the discussion below will take place ("what about XMPP mappings",
"what about SIP mappings", etc.).  

If we architect CoRE for mappings to all of these other standards I am
doubtful it ever achieves it primary goal of a simple RESTful protocol
implementation for constrained devices.

Don

-----Original Message-----
From: core-bounces@ietf.org [mailto:core-bounces@ietf.org] On Behalf Of
Adriano Pezzuto (apezzuto)
Sent: Friday, March 26, 2010 2:09 AM
To: core@ietf.org
Subject: [core] CoAP requirements and HTTP iwf

Hello,
a great session in Anaheim!

For what concerns CoAP and HTTP mapping (REQ7: of
draft-shelby-core-coap-req-00), I understood that there is not "the"
CoAP-HTTP mapping but more possible ways to do the mapping are possible.
Also, further mappings, e.g.  CoAP-XMPP,   CoAP-SIP, ..  might be
defined in the future, if required.

What about to split the CoAP specs from the  CoaP-*P mapping specs? I
mean to have different specs for CoAP core protocol, CoAP-HTTP mapping,
CoAP-XMPP mapping, CoAP-*P mapping and so on.

Not sure if this make sense ...

regards,
Adriano
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