Subject: [core] Comments on SOAP over CoAP

From: Linyi Tian <[email-masked]>
Date: Wed, 30 Mar 2011 12:09:12 +0200

Hi, Guido Moritz

I want to know why this is related to constrained environment. I gues the
sOaP over UDP (OASIS work) is not for constrained devices. It is just a
binding (same level as HTTP Binding)  to address two scenarios: one request
& request/response in UDP.

During the meeting I also asked the question why do we need large data in
response to POST request. This feature is required if we want to work on
SoAp over CoAP. I am not sure whether this is too much for CoAP. It may not
fit our charter and objective in CORE.

What do you think?

Cheers,
Linyi

---

From: Guido Moritz <[email-masked]>
Date: Wed, 30 Mar 2011 12:30:56 +0200

Linyi,

indeed I am not completely sure if this work fits in the IETF, working on
this in OASIS (especially in the WS-DD TC, i.e. DPWS) might be another and
maybe the right option. But as stated in the draft, we also wanted to point
at issues coming up when using CoAP. And yes, we are using CoAP not as it
was intended. But the same happened to HTTP (e.g. XMPP over HTTP ‘BOSH’,
WebDav, SOAP over HTTP…). So even if CoAP was designed as a RESTful
protocol, it might be ‘misused’ in future developments just as reliable
transport mechanism (as we are doing with SOAP over CoAP). So we wanted to
point at the critical issues that might have to be changed.

For example having a payload in a POST response is required by all such
kinds of Foo over CoAP solutions. POST is too unclear as it just says
‘server, process this and do whatever you have to do with it’. And in our
case this requires maybe a payload in the response also.

So since we have implementations for DPWS and EXI for TelosB motes, we are
quite optimistic to push DPWS/SOAP down to these constrained environments
also. Maybe not ‘Class 1’ devices and only ‘Class 2’ (c.f. Carstens
classification), but this is what we try to find out. So the CoAP binding is
just another building block to be required. 

Best,

Guido

Von: [email-masked] [mailto:[email-masked]] Im Auftrag von
Linyi Tian
Gesendet: Mittwoch, 30. März 2011 12:09
An: 'core'
Betreff: [core] Comments on SOAP over CoAP

Hi, Guido Moritz

What do you think?

Cheers,
Linyi

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From: Carsten Bormann <[email-masked]>
Date: Wed, 30 Mar 2011 12:45:22 +0200

(Chair Hat off)

> So even if CoAP was designed as a RESTful protocol, it might be ‘misused’ in future developments just as reliable transport mechanism (as we are doing with SOAP over CoAP). So we wanted to point at the critical issues that might have to be changed.

Actually, using POST on a resource to affect its state in a fashion not defined by REST does not contradict the REST architecture at all.  So in this respect, the proposed mapping does not misuse the protocol or violate REST. SOAP's architecture does, but that doesn't make it less useful as a benchmark to see whether we've done POST right.  Thank you, Guido, for insisting on this -- I'm looking forward to your presentation later today and your comments whether we got the details right in the next version of core-coap and -block.

Gruesse, Carsten

---

From: Linyi Tian <[email-masked]>
Date: Wed, 30 Mar 2011 13:03:47 +0200

Hi, Guido and Carsten

What I heard is that there maybe some scenarios require Large data in
response to POST. However I didn't hear real world use cases for this. It is
better to show some examples.

It would be good to have some discussions on this before we move to the
decision to change CoAP and Block.

To Guido:
I think if OASIS can analyze CoAP binding would be better since they have
the requirements in mind for SoAP over UDP. However I am fine to have some
discussions here as well. Just need to keep in mind the major goal for CORE
so far is still to identify the need for constrained environment:)

Cheers,
Linyi 

On 11-3-30 下午12:45, "Carsten Bormann" <[email-masked]> wrote:

> (Chair Hat off)
> 
>> So even if CoAP was designed as a RESTful protocol, it might be ‘misused’ in
>> future developments just as reliable transport mechanism (as we are doing
>> with SOAP over CoAP). So we wanted to point at the critical issues that might
>> have to be changed.
> 
> Actually, using POST on a resource to affect its state in a fashion not
> defined by REST does not contradict the REST architecture at all.  So in this
> respect, the proposed mapping does not misuse the protocol or violate REST.
> SOAP's architecture does, but that doesn't make it less useful as a benchmark
> to see whether we've done POST right.  Thank you, Guido, for insisting on this
> -- I'm looking forward to your presentation later today and your comments
> whether we got the details right in the next version of core-coap and -block.
> 
> Gruesse, Carsten
>