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David,
Thanks, that while not excusing it, would explain the imprecise manner these examples handle Units of Measurements, like the mentioned glitch of turning Temperature into the Speed of Light
People defining a protocol on such a low level like replacing HTTP with something else may not pay as much attention to such details and their examples should be seen in this light, as let's say someone who tries to standardize true M2M payload or metadata for sensors and similar devices (also and especially automotive or other vehicles) or healthcare messaging similar to HL7.
Where literally life and death depends on the right Unit system and code applied and understood. Coming back to what we heard about Cosm and Fukushima, such misinterpretation may also lead to a
slow death, let's say a person relies on the wrong radiation scale when judging if a visit to their home or a place close to such fallout was safe or not.
I got this message a bit late, the call must already be on, but where a JCP JSR EG call I normally attend at least every other week is cancelled like today or I could swap, I hope, I may also join this IWG call some time. Maybe after my M2M talk at JavaOne Moscow next week, otherwise I'll share any noteworthy details on the list.
Regards,
Werner
On Tue, Apr 16, 2013 at 6:32 PM,
<m2m-iwg-request@xxxxxxxxxxx> wrote:
Message: 2
Date: Tue, 16 Apr 2013 16:28:31 +0000
From: "Navarro, David" <david.navarro@xxxxxxxxx>
To: m2m Industry Working Group <m2m-iwg@xxxxxxxxxxx>
Subject: Re: [m2m-iwg] COAP
Message-ID:
<D4775DF50A67AE42A7B3D9F6517B8786194F4BB3@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="us-ascii"
Hi all,
Please allow me to jump in. I'm working for Intel's Opensource Technology Center and I participated in the development of OMA's LWM2M (which relies on CoAP as Julien said).
I don't think CoAP and MQTT are designed to answer the same use cases. MQTT (as I understand it) is all about publishing events with a subscribe mechanism. CoAP is designed to be a replacement of HTTP in constrained environments. So even if CoAP features an Observe mechanism to be notified of value changes, it is not its main purpose and in this, it will be inferior to MQTT. And as an HTTP equivalent, CoAP makes no assumption on the system topology.
At the OMA, we choose to base LWM2M protocol on CoAP because it provides the core functionnalities of HTTP (GET, PUT, POST, DELETE commands, TLS security) in a reduced footprint. The Observe mechanism is a nice-to-have feature but not essential in the LWM2M use-case.
Regards,
David Navarro
From: m2m-iwg-bounces@xxxxxxxxxxx [mailto:m2m-iwg-bounces@xxxxxxxxxxx] On Behalf Of Matteo Collina
Sent: Monday, April 15, 2013 6:19 PM
To: m2m Industry Working Group
Subject: Re: [m2m-iwg] COAP
The real difference between CoAP and MQTT is in how the notification of events works:
http://tools.ietf.org/html/draft-ietf-core-observe-08
In practice, it is the "gateway" or end-user that start observing for changes on the sensor.
In MQTT, it is the other way around, it is the sensor that publishes stuff on a broker.
However CoAP allows some true P2P communication between devices, which is not possible in a central system like MQTT.
It has a real difference, and it may be the reason because it lacks adoption.
I think deploying a central client-server system is much easier.
Cheers,
Matteo
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Message: 3
Date: Tue, 16 Apr 2013 16:32:34 +0000
From: Rick Bullotta <rick.bullotta@xxxxxxxxxxxxx>
To: m2m Industry Working Group <m2m-iwg@xxxxxxxxxxx>
Subject: Re: [m2m-iwg] COAP
Message-ID:
<C7D31C647F791B439B6E65E10053D5370D9D80E4@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="us-ascii"
IMO, change and event-based notification will be a "must have" rather than a "nice-to-have" in current and future M2M applications and protocols. The "poll to see if there are any changes" approach can often consume more device energy/communications bandwidth than change-based.
Rick
From: m2m-iwg-bounces@xxxxxxxxxxx [mailto:m2m-iwg-bounces@xxxxxxxxxxx] On Behalf Of Navarro, David
Sent: Tuesday, April 16, 2013 12:29 PM
To: m2m Industry Working Group
Subject: Re: [m2m-iwg] COAP
Hi all,
Please allow me to jump in. I'm working for Intel's Opensource Technology Center and I participated in the development of OMA's LWM2M (which relies on CoAP as Julien said).
I don't think CoAP and MQTT are designed to answer the same use cases. MQTT (as I understand it) is all about publishing events with a subscribe mechanism. CoAP is designed to be a replacement of HTTP in constrained environments. So even if CoAP features an Observe mechanism to be notified of value changes, it is not its main purpose and in this, it will be inferior to MQTT. And as an HTTP equivalent, CoAP makes no assumption on the system topology.
At the OMA, we choose to base LWM2M protocol on CoAP because it provides the core functionnalities of HTTP (GET, PUT, POST, DELETE commands, TLS security) in a reduced footprint. The Observe mechanism is a nice-to-have feature but not essential in the LWM2M use-case.
Regards,
David Navarro
From: m2m-iwg-bounces@xxxxxxxxxxx<mailto:m2m-iwg-bounces@xxxxxxxxxxx> [mailto:m2m-iwg-bounces@xxxxxxxxxxx] On Behalf Of Matteo Collina
Sent: Monday, April 15, 2013 6:19 PM
To: m2m Industry Working Group
Subject: Re: [m2m-iwg] COAP
The real difference between CoAP and MQTT is in how the notification of events works:
http://tools.ietf.org/html/draft-ietf-core-observe-08
In practice, it is the "gateway" or end-user that start observing for changes on the sensor.
In MQTT, it is the other way around, it is the sensor that publishes stuff on a broker.
However CoAP allows some true P2P communication between devices, which is not possible in a central system like MQTT.
It has a real difference, and it may be the reason because it lacks adoption.
I think deploying a central client-server system is much easier.
Cheers,
Matteo
---------------------------------------------------------------------
Intel Corporation SAS (French simplified joint stock company)
Registered headquarters: "Les Montalets"- 2, rue de Paris,
92196 Meudon Cedex, France
Registration Number: 302 456 199 R.C.S. NANTERRE
Capital: 4,572,000 Euros
This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.
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