| Hi Werner, thanks for the feedback! My comments below…
I find the absense of proper Units disturbing and dangerous. How would the receiver of such message kow, if it's 33 kpH or mpH or any other unit?<322.gif>
I very much agree units are important, but I am not sure they should be mandatory at the protocol level. The hierarchical data structure of M3DA payloads could certainly be used to have a convention for transmitting the unit associated to a given variable. e.g. car.temperature node would contain the value, and car.temperature._unit_ would be the unit. Also as I said in my previous email, it may be unrealistic/unnecessary to try to transmit all the metadata related to sensors/actuators/devices on the very same wire they are chatting all-day long, and I think there will always be a need for a model of the m2m applications deployed on the field. This representation of the capabilities of a given application/device on the field could of course be synchronized with the current state of the app (a new sensor has been connected, another has died, …), but I would imagine these updates to be relatively unfrequent, thus maybe there's no need for a dedicated protocol.
Other approaches (I may share it here, or with the recently joined automotive-iwg) like Ford's OpenXC use a typesafe Units of Measurement API not so different from UOMo in fact, and once the "Raw" sensor data coming from a telemetric box is converted into its typesafe Java/Android code, it only allows something like
BaseMeasurement<KilometersPerHour> making clear, what the value refers to. Somewhat similar, but with more modern (Java 5+) code than OSGi Measurement did over a decade ago. How this works for US cars and their dashboard, we'll see, but at least they put the unit in context already.
It would be interesting to see how UOMo can be plugged on top of MQTT and M3DA clients to expose to the developer the units that may have been associated to given variables using the kind of conventions aforementioned...
Cheers Benjamin
How about M3DA?
Thanks, Werner On Wed, Jan 30, 2013 at 10:54 PM, <m2m-iwg-request@xxxxxxxxxxx> wrote:
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Today's Topics:
1. M3DA protocol proposed as part of initial contribution of
Mihini (was: Re: AXEDA Comments on MQTT contribution to ECLIPSE
PAHO & OASIS) (Benjamin Cab?)
----------------------------------------------------------------------
Message: 1
Date: Wed, 30 Jan 2013 13:53:55 -0800
From: Benjamin Cab? <bcabe@xxxxxxxxxxxxxxxxxx>
To: m2m Industry Working Group <m2m-iwg@xxxxxxxxxxx>
Subject: [m2m-iwg] M3DA protocol proposed as part of initial
contribution of Mihini (was: Re: AXEDA Comments on MQTT contribution
to ECLIPSE PAHO & OASIS)
Message-ID: <CD2F5502.33DD4%BCabe@xxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="windows-1252"
Greetings,
During our weekly call yesterday, I briefly mentioned the e-mail below that apparently went unnoticed in what was already a pretty long e-mail thread? hence this new thread :)
We are hoping it can be a good basis for discussion, and we are looking forward to getting the group's feedback on the protocol, and discuss how it can maybe complement MQTT for some use cases during one of our weekly calls and/or in a Paho call. FWIW I won't be able to make it to next week's call, I'll be on the Eclipse Foundation booth at JFokus<http://www.jfokus.se/jfokus/?lang=en> demoing our technologies!
Cheers,
Benjamin.
_________________
--
Werner Keil | Eclipse UOMo Lead, Babel Language Champion | Java Godfather
Twitter @wernerkeil | @JSR354 |#EclipseUOMo
* Nordic Java NightHacking: January 31 2013, Copenhagen, Denmark. Werner Keil, JCP Executive Committee Member welcomes Stephen Chin's "Nordic NightHacking Tour" in Copenhagen
* Social Media Week: February 18 2013, Hamburg, Germany. Werner Keil, JCP Executive Committee Member, Agorava Co-Founder will present "Enterprise Social using Open Source Frameworks like Agorava"
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