Hi Brian, I had to think about this for a day! Perhaps my statements
are going to cause a heated debate, but, here I go:
I really do not see why everything has to communicate IP. What’s
wrong with having devices communicate in their own native languages and over
their desired (most optimal) media? What do we gain by having all devices
communicate IP if – and as you (Brian) suggested – we do not first
come up with the abstract model? We have a hammer?
With kind regards,
********************************
Michel
Kohanim, C.E.O
Universal
Devices, Inc.
(p)
818.631.0333
(f)
818.708.0755
http://www.universal-devices.com
********************************
From: Brian Frank
[mailto:brian@skyfoundry.com]
Sent: Tuesday, March 31, 2009 11:11 AM
To: smartgrid-interest@lists.oasis-open.org
Subject: Re: [smartgrid-interest] Draft Charter - Energy Market
Information Exchange
Couple of my thoughts since Toby cross-posted some of my
oBIX ideas...
I don't suspect that many in this group need to be convinced that technologies
like 6LoWPAN create the opportunity to communicate IP all the way out to the
edge. In fact, it is hard to imagine using anything but IP for
communication these days - even for sub $10 devices (legacy devices excluded of
course).
But just because a 6LoWPAN device speaks IP doesn't necessarily mean that it
going to run a SOAP stack:
- These are typically sub-3$ dollar microprocessors with less than 100KB
of memory
- Low end wireless networks don't run TCP well, only UDP; this
means common techniques for end-to-end security such as TLS are not available
- Payload size on a 6LoWPAN packet is ideally less than ~80 bytes
- 6LoWPAN nodes spend most of their time sleeping which makes
communication difficult
But these are all surmountable problems if you define an information model
which works well end-to-end. Translating between protocols (HTTP-to-UDP)
is pretty easy. Translating between data encodings is also easy
(XML-to-Binary). But translating between data models is really, really
hard and almost always results in a degradation of information.
So my perspective is that the most important task is define the abstract
model. Then you can apply different protocols and encoding as needed as
long as everyone is working off the same basic ontology.
This is exactly what oBIX does. It defines a very simple, but powerful
meta-model for building models. The oBIX meta-model is based on type
theory that embraces the notion that modeling the real-world is a messy and
inexact science. But it turns out to work really well for simple sensors
all the way up to million point SCADA systems.
Brian