Re: [smartobjectdir] "Management" vs "control and telemetry"

[Fred Baker <[e-mail]>]

:-)

On Oct 9, 2011, at 5:11 PM, Vint Cerf wrote:

> If everyone interpreted my "management" suggestion as identical to
> SNMP, give me a break!
> 
> I was commenting on terminology and not invoking any particular protocol.
> 
> sheesh!
> 
> v
> 
> 
> On 10/9/11, Fred Baker <[e-mail]> wrote:
>> Let me step out on a limb here, one which Ersue and Dan will very quickly
>> try to saw off. I'm of the opinion that our "Management" protocols, SNMP and
>> NetConf, are very poorly suited to the world of Smart Objects, and that if
>> we simply describe this as "management" the Internet Community will dismiss
>> it as a previously solved problem.
>> 
>> Let me give you two relatively simple examples.
>> 
>> You will recall that when we were developing SNMP, we talked a lot about the
>> Internet Toaster, and that Epilogue developed a Toaster MIB (which can still
>> be found of you ask Google) to demonstrate the operation of it. The premise
>> of the Toaster MIB is that there is some central controller; someone places
>> bread into the toaster, wanders off to the toaster controller, and the
>> toaster controller might do a SET to put actuate the toaster, and then might
>> monitor is SNMP objects to see how things were going.
>> 
>> The simplest example is what I call the Internet Light Bulb, something on
>> which I have an internet draft half written. Let's imagine I have a single
>> light bulb (or a multicast group full of lightbulbs, but for the moment it
>> is one bulb) that is operated by two (or more) switches. Electrically,
>> that's not hard -
>> 
>>                            ,-.
>>         +-----|||---------(   )----------------+
>>         |                  `-'                 |
>>         |      /-------------------------      |
>>         +-----/                           /----+
>>                 -------------------------/
>> 
>> I have two switches, each with two positions. If they are both in the same
>> position current flows, and if they are in different positions current
>> doesn't flow.
>> 
>> In a building control environment (Echelon makes this product, and I am
>> describing their implementation), each switch has an identity and each light
>> bulb has an identity. When someone throws a switch, the switch announces "I
>> am X, and I command Y to go to the state 'ON'". Y receives the command,
>> verifies that it is still Y (all the other light bulbs receive it too, and
>> note that they are not Y), verifies that X is authorized to give it that
>> command, and turns itself on. It then announces "I am Y, and I am in the
>> state 'ON'". Each other switch X' receives the announcement, decides whether
>> it cares what state Y is in, and if so records that Y is in fact on.
>> Subsequently, if someone else tells another switch to turn Y on, it will do
>> nothing; Y is already on. But if someone throws any of the switches to turn
>> Y off, the switch will say "I am X', and I think Y should be off".
>> 
>> Here's a slightly more complex example: a thermostat. Somewhere, there is,
>> let's imagine, an energy management system. It is being told by the utility
>> that between this time and that the price is HIGH and is otherwise LOW. It
>> has a policy that includes telling the thermostat (at times this and that)
>> to change its thresholds. The thermostat, in turn, has two thresholds. If
>> the temperature falls below one temperature it will turn on the heat, and if
>> the temperature goes above that it will turn off the heat. If the
>> temperature rises above a second threshold it will turn on the air
>> conditioning, and if it falls below, it will turn the air conditioning off.
>> When the price is LOW, the two thresholds might be at 71 and 73 degrees
>> Fahrenheit respectively; when the price is HIGH, they might be at 68 and 78.
>> So the EMS might set the thresholds from time to time using whatever
>> protocol it likes, perhaps NetConf; when the thermostat observes the
>> temperature crossing one threshold or the other, it could report that to the
>> EMS and let the EMS send a command to the heater or the air conditioner;
>> more likely, it will announce that it thinks the temperature is "Cold",
>> "Nice", or "Hot", and the heater and the air conditioner will observe that
>> their policy is that when it is "Cold" or "Hot" (respectively) it policy
>> (controlled by the EMS) is to turn itself on, and when it is "Nice" to turn
>> itself off.
>> 
>> The information that needs to be exchanged, in each case, is the source's
>> identity ("I am X"), the target's identity ("I think that Y..."), a variable
>> name ("on/off status"), and a value ("on"). It also needs to announce a
>> method (it is reporting current state or it is requesting a state change),
>> and it needs whatever information is necessary to prove its identity.
>> Current equipment used in embedded systems - the stuff our proposed system
>> is trying to displace - does this (Echelon's equipment) in a total of 11K
>> ROM and 2-4K RAM for the entire system, never mind the management
>> interpreter. I know of no SNMP implementation that can do that, nor any XML
>> implementation, and they certainly don't use one protocol to read
>> information and another to write it. So for the purpose at hand, protocols I
>> am seeing presented as The One True Religion have implementers of existing
>> commercial systems telling me while giggling in their sleaves that they have
>> "no fear of real competition" from an IETF/IRTF implementation. That's
>> quote/unquote.
>> 
>> I could imagine the thing being in JavaScript Object Notation, a notation
>> designed along the lines of RFC 5545, or a variety of other approaches. My
>> point is S-I-M-P-L-E, and designed to enable conversations among actors in
>> the game but without religious dogma about who is a controller and who is
>> controlled. They are actors with state, and an actor might be a controller
>> or a controllee in subsequent milliseconds.