Saturday, July 3, 2010

On Reliability (rant: from Nikon to Hyatt)

In BACnet we have this notion, currently embodied in many objects and if I remember correctly (IIRC)* most but not all objects have a property named Reliability.**

The notion of "reliability" pervades BACnet.

Back in 1995 one of Alerton's founders decided we would not rely on BACnet COV ("Change of Value") notifications because BACnet allowed the COV-notifier device to forget the list of who was subscribed if the device reset or power was lost. This meant that any device that required some item of data (such as the classic "Outside Air Temperature") via COV had to re-subscribe at least at the longest interval it was willing to perform its calculations on out-of-date data. It was easier, and required less network traffic, simply to poll.

(Ironically Alerton's Ibex protocol uses COV quite extensively -- but without volatile subscriptions.)

In any event, I had put some time in on a proposal to improve the situation regarding COV servers in BACnet. That the committee not only did not reach consensus but last week split among various possible directions forward, resulting in my working successfully to kill my own proposal -- well, that's life. We discussed it, the concept failed, it's withdrawn, and I have filed a new approach that puts the onus where it belongs, on the subscriber, for more fun-filled debates in the next Objects & Services meeting this fall.

But the notion of "reliability" goes far beyond BACnet. [rant on]

I have a Nikon D70 digital SLR camera (dSLR), dead the second time for a failure in its "shutter block" -- a several hundred dollar repair and a now-known weakness in the camera. Do I spend a few hundred dollars to get it fixed yet again? For three years now, the answer has been "no."

The Nikon D70 died on a trip to Mt. Lassen (California) where I needed a good camera but the best available replacement locally was a Canon Powershot IS-3, like the D70 a 6 megapixel camera but a faux dSLR point&shoot: it has an eyepiece, but you look into a screen instead of through the lens. (This is good, actually, usually far better for shooting than camera-back screens though it has one of those too.)

However, this old Nikon fan hates to say it, but when you add the CHDK extensions to the Canon firmware, you end up with a camera with capabilities FAR beyond the Nikon. To have an active histogram before you press the shutter, for example -- priceless. (If possible I shoot using manual settings.) And there is so much more that CHDK does; all I'm lacking here is good glass, (Speedflash) hot shoe, and interchangeable lenses.

The Nikon S3 pocket camera's card ejector also failed. Takeaway: Nikons do not appear to be very reliable mechanically.

Nikon has lost a customer. Their new camera bodies won't take my old lenses; the old Nikon len$e$ will either revert to the film body (if I ever shoot film again) or be sold with everything else Nikon on eBay. I'm back at ground zero: when it comes to pass that I buy a new dSLR it will not be Nikon; it might be a Canon.


Hyatt fell flat on its face too this year. I've been a "Gold Passport" (I think that's the entry level on their program) member since 2003 though I have no recollection of staying at a Hyatt until this year. Hyatt gets some of it really right: check-in is quick and easy, very much unlike the glacially slow Hilton-chain process.

But like Nikon, Hyatt got it fatally wrong. In the past couple of months I stayed at Hyatts in Santa Clara CA and Albuquerque for conferences. I have no personal complaint with either, but in both cases a well-known colleague arrived late only to be told, yes, he had a reservation but they didn't have a room! (The second time he had called ahead to advise of his late arrival.) They put him up overnight in some other hotel and in Albuquerque they wanted him to stay at that other hotel. This goes far beyond unacceptable.

It has cost them a little already; for the ASHRAE winter meeting I reluctantly booked the Las Vegas Hilton (HQ hotel) before it filled up -- not that great a hotel but with relatively convenient access to the conference center, good for one with mobility issues. I had to make the Hilton reservation instantly upon announcement (received in the airport halfway to the summer meeting now concluded!) and had been considering a subsequent switch to the Las Vegas Hyatt, but definitely not now.

Lessons learned: Don't buy Nikon and don't book Hyatt. [rant off]

Reliability. It's a really important property and not just in BACnet.

* It's 4 AM, I'm wide awake, and I am on my home computer which does not contain a copy of the BACnet standard -- what elements in this picture are wrong!?

** Without a copy immediately at hand to confirm, this may change with one of the addenda going to public review; among the sweeping improvements to the BACnet alarm system was the introduction of the notion of "Reliability" to objects that never had it before, such as the Schedule object. It doesn't have runtime issues such as a dead sensor but it can detect misconfiguration such as scheduled writes of analog values to an on/off relay control: if you tell a relay "go to 5.375," what is it supposed to do?

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