FW: Problems related to HTCPCP/1.0

Larry Masinter (masinter@parc.xerox.com)
Thu, 9 Sep 1999 21:06:19 PDT

(first distribution of this lost)

I attribute most of his difficulties to SSDP/HTTPU layer of UPnP,
and the reimplementation of HTCPCP without proper checks for
buffer overflow, results out-of-order, or too-many-coffee-pots.
Certainly a cause of unreliability.

-----Original Message-----
From: Ron Sherwood <Sherwood@islands.vi>
Sent: Monday, September 06, 1999 7:24 AM
To: masinter@parc.xerox.com
Subject: Problems related to HTCPCP/1.0

Dear Mr. Masinter:

I recently became aware of a copy of the HTCPC protocol that you
were instrumental in distributing.

I used it immediately to write a subroutine for my HALAN (Household
Appliance Local Area Network) system. Everything worked fine until I ran
across a conflict between the KAIDP (Kitchen Appliance Ingredient
Dispensing Protocol) and the UAIRDP (Universal Apliance Ingredient
Receptical Description Protocol). The net result was somewhat of a disaster.

The first thing that happened was that the timing script called for the
coffee maker to complete its operation at exactly 7:00am. The ATCOC
(Appliance Timing Control Object Code) correctly calculated that the coffee
making appliance needed 8 minutes and 17 seconds to complete the BREW
program for 2 (6.oz) cups of coffee. Unfortunately (at exactly 6:51:43am)
the subroutine called for the PWSD (Potable Water Supply Dispenser) to load
the coffee maker with 13.47 oz of water since the KAIQCOC (Kitchen Appliance
Ingredient Quantity Control Object Code) had correctly calculated that the
addition of 1.47oz of water would be required to compensate for evaporation

I use the word unfortunate because the conflict between the KAIDP and
the UAIRDP caused the HFSSP (Household Fuel Supply Systems Protocol) to
initiate the introduction of 13.47oz of white spirit from the LFOLS (Luau
Firepot Outdoor Lighting System) into the coffee maker heating chamber. At
the same time the error capture code failed and the KAIDP delivered 2
rounded tablespoons of finely ground Blue Mountain coffee to the PIULD
(Personal Intimate Use Lubrication Device).

Well, it was about 6:59am, while I was standing under a cold shower in
an attempt to reduce the pain suffered as as result of the last error, when
the coffee maker attempted to eject the superheated white spirit from the
heating chamber into the coffee carafe which sits on the heating plate at
the base of the coffee machine.

Unfortunately the conflict between KAIDP and UIARDP had caused the
coffee carafe to be relocated to the SDR (Sanitary Disposal Receptical). The
result was that the stream of superheated white spirit was delivered
directly to the coffee maker hot plate where it immediately evaporated and
the vapor collected in the upper area of the coffee maker control housing.

At exactly 7:00am this morning the HTCPCP code caused the coffee maker
to announce the completion of the BREW cycle by closing the "coffee ready"
alarm relay. The tiny spark between the the relay contacts ignited the white
spirit vapor in the coffee maker control housing causing an explosion of
some consequence.

The location of the coffee maker on the kitchen counter, under the
UHRSADC (Universal Household Resource Supply And Distribution Center), appears
to be an unfortunate choice. The explosion seems to have affected the
UHRSADC control module, for immediately after the mishap the module sent an
incorrect command to the HPAWDCS (Household Plumbing And Waste Disposal
Control System). As a result of this command the HPAWDCS closed the city
water supply valve and opened the septic tank effluent diversion valve. This
would not have mattered except that the closure of the city water supply
valve caused the automatic opening of the emergency water containment valve
just as the diverted septic tank effluent was being redirected to that

It was very fortunate that I leapt from the shower soon after I realized
that the water I was using had been replaced with the septic tank effluent,
for the HPAWDCS closure of the waste disposal valve had caused the shower
drain to be closed off and there was no way for the incoming septic tank
effluent to drain away. As the bathroom continued to fill with effluent and
I ran to escape, I noticed an additional offensive smell. It appeared that
the damaged UHRSADC had diverted the cooking stove gas supply to the CCAES
(Climate Control Atmospheric Enhancement System).

In order to close the natural gas emergency cut off valve which is
located at the kerbside I had to run from the house without time to clean
the septic tank effluent from my body or to collect clothes with which to
cover myself. As I was bending over the gas valve access point at the
kerbside, two police patrolmen (complaining bitterly about my offensive
condition) dragged me into their car. They did not heed my warning that
there was an immediate need to restrict the flow of gas into my house.

It was approximately 7:05am when one of the police officers rang the
doorbell of my house to see if there was anyone who could account for my
condition. The spark from the bell clapper relay ignited the gas filled
house which exploded into a fireball killing my wife and the police officer
at the door.

While I was attempting to explained the sequence of these events to the
investigating officers at the police station... they offered me a cup of

Ron Sherwood