A tale about overdesign or how to embed a computer into toaster

How to make Toast:
Electrical Engineering vs. Computer Science

Once upon a time, in a kingdom not far from here, a
king summoned two of his advisors for a test. He showed
them both a shiny metal box with two slots in the top, a
control knob, and a lever. “What do you think this is?”

One advisor, an engineer, answered first. “It is a
toaster,” he said. The king asked, “How would you design
an embedded computer for it?” The engineer replied, “Using
a four-bit microcontroller, I would write a simple program
that reads the darkness knob and quantizes its position to
one of 16 shades of darkness, from snow white to coal black.
The program would use that darkness level as the index to a
16-element table of initial timer values. Then it would turn
on the heating elements and start the timer with the initial
value selected from the table. At the end of the time delay,
it would turn off the heat and pop up the toast. Come back
next week, and I’ll show you a working prototype.”

The second advisor, a computer scientist, immediately
recognized the danger of such short-sighted thinking. He
said, “Toasters don’t just turn bread into toast, they are
also used to warm frozen waffles. What you see before you is
really a breakfast food cooker. As the subjects of your kingdom
become more sophisticated, they will demand more capabilities.
They will need a breakfast food cooker that can also cook
sausage, fry bacon, and make scrambled eggs. A toaster that only
makes toast will soon be obsolete. If we don’t look to the
future, we will have to completely redesign the toaster in just
a few years.”

“With this in mind, we can formulate a more intelligent
solution to the problem. First, create a class of breakfast foods.
Specialize this class into subclasses: grains, pork, and poultry.
The specialization process should be repeated with grains divided
into toast, muffins, pancakes, and waffles; pork divided into
sausage, links, and bacon; and poultry divided into scrambled
eggs, hard- boiled eggs, poached eggs, fried eggs, and various
omelet classes.”

“The ham and cheese omelet class is worth special attention
because it must inherit characteristics from the pork, dairy,
and poultry classes. Thus, we see that the problem cannot be
properly solved without multiple inheritance. At run time, the
program must create the proper object and send a message to the
object that says, ‘Cook yourself.’ The semantics of this message
depend, of course, on the kind of object, so they have a different
meaning to a piece of toast than to scrambled eggs.”

“Reviewing the process so far, we see that the analysis
phase has revealed that the primary requirement is to cook any
kind of breakfast food. In the design phase, we have discovered
some derived requirements. Specifically, we need an object-oriented
language with multiple inheritance. Of course, users don’t want
the eggs to get cold while the bacon is frying, so concurrent
processing is required, too.”

“We must not forget the user interface. The lever that
lowers the food lacks versatility, and the darkness knob is
confusing. Users won’t buy the product unless it has a
user-friendly, graphical interface. When the breakfast cooker
is plugged in, users should see a cowboy boot on the screen.
Users click on it, and the message ‘Booting UNIX v.8.3’ appears
on the screen. (UNIX 8.3 should be out by the time the product
gets to the market.) Users can pull down a menu and click on
the foods they want to cook.”

“Having made the wise decision of specifying the software
first in the design phase, all that remains is to pick an
adequate hardware platform for the implementation phase. An
Intel 80386 with 8MB of memory, a 30MB hard disk, and a VGA
monitor should be sufficient. If you select a multitasking,
object oriented language that supports multiple inheritance
and has a built-in GUI, writing the program will be a snap.
(Imagine the difficulty we would have had if we had foolishly
allowed a hardware-first design strategy to lock us into a
four-bit microcontroller!).”

The king wisely had the computer scientist beheaded, and
they all lived happily ever after.

Source: http://web.cs.wpi.edu/~gogo/humor/hum_toast.html

P.S.: no wonder microservices are getting so popular.

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