Re: [xml-dev] My Daily Diary of Validation

[Alexander Johannesen <alexander.johannesen@gmail.com>]

On Wed, Sep 30, 2009 at 04:37, Costello, Roger L. <costello@mitre.org> wrote:
> I wake up. Before entering the bathroom I validate that it is not occupied.

The door is old and rusty and sometimes doesn't open, even if someone
isn't in there. And, you've got explosive diarrhoea. There's only one
toilet in the house, and no one in the toilet is answering your
desperate call.

> I walk down stairs and get a can of V-8 juice from the 'frig. Before I open it I validate that the expiration date hasn't passed.

You're out of fresh juice, and the open bottle is two days out of
date. And you're deadly thirsty.

> Tonight there's a nice movie on TV. I set the VCR to  record the show. I validate that it is programmed correctly.

The video player still didn't record it. Did validation or the VCR fail?

> I'm short on groceries. I write a list of items I need. I go to the store and shop. When finished, I validate the items in my shopping cart against the items on my grocery list.

When you got to the grocery-shop, they didn't have any normal milk
left, but had plenty of lite milk, which you hate but the wife would
love you for getting. Also, the old smelly-socks cheese you always get
was out of date, but there's a slightly less smelly-socks but
oh-still-so-yummy cheese next to it. What to do?

> I pay for the groceries by check. I validate that the total purchase amount is less than the balance in my checking account.

The clerk thought your signature looked a bit funny, and is asking if
you don't have any other means of paying?

> Time for work. I start my car. I validate that the amount of fuel is greater than 1/8 tank (I have a rule that I get gas when the tank gets to 1/8 or less).

You have more than 1/8 left in the tank, but not more than 2/8. Should
you plan for a refueling session, or wait until it drops further?

> As I drive I validate that my speed doesn't exceed the posted limit.

A terrorist is on your tail, screaming he'll make you eat smelly-socks
without cheese if he catches you!

> When entering the  highway I validate that I am entering it in the
> correct direction.

The highway is taking you in the wrong direction.

> When exiting the highway I validate that I am taking the correct  exit.

What is the correct exit if your direction is lost?

> Before proceeding through the intersection I validate that the traffic
> signal is green.

You're a police-car in pursuit of a known terrorist, and the lights
are shifting to red just before your turn, letting the terrorist
through.

> Before turning I validate there are no oncoming cars.

Then, from behind a corner comes a speedy car flying, and a police car
in pursuit behind it! (The air is pugent of the smell of smelly
socks...)

[ and on and on and on ]

> Validation is fundamental.

Exceptions are fundamental. Validation is basic. Don't make systems
that only validate things; your systems will stop at every turn,
solving nothing.


Alex
-- 
 Project Wrangler, SOA, Information Alchemist, UX, RESTafarian, Topic Maps
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