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

[rjelliffe@allette.com.au]

> Hi Folks,
>
> Thanks Rick, Frank, and Alexander for your comments. The distinction
> between validation and verification has been illuminating. Wikipedia says
> that validation is, "Are you building the right thing?" and verification
> is, "Are you building the thing right?" I've recast my diary to consist
> of, I think, entirely validations.

I still don't think they are mostly validations.

Validation is ex ante, verification more ex post.

So when you are checking that an incoming document is OK against a schema,
you are validating it: the pre-condition. When you check the result of a
process is OK against a schema, you are verifying it: the post-condition.

So checking the totals against the list, for example, is verification.

The water is muddy because in a single-party pipeline the verification of
a previous stage may be the validation requirement for the next.

Cheers
Rick Jelliffe


>
> -------------------------------------------------
>
> I wake up. I walk down stairs and get a can of V-8 juice from the 'frig.
> Before I open it I validate that its expiration date is greater than the
> date on my calendar.
>
>
> Tonight there's a nice movie on TV. I set the VCR to record the show. I
> validate the time and channel against that listed in the TV Guide.
>
>
> 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.
>
>
> The cashier tells me the total cost for the groceries. I validate the
> total against the total I computed on my calculator.
>
>
> Time for work. I start my car. My car's computer validates the sensor
> readings (oil level, fuel level, and engine RPM) against the
> factory-expected values.
>
>
> As I drive I pass a speed limit sign. I validate that the reading on my
> speedometer is less than or equal to that posted on the sign.
>
>
> My GPS tells me to, "Take the next right onto Route 3 south." I validate
> the sign at the entrance to confirm it says "Route 3 south."
>
>
>
> My GPS tells me to, "Take exit 27." I validate the sign on the exit ramp
> to confirm it says "exit 27."
>
>
> I arrive at the subway station. I need cash for the subway train. At the
> ATM I validate the amount it dispensed against the amount I entered on its
> keypad.
>
>
> Before getting on the subway train I validate that it is the right one by
> comparing the train number against the number listed on the directions
> that I brought with me.
>
>
> Before getting off the subway train I validate that the stop is the right
> one by comparing the name posted at the stop against the name listed on
> the directions that I brought with me.
>
>
> I arrive at the office. The guard validates that the picture on my badge
> matches my face.
>
>
> I need to FAX a document. I validate the direction of my document against
> the direction icon on the FAX machine. After FAX'ing I validate that my
> document was sent to the right number by examining the phone number on the
> FAX receipt against the phone number on my document.
>
>
> I check my inter-office mail. I received a letter. I validate that the
> mail stop number on the letter matches the number on my mail box.
>
>
> I need to send an email message. I validate that the recipient is in my
> address book.
>
>
> Time to go home. I need to first pick up a prescription. I validate that
> the prescription is correct (it is mine and the medicine is the right
> one).
>
>
> Time for bed. I check my calendar for tomorrow's meetings and validate
> that the alarm is set at least 3 hours prior to the first meeting.
>
> .........................................
>
> Validation is fundamental. It is not a one-time event - it occurs
> continuously. It confirms that my action is consistent with a "standard."
>
>
> /Roger
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