Why validate?

[Thomas B. Passin]

Thinking about "why validate", why did HTML become so wide-spread so fast?
I think that a big part of the reason is that almost anyone could learn how
to write usable pages quickly and with no formal training or programming
experience.  If validation or even DTDs without validation had been
required, most of those sites would never have sprouted up.  You looked at
the source for a page, and you could see the whole scheme behind HTML in a
few glances.  I had never heard of markup languages, and I remember thinking
"what an interesting way to do things".

And then the browsers were somewhat tolerant of mistakes, too.  I remember
writing quite a few HTML pages or fragments, which I did by copying ideas
from other pages.  And they worked!  The first few times I looked at the
HTML standard, I was revolted and couldn't get anyting useful out of it.

The same thing has been happening with css, although it's harder to pick up
on the fly.

Now, it's true you probably can't design a big e-commerce site these days by
just winging it this way.  Nor complex document managment systems.  But this
ease-of-use, fault-tolerant aspect is likely to be of major importance in
building wide usage and acceptance of XML (or "SML").  And this aspect does
not include validation and probably not DTDs either.  If we have developed a
truly good system in XML, it will be able to adapt well to both ends of the
spectrum.  HTML wasn't up to this.  XML, I think, has the possiblity of
being up to it.

Tom Passin

From: Henry S. Thompson <ht at cogsci.ed.ac.uk>


> Maybe I was overly influenced by the fact that my first exposure to
> pointy brackets was in the context of SGML, but I think validation is
> pretty fundamental.  A DTD is like a contract, it helps both
> clients and service providers to maintain a satisfactory working
> relationship.
>
> 1) As a client, I validate to save wasted round-trips when service
providers
> bounce my submissions for syntactic errors;
>
> 2) As a service provider, I validate to save resources, at two levels:
>
>   2a) During application development, the earlier phases of system
>       structure are much simpler and clearer because they don't mix
>       (syntactic) error detection and basic structure construction;
>
>   2b) During application operation, syntactic errors are detected and
>       reported in a standard way likely to be familiar to clients,
>       reducing handholding requirements.
>
> In my own development work, I find (2a) particularly pertinent,
> whether the applications involved are programs OR stylesheets.
>
> ht
> --



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