Re: [xml-dev] When to Validate XML Guidelines

[David Brownell <david-b@pacbell.net>]

> Early Validation, validate as early as possible, i.e. if you send XML,
> insure it's valid, if you process XML, assume it's valid. It's not
> feasible to let both validate. Validation is always necessary, since
> processing applications must assume some general structure of the
> document.

Unless you control the document sender/creator and have some
reason to _know_ the document is valid, I'd say to assume it won't
be, and thus always validate inputs.  Not so different from any
other application, in short:  perimeter security is essential.

Validation adds maybe 10% to parsing time, which is rarely as
much as 5% of the overall application cost.  That means well
under one percent extra time spent on checking/conditioning
inputs ... would you rather risk bad data entering your database,
or pay an imperceptible increment in latency?  :)

So I guess I'm disagreeing with Bjoern since I don't want to
trust the other end enough to believe it won't send bad data
that'll break something on my end.  Unless maybe the other
end is under my control.

- Dave