Steve Jones: To use a physical engineering analogy, you check that the wing is put on properly as soon as it is attached, not by looking out of the window at 30,000ft to see if it is still there.
Clearly requiring validation for airplane wings prior to use is sane. Leaping from that point to requiring validation for all web based services is not only overkill, it actively creates an unacceptable level of impedance. That’s why most engineers talk in terms of tolerance. I would also assert that acceptable levels of tolerance differ depending on whether or not a given operation is safe or not.
That’s why I get irritated when people implicitly tightly couple the need for distributed extensibility with draconian processing. There always will be long tail requirements, and while I realize that that such requirements may be addressed in due course, that approach clearly doesn’t scale.
While I see some inspiration from Google Mobile Services, the right next step is to prototype my ideas and then to get the browser vendors to implement it first.