> Any constraints that are missing from the schema have to be recreated separately in each implementation Not true at all. The server can implement them -- on

> Any constraints that are missing from the schema have to be recreated separately in each implementation Not true at all. The server can implement them -- once -- and any client who makes an invalid request to the server will get an error message. These constraints can be expressed in comments in the interface (.proto) file. > Like HTML vs. XHTML—I shudder to think how much work was wasted trying to handle the worst tag soup imaginable, simply for lack of a well-formedness (or DTD validity) requirement. HTML and XHTML is a completely different ball of wax. Insisting on even well-formedness is simply unreasonable in practice, because it is so difficult to ensure, and it is the user who pays the price when the software isn't perfect. If you're still convinced that the world would have been better if strict XHTML had won, you should read: http://diveintomark.org/archives/2004/01/14/thought_experiment http://diveintomark.org/archives/2004/01/14/thought_experime...