RE: Hostility to "binary XML" (was Re: XML 2004 webl
> From: Liam Quin [mailto:liam@w...] > Sent: Monday, November 22, 2004 1:34 PM > > On Mon, Nov 22, 2004 at 01:09:06PM -0800, Derek Denny-Brown wrote: > > Most of the CPU cost of parsing is related to the abstract model > > of XML, not the text parsing: Duplicate attribute detection, > > character checking, namespace resolution/checking. Every binary-xml > > implementation I have researched which improves CPU utilization does > > so by skipping checks such as these. At that point you are no longer > > talking about XML. > > One can do validation in the writer and then plausibly skip the sort of > checks you mention in a reader, and still be talking about XML, even > with today's textual interchange formats. The problem with that is that it now becomes possible to load invalid XML. Yes, that means you are using a non-conformant writer, but when dealing with data formats designed for interop, the receiver should be conservative, which means checks. If it is an error for there to be two attributes with the same name, then it should either be impossible to represent, or checked in the reader. Anything else is asking for trouble. That doesn't mean that parsers can't provide options to turn off expensive checks, just that they should be enabled by default for a generic implementation. > > I have yet to hear of any proposed solution which successfully > > balances the different demands. I'm not sure it is possible, without > > creating a homunculus. > > Neither am I, which is why W3C has a Working Group to investiate whether > it might be possible, rather than a WG to implement a homunculus :-) And I totally concur with others, that spending the time to really do some serious requirements gathering is key, and am glad to see it happening. -derek
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