Re: [OT] AxKit for web applications

[S Woodside]

I think this is a bit off-topic but still interesting.

On Friday, February 7, 2003, at 03:51  PM, Tod Harter wrote:

Well, I'm not an expert on RNG by any means, so I won't get into a debate
about which is better. I expect it depends on the task... SOME form of schema
is very necessary however for many applications. When you say below "let the
software figure out" the way the software figures out IS TO USE A SCHEMA!!!
Thats what a schema is for, is to let a piece of software know how to tell if
the document its validating is actually a valid instance or not.

There's a big difference, though, between validating the structure of the document and validating the data. Also, using a (structural) schema implies a certain level of formalism, that can be very useful and important but isn't always necessary. Actually, I think in many cases writing an XSLT implies a schema even if you don't have one written up.

Data types
in XML are just a part of that, a shorthand if you will, so that if you say
"oh thats a date" then you don't have to spell out that its text with
DD::MM::YYYY (or whatever) and deal with all the possibly acceptable minor
subvariations thereof on your own. XML data types when used in things like
XML Schema or RNG just moves a lot of definition to another level, and in the
process insures that because that level is standardized its more likely to be
adhered to in more places.

Well, not exactly. I've been looking at schemas that are too formal on dates (picking on that example, because it's shown up most often as a problem for me), e.g. instead of having <date/> they have <year/><month/><day/>, or else they use WXS typing expressions to try to define what a proper date looks like. Well, what if I want to type in February 5, 2001, instead of 2001/02/05 ? Or Feb 5, 01, or 2002/Feb/5 or whatever. I think the best way to handle this is to just have <date/> and let the application that needs to do something intelligent with the date figure it out. Push the intelligence to the edge of the network, because there's plenty of code out there that can take a string that's supposed to be a date and figure it out.

SQL and XML are meant to solve different problems. They can be complementary
in some cases or alternatives in others, but mastering both the relational
and tree/hedge/graph ways of representing data is necessary to have a
complete basis in data processing theory and practice. Just as its necessary
to understand both declarative and procedural/OO systems on the processing
side.

Right, I'm not saying SQL is a bad thing, just that I don't like it. I think that it's very cool that XML is flexible and self-describing. Part of my angst comes from my impression that it's moving towards strong typing and that's a bad thing. Heck, perl is not strongly-typed, Objective-C is not strongly type, and really those are my languages of choice right now, and both are perfectly capable of high-powered tasks.

simon

---
www.simonwoodside.com


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