Re: [xml-dev] Build Rich Complexity from a Small Set ofWell-Defined Mark

[rjelliffe <rjelliffe@allette.com.au>]

 On Wed, 24 Aug 2011 10:16:23 -0400, "Costello, Roger L." 
 <costello@mitre.org> wrote:

> Interestingly, XML Schemas is considered to be a complicated
> language. Perhaps 7 markup combinators are too many in a markup
> language?

 I'd say what people call complexity comes from two things:

  1) application power: is it easy to express the kinds of thing I am 
 interested in expressing?

  2) how memorable is it? does my normal routine reinforce my memory of 
 its details or let them fade?

  3) how many caveats or special cases pr multiple ways to do the same 
 thing does it have?

 The first relates to the problems being addressed and the scientific 
 limits to the technology.

 The second relates to people's tasks and the amount the schema language 
 re-uses concepts/syntax/vocabulary/models from elsewhere: if you use 
 DTDs everyday, XML Schemas will not be so complex; if you use DTDs every 
 day, Schematron will not be so complex.

 XML Schemas rather suffers from low bangs per buck in the first case 
 (many flowing out of the requirement to act in a streaming fashion for 
 grammars), low connection with XML processing tasks in the second 
 (depending on whether you do schemas all day or not), and is riddled 
 with caveats and alternatives in the third case.
 
> When creating an XML markup language consider following this 
> approach:
>
>     1.  Create a small set of well-defined markup combinators. From
> experience with XML Schemas, 7 or less markup combinators might be
> adequate.
>     2.  Create well-defined mechanisms for combining the markup
> combinators. Again, from experience with XML Schemas, 4 or less
> combining mechanisms might be adequate.

 Lets take three things that contribute to XML Schema 1.0's perceived 
 complexity: @elementFormDefault, xsd:complexContent, and compex type 
 extension by suffixation only.  Where do they fit in your scheme?

 Cheers
 Rick Jelliffe