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

[cbullard@hiwaay.net]

Seems like we've been here before:

1.  Complexity of the expression (an instance of the language)
2.  Complexity of the expressible (the space of all possible expressions)
3.  Fitness for the expressed (given some goal, is the expression fit,  
that is, will it be understood in the most efficient way)

Of these, the controls over the evolution of the language affect what  
is expressible and all too often that interferes with the fitness for  
the expressed:  a common problem of type definitions where too many  
document types are captured under a single root.  IOW, there are  
co-occurring requirements from the controlling dimensions that create  
strong consensus but weak control.

Over time, increased expressibility weakens the practice.  This  
weakens production and evolution (Where evolution is learning applied  
to practice).

There are two basic approaches both of which are used at different  
phases of learning by doing:

1.  Vikings: 12 stout men and a boat.
2.  Next generation Vikings:  12 stout men, a boat, and a map.

The number of wise men, priests and kings who must touch the map  
before the voyage approximate the number of wrinkles in the map.   
Excessively wrinkled maps become dangerous and if over annotated,  
almost useless.

len


Quoting 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
>
>
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