Re: [xml-dev] What is declarative XML? (And what's not)

[Peter Hunsberger <peter.hunsberger@gmail.com>]

On Wed, Jun 3, 2009 at 6:31 PM, Costello, Roger L. <costello@mitre.org> wrote:
>
> Hi Folks,
>
> I'd like for us to nail down exactly what we mean by "descriptive markup" and "algorithmic markup."

Ok, I'll bite, why?

> Here's a stab at it:
>
>
> 1. XML documents just contain markup and data. There are no semantics in XML documents. An XML document is just syntax.
>

XML documents describe a graph.  Computer programs describe a graph.
The semantics are dependent on who / what is traversing the graph.

>
> 2. A software application can be written to perform specific, repeatable actions when it encounters markup in an XML instance document. Stated differently, applications can be written to add a layer of semantics on top of the XML syntax.
>

See above  :-)  But the applications aren't "adding" anything, rather
they are expecting the syntax of the XML to map to the syntax expected
by the application so that they can interpret the semantics in
accordance to the vocabulary the application and the XML presumably
share.

> 3. When creating an XML vocabulary, it is common practice to write prose that specifies semantics for the XML vocabulary. Then software applications can be written to implement the semantics specified by the prose.
>

The semantics can be stored as meta data (a third graph), external to
both the XML and the application if one wishes...

>
> 4. Sometimes the prose just assigns a definition to each element and attribute in the XML vocabulary. Software applications that implement these semantics "understands" the XML vocabulary. These applications don't execute any actions when given an XML instance document, beyond simply informing itself. For these applications the markup is purely informational or descriptive.
>
>    For applications faithful to the semantics
>    specified by the prose, the XML vocabulary
>    is descriptive markup.
>

How is this useful?  Configuration?  I believe you are grasping for
something more...

>
> 5. Sometimes the prose associates actions to each element and attribute in the XML vocabulary. Software applications that implement these semantics will execute the actions when given an XML instance document. For these applications the markup represents instructions or prescriptions.
>
>    For applications faithful to the semantics
>    specified by the prose, the XML vocabulary
>    is algorithmic markup.
>
>
> I'm sure that these can be expressed more clearly. I welcome your suggestions.
>

It's not clear what distinction you are trying to draw.  As such, it's
not clear how to clarify it....

--
Peter Hunsberger