RE: Re: dynamics: comment about MBdyn...

> -----Original Message-----
> From: Herman Bruyninckx [mailto:[email protected]]
> Subject: RE: [Orocos] Re: dynamics: comment about MBdyn...
> 
> 
> On Tue, 15 Jul 2003, Tiller, Michael (M.M.) wrote:
> 
> [... XML is easy to "parse"...]
> 
> > The key thing is that "Syntax is not semantics".  Don't get me
> > wrong, XML is a very nice technology and I use it every 
> chance I get.  But
> > it only covers the *SYNTAX*.  Modelica is much more than 
> that.  Only a small
> > part of the specification covers syntax.  
> 
> INdeed, and that's what the Schema's (formerly DTDs) are for: they
> attach information about what is _meant_ with the parsed symbols.
> So, I think Modelica would now talk about its XML and Schema
> standards, instead of about its file format.

Not quite...schemas and DTDs only cover the structure of the file.  They describe the grammar (what elements can appear nested what other elements, what attributes are associated with what nodes, etc).  They still don't cover meaning.

Remember my description of parsing?  I had #1 (lexical analysis), #2 (grammatical parsing) and #3 (tree walking).  XML covers #1, DTDs really describe what should happen in #2.  Things like XSLT are closer to #3 (not quite the right fit because XSLT is a language for doing #3, not the actions in #3 which is where the meaning is).

--
Mike