RE: 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.

> One of the big problems I see with XML (and one that, for some reason, I
> have a hard time getting across) is that everyone gets all excited saying
> "Hey, now we have a common file format...hoorah!".  
Indeed! I've seen so many people that think Microsoft Word is now an
open format, because they use XML to store their information :-)
And I am pretty sure they will not release the accompanying Schema any
time soon :-)

[...]
> There is a considerable effort required to define meaning and that
> is why I keep bringing up Modelica...because it defines not just
> what the files should look like, but what they mean (i.e. their
> semantics).

I _fully_ understand that! And second it.
(BTW, my bringing up Bond Graphs is motivated by the same reasons :-)
Both "communities" are doing exactly the same things, but they speak
another language... Remember what I said about the importance of
terminology in a previous email? I think I am one of the few people
that has done (or rather, is trying to do) a fair effort in
understanding both languages, and seeing where the differences are.
(There are none... as it should be.)

Herman
-- 
  K.U.Leuven, Mechanical Engineering, Robotics Research Group
<http://people.mech.kuleuven.ac.be/~bruyninc> Tel: +32 16 322480