Re: XML and VisAD.

• To: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Subject: Re: XML and VisAD.
• From: "Armin S. A. Roehrl" <Armin.Roehrl@xxxxxxx>
• Date: Fri, 10 Dec 1999 12:43:50 +0100

Hello, I'm far from an XML expert, but I believe in XML for data
interchange.
and use it in one other project.
> 
> No one I know of is currently working on an XML adapter for
> VisAD, but it would be a good thing.  Ideally it would be an
> extension of visad.data.Form and reside in the visad.data.xml
> package.  It would require some decisions about how XML fields
> get mapped to the VisAD data model.  Certainly a table full of
> records with named fields could be mapped to a FunctionType
> like:
> 
>   (index -> (field1, field2, ..., fieldN))
> 
> where 'index' is just an ordinal record number in the table,
> and the fields may be either numerical or text.  You could
> also do nested tables as nested FunctionTypes.

> I don't know enough about XML to know if it defines standard
> fields for units, coordinate systems, topologies, missing
> values, etc.

You can define any units, coordinate systems, etc. in DTDs -- it doesn't
support anyuthing like that by default.
The problem is that XML on purpose doesn't do anything like
type-checking.
i.e. you can't say that a field in a DTD must be a positive integer.

> 
> If you or anyone wants to do any of this, we will be supportive
> and also interested in helping to make your work available to
> the VisAD community, by web links or inclusion of source with
> our distribution.
Right now, I have really tight constraints, but if s.b. else helps,
I'd try my best to help.

We would have to do two things:
-think about the DTDs we're interested in to give meaningful
describtion.
-finally do the coding, but that is the easier part, as really good XML
parsers
 exist.         

Thanks
        Armin

• Follow-Ups:
  • RE: XML and VisAD.
    • From: John Caron

• References:
  • XML and Visad.
    • From: Armin S. A. Roehrl
  • Re: XML and VisAD.
    • From: Bill Hibbard