Re: XML and Octave: review of tools

[Alois Schloegl]

Hi Andy,

Andy Adler wrote:

> Alois,
>
> A few comments about XML and Octave.
>
> - Matlab does not have a proper / approved XML
>  approach yet. They may very well invent one in the
>  future, and we will be almost certainly incompatible.
>  
I agree that Mathworks does not have a proper approach. However, XMLTREE 
is very useful, it is GPL and it will stay around. If we provide a 
solution that works on both platforms, who cares if Mathworks tries to 
do it differently.

> - XML approaches based on the classic parsers (DOM, SAX)
>  suck. They make the programmer write way too much
>  code, and encourage broken micro-optimizations.
>
>  For a detailed rant about problems with XML, see my
>  talk: "10 Mistakes with XML and Perl"
>   http://www.site.uottawa.ca/~adler/talks/2003/YAPC-CA-2003-XML-talk.pdf
>  
I enjoyed reading these slides of yours. It shows many possible pitfalls 
in supporting XML.
However, there is no way around XML - everyone is using. And now also 
the OpenDocumentFormat (ODF) is based on XML, we have to deal with it on 
one way or another.
 

> - A good / easy to use approach needs to provide vectorized
>  output. This means we cannot iterate to read the XML
>  structure.
>
> As you point out, none of the current offerings are
> satisfactory for various reasons (reading all xml files,
> code complexity).
>
> Before we put effort into this, could we have a discussion
> on this list of what we want to get out of XML tools
> for Octave.
>  
For most applications, a result similar to the output of XMLTREE would 
be sufficient.
Using a modified version of XMLTREE, I'm already able to load ODF data 
into the workspace.

> As a start, we can compare to what is offered by other
> scripting languages. I propose something like XML::Simple
> in perl.
>  

Do you suggest to use XML::Simple for reading XML data into Octave? Or 
do you suggest to (re-)implement something similar within Octave?


Alois


> --
> Andy Adler <address@hidden> 1(613)562-5800x6218
>
> On Wed, 26 Apr 2006, Alois Schloegl wrote:
>
>  
>
> > XML support would important for a variaty of data formats. For example,
> > it would also enable a simple interface to the ODF-spreadsheet format.
> > In order to indentify the most useful approach, I was investigating the
> > various XML tools available. Here is the result:
> >
> > (1) There are XMLREAD and XMLWRITE in Octave-forge. That these functions
> > support (only) XML data which follow octave.dtd; other .DTD's are not
> > supported.
> >
> > (2) Then, there is XMLTREE from http://www.artefact.tk/software/matlab/xml/
> > It is GPL,  but  it uses object-oriented language elements which are not
> > (yet?) supported in Octave.
> > Although, XMLTREE extracts only parts of the information in XML files,
> > it seems to be the most powerful and flexible approach for reading XML
> > files.
> >
> > (3) XML-toolbox from http://www.geodise.org/downloads/ :
> > BSD-like license, The software is distributed as p-code, the m-files
> > contain just the help documentation.
> > Therefore, it can not be used with Octave.
> >
> > (4) And there is XML4MAT from http://xml4mat.sourceforge.net/
> > It is GPL and come as pure M-file, this would be suitable for Octave.
> > However, it requires REGEXPREP. Paul Kienzle did a M-file implemenation
> > - Thanks - its already in Octave-forge; an oct-implementation will
> > certainly improve speed.
> > Unfortunately, XML4MAT does not work with all XML-files. For example,
> > it does not work for  the XML files extracted from an ODF spreadsheet.
> >
> > (5) Finally, there is the attempt to use LIBXML for reading XML files.
> > Muthu is familiar with libxml2 and will look into this.
> >
> > Any thoughts on that ? Did I miss any other approach on XML support in
> > Octave?
> > Currently, no solution is fully satisfying. If anyone is interested
> > working on this, I can provide a suite of XML files for testing and/or
> > I'm willing to do the tests.
> >
> >
> > Alois
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