XML again

Mark Koennecke Mark.Koennecke at psi.ch
Wed Jan 9 13:58:57 GMT 2002

Dear Alan,

On Wed, 9 Jan 2002, A.Buteau wrote:

> Mark Koennecke wrote: 
> > Currently there are no plans for the development of a separate NeXus-API 
> >   for XML. You are the first one lobbying for this. 
> > 
> of the API . We can imagine that without changing the API but just by setting a 
> flag,the NeXus library write the file in XML or HDF format. 
  True, this can be done. This is the way how the HDF-4, HDF-5 switching 

> XML may be the "killer application" we were looking at (remember the
> workshop at the PSI) because, for many experiments with a low volume of data 
> (like triple axis, diffractometers with few detectors), it is really difficult 
> to convince scientists to adopt a binary format which is by many way difficult 
> to work with (for instance to get a simple plot with Excel or Kaleidagraph). 

  Does Excel or Kaleidograph support XML files? And if so which? XML is
  only a rule for describing an application language. So we can have a 
  variety of XML files with different tags for the same things which are
  still valid. 
> >  - a cron job triggers a progam any 24 hours which scans for new files
> >     and extracts interesting information (user, title, etc.) from new
> >     files and writes this information into a mySQL database. 
  Oops, sorry it is more like miniSQL from Hughes Technology. The scanning
  program is a C program. It has some degree of configurability, however.
> Did you write your scanning program with a scripting langage like perl or 
> python ? Is there a way to read NeXus files directly from a python or perl  
> script ? 

  There is an older package from Przemek which allows towork with NeXus
  files in Tcl. I do not know anything for perl or python. If I would have
  to do those languages it might be a good idea to try the swig scripting
  language interface generator on the raw NeXus API. 
> Ps: About NeXus WEb site 
> - the Nexus web site says nothing about HDF5 . Is it normal ? Is there any 
> place telling more about that 

  This has not been updated yet. We still consider the HDF-5 API somewhat
  beta software. Currently it is only available from the NeXus CVS 
  repository. There were a couple of postings about it in the napi and 
  nexus mailing lists. 


				Mark Koennecke

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