Future of NeXus

[Mark Koennecke]

On Mon, 19 Jun 2000, Ray Osborn wrote:

> The SNS is extremely interested in adopting NeXus as their standard format,
> but want us to assure them that we do intend to migrate to HDF5.  The reason
> is that they anticipate needing larger files than HDF4 permits (2GB, I
> think) and think the HDF5 performance will more closely meet their needs. 
> 
> We have, of course, discussed this before, and I think the general consensus
> then was that we would definitely migrate at some stage, but that we were
> holding off until there was greater third-party support.  
> 
> While accepting that, I don't think that we are going to be able to hold off
> the migration for too long, since it will only make it more difficult to
> make the transition.  

  Ray,

  hold on! Within a european SCANS project there will soon be a person to
  work halftime at NeXus. Hers or his first project should be a
  reimplementation of the NeXus-API in HDF5. At least that is what I
  thought. I would have placed a message with our plans into this mailing
  list as soon as we know when this person actually starts for everybody
  to object or aprove. When will soon be? We have a candidate, actually I
  believe even two, but the swiss authorities are very slow in confirming
  the position.   

The issue of third-party tools won't be so serious
> once our own tools become better developed.  For example, do we need IDL
> support for HDF5, or can we implement Mark's IDL interface as external
> procedures?  

  If RSI is too slow with HDF5 support we can use IDL's C-API for NeXus5
  support. This can become maintaince nightmare though as we would need
  to maintain shared libraries for a couple of platforms. 

On the other hand, there isn't even a VMS version of the HDF5
> library yet, so I'm not saying we make the transition tomorrow (actually, we
> might have to do that one ourselves - any volunteers).

  Are there many people insisting on this? VMS is slowly being phased
  out.......
 
> I hope that those of you who attended thought that NeXus was
> well-represented at NOBUGS.  I've read the abstracts, and would like to
> update the web pages with some of the new stuff you presented e.g. on the
> XML proposal, web servers at PSI, and the NIST open source effort.  

  I'll send you something. At NOBUGS it turned out that people feel a need
  for a Java-NeXus-API. We probably have to do that on top of NeXus and
  JNI. 

  Furthermore I think it is time to have another SoftNESS meeting in order
  to nail out a procedure for verifying instrument type descriptions or a
  more complete glossary. Perhaps we use Chris XML ideas for verification. 

 
                           Cheers,

                                    Mark