[Nexus] NAPI-Release 4.3.0, Nexus Application definitions 3.1

Mark Koennecke Mark.Koennecke at psi.ch
Thu Feb 7 14:44:29 GMT 2013

Hi everyone,

I am pleased to announce the release of:

  - The NeXus-API 4.3
  - And the NeXus Application Definitions 3.1.0

The NeXus-API 4.3  can be downloaded from: 
The NeXus Application Definitions from: 

The NeXus-API 4.3

This is mainly a bug fix release but we do have a couple of new feautures:
- We now allow 64 bit dimensions when creating and interacting with 
   This solved a problem for the guys writing lots of event data at SNS 
and ISIS.
- The NAPI now requires HDF-5 version 1.8 and above. HDF-5 1.6 is 
deprecated. The new
   version of HDF-5 allowed us to do some things, espcially regarding 
external linking,
   much better then they were before.
- Up To NAPI 4.2 only the first dimension of a dataset could be 
unlimited. This restriction
   has now been lifted for NAPI 4.3 with HDF-5. All dimensions can now 
be unlimited.
- Included in the release kit is an alpha version of a higher level 
python tree API for
   NeXus which allows to read a NeXus file with one call.

NeXus Application Definitions 3.1.0

This is the first release of a set of application definitions for 
various classes of
instruments. An application definition is a strict standard of required 
data fields for
a specific use case of NeXus. The version 3.1 is misleading, it is 
really a 1.0 release.
The NIAC has decided to release this now after having waited for 
feedback from the community
for much to long on our candidate application definitions. There are 
currently definitions

  * archived data
  * direct geometry TOF spectrometer
  * X-ray fluorescence
  * indirect geometry TOF
  *  I(Q) processed data
  * TOF laue
  * monochromatic powder diffraction
  * scanning mode reflectometer
  * TOF reflectometer
  * Small Angle Scattering including related techniques
  * TOF small angle scattering
  * Simple scan
  * S(Q,OM) processed data
  * triple axis spectrometer
  * TOF neutron powder diffraction
  * TOF raw data for a generic TOF instrument
  * tomohraphy raw data
  * phase contrast tomography raw data
  * processed tomography data
  * X-ray absorption spectroscopy
  * X-ray absorption spectrosocopy raw data
  * Eulerian cradle single crystal diffractometer with or without area 
  * Kappa single crystal diffractometer with or without area detector
  * Normal beam geometry single crystal diffractometer with or without 
area detector
  * Laue diffratometer
  * Laue diffractometer with image plate
  * PX rotation camera

We hope for lively discussion about these application definitions. As 
long as no data
complying to these application definitions has been written the NIAC is 
very willing
to improve these applicaton definitions in collaboration with the 
respective communities.
We are ready to ship  an updated 1.1 release of application definitions 
as soon as the
first storm of comments is done with.

The application definition release also contains a copy of the new 
upgraded NeXus manual.
Much work went this manual in order to make it consistent, readable and 
up to date.

Further NeXus News

* The company DECTRIS is going to use NeXus-HDF5 to store data from 
their upcoming EIGER
   series of detectors. The detector is so fast that the CBF format used 
with Pilatus
   detectors  cannot keep up. The programming model will be that the 
EIGER server
   writes the detector part of the NeXus file and the local DAQ system 
adds metadata to
   the file.
* At a recent EIGER workshop in Baden data aquisition and data analysis 
people met
   and decided to agree on and implement a couple of NeXus application 
definitions in
   the next few months.
* In response to demands from the community, we have documented how to 
   NeXus compliant HDF files using the HDF APIS alone. This is a very 
short section
   in the new manual.
* The NeXus WWW-site at http://www.nexusformat.org has been refurbished. 
Its content
   is now automatically generated from the manual. And as the manual is 
up to date, so
   is the WWW-site.
* The CIF way to describe instrument component positions and 
orientations through the
   application of transformations has been integrated into NeXus.
* In summer, there will be a meeting between IUCR-CIF representatives 
and NIAC members
   in order to  discuss a closer collaboration/mapping between CIF and 

I thank all volunteers for all the good work which went into this release.

Best Regards,

        Mark Koennecke
        on behalf of the NIAC

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