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NeXus News and Updates

Saturday, December 14, 2002

• Another proposal made at the NOBUGS conference was that we set up an interactive web forum to allow anyone to suggest changes to the NeXus format. We have now set up the NeXus Swiki for this purpose. This is an implementation of a Wiki Wiki Web which allows visitors to edit the web pages directly in their browser. We welcome any constructive contributions, and just ask that you respect the guidelines that are referenced on the Swiki home page.

Monday, December 2, 2002

• Following a meeting of NeXus users and developers at the recent NOBUGS conference, we have decided to set up the NeXus Advisory Committee to oversee future developments of the format. The proposed Terms of Reference are given here. The membership of the committee will be nominated by neutron, x-ray, and muon facilities, and announced in the next few weeks.

Saturday, September 14, 2002

• This is the official release of version 2.0.0 of the NeXus API. Mark Koennecke and Uwe Filges have produced a version that will read and/or write both HDF4 and HDF5 files. This is transparent to the user (except when he/she is choosing to write either an HDF4 or HDF5 file), i.e., the API calls are identical for both sets of files. Being able to migrate from one underlying format to another is one of the reasons why we developed a separate API, so it is good to see that it works in practice. Also included in this release are two new utilities, NXtoXML and NXtoDTD, which convert existing NeXus files to XML, with and without data values respectively. NXtoDTD can be used to produce the skeleton of a NeXus metaDTD file from an existing NeXus file.

Monday, July 8, 2002

• We have created a new XML meta-DTD format for specifying the contents of NeXus files. These files are well-conformed DTD-less XML files, which therefore allow us to use standard XML forms to edit or display them. The aim is to make the instrument and other formats much more formally defined.

Thursday, December 14, 2000

• The first public workshop devoted to the NeXus format will occur from March 20-21, 2001, at PSI, near Zurich, Switzerland. Check the NeXus'2001 web page for further details.

Wednesday, December 6, 2000

• Version 1.3.3 of the API has been released. It includes a new routine, NXflush, to flush data to the output file, and the new Java API as part of the standard distribution.

Friday, October 20, 2000

• Mark Koennecke has released the initial version of NeXus API in the Java programming language. It uses the Java Native Methods Interface in order to access the C language NAPI calls, so it can only be used by Java applications, not by applets. A shared library is needed in order to run a NeXus for Java program.

Tuesday, September 5, 2000

• The NeXus FTP site has been moved to a (hopefully permanent) location at <ftp://ftp.neutron.anl.gov/nexus>. The API installation section has been updated accordingly.

Tuesday, June 20, 2000

• At the recent NOBUGS III conference, several members of the NeXus design team made presentations of their work on NeXus. Mark Koennecke described a java web-based data server and browser, Przemek Klosowski discussed efforts at NIST to build a Tcl/Tk-based data explorer, and Chris Moreton-Smith presented a proposal to formalize the NeXus format in XML. NeXus was also discussed in a data formats subgroup. Watch these pages for further developments.

Thursday, March 9, 2000

• Version 1.3.2 has now been released. It contains some enhancements to the functionality of the NeXus terminal browser, NXbrowse, including the ability to specify the file name in the command line and to dump data into an ASCII file. It also fixes potential problems when compiling on systems which do not use 4-byte int's and simplifies the interface between Fortran and C on Windows systems. See the release notes for more details.

Monday, January 24, 2000

• The latest version of the NeXus terminal browser, NXbrowse, is now written in ISO C (NXbrowse.c), and can be installed from the NAPI Makefile (i.e. make NXbrowse). See the section on NeXus browsers for more details.
• Four extra routines have been added to the C and F77 core API's. They are NXgetgroupinfo, NXinitgroupdir, NXgetattrinfo, and NXinitattrdir. NXinitgroupdir and NXinitattrdir allow the reinitialization of group and attribute searches using NXgetnextentry and NXgetnextattr respectively. The NeXus API version number is now 1.3.1.

Tuesday, December 14, 1999

• Following popular demand, Mark Koennecke has updated the NeXus API to include data compression. In the core API, compression is invoked by a call to NXcompress between calls to NXopendata and NXputdata.

  N.B. Mark Koennecke pointed out that earlier claims that NXcompress could be used with NXputslab are incorrect; if data are to be compressed, they must be written in one go using NXputdata. It may be possible to relax this constraint when appending data along an unlimited dimension. We will let you know when that's possible.

  The C, F77 and F90 API's have been updated. Data is automatically compressed in NXUwritedata (currently only a part of the F90 Utility API) if there has been a call to NXUsetcompress, which defines the compression algorithm and the minimum size of data set to be compressed (it makes no sense to compress very small arrays).
• The current version of the NeXus API is v1.3.0.

Wednesday, November 24, 1999

• There was yet another small error in the Fortran 90 example program. The call to NXUwriteglobals did not have the correct syntax. This has prompted a change to NXUwriteglobals to make all the arguments optional, allowing the use of the F90 keyword syntax when only a few attributes are to be written.

Monday, November 22, 1999

• The latest version of the ILL's popular data analysis package LAMP is able to read and write NeXus files. Although it normally requires an IDL license, they are also distributing a run-time version for various operating systems.

Friday, November 5, 1999

• The NeXus API has been re-released as version 1.2.1 under the terms of the GNU Lesser General Public License. While this maintains the freedom of use of the NeXus API available under the GNU General Public License, it allows commercial developers to incorporate the code into any software that is subsequently sold for profit. We feel that this should be beneficial to the NeXus community in the long run. If you have any comments on this decision, please send them to the NeXus mailing list.

Monday, October 18, 1999

• A new version of the NeXus API has been released. It is now version 1.2.0. Check the release notes for information concerning the changes, which mostly involve minor bug fixes.

Monday, September 20, 1999

• The NeXus Home Page has been redesigned to make it easier to find individual web pages. If it does not format well in your browser, please let me know.

Friday, September 10, 1999

• A small (but significant) error has been corrected in the Fortran 90 example program. The "file_id" variable should be declared as the derived type NXhandle, i.e.

  
     type(NXhandle) :: file_id
     

  and not as a character string. Apologies if that caused any confusion.
• Separate HTML files dedicated to the three language interfaces, C, F77 and F90 have been added, along with improved navigation aids within them.

Thursday, August 19, 1999

• The first version of the Fortran 90 API has been installed on the FTP server and updated the API file accordingly. It includes both an F90 version of the core API and a utility API to simplify some of the NeXus file navigation. If they prove useful, we will see if they can be implemented in C and/or F77.
• A simple terminal browser for a NeXus file, NXbrowse.f90, has been written. After compiling, linking, and running, type HELP at the terminal for a list of available commands (upper or lower case).

Thursday, August 12, 1999

• Freddie Akeroyd has set up an archive of the NeXus mailing list.
• The latest version of the NeXus API, which contains changes to the way NeXus groups are linked, has been installed. The previous method was not 100% reliable.
• Some of the links to Fortner Software have been updated at their request.

Saturday, June 5, 1999

• Some extra definitions to the NeXus glossary have been added e.g. definitions of NXdetector, NXcollimator, and NXattenuator. These are based on suggestions by Ron Ghosh and Chris Moreton-Smith a while ago, but I never got around to putting them on the web. Please view these definitions critically when you have need to use them.

Friday, April 2, 1999

• A site map has been added so that it is easier to find some of the lower-lying web pages.

Wednesday, November 25, 1998

• An explicit set of instructions for identifying plottable data has been added, since this is an important aim of the NeXus format. This issue came up in the NeXus mailing list a while ago, but I never added it to the web pages. The instructions reported here will, at some stage, be incorporated into a higher-level suite of API routines.

Friday, November 20, 1998

• The first release of HDF5 v 1.0.0 is now available. Only Unix platforms are currently supported, so we will not change the NeXus API just yet. However, preliminary views of the revised HDF API suggest that we can layer the NeXus API transparently on top of HDF5 with no effect on user applications. Since HDF have not yet finalized their plans to ensure backward compatibility, we don't know what the implications for existing NeXus files are yet. I have added some notes to the introduction to the NeXus API.
• Fortner Research have just released version 1.3 of their HDF Browser for both Windows NT/98 and Macintosh platforms. I can recommend it as a simple way of seeing what NeXus files contain. I have added further pointers to their HDF web pages in the NeXus Utilities section..

Tuesday, October 6, 1998

• References to the ISO 8601 description have been updated since the original web site has closed down.
• The Utilities section includes some more HDF browsers and now refers to the NeXus developments concerning Open Genie and IDL.

Friday, September 4, 1998

• Mark Koennecke has provided an IDL 5.1 interface to the NeXus API. I have included links to it in the API section. I also updated the Status section.

Friday, April 17, 1998

• The NAPI code has been updated on the FTP site to change the type specification in NXgetattr from "char *data" to "void *data".

Tuesday, April 14, 1998

• Although there have been no major changes to the NeXus web pages for several months, there has been considerable activity behind the scenes in developing the NeXus API. A CVS (Concurrent Versions System) server has been set up by Freddie Akeroyd to coordinate those involved in developing the NeXus API. The FTP site has just been updated to the latest version of the API, and we intend to provide more examples of its use very soon, in order to make the operation of NeXus easier to understand.
• The new version of the API does define the NX_ datatypes so I have removed the previous instructions to use the HDF DFNT_ datatypes in the API section. From now on, we encourage the use of the NX_ datatypes to ensure compatibility with future versions of the API.
• In order to ensure the most efficient reads and writes in each language, the Fortran API has been amended so that the array index order is reversed from that in C i.e. a set of time-of-flight spectra for 150 detectors with 800 time channels would be stored as S(800,150) in Fortran and S[150][800] in C i.e. the actual values are stored in the same order but addressed differently in the two languages. At the moment, this means that there would be a discrepancy in the meaning of the "axis" attribute in NXdata groups, unless the NeXus files are written and read in the same language. We have not yet decided how to address this issue, though the most likely is that the "axis" attribute will have to have different meanings in the two languages i.e. in C, axis=1 will refer to the first dimension whereas in Fortran, it will refer to the last. If you have any views on this vexed subject, please address them to the NeXus mailing list.

Thursday, February 12, 1998

• The latest version of openGenie can read and write NeXus files. Check the openGenie web pages for more details.

Monday, August 25, 1997

• A few minor errors in the example programs in the NeXus API section have been corrected.
• Following Freddie Akeroyd's suggestion, I have added a conversion table from C to Fortran for the subroutine arguments.
• Some of the instrument descriptions have been modified to make them simpler. The aim of this section is to give the minimum required parameters for meaningful data analysis although, in general, people will want to store extra information.
• Installation instructions have been added to the end of the API section.

Thursday, August 14, 1997

• As I warned, we have moved the FTP site to its semi-permanent location. Look for the API at <ftp://ftp.neutron.anl.gov/nexus/>. The web pages have been updated accordingly.

Sunday, August 10, 1997

• A discussion of the storage of histograms in NXdata groups to the NeXus structure chapter has been added following some comments by Phil Seeger (LANL).
• Phil Seeger also pointed out that we had omitted to specify the storage of data errors. This has been added to the NeXus glossary.

Friday August 8, 1997

• The FTP URLs have been moved to <ftp://coral.pns.anl.gov/pub/NeXus> because of some problems with the original server. This is a temporary move, so please check these pages before downloading future versions of the API.
• A set of helper routines designed to simplify the base API by combining multiple function calls into a single function call ,e.g. NXmakedata, NXopendata and NXputdata, is under development. This may be ready in the next week, so watch this space.
• There will be a symposium during ICNS'97 in Toronto in order to present the NeXus proposal to the neutron scattering community, and to receive feedback on its design. It will be held at 8pm on Tuesday evening in McLennan Physical Laboratories room 134, adjacent to where the poster sessions are being held.