Data Formats Working Group

Mailing List Archive

Timeline

• 2007-12-31 agree on v1.0 format
• 2008-01-01 start implementing v1 at facilities
• 2008-06 representative sampling of data available for inter-facility comparison
• 2008-10 presentation of results at NOBUGS2008 meeting (date TBA)

Considerations

• a key point of what we discussed at NIST:

namely that our goal is to agree a format which that whilst using as much best XML practice as is reasonable, leaves the file instantly human-readable, editable in the simplest of editors, and importable by simple text import filters in programs that don't recognise the XML.

• document what we decide
  • 1DWG will take care of documenting the format it defines.
    • make that definition with a schema (for absolute validation of any proposed XML file against the standard)
    • instructions on how to use that schema
    • XSL style sheets to present the XML contents in various forms (also serves as examples)
    • a couple of examples
    • maybe also some words.
  • move some of this discussion to
    • discussion page
    • other wiki pages
    • /dev/null after its usefulness has been exhausted
• coordinate with other communities
  • NeXus (http://www.nexusformat.org)
  • reflectivity
  • powder diffraction
    • XRDML (http://www.xrdml.com)
• should we consider a file naming convention?
• should we consider a SAS scan naming convention?
  • sequential run number from facility
  • convention set by the detector software provider
• XML representation of the I vs. Q data
  • tabular format
  • vector format
• general XML coding style
  • readability by humans
    • with lots of computer skills
    • with rudimentary computer skills
  • readability by computers
    • standard XML libraries
    • generic visualization tools
    • common software such as MS Excel or Open Office or XMLPLO source code for windows/linux/OSX86
    • A plugin for IGOR has been written, XMLutils.xop, that can handle XML data. The sasXML and IGOR page gives details on the IGOR code required to write the prototype sasXML file.
  • availability of style sheets
• scalability of XML format to 2D data?
• What is required?
• What is optional?
• Use the same tags again in similar contexts
  • X,Y pairs for example, whether detector position, beam center, sample position

inconsistent	consistent
<beam_size axis="x" units="mm">12.00</beam_size> <beam_size axis="y" units="mm">12.00</beam_size> <x0 units="mm">322.64</x0> <y0 units="mm">327.68</y0> <pixel_x units="mm">5.00</pixel_x> <pixel_y units="mm">5.00</pixel_y>	<beam_size axis="x" units="mm">12.00</beam_size> <beam_size axis="y" units="mm">12.00</beam_size> <beam_center axis="x" units="mm">322.64</beam_center> <beam_center axis="y" units="mm">327.68</beam_center> <pixel_size axis="x" units="mm">5.00</pixel_size> <pixel_size axis="y" units="mm">5.00</pixel_size>

Points for Discussion

• Do we want to advocate/recommend particular names for particular tags; eg, SASdata, SASsample, Idata, etc.?
  • which ones?
• provide for (optional) inclusion of sample prep details
• provide for (optional) inclusion of other (non-SAS) data in the XML
• Need to allow for more than a single SAS data set in one .xml file

Other Points

• It's not clear how to specify that multiple runs were reduced together
  • (AJJ) Assuming that those multiple runs were first stored as XML then referencing the individual files would give all that back information (a la Ghosh suggestion). At NIST we take absolute I vs Q files and combine them to produce an absolute I vs Q file thus that is reasonable here. What about elsewhere?
• How does one include the instrument information of the many runs that we used to make up the composite file
• If we have reduction information, then everything needs to be in there, i.e. the run numbers for the can, the standard, the uniform field, etc.
• Information on the averaging, is it radial, sector, rectangular, etc.

Members

• Andrew Jackson (NIST)
• Pete Jemian (APS)
• Steve King (ISIS)
• Ken Littrell (ORNL)
• Andy Nelson (ANSTO)
• Ron Ghosh (ILL)
• Jan Ilavsky (APS)