Linter to fulfill VizSchema

[ax3l]

Comparison of the openPMD standard to Tech-X's VisSchema:

Facts about VisSchema:

• very free set of namings of groups and records (can be good and bad at the same time)
• developed for visualization of various particle & mesh codes, but mainly for VORPAL
• very close to (serial) VTK/XDMF namings (can again be good and bad at the same time)
• they sometimes refer to it as a "markup language" for HDF5/NetCDF which is actually a good naming (e.g., in their composer)
• wiki, talk, IPAC2010, ICAP2009
• ADIOS (meshes only?), HDF5 & NetCDF VisIt plugins
• also a minimal kernel of required mark-ups
• provides C/Fortran/Python API (HDF5 & NetCDF? open source?)
• time: also with data sets, but allow axis of a multi-dim mesh to "represent time"
• markup-features:
  • allows "time" as an axis for multi-dimensional data sets
  • general section: try to capture also: compiler (version, tries to record flags...), host, cmd startup-line
  • some labels (e.g., strings including non-generic units for axis)
  • meshes are records that are defined and can be referenced by other records (useful abstraction for complicated geometries)
  • dx, dy, ... implicit from lower and upper bounds & number of elements (for structured grids)
  • derived records via groups; functions only what VisIt (better say VTK?) directly supports
  • checker tool VizSchemaH5DataValidator.py open source?
• (intentionally) missing in VisSchema:
  • not open source? (or only parts of it)
  • out of VizSchema-scope: human-readability, documentation for archives/supplementary materials, domain-specific extensions, code-interoperability, filtered data sets (e.g., storing the same particle in multiple records)
  • generally missing: a documentation that is not the wiki and not the code itself (xml descr.)? lacking parallel particle patch hints? staggered positions of components? units (besides hard-coded string labels)?

It might be actually possible to add all required "vs..." attributes out of an openPMD file.

[ax3l]

If we find enough documentation (and if the performance is not as bad as "parallel"-xdmf reading in tools), we can add a small script that automatically adds VizSchema markdown for our records. nevertheless, for parallel reading hints like our particlePatches should lead to high(er) performance in native ParaView/VisIt implementations.