Is NDFileNexus still relevant? Could we remove it entirely?

[ericonr]

It is possible to feed an XML file layout specification to NDFileHDF5 which generates a file with the Nexus layout, and it has the added benefit of taking advantage of all existing functionality of the plugin. NDFileNexus uses napi which also seems to be somewhat stagnant...

@prjemian what do you think?

[prjemian]

I believe it is completely removed by the HDF File Writer. It can be removed, with instruction to use the HDF file writer.

[kgofron]

From ADTimePix3 (R1-6-1+): We ship IOC examples for NeXus-style output with both ADCore mechanisms:

nexus_minimal.xml — NDFileHDF5 hdf5_layout (2D NXentry / NXdata)
nexus_plugin_template.xml — NDFileNexus NXroot (different dialect; validated with template.sch)
nexus_prvhst_histogram.xml — NDFileHDF5 1D spectrum + axis metadata via source="ndattribute"
Our docs already recommend NDFileHDF5 + hdf5_layout for new setups; we do not rely on NDFileNexus for new features. Deprecating/removing NDFileNexus would be fine on our side—we’d drop or relocate nexus_plugin_template.xml and update README/docs.

ADCore vs driver repos: Generic templates (nexus_minimal-class 2D layout, generic 1D spectrum with example attribute names, and clear “HDF5 vs Nexus plugin XML” docs) fit well in ADCore next to NDFileHDF5. Detector-specific pieces should stay in drivers: NDArrayAddress wiring and driver-specific NDAttributes (e.g. our PrvHstTimeBin0Ms / PrvHstTimeBinStepMs / PrvHstNumBins in nexus_prvhst_histogram.xml).

1D histogram: HDF5-only via NDFileHDF5 is the right path; no need for NDFileNexus.

Suggestion: Ship 2–3 canonical hdf5_layout examples in ADCore, document migration from NDFileNexus → NDFileHDF5, then deprecate NDFileNexus. I can open a PR to contribute generalized versions of our nexus_minimal.xml and a spectrum layout (and adjust ADTimePix3 to point at ADCore examples) if that helps close this issue.

@prjemian — happy to align with whatever direction you prefer for NDFileNexus.

[prjemian]

FWIW the default layout with the HDF file writer is Nexus