NXxas refactoring

[woutdenolf]

WIP: everything will be moved to contributed_definitions once this is up for review.

Contributing: PR to the main branch of https://github.com/XraySpectroscopy/nexus_definitions (merge commits will be removed regularly).

Rendering: https://hdf5.gitlab-pages.esrf.fr/nexus/nxxas/classes/applications/NXxas_new.html

NXDL questions:

- how to re-use an enum
- when enum field X has a specific value, make field Y required OR how to define enum properties
- possibly link to
- how to make a field required in a base class

[lukaspie]

Hi @woutdenolf, I came across this PR by chance and noticed that you are working on a base class for describing an electron level. In the context of photoemission spectroscopy, we in FAIRmat have also been working on something very similar: https://github.com/FAIRmat-NFDI/nexus_definitions/blob/fairmat/contributed_definitions/NXelectron_level.nxdl.xml. In fact, some of the base class we developed was originally adapated from another XAS-related PR: https://github.com/nexusformat/definitions/pull/1293. Would you be open to harmonizing the concept that we were developing with your approach here? I think the two approaches are already very similar right now.

[woutdenolf]

@lukaspie Yes since we are doing the same thing we should try to converge. We are currently discussing this very topic: https://github.com/XraySpectroscopy/nexus_definitions/pull/2. Feel free to get involved.

The XAS working group will work in https://github.com/XraySpectroscopy/nexus_definitions. It would be helpful to add comments in that repo. This PR will be a draft and is subject to lots of changes until we are finished.

[lukaspie]

@woutdenolf great, thanks for the pointers. I will add some comments there.

[woutdenolf]

another XAS-related PR: https://github.com/nexusformat/definitions/pull/1293

This was the first attempt before we created the XAS working group. It will most likely be closed.

[whs92]

@woutdenolf after asking a question to the nexus mailing list and reading:

https://github.com/nexusformat/definitions/issues/1011 https://github.com/nexusformat/definitions/pull/1293

I arrived here :)

I have had a look at the proposal you made to the NXxas_new

I am particularly interested in the topic raised in #1011 of adding the ability to work with multiple detectors. I see that you've added the entry intensity that is still tied to a single mode (TFY, PFY, TEY etc). How might I add other signals acquired at the same time? How might I add more than one PFY signal?

Do you plan to include the suggestions from @padraic-shafer in https://github.com/padraic-shafer/definitions/blob/1011-multixas/contributed_definitions/NXmultixas.nxdl.xml

When is the next planned meeting of the working group? Can I come along?

[woutdenolf]

Currently we only support a single XAS spectrum. I'm very much open to support multi-detector and/or multi-scan. You are very welcome to join the XAS working group. I'll contact you directly.