2025.12.1 drivers x3 port

[Harry Shepherd (harry-shepherd)]

PR Summary

Code Reviewer: Sam Clarke-Green (@t00sa)

There is an aim to move all NGMS workflows to use XIOS3 (version 3 of the XML IO server). As part of the control of the coupled model, the XIOS driver contains lines to ensure that the iodef.xml control file is set up correctly to run a coupled model. However a variable name has changed between the XIOS2/XIOS2.5 versions, and the XIOS3 versions.

This is further complicated by the fact that the coupled model drivers need to deal with these earlier versions for use with the UM based coupled model used in both climate and operational NWP workflows.

I have modified the XIOS driver, to set the control variable to:

• oasis_codes_id for non-XIOS3 runs
• clients_code_id for XIOS3 runs.

XIOS3 based runs must specify an environment variable XIOS_VERSION=3. This defaults to 2 in the case of not being set.

This change has been tested in XIOS2 mode with the lfric_coupled test in LFRic apps trunk, and in the same test in the XIOS3 prototype test in the branch of LFRic apps used in tcd-XIOS3-extras/issue/49

By merging main in the branch, I could test using the drivers group of MOCI rose-stem.

Code Quality Checklist

(Some checks are automatically carried out via the CI pipeline)

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid undertanding and enhance the
  readability of the code
• My changes generate no new warnings

Testing

• I have tested this change locally, using the Moci rose-stem suite
• If any tests fail (rose-stem or CI) the reason is understood and
  acceptable (eg. kgo changes)
• I have added tests to cover new functionality as appropriate (eg. system
  tests, unit tests, etc.)

Security Considerations

• I have reviewed my changes for potential security issues
• Sensitive data is properly handled (if applicable)
• Authentication and authorisation are properly implemented (if applicable)

Performance Impact

• Performance of the code has been considered and, if applicable, suitable
  performance measurements have been conducted

AI Assistance and Attribution

• Some of the content of this change has been produced with the assistance
  of Generative AI tool name (e.g., Met Office Github Copilot Enterprise,
  Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the
  Simulation Systems AI policy
  (including attribution labels)

Documentation

• Where appropriate I have updated documentation related to this change and
  confirmed that it builds correctly

Code Review

• All dependencies have been resolved
• Related Issues have been properly linked and addressed
• CLA compliance has been confirmed
• Code quality standards have been met
• Tests are adequate and have passed
• Documentation is complete and accurate
• Security considerations have been addressed
• Performance impact is acceptable

[Sam Clarke-Green (t00sa)]

See suggestion inline. It's a style question, so it's up to you whether you want to go with it or not

[Sam Clarke-Green (t00sa)]

If you don't need to pad the IDs to get them to line up and you're happy to go with f-strings, you can simplify things a bit:

Suggested change

	if xios_version == '3':
	# The appropriate variable is clients_code_id
	line = '<variable id="clients_code_id" type="string" >' \
	+ oasis_components+'</variable>'
	else:
	# For XIOS2/2.5 the appropriate variable is oasis_codes_id
	line = '<variable id="oasis_codes_id" type="string" >' \
	+ oasis_components+'</variable>'
	# Variable name changes at version 3
	vname = "clients_code_id" if xios_version == '3' else "oasis_codes_id"
	line = f'<variable id="{vname}" type="string" >{oasis_components}</variable>'

[Sam Clarke-Green (t00sa)]

Not sure where we are with this - I suspect I might have pressed the comment button rather than the changes one! Can you take a look at the comments in-line and see what you think?