Share Keyword Block

[PaulHuwe]

The keywords in base_exposure are presently duplicated in exposure and similarly for base_guidestar and guidestar. This is due to the sharing of base_exposure causing the ASDF schema_info function to fail. We need a new way to share keyword blocks between schemas.

[stscijgbot-rstdms]

This issue is tracked on JIRA as RAD-190.

[braingram]

To provide an update on untangling this.

asdf.schema_info currently does not follow schema $refs. That seems like a bug. asdf-format/asdf#1875 addresses the issue but currently causes rad/roman_datamodels failures.

The failures are due to rad schemas using $ref in objects alongside other attributes. This violates the JSON reference specification: https://datatracker.ietf.org/doc/html/draft-pbryan-zyp-json-ref-03#section-3 and the above asdf change correctly ignores all non-$ref items in an object with a $ref (which causes critical information in the rad schemas to be correctly discarded). #525 updates the rad schemas putting $ref under an allOf combiner if the containing object has more keys than $ref.

Once #525 is merged the asdf PR can be merged, released and required versions updated. At that point we will have more flexibility in the rad schemas to use $ref (and can drop tagged scalars entirely).

One related item to consider is that schema_info is limited in what schema structures it can parse. The following schema usage presents an ambiguous archive_catalog keyword:

{
  "archive_catalog": "foo",
  "allOf": [   # pretend this is a $ref
    {
      "archive_catalog": "bar",
    }
  ]
}

Unit tests in rad could be added to verify that this ambiguity never exists for archive_catalog (and other special keywords) or an alternative to schema_info used that can accommodate this ambiguity.