UNF Fixes

[djbrooke]

This issue is for fixing UNFs that were dropped from some of the dataset citations in production.

[landreev]

Status updates:
There are several underlying issues, fixed in separate steps:

1. Legacy UNFs - version 3, 4 and 5 - we no longer calculate these. These UNFs were supposed to be migrated from DVN 3 and, for published/archived versions of datasets, to stay frozen, preserved in perpetuity.
   Some of these were dropped from the citations of such old, published versions.
   However, all these legacy UNFs should now be back in place, and displayed in citations correctly.
   Example: an older version of Gary King's study hdl:1902.1/11044:
   https://dataverse.harvard.edu/dataset.xhtml?persistentId=hdl:1902.1/11044&version=6.0

[landreev]

Another case:
2) In some prod. dataset versions the new, version 6 UNFs haven't been properly calculated. This was caused by several bugs that have since been fixed: for example, creating a new version, without modifying any tabular data files was NOT automatically cloning the unf from the previous version.
In 4.6.1 we have added a new admin API for monitoring missing or invalid UNFs, and for fixing them with REST calls. When fixing the missing version 6 UNFs in production one of the 3 prod servers was patched with this updated API end point; which made the process much easier.
An example of a dataset version fixed:
https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/SD7SVE&version=2.0

Please note, that just like with the case 1) above the integrity of the UNF signatures was not compromised. They were not showing in the citations of some dataset versions, but the important file level UNFs were still in place.

[landreev]

3. This case is a more complex/special case of 2):
   If a version is missing the UNF, running our recalculation method will always produce the latest version UNF - v. 6. Even if all the tabular data files in the have versions < 6 - this is by design of the UNF algorithm. However, if the tabular files in this version are the same as in the previous one, and the previous version has the UNF, we SHOULD USE THE UNF FROM THE PREVIOUS VERSION, rather than recalculate. Because we don't want the UNF to change from UNF:5:XXX to UNF:6:YYY, even though the tabular data files are exactly the same. So that was the problem with our "fixi missing unf" algorithm - it always recalculates. So this is a TODO: it needs to be modified to only recalculate when necessary.
   For all such cases, the fixes have been done outside of Dataverse, via direct database updates.
   Note that this was the case with all of Gary's datasets that weren't showing the UNFs in later versions. All of Gary's studies except 1 should have older (< 6) versions UNFs - since all of his tabular data files were finalized in the days before Dataverse 4; and all the recent updates had to do with documentation/extra files and the metadata.

[landreev]

More TODO:s left:

• Create scripts and documentation that could be passed to other Dataverse installations who recently upgraded to Dataverse 4, to make sure they have their legacy UNFs preserved.

• Modify the recalculation method as described above;

• Fix the bug in import (jsonparser) that can drop the UNF of the imported version;

• Verify/double-check that we don't have any bugs in the app that can cause a version to lose the UNF. To the best of my knowledge all such issues have been fixed. HOWEVER, I heard some (anecdotal?) reports of UNFs disappearing from citations in the current production version (4.6)! We'll need to keep an eye on it and continue to run integrity checks.

[landreev]

Created a pull request: #3656

There are 2 Application code changes:

• A fix for the bug in the json parser that was dropping the version UNF on import. Note that this fix will prevent the loss of UNFs in any dvn3 migrations - but then it's unlikely that there are any un-migrated dvn3s left.

• Changed the logic of the fixMissingUnf api call. So that it will reuse the UNF of an earlier version, if available, and if the tabular file UNFs are identical; unless a recalculation is specifically requested, with a "force" option.