Remove soon-to-be-deprecated usage of AsdfFile.open

[drdavella]

This will take effect once asdf-format/asdf#579 is merged, but there's no harm in making this change now.

This closes #2795.

[jdavies-st]

This looks good. The clarifying variable names in model_base.py are good too.

Thanks!

[drdavella]

Seems like the Jenkins job is hung...

[drdavella]

Still failing. Is it just me or is there a problem with Jenkins?

[jdavies-st]

Yes, Jenkins was hosed. Matt hit the shiny red button to restart. I've restarted (I think the Jenkins CI test by closing and reopening this PR).

@stscieisenhamer & @nden, any idea what is going on with this failure in the TravisCI build?

https://travis-ci.org/spacetelescope/jwst/jobs/452031031#L1496

Does a gwcs object no longer have a pipeline attribute?

[nden]

The wcs tags were removed from asdf as they are now (and have been for quite a while) in gwcs. Something must be using an old tag or it's a bug. I'll investigate.

[drdavella]

I think the problem is files in jwst/exp_to_source/tests/data that contain references to !wcs/.... We just removed the old WCS tags and schemas from ASDF, so these tags won't resolve anymore.

I suspect that a simple search and replace of these for the corresponding tag name in gwcs should fix the problem. For example, !wcs/step-1.0.0 should become !<tag:stsci.edu:gwcs/step-1.0.0>.

[jdavies-st]

I see. Does this mean that all old data like this will now fail to to have a functioning GWCS object without it having to be rebuilt using a current version of asdf and gwcs?

[drdavella]

@jdavies-st the short answer is yes. Of course, you could grab an older version of asdf, but that's not ideal, is it?

@nden we made this change expecting that there would be no residual uses of ASDF WCS, but maybe we should go with a deprecation period instead.

We're in a tricky place here because if we don't try to be diligent about cleaning these things up, ASDF is going to become a giant crapball of spaghetti code that mostly supports legacy uses. We should handle this better going forward, but I don't think we were expecting this particular change to have any impact.

Unfortunately, making this change has exposed some other issues that will need to be addressed (see #2849).

Considering the hour, I think the best course of action is probably to sit down with a tall scotch and forget all about of this for a little while.

[stscieisenhamer]

hold it...wait...i'm in the wrong conversations....

[philhodge]

Is it (theoretically) possible to edit the ASDF extension to change the tags, as an alternative to rebuilding the extension?

[drdavella]

@philhodge if I understand correctly, it's probably possible in theory, but I'm not sure we want to support this for the general case since it will probably be fairly difficult to maintain. It would probably be easier just to write a one-off script to convert files like these, but at that point it might just be easier to regenerate them.

[jdavies-st]

@drdavella, can you rebase this to jwst/master? Tests should pass if you do.

[drdavella]

Looks like we're good now!

[jdavies-st]

Thanks @drdavella!