Explore the pros and cons of switching to node -> media relations from media -> node relations

[Natkeeran]

Currently, in Islandora 8 media of a digital object points to the node describing it. Generally, in Drupal nodes point to media via the field entity relationships.

If we switch the relationship to point node -> media, this will enable us to work with Drupal's ecosystem better.

• configure display modes and displays more easily (i.e without contexts or views, use https://www.drupal.org/project/view_mode_switch)
• use media browser
• allow for more than one media to be attached !
• the node's json will point to all media, thus for some use cases additional querying is not needed

From my understanding, the main reason for keeping media -> node relationship is performance. However, there is no solid use case to demonstrate this!

This does impact all derivatives and indexing modules as well as workbench and bagger. The major question is the migration path for existing installs.

[seth-shaw-unlv]

This discussion was happening back in late 2017 or early 2018 mid 2018 when I first started working with Islandora, when it was still CLAW. We started with Node→Media but we switched for a few reasons.

I don't recall details, but I believe it involved avoiding a "many members" problem (which was something to do with Fedora) but may not actually be a problem?

I seem to also recall there being a perceived benefit in that having Media reference the node was more flexible in terms of supporting the different media uses by tagging a media rather than relying on fields. Further, using a media use tag on the media better fit the PCDM model where the use property belongs to the media entity, something that we couldn't do if this use was a function of which field on the Node the media belonged to.

We probably have Tech Call minutes from these discussions... but someone would have to click through them to find which ones if we did indeed capture the discussion. Some brief searching shows we were talking about this in August of 2018 although I'm not finding a ton of details. See August 1st and August 25th.

[seth-shaw-unlv]

So, I guess leads me to the question how do we represent this object structure in Fedora's RDF?

[Natkeeran]

@seth-shaw-unlv
Thank you for the feedback.

The many members problem does not show up for all the current content models.

" Media reference the node was more flexible in terms of supporting the different media uses by tagging a media rather than relying on fields" - can you please provide a specific example for this.

Are we aiming to implement PCDM via Drupal relationships?

With respect to representation in Fedora, that is a larger discussion. The current representation does not align well with the Oxford Common File Layout (OCFL) object model. For instance, one OCFL Object does not equal one Islandora/Digital Object. My understanding is that, if we have one conceptual digital object (i.e one media with descriptive metadata), it should serialize that into one OCFL Object.