IIIF and Hydra Works

Owned by Bill Branan
Jun 16, 2017
1 min read

Discussion:

  • Hydra:Collection maps to IIIF:Collection
  • Hydra:Work maps to IIIF:Manifest
  • IIIF:Sequence is derived from the Ordering of the Work
  • Hydra:Work (representing a part of another work, at arbitrary depth) maps to IIIF:Canvas
  • Hydra:File (where the content is an Image) is the Image, annotated on to the Canvas 

The objects in Hydra could provide their JSON-LD representation.

Noted that IIIF:Canvas needs to know its height and width, but other than that the only required metadata are labels on the Manifest and Canvas.  Height and width can be derived from the h/w of the depicting image, which could be retrieved from the IIIf info.json response.  This could be slow, so should only be done once and thus ... 

We discussed speed – it's slow to walk through 500 pages.  The solution was to cache the responses as they only change when the resource is changed.  Could be done at the Varnish level, or lower in the stack.  

Noted the distinction between Image API's info.json response, which is technical information about the IIIF:Image / Hydra:File, and the Presentation API JSON-LD content, which is the descriptive, rights and structural metadata, as in the above mapping.

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