Cache-Control value on each response. Inventory-sensitive responses generally have shorter client cache periods than catalog or store metadata.
Retain the response ETag and send it as If-None-Match when revalidating:
304 Not Modified response has no body. Continue using the representation associated with that validator.
If-Modified-Since is available as an HTTP-date fallback when an integration cannot retain ETags. If both validators are sent, If-None-Match takes precedence, as required by HTTP semantics. Last-Modified is the Nektir publication time—not proof of when Utah DABS last changed its source data.
X-Publication-Revision identifies the immutable Nektir database revision used to create the response. It is not a Utah DABS version or upstream update timestamp.
API response caching and upstream polling are separate systems. Revalidating this API does not trigger an upstream refresh.