etag documentation?

[aarondcoleman]

Hi API Team,

We're looking at performance around reconciliation routines and want to fully understand the guarantees around etags returned with API responses. Are there docs that lay this out or a spec you adhere? Obviously the principle is that a resource change would result in a new etag, but are all collections implemented, and are there other scenarios where an etag would change that I'm not thinking of or where the collection is actually still the same?

Thanks,

--Aaron

[JeremiahFitbit]

Currently, Fitbit hashes the response JSON for the ETag. This saves your application data transfer, but will not result in faster first-byte response times. It only indicates whether or not the response has changed. This can be used to determine if an individual resource has changed. However, for collections, it cannot be used to determine if there are any changes within the collection, as the ETag would only reflect changes within the page of the current pagination.

This is something we hope to improve eventually, but I hope the current behavior is still useful in some manner.