Glossary
Offline Authorization Cache
An offline authorization cache stores a previously obtained authorization decision locally, for a device or application to rely on when it genuinely cannot reach the authoritative policy source — not a brief network hiccup, but a real, possibly extended period of disconnection, such as a field device operating without connectivity or an app used in transit. This is a more extreme version of the ordinary latency-and-caching tradeoff: there's no live source to fall back on to check freshness at all until connectivity returns.
The design question this raises is stark, since there's no live check available during the gap: how long should a cached decision remain valid before the device refuses to honor it at all, given that the principal's actual authorization could have changed at any point during the disconnection with no way for the device to know.