search

opencadc / caom2

Common Archive Observation Model
GNU Affero General Public License v3.0
5 stars 11 forks source link

RFE: add metadata checksum #22

Closed pdowler closed 7 years ago

pdowler commented 7 years ago

From thinking about the plan that emerged from the HST Archive Coordination Meeting:

Usage scenario: if site B has a mirror of the caom metadata from site A, they can harvest new/changed observation documents by looking for recent maxLastModified but they cannot feasibly perform a validation that the content they have is correct in detail.

Proposal: add a checksum of the metadata that could be transmitted with in the observation document and found via a query that lists observation identifiers, maxLastModified, and the checksum.

pdowler commented 7 years ago

Intention is to add add a checksum to CaomEntity so this feature would be available at various levels of the data structure. Will need to define the checksum algorithm and the order that metadata values are accumulated so that it can be independently implemented. The timestamp and checksum values defined in CaomEntity will not be part of the checksum.

Because CaomEntity fields are designed/intended to be pimitive types usable (eg usable as attribute values) the checksum algorithm and value will be exressed as a single URI. See https://github.com/opencadc/caom2/issues/15

To be included in CAOM-2.3

pdowler commented 7 years ago

Added in CAOM-2.3