Post by dmitry on Jul 13, 2021 10:09:04 GMT
Hi everyone,
Several redfish resource types contain constantly updating fields. E.g. sensor readings, temperature values, voltage values, various metrics, etc.
Some resource types embed excerpts from other resources with constantly updated fields.
For both of these use cases it is worth utilizing weak ETags since the contents of the GET may change over time while the essential part of the resource is not changed. Such, weak etags allow not to cache all the data and not to constantly update ETags for resource, thus saving memory and compute resource.
But weak ETags bring problems along with using conditional headers like If-Match which are required by rfc7232 to use strong comparison which is never true if the resource returns weak ETags.
The OData 4.0 protocol allows weak comparison for If-Match header effectively allowing services to return weak ETags for some resources. The Redfish specification doesn't explicitly allow that.
I would like to propose changes to the Redfish specification related to ETags comparison that would explicitly allow weak ETag comparison for resources with weak ETags.
Thank you.
Dmitry
Several redfish resource types contain constantly updating fields. E.g. sensor readings, temperature values, voltage values, various metrics, etc.
Some resource types embed excerpts from other resources with constantly updated fields.
For both of these use cases it is worth utilizing weak ETags since the contents of the GET may change over time while the essential part of the resource is not changed. Such, weak etags allow not to cache all the data and not to constantly update ETags for resource, thus saving memory and compute resource.
But weak ETags bring problems along with using conditional headers like If-Match which are required by rfc7232 to use strong comparison which is never true if the resource returns weak ETags.
The OData 4.0 protocol allows weak comparison for If-Match header effectively allowing services to return weak ETags for some resources. The Redfish specification doesn't explicitly allow that.
I would like to propose changes to the Redfish specification related to ETags comparison that would explicitly allow weak ETag comparison for resources with weak ETags.
Thank you.
Dmitry
