Cache Policy Interaction—Maximum Age and Minimum Freshness
To help ensure that the freshest content is returned to the client application, the interaction of client cache policy and server revalidation requirements always results in the most conservative cache policy. All the examples in this topic illustrate the cache policy for a resource that is cached on January 1 and expires on January 4.
The following examples illustrate the cache policy that results from the interaction of the maximum age (maxAge) and minimum freshness (minFresh) values.
If the cache policy sets maxAge = 2 days and minFresh is not specified, the content is revalidated on January 3.
If the cache policy sets maxAge = 2 days and minFresh = 1 day, according to maxAge, the content is fresh until January 3. According to minFresh, the content is fresh until January 3. Therefore, the content must be revalidated on January 3.
If the cache policy sets maxAge = 2 days and minFresh = 2 days, according to maxAge, the content is fresh until January 3. According to minFresh the content is fresh until January 2. Therefore, the content must be revalidated on January 2.
参照
概念
Configuring Caching in Network Applications
Cache Policy Interaction—Maximum Age and Maximum Staleness