Efficient cache validation and content retrieval in a content delivery network

摘要

Some embodiments provide systems and methods for validating cached content based on changes in the content instead of an expiration interval. One method involves caching content and a first checksum in response to a first request for that content. The caching produces a cached instance of the content representative of a form of the content at the time of caching. The first checksum identifies the cached instance. In response to receiving a second request for the content, the method submits a request for a second checksum representing a current instance of the content and a request for the current instance. Upon receiving the second checksum, the method serves the cached instance of the content when the first checksum matches the second checksum and serves the current instance of the content upon completion of the transfer of the current instance when the first checksum does not match the second checksum.

主权项

1. A computer-implemented method comprising:
storing a first checksum identifying a cached instance of particular content; receiving a first request for the particular content; submitting a second request to an external source that remotely hosts a fresh instance of the particular content, wherein the fresh instance of the particular content is representative of a most recent version of the particular content; receiving from the external source, a second checksum identifying the fresh instance of the particular content contemporaneous with commencement of a transfer of the fresh instance of the particular content from the external source; serving responsive to the first request, the cached instance of the particular content that is locally cached without reference to said transfer from the external source of the fresh instance of the particular content when the first checksum matches the second checksum; and serving responsive to the first request, the fresh instance of the particular content after or contemporaneous with said transfer of the fresh instance of the particular content from the external source when the first checksum differs from the second checksum.