Patent ID: 7644108

Claim:
A method comprising: storing a first version of content to a cache within an intermediate network device located between a first client device and a network server from which the content was obtained; receiving a request for the first version of the content; in response to the request, modifying the cache to include a token that references the first version of the content; reading the first version of the content from the cache based on the token; after reading the first version of the content from the cache, transmitting the first version of the content from the intermediate network device to the first client device; retrieving a second version of the content from the network server with the intermediate network device and storing the second version to the cache, wherein retrieving and storing the second version with the intermediate network device both occur while transmitting the first version of the content from the intermediate network device to the first client device, and wherein the first version of the content is a historical version of the second version of the content in that the second version of the content is a content update for the first version of the content; transmitting the second version of the content from the intermediate network device to a second client device at least partially in parallel with the transmission of the first version from the intermediate network device to the first client device; removing the token from the cache upon finishing the transmission of the first version of the content; determining whether to remove the first version of the content from the cache based on the number of tokens currently referencing the first version of the content; removing the first version of the content from the cache upon determining that no tokens currently reference the first version of the content; and retaining the first version of the content in the cache upon determining that one or more tokens currently reference the first version of the content.