| 摘要 |
A method is described comprising: receiving a request for content stored on a network site from a data processing device, the request including and address for the content and first version information usable to identify a version of the content previously-downloaded to the data processing device; transmitting a first request to the network site on behalf of the data processing device, the first request including the address of the content but requesting only second version information related to the content, the second version information identifying a current version of the content stored on the network site; comparing the first version information with the second version information to determine whether the current version of the content stored on the data processing device is the latest version; transmitting an indication to the client that the client has the latest version of the content if the first version information matches the second version information; if the first version information does not match the second version information, then transmitting a second request to the network site requesting the latest version of the content and forwarding the latest version of the content to the data processing device.
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