1. A client-side assistant apparatus for assisting in delivering update contents in a computer network, the assistant apparatus comprising: at least one peer client which can communicate with the client-side assistant apparatus; an evaluating unit configured to evaluate a user's interaction preference according to a user's interaction history; and a prefetching unit configured to evaluate, in response to an update notification received from a server of the computer network, whether to prefetch the update contents corresponding to the update notification according to the evaluated interaction preference, and, if prefetching, obtain the update contents from at least one peer client in a peer-to-peer (P2P) manner and store them locally.