Abstract: A method (100) of caching data is disclosed. The method (100) optimises proactive caching of data by estimating future demand for particular data within a computer system (1900). The computer system (1900) is typically configured in accordance with the hybrid peer-to-peer model. The method (100) maintains the bandwidth cost of proactive caching in proportion to expected demand for particular data. The method (100) also determines the availabiliy of a peer. The availability of a peer is defined herein as the probability of a peer being online, for example, when particular data is required by another peer.

Abstract: A method (100), apparatus (200) and computer program product for editing an electronic document is disclosed. Editorial modifications that a first collaborator has made to the document are published. Receipt of the modifications is acknowledged by one or more other collaborators and the published modifications are merged with any local modifications to produce a merged version of said modifications. The merged modifications are applied to the document to produce an edited version of the document including the editorial modifications. The edited version containing data incorporated therein indicating acknowledgment of the editorial modifications by one or more of the collaborators.