Patent ID: 8527606

Claim:
A network system, comprising: one or more computers to function as: an update notification message generator for generating, for each of a plurality of services, an update notification message that stores update information of a content or metadata of the content, or a reference to the update information; a filter attribute setting unit for setting, in the update notification message for each service delivered from the update notification message generator, a filter attribute for categorizing the message; an update notification message accumulation unit to accumulate the update notification message in which the filter attribute has been set by the filter attribute setting unit; a local content/metadata storage unit in a home network appliance that stores a content of a specific service or metadata thereof; an update unit including an application corresponding to the specific service, for updating the content or the metadata in the local content/metadata storage unit using the update information; and an update information provision unit for managing in advance a correspondence between the application and the filter attribute, specifying, based on the filter attribute set in the update notification message acquired from the update notification message accumulation unit via a network and the correspondence, an application that provides the update information within the update notification message, and providing the update information by activating the application, wherein the update notification message generator generates, as the update information, full-update information as a full-update content of the content or the metadata and differential-update information as an update content of only a differential update while periodically switching them, and setting, in the update notification message, attribute information that indicates an update method of the update information of each update notification message, and wherein the update information provision unit acquires, from the update notification message accumulation unit via the network, based on the attribute information set in the update notification message accumulated in the update notification message accumulation unit, the update notification message necessary for synchronizing the content or the metadata in the local content/metadata storage unit with the content or the metadata on a side of a provider of the service.