Patent ID: 7980459

Claim:
A presence system comprising: a table of presences with attached category that associates and stores a presence identifier of a presence of each user, category information and the presence, a watcher list that stores a watcher that refers to the presence, for each presence identifier of the users; a first subscription receiving unit for receiving a subscription that includes category information corresponding to the presence that the subscriber wishes to subscribe to, a user identifier of the subscriber and a user identifier of a subscribee, and a registration unit for specifying the presence identifier corresponding to the user identifier of the subscribee and the category information included in the subscription by searching a table of presences with attached category, and for registering the identifier of the user of the subscriber onto the watcher list of the given presence identifier, wherein one or more of the table of presences, the watcher list, the first subscription receiving unit, and the registration unit are embodied in a computer.