Patent ID: 7716293

Claim:
A presence information sharing method for sharing presence information indicating a status of a user using a client application in a system comprising a plurality of service servers providing a different type of service for different types of client applications, respectively, and a presence server that manages the presence information of said user, wherein: a processing unit of each of said plurality of service servers executes: a reception operation, in which a change of presence information with respect to the service provided by the service server is received from said client application; a first change notification sending operation, in which a change notification for notifying the change of the presence information, received in said reception operation, is sent to said presence server; and a second change notification sending operation, in which a change notification message for notifying a change of presence information with respect to a service different from the service provided by the service server is received and said change notification message is sent to the client application; said presence server includes a processing unit and a storage unit for storing presence information of each user for each service of a plurality of services provided by said plurality of service servers; and said processing unit of the presence server executes: an update operation, in which said presence information stored in said storage unit is updated based on a change notification message sent from each of said plurality of service servers; and a third change notification sending operation, in which a change notification message for notifying the presence information updated in said update operation to service servers that provide services different from the service of the updated presence information.