In providing services in an environment in which apparatuses constituting a system change dynamically, flexible control of access control is performed for the apparatuses whose access rights and service providing policies are different or have not been set beforehand. In a distributed system where computers each having a function of storing data and processing a program and a communication facility perform data exchange through a communication medium, and thereby perform processing, control of limiting an access to the system etc. is performed as a shared session that is established by synthesizing access rights and service providing policies owned by the apparatuses, and accesses to the apparatuses and provision of services are performed through the shared session, whereby the access rights and the services to be provided are controlled according to a configuration of apparatuses constituting the system.