16. A non-transitory computer-readable medium having computer-readable instructions stored thereon that, upon execution by a processor, cause the processor to: record, in a context holding unit, a plurality of context information, wherein each context information includes a context entity identifier for distinguishing a context entity from other context entities, various information representing a state of the context entity, and association information; receive a request for information representing the state of a first context entity; instruct a context generation unit to, in response to the received request, from said context holding unit, extract the context information of the first context entity, extract the context information of a second context entity which is registered as the association information in the context information of the first context entity, and execute, at least once, a process of extracting the context information of a third context entity which is registered as the association information in the extracted context information excluding the context information of the first context entity, but not registered as the association information in the context information of the first context entity, to determine, as the information representing the state of the first context entity, the information contained in any of the extracted context information; and send back the information determined by said generation context unit to respond to the request.
16. A non-transitory computer-readable medium having computer-readable instructions stored thereon that, upon execution by a processor, cause the processor to: record, in a context holding unit, a plurality of context information, wherein each context information includes a context entity identifier for distinguishing a context entity from other context entities, various information representing a state of the context entity, and association information; receive a request for information representing the state of a first context entity; instruct a context generation unit to, in response to the received request, from said context holding unit, extract the context information of the first context entity, extract the context information of a second context entity which is registered as the association information in the context information of the first context entity, and execute, at least once, a process of extracting the context information of a third context entity which is registered as the association information in the extracted context information excluding the context information of the first context entity, but not registered as the association information in the context information of the first context entity, to determine, as the information representing the state of the first context entity, the information contained in any of the extracted context information; and send back the information determined by said generation context unit to respond to the request. 17. The non-transitory computer-readable medium according to claim 16 , wherein when the context information of the first and second context entities do not contain the same kind of information as the requested information, further comprising instructions to extract the context information of the second and third context information to determine, as the information representing the state of the first context entity, the information contained in the third context information.