A method of controlling operations of a network system, the network system comprising a server and a plurality of client terminals (20A-20N) linked to the server, the method comprising: the server establishing a file set; each of the client terminals (20A-20N) establishing a directory; individually setting for each of the client terminals (20A-20N) a first criterion (24A-24N) and a second criterion (14A-14N), - the first criterion (24A-24N) being stored in each of the client terminals (20A-20N) and being configured to set a first file schedule for each of the client terminals (20A-20N), and - the second criterion (14A-14N being stored in the server and being configured to set the second file schedule for each of the client terminals (20A-20N), wherein the second criterion includes types of files allowed to be respectively downloaded from the server to the client terminals (20A-20N) within a plurality of time periods of a second file schedule; a first client terminal of the client terminals (20A-20N) selectively uploading file(s) from the directory of the first client terminal to the server according to the first file schedule for the first client terminal, such that the server updates file(s) of the file set using the file(s) received from the first client terminal; and in response to updating of the file(s) of the file set, the server selectively transmitting updated content of the file(s) of the file set to each of the rest of the client terminals (20B-20N) other than the client terminal on the second file schedule for the each of the rest of the client terminals (20B-20N) according to the second criterion (14A-14N) for each of the rest of the client terminals (20B-20N), such that each of the rest of the client terminals (20B-20N) updates the file(s) of the directory for each of the rest of the client terminals (20B-20N) using the updated content of the file(s) received from the server. the server establishing a file set; each of the client terminals (20A-20N) establishing a directory; individually setting for each of the client terminals (20A-20N) a first criterion (24A-24N) and a second criterion (14A-14N), - the first criterion (24A-24N) being stored in each of the client terminals (20A-20N) and being configured to set a first file schedule for each of the client terminals (20A-20N), and - the second criterion (14A-14N being stored in the server and being configured to set the second file schedule for each of the client terminals (20A-20N), wherein the second criterion includes types of files allowed to be respectively downloaded from the server to the client terminals (20A-20N) within a plurality of time periods of a second file schedule; - the first criterion (24A-24N) being stored in each of the client terminals (20A-20N) and being configured to set a first file schedule for each of the client terminals (20A-20N), and - the second criterion (14A-14N being stored in the server and being configured to set the second file schedule for each of the client terminals (20A-20N), wherein the second criterion includes types of files allowed to be respectively downloaded from the server to the client terminals (20A-20N) within a plurality of time periods of a second file schedule; a first client terminal of the client terminals (20A-20N) selectively uploading file(s) from the directory of the first client terminal to the server according to the first file schedule for the first client terminal, such that the server updates file(s) of the file set using the file(s) received from the first client terminal; and in response to updating of the file(s) of the file set, the server selectively transmitting updated content of the file(s) of the file set to each of the rest of the client terminals (20B-20N) other than the client terminal on the second file schedule for the each of the rest of the client terminals (20B-20N) according to the second criterion (14A-14N) for each of the rest of the client terminals (20B-20N), such that each of the rest of the client terminals (20B-20N) updates the file(s) of the directory for each of the rest of the client terminals (20B-20N) using the updated content of the file(s) received from the server.