Multimedia information system

A request for transition from a process controlled by HTTP protocol to a special process controlled by a protocol different from the HTTP protocol is made by a URL as command transfer means. When the URL is input via an information terminal to a server, a client agent is started on the information terminal side, and an agent service section is started on the sever side. The client agent and the agent service section carry out the special process, such as an authentication process, while bi-directionally transmitting and receiving data to and from each other. A service manager controls the special process such that transition to another process, such as a channel-switching process, is inhibited during execution of the authentication process by the client agent and the agent service section.