1. Field of the Invention
The present invention relates to a communication apparatus, a communication system, and a communication method for performing a task involving the cooperative employment of a plurality of networked terminals that are remotely located.
2. Related Background Art
Conventionally, a variety of tasks are cooperatively performed by persons at remote locations while using systems comprising a plurality of terminals that are joined together to form networks. A conventional system is created for each task that constitutes a cooperative effort (session). That is, a remote conference convening system is activated convening a remote conference, a remote lecture assembly system is activated for presenting a remote lecture, and a status evaluation system is activated for evaluating existing conditions.
These systems are independently developed, and the user interfacing specifications for each of them differ.
When an independent system is created for each task that involves a cooperative effort, it is not possible to smoothly shift the performance of one task to another.
For example, when a user is performing a task that involves using the status evaluation system to obtain an understanding of the status of a person located at a remote side, and he or she desires to converse with that person, the user must activate a conversation participation system.
Since the user interface specifications differ from system to system, the user must understand all of the user interface specifications for all of the systems he or she uses.
As a security problem that is conventionally encountered, a conventional system can not clearly distinguish between the access management procedures that apply when a third party is to participate in a session and the privacy management procedures that apply when a third party is to be provided information concerning the session. Therefore, a conventional system can not adequately respond to a request for information concerning a session when participation in the session is not contemplated.
As another security problem, since conventionally a plurality of terminals are employed and are used in common during a session in which static images are mutually transmitted, the reception programs at all of the receiving terminals access and display data output by a transmission program that is employed at one terminal. In this case, when the transmission and reception programs are intended for a special application, such as for a video conference, special authentication means and operation rejection and acceptance means are provided for the transmission and the reception programs, so that a system having no security problem can be provided.
Further, in order to use in common a general program, not a special one, among a plurality of terminals networked for a video conference, or to eliminate the labor involved in creating a special reception program, a display instruction from a general program that is operating on one terminal may be received by general-purpose display programs at the other, individual terminals, which thereafter display the data they receive. This reception and display operation is accomplished at a workstation by using a server program, a so-called window server.
Besides window servers, file I/O servers are popular server programs that provide some services in response to external requests. A file I/O server may, for example, respond to an external request by transferring data from a file to a requesting person. But since the file I/O servers, as well as the window servers, have not been developed for the purpose of supporting the convening of video conferences, setups by which access of conference is enabled can not be provided, with the result that the security procedures are either excessively strict, such as one that requires the use of a password by each participant, or they are excessively lax, such as one that grants access to anybody.
A window server, for example, includes a procedure for designating users to whom operating permission is to be provided, so as to prevent the execution of display instructions that are issued by unauthorized persons. Since the persons for whom communication is authorized can not be selected in advance when a window server is employed for a video conference, the server is so set that it permits the execution of display instructions it receives from any person.