System for and method of exchanging server data in packet unit

#The present invention relates to a server system of a type wherein the sharing of resources can be carried out using extensions of a private branch exchange (PBX), and more specifically to a system for and a method of exchanging server data in a packet unit, of a type wherein a plurality of users can simultaneously utilize the same resource.

#As one of conventional arts, there is known one disclosed in Japanese Patent Application Laid-Open No. 1-109847. According to the disclosure, peripheral devices such as a printer, hard disc are electrically connected to an exchange network of a digital exchanger through a data interface unit. On the other hand, a data Processing unit is electrically connected to the exchange network of the digital exchanger through a data access unit. In the conventional art having such an arrangement, terminals are electrically connected to the data Processing unit and the peripheral devices (servers) by making use of exchange functions of the digital exchanger. The digital exchanger is provided with connecting shared buses for the purpose of control of the peripheral devices. The buses are interconnected to internal buses of a data processing control device. When a plurality of peripheral devices are connected to the exchange network, the data processing control device can accept operation requests of other peripheral devices while one peripheral device is in operation. Thus, the data processing control device connects a line for a peripheral device to which a use request has been made to a line for a corresponding peripheral device. According to the prior art, as described above, a plurality of peripheral, devices can simultaneously be utilized by connecting the peripheral devices to separate lines.

#The above disclosure does not take into consideration a case where use requests are made to the same peripheral device from a plurality of terminals (lines). When one terminal makes use of the peripheral device, other terminals cannot use it, with the result that they had to wait for its use until a process of the terminal while being using the peripheral device is completed.

#FIG. 1 is a diagram showing a PBX server system according to a first embodiment of the present invention;

#FIG. 2 is a diagram schematically showing an internal structure of a PBX in the system shown in FIG. 1;

#FIG. 3 is a diagram schematically illustrating an internal structure of terminal equipment in the system shown in FIG. 1;

#Preferred embodiments of the present invention will hereinafter be described with the accompanying drawings. FIG. 1 shows a PBX server system according to a first embodiment to which a system for exchanging server data in a packet unit, i.e., a sever data packet exchange system of the present invention is applied. The PBX server system basically comprises a digital public branch exchange (hereinafter referred to as a “PBX”) 100, a plurality of pieces of terminal equipment 101, and a server 104. The terminal equipment 101 and the server 104 can be connected to extensions 105 of the PBX through physical interfaces identical to those of devices such as telephones 102, facsimiles 103, the devices being used for a public telephone communication line. As has been provided in the advice 1.441 (ISDN user/network interface) of CCITT, each extension 105 of the PBX 100 is used to send a control signal transmitted and received between the PBX 100 and each terminal equipment 101 for the purpose of terminal connection and an information signal used to make a telephone call and transmit data, through separate or discrete channels. Each extension 105 has at least one control signal channel and one information signal channel. A plurality of devices can be connected to one extension 105, and they can simultaneously communicate with one another. The PBX server system is activated to transmit data to the server 104 from the terminal equipment 101 through the PBX 100. In addition, the transfer of data between the terminal equipment and the PBX and between the server and the PBX is carried out in the form of a packet unit, using either the control signal channel (D channel) or the information signal channel (B channel) in accordance with the provision of the advice X.25 of CCITT. The exchange of a data packet delivered to the sever from the terminal equipment is performed in the PBX 100. FIG. 33 shows a packet format provided in the advice X.25 of CCITT. FIG. 33(a) illustrates a format of a call control packet. The format comprises a general format identifier (GFI), a logical channel group number (LCGN), a logical channel number (LCN), a packet type identifier, a packet header including a called terminal address, etc. necessary for the connection of a calling side to a called destination or terminal, and user data divided into blocks of given sizes. FIG. 33(b) shows a format of a data packet. The format comprises a general format identifier (GFI), a logical channel group number (LCGN), a logical channel number (LCN), a packet header including sequence numbers (P(R), P(S)) of the packet, and user data divided into blocks of predetermined sizes. In order to distinguish between special communications carried out between the terminal equipment 101 and the extension control 206, a logical channel number is applied to each packet in the form of the packet format referred to above. A packet communication is carried out for every destinations of respective terminal equipment connected to one physical line, so that it can be distinguished from others by an identifier of data indicative of the so-applied logical channel number. Thus, when a logical channel number corresponding to address information is firstly applied to one of packets and a packet communication service is initiated, the PBX can subsequently recognize a desired destination by simply applying the logical channel number to data. FIG. 34 illustrates a transmission format of a user packet based on the D channel provided in the advice I.441, I.462 of CCITT. In other words, there are provided a service access point identifier (SAPI) used to manage terminal information for each physical line and indicate either call control information or packet information, and a circuit-terminal control indicative of a number (TEI) used to identify each multipoint-connected terminal, etc.

#FIG. 2 is a diagram schematically showing the structure of the inside of the PBX 100. FIG. 2(a) shows the structure of the PBX in which a packet exchange 201 for changing over packet data from the terminal equipment to the server is directly connected to a time-division multiplex (TDM) path 202 in the PBX 100. Also connected to the TDM path 202 are a central processing unit (CPU) 203 for controlling the entire operation of the PBX 100, an extension control 205 for controlling the electrical connections among the extensions 105, and a public line control 206 for controlling the electrical connections among public lines 106. A memory 204 and control terminal equipment 208 are electrically connected via a CPU bus 207 to the CPU 203, and the memory 204 stores therein information about the attribute of each extension and communication records. The control terminal equipment 208 is used to cause a system controller to examine the condition of the PBX in use and to enter the attribute of the extension and change it to another. FIG. 2(b) illustrates the structure of the PBX in which a computer 210 is electrically connected to a CPU 203 of a PBX 100 through a computer interface 209, with the computer 210 having in its inside a packet exchange 211 identical to the above packet exchange 201. Other elements of structure are identical to those shown in FIG. 2(a). According to the structure of FIG. 2(a), the extension control 205 first receives data supplied from one of a plurality of pieces of terminal equipment electrically connected to the extensions 105. Then, the data thus received passes through the TDM path 202, after which it is delivered to the packet exchange 201. Thereafter, the data is sent to a server electrically connected to one extension 105 through the transmission path opposite the above path. According to the structure of FIG. 2(b), data supplied from one of a plurality of pieces of terminal equipment electrically connected to the extensions 105 is first received by the extension control 205, and passes through the TDM path 202, followed by delivering to the CPU 203. Then, the CPU ˜03 delivers the so-received server use data to the computer interface 209 via the CPU bus 207. After that, the computer interface 209 sends the data to the packet exchange 211 of the computer 210 provided outwardly of the PBX 100. Further, the data is supplied to the server electrically connected to one extension 105 through the opposite route referred to above.

#FIG. 3 shows the structure of the terminal equipment 101 connected to the extension 105, for furnishing communication services of the PBX server system according to the first embodiment of the present invention, to the user. The terminal equipment 101 basically comprises an IC card control 301 for accepting a user entry in response to the insertion of an IC card 30 therein, a main function 302 for providing functions identical to those of generally-used personal computers and work stations, a server use control 303, a user entry control 304 and a communication interface 305. In addition, the terminal equipment 101 is electrically connected to a connector 308 of the extension 105 via an extension cable 307 similar to that employed in a normally-used telephone, after which it is connected via the connector 308 to the extension 105. When the terminal equipment 101 is electrically connected to the extension 105 of the PBX 100, the communication interface 305 communicates with the extension control 205 of the PBX 100, using the control signal channel and the information signal channel of the extension 105. The server use control 303 is used to carry out communication control of data produced when the user makes use of the server 104. The user entry control 304 is used to examine whether or not the user entered in the terminal equipment 101 has been given a system use permit.