Communication unit, server, communication system, and communication method

Abstract

To transmit data to multiple data destination units at high speed under conditions where simultaneous one-to-many communication between multiple units is restricted.SOLUTION: A data transmission source unit (2) is connected to multiple data transmission destination units (4A to 4D) via a communication network (NT) where simultaneous one-to-many communication between multiple units is restricted. The data transmission source unit (2) transfers data (DT) to a storage unit (33) and issues an instruction to copy the transferred data (DT) within the storage unit (33) at least as many times as the number of data transmission destination units.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication unit, a server, a communication system and a communication method. [Background technology]

[0002] Patent Document 1 discloses a multiplexing device that uses a network to connect a central processing unit to multiple external storage devices. The multiplexing device has a means for storing the same data in multiple external storage devices with a single data transfer by using broadcast or multicast when writing data from the central processing unit to the external storage devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-328038 Summary of the Invention [Problem to be solved by the invention]

[0004] The multiplexing device disclosed in Patent Document 1 is designed to be used on a network in which broadcast or multicast communication is permitted. Therefore, there is a problem in that this multiplexing device cannot be used on a network in which broadcast or multicast communication is restricted. One aspect of the present invention aims to transmit data at high speed to multiple data destination units in a state in which simultaneous one-to-many communication between multiple units is restricted. [Means for solving the problem]

[0005] In order to solve the above problem, a communication unit according to one embodiment of the present invention is a communication unit connected to multiple data destination units via a communication network in which simultaneous one-to-many communication between multiple units is restricted, and comprises a transfer processing unit that transfers data to be shared between the multiple data destination units to a storage unit, and a copy instruction unit that gives instructions to copy the data transferred to the storage unit within the storage unit in at least an amount equal to the number of the data destination units.

[0006] In addition, a communication unit according to one embodiment of the present invention is a communication unit that is connected to a data source unit and multiple data destination units and is included in the multiple data destination units in a communication network in which simultaneous one-to-many communication between multiple units is restricted, and includes a receiving unit that receives notification that data to be shared between the data source unit and the multiple data destination units has been copied to a memory unit in an amount equal to at least the number of the data destination units, and a transmitting unit that sends a request to obtain the data copied in the memory unit.

[0007] In order to solve the above problem, a server according to one embodiment of the present invention is a server connected to a data source unit and multiple data destination units in a communication network in which simultaneous one-to-many communication between multiple units is restricted, and comprises: a receiving unit that receives data from the data source unit to be shared between the data source unit and the multiple data destination units; and a memory unit that copies and stores the data received by the receiving unit in at least the number of copies equal to the number of the data destination units.

[0008] Furthermore, a communication system according to one embodiment of the present invention is a communication system including a data source unit and multiple data destination units connected by a communication network in which simultaneous one-to-many communication between multiple units is restricted, wherein the data source unit comprises a transfer processing unit that transfers data to be shared with the multiple data destination units to a storage unit, and a copy instruction unit that gives instructions to copy the data transferred to the storage unit within the storage unit in amounts equal to at least the number of the data destination units, and at least one of the multiple data destination units comprises a receiving unit that receives notification that the data has been copied to the storage unit, and a transmitting unit that sends a request to obtain the data copied in the storage unit.

[0009] Furthermore, a communication method according to one embodiment of the present invention is a communication method executed by a communication system including a data source unit and multiple data destination units connected by a communication network in which simultaneous one-to-many communication between multiple units is restricted, and includes the following steps 1) and 2) executed by the data source unit, and the following steps 3) and 4) executed by at least one of the multiple data destination units.

[0010] 1) a transfer processing step of transferring data to be shared between a data source unit and a plurality of data destination units to a storage unit; 2) a copy instruction step of giving an instruction to copy the data transferred to the storage unit within the storage unit by at least the number of the data destination units; 3) receiving a notification that the data has been copied to the storage unit; 4) A transmission step of transmitting a request to acquire the data copied in the storage unit. [Effects of the Invention]

[0011] According to one aspect of the present invention, data can be transmitted at high speed to a plurality of data destination units in a state where simultaneous one-to-many communication between a plurality of units is restricted. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing an example of the configuration of a communication system according to a first embodiment of the present invention. [Figure 2] 2 is a sequence diagram showing an example of a communication method executed by the communication system shown in FIG. 1. [Figure 3] FIG. 10 is a block diagram showing an example of the configuration of a communication system according to a second embodiment of the present invention. [Figure 4] 4 is a sequence diagram showing an example of a communication method executed by the communication system shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Embodiment 1] <Configuration of communication system 1> 1 is a block diagram showing an example of the configuration of a communication system 1 according to a first embodiment of the present invention. The communication system 1 may be used, for example, in a monitoring system that monitors the operating status of a device that performs monitoring and control of a plant. Examples of the plant include a water and sewage treatment plant, a factory, a building, and a power receiving and transforming facility.

[0014] As shown in Fig. 1, the communication system 1 includes a data source unit 2, a server 3, and a plurality of data destination units 4A, 4B, 4C, and 4D. Note that, in Fig. 1, the communication system 1 includes four data destination units 4A to 4D, but is not limited to this and may include two or more data destination units.

[0015] In the communication system 1, a data source unit 2, a server 3, and a plurality of data destination units 4A to 4D are connected to one another by a communication network NT. The data source unit 2, the server 3, and the plurality of data destination units 4A to 4D are installed within the communication network NT.

[0016] In the communication network NT, simultaneous one-to-many communication between a plurality of units is restricted. In other words, in the communication network NT, simultaneous one-to-many communication between the data source unit 2 and a plurality of data destination units 4A to 4D is restricted. The above-mentioned plurality of units are the data source unit 2 and a plurality of data destination units 4A to 4D. Note that simultaneous one-to-many communication may also be restricted between the server 3 and the data source unit 2 and a plurality of data destination units 4A to 4D.

[0017] Examples of simultaneous one-to-many communication that is restricted in the communication network NT include broadcast communication and multicast communication. Restriction on simultaneous one-to-many communication means that simultaneous one-to-many communication is not permitted. Only one-to-one point-to-point communication is possible in the communication network NT. The communication network NT is capable of connecting to the Internet.

[0018] When the communication network NT is connected to the Internet, broadcast communication and multicast communication are restricted in order to prevent the communication system 1 from being subjected to a DOS attack. This improves security and enables stable transmission of data from the data source unit 2 to the data destination units 4A to 4D.

[0019] <Configuration of data sender unit 2> The data source unit 2 includes a receiving unit 21, a transmitting unit 22, a storage unit 23, and a control unit 24. The data source unit 2 is an example of a communication unit. The receiving unit 21 and the transmitting unit 22 are communication interfaces connected to a communication network NT. The receiving unit 21 receives data from outside the data source unit 2 via the communication network NT. The transmitting unit 22 transmits data to outside the data source unit 2 via the communication network NT.

[0020] The storage unit 23 stores data and is a non-volatile memory such as a hard disk. The control unit 24 is, for example, a CPU (Central Processing Unit) and controls each part of the data transmission source unit 2. The control unit 24 has a transfer processing unit 241 and a copy instruction unit 242.

[0021] <Server 3 configuration> The server 3 includes a receiving unit 31, a transmitting unit 32, a storage unit 33, and a control unit 34. The receiving unit 31 and the transmitting unit 32 are communication interfaces connected to the communication network NT. The receiving unit 31 receives data from outside the server 3 via the communication network NT. The transmitting unit 32 transmits data to outside the server 3 via the communication network NT.

[0022] The storage unit 33 stores data and is, for example, a memory such as a RAM. The storage unit 33 may be a volatile memory because it is used to temporarily store data DT, which will be described later. The control unit 34 is, for example, a CPU, and controls each unit of the server 3. The control unit 34 has a reception unit 341, a storage processing unit 342, a notification unit 343, and a transmission processing unit 344.

[0023] <Data destination units 4A to 4D> The data destination unit 4A is connected to the data source unit 2, the server 3, and a plurality of data destination units 4B to 4D in the communication network NT, and is included in the plurality of data destination units 4A to 4D. The data destination unit 4A includes a receiving unit 41, a transmitting unit 42, and a control unit 43.

[0024] The receiving unit 41 and the transmitting unit 42 are communication interfaces connected to the communication network NT. The receiving unit 41 receives data from outside the data destination unit 4A via the communication network NT. The transmitting unit 42 transmits data to outside the data destination unit 4A via the communication network NT. The control unit 43 is, for example, a CPU, and controls each part of the data destination unit 4A.

[0025] Like the data destination unit 4A, the data destination units 4B to 4D each include a receiving unit 41, a transmitting unit 42, and a control unit 43. Note that at least one of the multiple data destination units 4A to 4D may include the receiving unit 41, the transmitting unit 42, and the control unit 43. The data destination units 4A to 4D are an example of a communication unit.

[0026] <Processing Executed in Communication System 1> Fig. 2 is a sequence diagram showing an example of a communication method executed by the communication system 1 shown in Fig. 1. First, the transfer processing unit 241 of the data source unit 2 transfers data DT to be shared between the data source unit 2 and the plurality of data destination units 4A to 4D to the storage unit 33 of the server 3 (S1, transfer processing step).

[0027] Specifically, the transfer processing unit 241 uses the sending unit 22 to send the data DT stored in the memory unit 23 of the data source unit 2 to the server 3 via the network NT. Note that the transfer processing unit 241 may also send the data DT that the receiving unit 21 has received from outside the data source unit 2 via the network NT to the server 3. The receiving unit 31 of the server 3 receives the data DT from the data source unit 2 via the network NT. The storage processing unit 342 of the server 3 stores the data DT received by the receiving unit 31 in the memory unit 33.

[0028] The copy instruction unit 242 of the data transmission source unit 2 issues an instruction to copy the data DT transferred to the storage unit 33 of the server 3 within the storage unit 33 by at least the number of data transmission destination units (S2, copy instruction step).

[0029] Specifically, the copy instruction unit 242 uses the transmitter 22 to transmit a signal indicating an instruction to copy the data DT to the server 3 via the network NT. The receiver 31 of the server 3 receives the signal indicating an instruction to copy the data DT from the data source unit 2 via the network NT.

[0030] Consider a case where the receiving unit 31 of the server 3 receives a signal instructing to copy the data DT. In this case, as shown in Fig. 1, the storage unit 33 of the server 3 copies and stores at least the number of data destination units of the data DT received by the receiving unit 31 and stored in the storage unit 33 (S3).

[0031] Specifically, the storage processing unit 342 of the server 3 copies and stores the data DT in the storage unit 33 in an amount equal to at least the number of data destination units. The number of data destination units is the number of data destination units connected to the network NT. In Fig. 1, data destination units 4A to 4D are connected to the network NT, so the number of data destination units is four.

[0032] After the storage unit 33 copies the data DT, the notification unit 343 of the server 3 notifies the data destination units 4A to 4D that the data DT has been copied to the storage unit 33 (S4). Specifically, the notification unit 343 uses the transmission unit 32 to sequentially transmit signals indicating that the data DT has been copied to the storage unit 33 to the data destination units 4A to 4D via the network NT.

[0033] At this time, the notification unit 343 transmits the signals to the data destination units 4A to 4D simultaneously. Here, "simultaneous" is a concept that includes cases where the communication timings are perfectly synchronized and cases where there is a predetermined small time difference in the communication timings. The same applies to "simultaneous" described below (excluding "simultaneous" in "one-to-many simultaneous communication"). "Simultaneous" may also be expressed as "approximately simultaneous." The predetermined small time difference is a difference to the extent that the data DT can be transmitted to the data destination units 4A to 4D at high speed.

[0034] The receiving unit 41 of the data destination units 4A to 4D receives a notification that the data DT has been copied to the storage unit 33 of the server 3 by at least the number of data destination units (S5, receiving step). After the receiving unit 41 receives the notification that the data DT has been copied to the storage unit 33, the transmitting unit 42 of the data destination units 4A to 4D transmits to the server 3 a request to acquire the data DT copied in the storage unit 33 (S6, transmitting step).

[0035] The accepting unit 341 of the server 3 accepts, from the plurality of data destination units 4A to 4D, requests to acquire the data DT copied in the storage unit 33 (S7). Specifically, the receiving unit 31 of the server 3 receives the requests to acquire the data DT from the plurality of data destination units 4A to 4D. The accepting unit 341 accepts the requests to acquire the data DT received by the receiving unit 31.

[0036] The transmission processing unit 344 of the server 3 simultaneously transmits the data DT copied in the storage unit 33 to each of all of the data destination units 4A to 4D that have made the acquisition requests (S8). Specifically, the transmission processing unit 344 uses the transmission unit 32 to simultaneously transmit the data DT copied in the storage unit 33 to each of all of the data destination units 4A to 4D that have made the acquisition requests.

[0037] 1, the transmission processing unit 344 uses the transmitting unit 32 to transmit the data DT stored in the storage unit 33 to the data destination unit 4A via the network NT. In other words, the control unit 43 of the data destination unit 4A uses the receiving unit 41 to access the storage unit 33 via the network NT and acquires the data DT from the storage unit 33.

[0038] 1, the transmission processing unit 344 transmits the data DT stored in the storage unit 33 to the data destination unit 4B. In other words, the control unit 43 of the data destination unit 4B accesses the storage unit 33 using the receiving unit 41 and acquires the data DT from the storage unit 33.

[0039] 1, the transmission processing unit 344 transmits the data DT stored in the storage unit 33 to the data destination unit 4C. In other words, the control unit 43 of the data destination unit 4C accesses the storage unit 33 using the receiving unit 41 and acquires the data DT from the storage unit 33.

[0040] 1, the transmission processing unit 344 transmits the data DT stored in the storage unit 33 to the data destination unit 4D. In other words, the control unit 43 of the data destination unit 4D accesses the storage unit 33 using the receiving unit 41 and acquires the data DT from the storage unit 33.

[0041] Each of the data destination units 4A to 4D can simultaneously acquire the data DT from the server 3. Furthermore, each of the data destination units 4A to 4D can acquire the data DT in parallel with one another. The process of step S8 may be different from one-to-many simultaneous communication. After the transmission processing unit 344 transmits the data DT to each of the data destination units 4A to 4D, the storage processing unit 342 deletes the multiple pieces of data DT from the storage unit 33 (S9).

[0042] <Effects> In step S2, the copy instruction unit 242 issues an instruction to copy the data DT within the storage unit 33, thereby allowing the process of copying the data DT within the storage unit 33 to proceed. Thus, the multiple pieces of data DT generated by copying can be transmitted to the multiple data transmission destination units 4A to 4D. Therefore, in a state where simultaneous one-to-many communication between multiple units is restricted, the data DT can be transmitted at high speed to the multiple data transmission destination units 4A to 4D.

[0043] In step S1, the transfer processing unit 241 transfers the data DT to the storage unit 33 of the server 3 installed in the communication network NT, thereby allowing the data DT to proceed to a process of copying the data DT within the storage unit 33 of the server 3. Therefore, the data DT can be transmitted at high speed to a plurality of data destination units 4A to 4D while reducing the load on the data source unit 2.

[0044] In step S5, the receiving unit 41 receives a notification that the data DT has been copied to the storage unit 33. In step S6, the transmitting unit 42 transmits a request to acquire the data DT copied to the storage unit 33. Furthermore, since the notification that the data DT has been copied to the storage unit 33 contains a small amount of information, the copying of the data DT to the storage unit 33 can serve as a trigger for the data destination units 4A to 4D to immediately proceed to processing to acquire the data DT.

[0045] Furthermore, the multiple data DT generated by copying can be received by the multiple data destination units 4A to 4D. Therefore, in a state where simultaneous one-to-many communication between multiple units is restricted, the data DT can be transmitted at high speed to the multiple data destination units 4A to 4D.

[0046] In steps S1 to S3, the receiving unit 31 receives the data DT from the data source unit 2, and the storage unit 33 copies and stores the data DT. Therefore, the multiple data DT generated by copying can be transmitted to the multiple data destination units 4A to 4D while reducing the load on the data source unit 2. Furthermore, in a state where simultaneous one-to-many communication between multiple units is restricted, the data DT can be transmitted at high speed to the multiple data destination units 4A to 4D.

[0047] In step S8, the transmission processing unit 344 simultaneously transmits the data DT copied in the storage unit 33 to all of the data destination units 4A to 4D that have made the acquisition request. Therefore, in a state where simultaneous one-to-many communication between multiple units is restricted, the server 3 can transmit the data DT to the multiple data destination units 4A to 4D at high speed.

[0048] Furthermore, communication between the server 3 and each of the data destination units 4A to 4D may be one-to-one communication. If the server 3 has, for example, one CPU as the control unit 34, transmission of data DT from the server 3 to the data destination units 4A to 4D is processed sequentially, but because overhead is small, the transmissions can be executed simultaneously.

[0049] The data DT is transmitted from the data source unit 2 to the data destination units 4A to 4D via the server 3. This allows processing other than processing related to the data DT by the data source unit 2 and processing related to the data DT by the server 3 to proceed in parallel, preventing the processing of the data source unit 2 from being delayed.

[0050] Also, by having the server 3 execute the processes of copying and transmitting the data DT, it is possible to have the data source unit 2 execute processes other than those related to the data DT in a concentrated manner. Furthermore, since the processing of the data source unit 2 is faster than when the server 3 is not installed, it is possible to shorten the time it takes for the data DT to move from the data source unit 2 to the data destination units 4A to 4D.

[0051] Through steps S4 to S8, each of the data destination units 4A to 4D accesses the storage unit 33 of the server 3 and acquires the data DT from the storage unit 33. Therefore, even if simultaneous one-to-many communication is restricted in the communication network NT, the data DT can be moved at high speed from the data source unit 2 to the data destination units 4A to 4D, just as in the case where simultaneous one-to-many communication is permitted.

[0052] <Monitoring system> For example, consider a case where the communication system 1 is used in a monitoring system that monitors the operating status of a device that monitors and controls a plant. In this case, the data transmission source unit 2 and the data transmission destination units 4A to 4D may be installed in the plant (on-site). Furthermore, the control unit 24 of the data transmission source unit 2 may have a collection unit (not shown) that collects information on the operating status.

[0053] The collection unit also generates the collected information as data DT. Then, the data DT can be transmitted at high speed from the data source unit 2 to the data destination units 4A to 4D via the server 3. This allows the same information collected by the data source unit 2 to be instantly shared with the workers operating each of the data destination units 4A to 4D. In this case, the data destination units 4A to 4D may be provided with a display unit that displays the information of the data DT.

[0054] Furthermore, when the data source unit 2 executes a process for automatically controlling a device that monitors and controls a plant, for example, it is preferable to prevent a delay in the process of the data source unit 2. Therefore, transmitting the data DT from the data source unit 2 to the data destination units 4A to 4D at high speed is particularly effective when the communication system 1 is used as a monitoring system.

[0055] <Variation 1> The data DT may be something to be shared between the data source unit 2 and at least one of the plurality of data destination units 4A to 4D. In this case, in step S4, the notification unit 343 of the server 3 notifies at least one of the data destination units 4A to 4D that the data DT has been copied to the storage unit 33.

[0056] In step S5, the receiving unit 41 of at least one of the data destination units 4A to 4D receives a notification that the data DT has been copied to the storage unit 33 in an amount equal to at least the number of data destination units. In step S6, the transmitting unit 42 of at least one of the data destination units 4A to 4D transmits to the server 3 a request to acquire the data DT copied in the storage unit 33.

[0057] <Variation 2> In step S8, the transmission processing unit 344 may shift some of the transmission timings of the data DT to the data destination units 4A to 4D from the other transmission timings. For example, the transmission processing unit 344 may transmit the data DT to the data destination unit 4D after a predetermined time has elapsed since the data DT was simultaneously transmitted to the data destination units 4A to 4C.

[0058] Alternatively, after a predetermined time has elapsed since the transmission processing unit 344 simultaneously transmitted the data DT to the data destination units 4A to 4C, the transmission unit 22 of the data source unit 2 may transmit the data DT to the data destination unit 4D.

[0059] [Embodiment 2] A second embodiment of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the first embodiment, and the description thereof will not be repeated.

[0060] <Configuration of communication system 1A> Fig. 3 is a block diagram showing an example of the configuration of a communication system 1A according to a second embodiment of the present invention. As shown in Fig. 3, the communication system 1A differs from the communication system 1 in that the data source unit 2 is changed to a data source unit 2A and in that the communication system 1A does not include a server 3. In the communication system 1A, the server 3 is not connected to the communication network NT and is not installed within the communication network NT.

[0061] The data source unit 2A differs from the data source unit 2 in that the control unit 24 is replaced with a control unit 24A. The control unit 24A differs from the control unit 24 in that it further includes a storage processing unit 243, a notification unit 244, a reception unit 245, and a transmission processing unit 246.

[0062] <Processing Executed in Communication System 1A> Fig. 4 is a sequence diagram showing an example of a communication method executed by the communication system 1A shown in Fig. 3. The transfer processing unit 241 of the data source unit 2A transfers the data DT to the storage unit 23 of the data source unit 2A (S21, transfer processing step). Specifically, the transfer processing unit 241 transfers the data DT received by the receiving unit 21 from the network NT or the data DT generated by the above-mentioned collection unit to the storage unit 23. The data DT is data to be shared between the data source unit 2A and multiple data destination units 4A to 4D.

[0063] The copy instruction unit 242 of the data source unit 2A instructs the storage processing unit 243 to copy the data DT transferred to the storage unit 23 within the storage unit 23 by at least the number of data destination units (S22, copy instruction step).

[0064] 3, the storage processing unit 243 copies and stores the data DT in the storage unit 23 in an amount equal to at least the number of data destination units. As a result, the storage unit 23 copies and stores the data DT in an amount equal to at least the number of data destination units (S23).

[0065] After the storage unit 23 copies the data DT, the notification unit 244 of the data source unit 2A notifies the data destination units 4A to 4D that the data DT has been copied to the storage unit 23 (S24). Specifically, the notification unit 244 uses the transmission unit 22 to sequentially transmit signals indicating that the data DT has been copied to the storage unit 23 to the data destination units 4A to 4D via the network NT. At this time, the notification unit 244 simultaneously transmits the signals to the data destination units 4A to 4D.

[0066] The receiving unit 41 of the data destination units 4A to 4D receives a notification that the data DT has been copied to the storage unit 23 of the data source unit 2A by at least the number of data destination units (S25, receiving step). After the receiving unit 41 receives the notification that the data DT has been copied to the storage unit 23, the transmitting unit 42 of the data destination units 4A to 4D transmits an acquisition request for the data DT copied in the storage unit 23 to the data source unit 2A (S26, transmitting step).

[0067] The reception unit 245 of the data source unit 2A receives, from the plurality of data destination units 4A to 4D, requests to acquire the data DT copied in the storage unit 23 (S27). Specifically, the reception unit 21 of the data source unit 2A receives the requests to acquire the data DT from the plurality of data destination units 4A to 4D. The reception unit 245 receives the requests to acquire the data DT received by the reception unit 21.

[0068] The transmission processing unit 246 of the data transmission source unit 2A simultaneously transmits the data DT copied in the storage unit 23 to each of all of the data transmission destination units 4A to 4D that have made the acquisition requests (S28). Specifically, the transmission processing unit 246 uses the transmission unit 22 to simultaneously transmit the data DT copied in the storage unit 23 to each of all of the data transmission destination units 4A to 4D that have made the acquisition requests.

[0069] 3, the transmission processing unit 246 uses the transmitter 22 to transmit the data DT stored in the memory unit 23 to the data destination unit 4A via the network NT. In other words, the control unit 43 of the data destination unit 4A uses the receiver 41 to access the memory unit 23 via the network NT and acquires the data DT from the memory unit 23.

[0070] 3, the transmission processing unit 246 transmits the data DT stored in the storage unit 23 to the data destination unit 4B. In other words, the control unit 43 of the data destination unit 4B accesses the storage unit 23 using the receiving unit 41 and acquires the data DT from the storage unit 23.

[0071] 1, the transmission processing unit 246 transmits the data DT stored in the storage unit 23 to the data destination unit 4C. In other words, the control unit 43 of the data destination unit 4C accesses the storage unit 23 using the receiving unit 41 and acquires the data DT from the storage unit 23.

[0072] 1, the transmission processing unit 246 transmits the data DT stored in the storage unit 23 to the data destination unit 4D. In other words, the control unit 43 of the data destination unit 4D accesses the storage unit 23 using the receiving unit 41 and acquires the data DT from the storage unit 23. Each of the data destination units 4A to 4D can simultaneously acquire the data DT from the data source unit 2A. The processing of step S28 is different from simultaneous one-to-many communication.

[0073] After the transmission processing unit 246 transmits the data DT to each of the data destination units 4A to 4D, the storage processing unit 243 deletes the plurality of pieces of data DT from the storage unit 23 (S29). In the communication system 1A, since the server 3 is not installed, the cost required to configure the system can be reduced compared to the communication system 1.

[0074] [Software implementation example] The data source units 2, 2A, server 3, and data destination units 4A to 4D are hereinafter referred to as "devices." The functions of the devices can be realized by a program that causes a computer to function as the devices, and a program that causes a computer to function as each control block of the devices. The control blocks are, in particular, the units included in the control units 24, 24A, and 34, and the control unit 43.

[0075] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0076] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0077] Furthermore, some or all of the functions of the control blocks can be realized by logic circuits. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of the control blocks can also be realized by, for example, a quantum computer.

[0078] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0079] 1, 1A Communication system 2, 2A Data source unit (communication unit) 3 Server 4A~4D Data destination units (communication units) 31, 41 receiving unit 42 transmitting unit 23, 33 Storage unit 241 Transfer processing unit 242 Copy instruction section 341 Reception section 344 Transmission Processing Unit DT Data NT Communications Network

Claims

1. A communication unit connected to a plurality of data destination units via a communication network in which simultaneous one-to-many communication between the plurality of units is restricted, a transfer processing unit that transfers data to be shared among the plurality of data destination units to a storage unit; a copy instruction unit that instructs the data transferred to the storage unit to be copied within the storage unit by at least the number of data destination units.

2. The communication unit according to claim 1 , wherein the transfer processing unit transfers the data to a storage unit of a server installed within the communication network.

3. In a communication network in which simultaneous one-to-many communication between a plurality of units is restricted, a communication unit is connected to a data source unit and a plurality of data destination units and is included in the plurality of data destination units, a receiving unit that receives a notification that data to be shared between the data source unit and the plurality of data destination units has been copied to a storage unit by at least the number of the data destination units; a transmitting unit that transmits a request to acquire the data copied in the storage unit.

4. In a communication network in which simultaneous one-to-many communication between a plurality of units is restricted, a server connected to a data transmission source unit and a plurality of data transmission destination units, a receiving unit that receives data to be shared between the data source unit and the plurality of data destination units from the data source unit; a storage unit that copies and stores the data received by the receiving unit in an amount equal to at least the number of data destination units.

5. a receiving unit that receives requests from the plurality of data destination units to acquire the data copied in the storage unit; 5. The server according to claim 4, further comprising: a transmission processing unit that simultaneously transmits the data copied in said storage unit to each of all of said data transmission destination units that have made said acquisition requests.

6. A communication system including a data source unit and a plurality of data destination units connected by a communication network in which simultaneous one-to-many communication between the plurality of units is restricted, The data source unit: a transfer processing unit that transfers data to be shared among the plurality of data destination units to a storage unit; a copy instruction unit that issues an instruction to copy the data transferred to the storage unit within the storage unit by at least the number of the data destination units, At least one of the plurality of data destination units a receiving unit that receives a notification that the data has been copied to the storage unit; a transmitting unit that transmits a request to acquire the data copied in the storage unit.

7. 1. A communication method executed by a communication system including a data source unit and a plurality of data destination units connected by a communication network in which simultaneous one-to-many communication between the plurality of units is restricted, comprising: The following steps 1) and 2) are executed by the data source unit; and the following steps 3) and 4) executed by at least one of the plurality of data destination units. 1) a transfer processing step of transferring data to be shared between a data source unit and a plurality of data destination units to a storage unit; 2) a copy instruction step of giving an instruction to copy the data transferred to the storage unit within the storage unit by at least the number of the data destination units; 3) a receiving step of receiving a notification that the data has been copied to the storage unit; 4) A transmission step of transmitting a request to acquire the data copied in the storage unit.

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