JP2008140214A - Software update system, terminal equipment, software update method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently reduce the band of WAN to be used for acquiring update data. <P>SOLUTION: Terminal equipment 1-1 which tries to update software checks whether or not terminal equipment in which the update data of the software are stored exists in the other pieces of terminal equipment 1-2 to 1-k connected to its own terminal equipment 1-1 and the same LAN 5. Then, when any terminal equipment in which the update data are stored does not exist, the terminal equipment 1-1 checks whether or not the terminal equipment under communication which is communicating through an WAN 7 with a server 3 exists on the LAN 5. When the terminal equipment under communication exists, it is considered that there is possibility that the terminal equipment under communication has acquired the update data of the software from the server 3 through the above communication. Then, the terminal equipment 1-1 checks whether or not the terminal equipment in which the update data are stored exists in the pieces of terminal equipment 1-2 to 1-k on the LAN 5 again after the end of the communication of the terminal equipment under communication. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to software update technology in which a terminal device connected to a local area network (LAN) updates software, and in particular, software update data is held in a server connected to a LAN via a wide area network (WAN). It is related with the software update technique which can reduce communication with a server as much as possible.

  2. Description of the Related Art Conventionally, companies and the like use various terminal devices connected to a LAN to construct various systems such as an in-house information system. Since software for realizing an in-house information system and the like is upgraded as necessary, the terminal device connected to the LAN needs to be updated every time the version is upgraded.

  By the way, when updating software of a terminal device connected to a LAN, conventionally, each terminal device individually obtains software update data from a server on the WAN holding software update data. However, this method has a problem in that all terminal devices acquire software update data via the WAN, so that a large amount of bandwidth is used for acquisition of update data. In addition, software update data is acquired using a WAN having a low communication speed (generally, the WAN communication speed is about 1/10 to 1/100 that of a LAN). There is also a problem that it takes a lot of time to acquire.

  Therefore, in order to solve such a problem, instead of always obtaining update data from the server, if there is a terminal device that holds software update data, the update data is sent from the terminal device. A technique for obtaining the information has been proposed (see, for example, Patent Document 1). In the conventional technique described in Patent Document 1, a terminal device that updates software transmits an update data request for requesting software update data to the server, and the server that has received this update data request If there is no terminal device that holds the requested update data, the requested update data is sent to the request source, and if there is a terminal device that holds the requested update data, the list Is sent to the requester. When a list is sent, the requesting terminal device acquires update data from the terminal devices on the list.

JP 2006-172472 A

  In the conventional technique described in Patent Document 1 described above, when there is a terminal device that holds software update data, the update data is acquired from the terminal device. As a result, it is possible to reduce the bandwidth of the WAN used to acquire the update data and to shorten the time required for acquiring the update data.

  However, in the conventional technique described in Patent Document 1, a terminal device that updates software sends an update data request to the server without considering whether another terminal device is communicating with the server. Since transmission is performed, there is a problem in that the bandwidth of the WAN used to acquire update data cannot be sufficiently reduced. That is, the terminal device that updates the software transmits an update data request to the server even when there is another terminal device that communicates with the server to obtain the update data. Therefore, the WAN bandwidth used for acquiring update data cannot be sufficiently reduced.

(Object of invention)
Accordingly, an object of the present invention is to make it possible to sufficiently reduce the bandwidth of a WAN used for acquiring update data.

A first software update system according to the present invention includes:
A plurality of terminal devices connected to the LAN, and a server that is connected to the LAN via the WAN and holds update data necessary for updating software;
Each of the plurality of terminal devices is
When updating the software of its own terminal device, the terminal device that checks whether there is a terminal device that holds the update data of the software among other terminal devices connected to the LAN, and holds the terminal device If there is no communication terminal device that is communicating with the server among other terminal devices connected to the LAN, and if there is, the communication terminal device It is characterized by comprising processing means for waiting for the device to end communication and checking again whether or not the terminal device holding the update data exists on the LAN.

A second software update system according to the present invention is the first software update system,
The communicating terminal device is a terminal device communicating with the server in order to obtain software update data.

A third software update system according to the present invention is the second software update system,
Whether or not there is a communicating terminal device that communicates with the server to obtain the update data by making an inquiry to another terminal device connected to the LAN. It is characterized by investigating.

A fourth software update system according to the present invention is the third software update system,
The processing means checks whether there is a terminal device holding the software update data by making an inquiry to another terminal device connected to the LAN. .

A fifth software update system according to the present invention is the fourth software update system,
The update data is digitally signed with an encryption key, and
The processing means discards update data whose validity could not be confirmed with a public key corresponding to the encryption key.

The first terminal device according to the present invention is:
When updating the software of its own terminal device, it is checked whether there is a terminal device that holds the update data of the software among other terminal devices connected to the LAN. If not, whether or not there is a communicating terminal device communicating with a server holding update data necessary for updating software among other terminal devices connected to the LAN A processing means for waiting for the terminal device in communication to end communication and checking again whether the terminal device holding the update data exists on the LAN. It is characterized by having.

The second terminal device according to the present invention is the first terminal device,
The communicating terminal device is a terminal device communicating with the server in order to obtain software update data.

A third terminal device according to the present invention is the second terminal device,
Whether or not there is a communicating terminal device that communicates with the server to obtain the update data by making an inquiry to another terminal device connected to the LAN. It is characterized by investigating.

A fourth terminal device according to the present invention is the third terminal device,
The processing means checks whether there is a terminal device holding the software update data by making an inquiry to another terminal device connected to the LAN. .

A fifth terminal device according to the present invention is the fourth terminal device,
The update data is digitally signed with an encryption key, and
The processing means discards update data whose validity could not be confirmed with a public key corresponding to the encryption key.

A first software update method according to the present invention includes:
A method of updating software of the terminal device by a computer that realizes the terminal device,
An update data presence check step for checking whether or not there is a terminal device holding the update data of the software among other terminal devices connected to the LAN when the computer is updating software;
A server that holds update data necessary for updating software in another terminal device connected to the LAN when the computer does not have a terminal device that holds the update data; In-communication terminal investigation step for examining whether there is an in-communication terminal device performing communication; and
When there is a communicating terminal device, the computer waits for the communicating terminal device to end communication, and whether or not there is a terminal device holding the update data on the LAN again. And a re-investigation step for examining whether or not.

A second software update method according to the present invention is the first software update method,
The communicating terminal device is a terminal device communicating with the server in order to obtain software update data.

A third software update method according to the present invention is the second software update method,
In the in-communication terminal investigation step, there is an in-communication terminal device that communicates with the server to obtain the update data by making an inquiry to another terminal device connected to the LAN. It is characterized by investigating whether to do.

A fourth software update method according to the present invention is the third software update method,
In the update data presence / absence checking step, it is determined whether or not there is a terminal device holding the update data of the software by making an inquiry to another terminal device connected to the LAN. Features.

A fifth software update method according to the present invention is the fourth software update method,
The update data is digitally signed with an encryption key, and
The computer includes a discarding step of discarding update data whose validity could not be confirmed with a public key corresponding to the encryption key.

The program according to the present invention is:
To the computer that realizes the terminal device,
An update data presence check step for checking whether or not there is a terminal device holding the update data of the software among other terminal devices connected to the LAN when updating the software;
A server that holds update data necessary for updating software in another terminal device connected to the LAN when the computer does not have a terminal device that holds the update data; In-communication terminal investigation step for examining whether there is an in-communication terminal device performing communication; and
When there is a communicating terminal device, the computer waits for the communicating terminal device to end communication, and whether or not there is a terminal device holding the update data on the LAN again. And a re-investigation step.

[Action]
First, a terminal device that intends to update software checks whether there is a terminal device that holds software update data among other terminal devices connected to the same LAN as the terminal device itself. . Then, when there is no terminal device that holds the update data, it is checked whether or not a communicating terminal device that is communicating with the server exists on the LAN. If there is a communicating terminal device, there is a possibility that the communicating terminal device has acquired the software update data from the server by the above communication, so wait for the communicating terminal device to end communication, It is checked again whether there is a terminal device that holds update data among the terminal devices on the LAN.

  According to the present invention, it is possible to obtain an effect that the bandwidth of the WAN used for acquiring software update data can be sufficiently reduced. The reason for this is that when software is updated, it is checked whether there is a terminal device that holds software update data among other terminal devices connected to the LAN. If not, check whether there is a communicating terminal device communicating with the server among other terminal devices connected to the LAN, and if there is a communicating terminal device, the communicating terminal This is because, after waiting for the device to finish communication, it is checked again whether there is a terminal device holding update data on the LAN.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

[Description of Configuration of Embodiment]
Referring to FIG. 1, an embodiment of a software update system according to the present invention includes a plurality of terminal devices 1-1 to 1-k connected to a LAN 5 and a plurality of terminal devices 2-1 to 2-1 connected to a LAN 6. 2-j, a server 3 connected to the LANs 5 and 6 via the WAN 7, and a signature terminal device 4. The terminal devices 1-1 to 1-k and 2-1 to 2-j are, for example, terminal devices that are constituent elements of the in-house information system, and each of the terminal devices 1-1 to 1-k, 2-1 ..., 2-j are installed with various programs such as software necessary for realizing an in-house information system.

  The server 3 updates data for updating the software installed in each of the terminal devices 1-1 to 1-k and 2-1 to 2-j (in some cases, the upgraded software itself may be software, It manages the data used and may be patches.

  FIG. 2 is a block diagram illustrating a configuration example of the server 3, and includes a transmission / reception unit 31, a processing unit 32, and an update data storage unit 33.

  The transmission / reception means 31 has a function of exchanging data via the WAN 7.

  The update data storage unit 33 stores update data for updating software installed in each of the terminal devices 1-1 to 1-k and 2-1 to 2-j. The update data has an electronic signature.

  The processing means 32 has a function of transmitting the requested update data to the requesting terminal device when an update data acquisition request is sent from the terminal devices 1-1 to 1-k and 2-1 to 2-j. Have.

  A server having such a function can be realized by a computer. When the server is realized by a computer, for example, the following is performed. A disk, a semiconductor memory, and other recording media recording a program for causing the computer to function as the server 3 are prepared, and the computer is caused to read the program. The computer realizes the transmission / reception means 31 and the processing means 32 on its own computer by controlling its own operation according to the read program.

  The signature terminal device 4 has a function of applying an electronic signature to the update data using a secret key. The update data that has been digitally signed by the signature terminal device 4 is stored in the update data storage unit 33 in the server.

  Each of the terminal devices 1-1 to 1-k and 2-1 to 2-j connected to the LANs 5 and 6 is realized by a personal computer or the like. FIG. 3 shows a configuration example of the terminal device 1-1. Other terminal devices have the same configuration as the terminal device 1-1.

  Referring to FIG. 3, the terminal device 1-1 includes a transmission / reception unit 11, a processing unit 12, a storage device 13, an input unit 14 such as a keyboard, and a display unit 15 such as an LED.

  The storage device 13 includes a software storage unit 131, an update data storage unit 132, and a public key storage unit 133.

  The software storage unit 131 stores a plurality of software. The update data storage unit 128 stores software update data. The public key storage unit 133 stores a public key corresponding to a secret key used when the signature terminal apparatus 4 performs an electronic signature.

  The transmission / reception means 11 has a function of transmitting / receiving data via the LAN 5.

  The processing means 12 has the following functions.

-When updating the software of the own terminal device 1-1, the software to be updated with respect to the other terminal devices 1-2 to 1-k connected to the same LAN 5 as the own terminal device 1-1 ( A function to send an update data presence / absence inquiry that inquires whether update data of the update target software) is held.
A function of returning an update data presence / absence response indicating whether or not the inquired update data is held when an update data presence / absence inquiry is received from another terminal device 1-2 to 1-k.
A function of determining whether or not there is a terminal device holding update data on the LAN 5 based on the update data presence / absence responses from the other terminal devices 1-2 to 1-k.
If there is a terminal device holding update data on the LAN 5, the update data is acquired from the terminal device. If there is no terminal device, the other terminal devices 1-2 to 1-k on the LAN 5 are acquired. A function of transmitting a communication status inquiry for inquiring whether or not communication is being performed with the server 3 via the WAN 7 in order to acquire update data.
In response to the communication status inquiry sent from the other terminal devices 1-2 to 1-k, it is determined whether or not the own terminal device 1-1 is communicating with the server 3 in order to obtain update data. A function that returns a communication status response to the inquiry source.
A terminal device that is communicating with the server 3 in order to obtain update data on the LAN 5 based on the communication status response sent from the other terminal devices 1-2 to 1-k (terminal device in communication) A function to check whether or not exists.
If there is no terminal device in communication on the LAN 5, update data is acquired from the server 3, and if it exists, the terminal device 1-2 in waiting for the communication of the terminal device in communication to end is completed. A function of transmitting an update data existence inquiry again to 1-k.
A function of confirming the validity of the update data to which the electronic signature obtained from the other terminal devices 1-2 to 1-k and the server 3 is applied by using the public key stored in the public key storage unit 133.
A function of discarding the update data when the validity of the update data cannot be confirmed, and registering the update data in the update data storage unit 132 and updating the update target software according to the update data when it is confirmed.

  The terminal device 1-1 having such a function can be realized by a computer. When the terminal device 1-1 is realized by a computer, for example, the following is performed. A program for causing the computer to function as the terminal device 1-1 is recorded, a disk, a semiconductor memory, and other recording media are prepared, and the computer is caused to read the program. The computer realizes the transmission / reception means 11 and the processing means 12 on its own computer by controlling its own operation according to the read program.

[Description of Operation of Embodiment]
Next, the operation of the present embodiment will be described in detail.

  First, the operation of the signature terminal device 4 will be described. In the present embodiment, an electronic signature using a public key encryption method is used in order to guarantee the validity of the update data. As shown in FIG. 4, when the unsigned update data 41 is input, the signature terminal device 4 applies an electronic signature to the update data 41 using the secret key 42 and generates signed update data 43. The signed update data 43 generated in this way is stored in the update data storage unit 33 in the server 3.

  Next, the operation at the time of software update will be described with reference to the flowchart of FIG.

  Now, for example, it is assumed that the terminal device 1-1 connected to the LAN 5 needs to update the software A (for example, software with the identifier IDa) stored in the software storage unit 131.

  When updating the software A, the user of the terminal device 1-1 uses the input unit 14 to instruct the processing unit 12 to make the software A the update target software.

  Thereby, the processing means 12 makes an inquiry using P2P communication in order to check whether or not a terminal device holding the update data DA of the update target software A exists on the LAN 5 (step S51).

  More specifically, the processing means 12 in the terminal device 1-1 performs the following processing on the other terminal devices 1-2 to 1-k connected to the LAN 5 as inquiries sequentially. First, the terminal device 1-2 is set as an inquiry target, an update data presence / absence inquiry including the identifier IDa of the update target software A is transmitted, and an update data presence / absence response is returned. On the other hand, when the processing unit 12 in the terminal device 1-2 receives an update data presence / absence inquiry from the terminal device 1-1, is the update data DA of the update target software A stored in the update data storage unit 132? If it is stored, an update data presence / absence response indicating the presence of update data is returned to the terminal device 1-1. If not, an update data presence / absence response indicating no update data is returned to the terminal device 1-1.

  When the update data presence / absence response returned from the terminal device 1-2 indicates that there is update data, the processing means 12 in the terminal device 1-1 holds the update data DA in the terminal device 1-2. The processing of step 51 is terminated. On the other hand, if the update data presence / absence response returned from the terminal device 1-2 indicates that there is no update data, the next terminal device (for example, the terminal device 1-3) is the target of the inquiry. The same processing as that described above is performed. The processing means 12 in the terminal device 1-1 repeatedly performs the above-described processing until an update data presence / absence response indicating the presence of update data is received or there is no unqueried terminal device. When an update data presence / absence response indicating the presence of update data is received, it is recognized that the update data DA is held in the terminal device of the transmission source, and all the other terminal devices 1-2 to 1-k are recognized. When an update data presence / absence response indicating no update data is sent from, it is recognized that there is no terminal device holding the update data DA. The above is a specific example of the process performed in step S51. Note that the other terminal devices 1-2 to 1-k connected to the LAN 5 check in advance before starting the processing of FIG. 5 by a survival confirmation inquiry using the network address of the LAN 5. In this example, the update data presence / absence inquiry is sequentially transmitted to each of the terminal devices 1-2 to 1-k. However, the update data presence / absence inquiry may be transmitted by broadcast.

  When there is a terminal device that holds the update data DA of the update target software A (YES in step S52), the update data DA is acquired from the terminal device using P2P communication (step S62). When the data acquisition is completed, the public key stored in the public key storage unit 133 is used to verify that the acquired update data DA is valid. If it is illegal, the acquired update data DA is discarded, and the process returns to the first step S51 to repeat the process. When the validity of the update data DA can be confirmed, the update target software A is updated using the update data DA, and the update data DA can be provided in response to a request from another terminal device. The update data is stored in the update data storage unit 132 (step S63), and then the update process is terminated. Note that the processing unit 12 deletes the update data DA from the update data storage unit 132 when a certain period of time has elapsed after storing the update data DA.

  On the other hand, when there is no terminal device that holds the update data DA (NO in step S52), the WAN 7 is used to acquire the update data (not limited to the update data DA). In order to check whether or not there is a terminal device (terminal device in communication) communicating with the server 3, an inquiry using P2P communication is performed (step S53).

  More specifically, the processing means 12 in the terminal device 1-1 performs the following processing on the other terminal devices 1-2 to 1-k in order as inquiries. First, the terminal apparatus 1-2 is set as an inquiry target, a communication state inquiry is transmitted, and a communication state response is returned. On the other hand, when a communication status inquiry is sent from the terminal device 1-1, the processing means 12 in the terminal device 1-2 receives the server 3 via the WAN 7 in order for the terminal device 1-2 to acquire update data. A communication status response indicating whether or not communication is in progress is returned to the terminal device 1-1.

  The processing means 12 in the terminal device 1-1 recognizes that the terminal device 1-2 is a communicating terminal device when the communication status response returned from the terminal device 1-2 indicates that the communication is in progress. Then, the process of step S53 is finished. On the other hand, if the communication status response returned from the terminal device 1-2 indicates that communication is not in progress, the next terminal device (for example, the terminal device 1-3) is the target of the inquiry. The same processing as the processing is performed. The processing means 12 in the terminal device 1-1 repeatedly performs the above-described processing until it receives a communication status response indicating that communication is in progress or until there is no uninquired terminal device. When a communication status response indicating that communication is in progress is received, the terminal device of the transmission source is recognized as a terminal device in communication, and communication is not being performed from all other terminal devices 1-2 to 1-k. When a communication state response indicating that the terminal device is in communication, it is recognized that there is no terminal device in communication. The above is a specific example of the process performed in step S53. In this example, the communication state inquiry is sequentially transmitted to each of the terminal devices 1-2 to 1-k. However, the communication state inquiry may be transmitted by broadcast.

  If there is a communicating terminal device that communicates with the server 3 in order to obtain update data (YES in step S54), a completion notification is sent to the communicating terminal device after completion of the communication. Request to receive and wait (steps S55 and S56). In this standby state, when a completion notice is sent from the communicating terminal device (step S56), the update data DA required by the terminal device 1-1 is acquired by the communication performed by the communicating terminal device with the server 3. Therefore, the process returns to the first step S51 to check whether or not a terminal device holding the update data DA exists on the LAN 5. In this case, it may be determined whether or not the update data DA is held only for the terminal device that has transmitted the completion notification.

  On the other hand, when there is no communicating terminal device communicating with the server 3 in order to obtain update data (NO in step S54), the processing means 12 of the terminal device 1-1 determines the update data request. Is transmitted to the server 3 via the WAN 7, and the update data DA of the update target software A is acquired from the server 3 (step S57). When the acquisition of the update data DA is completed, it is verified using the public key stored in the public key storage unit 133 that the acquired update data DA is valid. If it is illegal, the acquired update data DA is discarded, and the process returns to the first step S51 to repeat the process. When the validity of the update data DA can be confirmed, the update target software A is updated using the update data DA and can be provided in response to requests from other terminal apparatuses 1-2 to 1-k. The update data DA is stored in the update data storage unit 132 (step S58). Note that the processing unit 12 deletes the update data DA from the update data storage unit 132 when a certain period of time has elapsed after storing the update data DA.

  Thereafter, the control means 12 of the terminal device 1-1 confirms whether or not the completion notification is requested from the other terminal devices 1-2 to 1-k (step S59). If the completion notification is not requested (NO in step S60), the update process is terminated. If the completion notification is requested (YES in step S60), the completion notification is sent to the requesting terminal device. Is transmitted (step S61), the update process is terminated.

[Effect of the embodiment]
According to the present embodiment, it is possible to obtain an effect that the bandwidth of the WAN used for acquiring software update data can be sufficiently reduced. The reason is that when the terminal device 1-1 updates the software of its own terminal device, the terminal holds the software update data in the other terminal devices 1-2 to 1-K connected to the LAN 5. It is checked whether or not there is a device, and if no terminal device is held, communication is performed with the server 3 among the other terminal devices 1-2 to 1-K connected to the LAN 5. It is checked whether or not there is a terminal device in communication. If there is a terminal device in communication, the terminal holding the update data on the LAN 5 again after waiting for the terminal device in communication to end communication. This is because it is checked whether or not the device exists.

  The present invention is preferably used when a plurality of terminal devices connected to the LAN use the same software.

It is a block diagram which shows the example of whole structure of embodiment of the software update system concerning this invention. 3 is a block diagram illustrating a configuration example of a server 3. FIG. It is a block diagram which shows the structural example of the terminal device 1-1. FIG. 6 is a diagram for explaining the operation of the signature terminal device 4. It is a flowchart which shows the process example of this Embodiment.

Explanation of symbols

1-1 to 1-k, 2-1 to 2-j terminal device 11 transmitting / receiving unit 12 processing unit 13 storage device 131 software storage unit 132 update data storage unit 133 public key storage unit 3 server 31 ... Transmission / reception means 32 ... Processing means 33 ... Update data storage unit 4 ... Signature terminal device 41 ... Unsigned update data 42 ... Private key 43 ... Signed update data 5, 6 ... LAN
7 ... WAN

Claims (16)

A plurality of terminal devices connected to the LAN, and a server that is connected to the LAN via the WAN and holds update data necessary for updating software;
Each of the plurality of terminal devices is
When updating the software of its own terminal device, the terminal device that checks whether there is a terminal device that holds the update data of the software among other terminal devices connected to the LAN, and holds the terminal device If there is no communication terminal device that is communicating with the server among other terminal devices connected to the LAN, and if there is, the communication terminal device A software update system comprising processing means for waiting for a device to end communication and checking again whether a terminal device holding the update data exists on the LAN. The software update system according to claim 1,
The software updating system, wherein the communicating terminal device is a terminal device communicating with the server in order to obtain software update data. The software update system according to claim 2,
Whether or not there is a communicating terminal device that communicates with the server to obtain the update data by making an inquiry to another terminal device connected to the LAN. A software update system characterized by checking whether or not. In the software update system according to claim 3,
The processing means checks whether there is a terminal device holding the software update data by making an inquiry to another terminal device connected to the LAN. Software update system. The software update system according to claim 4,
The update data is digitally signed with an encryption key, and
The software update system, wherein the processing means discards update data whose validity could not be confirmed with a public key corresponding to the encryption key.   When updating the software of its own terminal device, it is checked whether there is a terminal device that holds the update data of the software among other terminal devices connected to the LAN. If not, whether or not there is a communicating terminal device communicating with a server holding update data necessary for updating software among other terminal devices connected to the LAN A processing means for waiting for the terminal device in communication to end communication and checking again whether the terminal device holding the update data exists on the LAN. A terminal device comprising the terminal device. The terminal device according to claim 6,
The terminal device, wherein the communicating terminal device is communicating with the server to obtain software update data. The terminal device according to claim 7, wherein
Whether or not there is a communicating terminal device that communicates with the server to obtain the update data by making an inquiry to another terminal device connected to the LAN. A terminal device characterized by checking whether or not. The terminal device according to claim 8, wherein
The processing means checks whether there is a terminal device holding the software update data by making an inquiry to another terminal device connected to the LAN. Terminal device. The terminal device according to claim 9, wherein
The update data is digitally signed with an encryption key, and
The terminal device, wherein the processing means discards update data whose validity could not be confirmed with a public key corresponding to the encryption key. A method of updating software of the terminal device by a computer that realizes the terminal device,
An update data presence check step for checking whether or not there is a terminal device holding the update data of the software among other terminal devices connected to the LAN when the computer is updating software;
A server that holds update data necessary for updating software in another terminal device connected to the LAN when the computer does not have a terminal device that holds the update data; In-communication terminal investigation step for examining whether there is an in-communication terminal device performing communication; and
When there is a communicating terminal device, the computer waits for the communicating terminal device to end communication, and whether or not there is a terminal device holding the update data on the LAN again. And a reviewing step for checking whether or not the software update method. The software update method according to claim 11,
The software updating method, wherein the communicating terminal device is a terminal device communicating with the server in order to obtain software update data. The software update method according to claim 12,
In the in-communication terminal investigation step, there is an in-communication terminal device that communicates with the server to obtain the update data by making an inquiry to another terminal device connected to the LAN. A software update method characterized by checking whether or not to perform. The software update method according to claim 13,
In the update data presence / absence checking step, it is determined whether or not there is a terminal device holding the update data of the software by making an inquiry to another terminal device connected to the LAN. Software update method characterized. The software update method according to claim 14,
The update data is digitally signed with an encryption key, and
A software updating method, comprising: a discarding step in which the computer discards update data whose validity cannot be confirmed by a public key corresponding to the encryption key. To the computer that realizes the terminal device,
An update data presence check step for checking whether or not there is a terminal device holding the update data of the software among other terminal devices connected to the LAN when updating the software;
A server that holds update data necessary for updating software in another terminal device connected to the LAN when the computer does not have a terminal device that holds the update data; In-communication terminal investigation step for examining whether there is a communicating terminal device performing communication; and
If there is a communicating terminal device, the computer waits for the communicating terminal device to end communication, and then whether or not the terminal device holding the update data exists on the LAN again. A program for performing a review step to find out.

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