Relay device

Abstract

To reduce a communication load between connection nodes and a processing load on a connection node of a request destination.SOLUTION: A storage unit 11 can store replies. When a storage processing unit 14 relays a reply returned to a request source node from a request destination node, the storage processing unit performs storage processing for storing the reply in the storage unit 11. When relaying a request transmitted to the request destination node from the request source node, a determination processing unit 15 performs determination processing for determining whether there is a corresponding reply, which is a reply corresponding to a relay target request that is a request to be relayed among the replies stored in the storage unit 11. When the corresponding reply exists, a relay processing unit 16 performs return processing for returning the corresponding reply stored in the storage unit 11 to the request source node as a reply to the relay target request, without transmitting the relay target request to the request destination node.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a relay device that relays communication between a plurality of connection nodes that perform request - reply type information acquisition communication.

Background Art

[0002] Conventionally, for example, an electronic control unit mounted on a vehicle such as an automobile communicates with other electronic control units also mounted on the vehicle and also communicates with a data center or the like provided outside the vehicle. In this specification, an electronic control unit may be referred to by its abbreviation, ECU. Among the above - described communications, the communication between the ECU and a data center or the like is, for example, performed when using a cloud application in a vehicle, so it can be rephrased as the communication between the ECU and the cloud application.

[0003] As disclosed in Patent Document 1, in such a communication system, there may be provided an ECU that functions as a relay device for relaying communication between a plurality of ECUs and communication between an ECU and a cloud application. In a communication system provided with such a relay device, the ECU and the cloud application are nodes connected to the relay device. Therefore, in this specification, the ECU and the cloud application may be collectively referred to as connection nodes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional relay device, when the communication volume increases due to an increase in the number of connected nodes, there is a risk that the communication bus load between the relay device and the connected nodes will increase and the communication quality will deteriorate. Further, in a conventional relay device, when the communication volume increases, much of the computing resources in the connected nodes will be used for communication, and there is a risk that the computing resources allocated to the crucial control processing will decrease.

[0006] In a vehicle-mounted communication system, request-reply type information acquisition communication may be adopted as communication between connected nodes. When such communication is adopted, the following problems occur in a conventional relay device. That is, a case where a plurality of connected nodes issue the same request to another connected node can be considered. In such a case, the relay device will transfer the same communication data to the same destination a plurality of times. As a result, there will be waste in communication and there is a risk that the communication bus load will increase.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a relay device capable of reducing the communication load between connected nodes and the processing load on the connected node that is the request destination.

Means for Solving the Problems

[0008] The relay device according to claim 1 relays communication between a plurality of connected nodes (3 to 8) that perform request-reply type information acquisition communication. Here, when a connected node that transmits a request for information acquisition is defined as a request source node, and a connected node that returns a reply including the information requested by the request source node to the request source node when receiving the request is defined as a request destination node, the relay device includes a storage unit (11), a storage processing unit (14, 23), a determination processing unit (15), and a relay processing unit (16, 24).

[0009] The memory unit can store replies. When the memory processing unit relays a reply sent from the request destination node to the request source node, it executes a memory process of storing the reply in the memory unit. When the determination processing unit relays a request sent from the request source node to the request destination node, it executes a determination process of determining whether there is a corresponding reply in the replies stored in the memory unit that corresponds to the relay target request, which is the request to be relayed. When there is a corresponding reply, the relay processing unit executes a return process of returning the corresponding reply stored in the memory unit to the request source node as a reply to the relay target request without sending the relay target request to the request destination node. When the memory processing unit (23) executes memory processing, it attaches and stores a reply time, which is the time corresponding to the time when the reply was relayed, to the reply. The relay processing unit (24) determines whether the corresponding reply is valid based on whether the elapsed time from the reply time of the corresponding reply to the current time is within a predetermined allowable elapsed time. When it is determined that the elapsed time of the corresponding reply is within the allowable elapsed time and the corresponding reply is valid, the relay processing unit executes a return process. When it is determined that the elapsed time of the corresponding reply exceeds the allowable elapsed time and the corresponding reply is not valid, the relay processing unit executes a relay process of transmitting the relay target request to the request destination node. The allowable elapsed time includes an AT-D that is a time individually set for each request destination node, an AT-S that is a time individually set for each piece of information requested by the request, and an AT-C that is a time individually set for each request transmitted by the request source node. The request source node attaches the AT-C to the request when transmitting the request. Regarding the AT-D, AT-S, and AT-C, a priority for use in determining whether the corresponding reply is valid is defined.

[0010] According to such a configuration, in a case where a plurality of connected nodes issue the same request to another connected node, the relay device does not transfer the same communication data to the same destination multiple times. Specifically, the relay device does not transfer the same request to the same request destination node multiple times. As a result, the communication between the relay device and the request destination node is reduced, and the processing load on the request destination node is reduced. Therefore, according to the above configuration, an excellent effect of reducing the communication load between the connected nodes and the processing load on the connected node of the request destination can be obtained.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In each embodiment, substantially the same configurations are denoted by the same reference numerals and the description thereof is omitted. (First Embodiment) Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 8.

[0013] As shown in FIG. 1, the relay device 1 of the present embodiment is used for a communication system of a vehicle 2 such as an automobile, and relays communication among a plurality of ECUs 3 to 7 mounted on the vehicle 2 and communication between the plurality of ECUs 3 to 7 and a cloud application 8 outside the vehicle 2. The relay device 1 is composed of ECUs mounted on the vehicle 2. The relay device 1 and the ECUs 3 to 7 can communicate with each other via an in-vehicle communication bus 9. Further, the relay device 1 and the cloud application 8 can communicate with each other via a network 10. Examples of the network 10 include a mobile communication network and a wireless LAN.

[0014] ECUs 3 to 7 are what are called so-called domain ECUs. ECU 3 is an ADA ECU that integrates and controls the entire advanced driver assistance system. ECU 4 is a meter ECU that integrates and controls the entire meter display. ECU 5 is a navigation ECU that integrates and controls the entire navigation function. ECU 6 is a body ECU that integrates and controls all body-related devices. ECU 7 is an engine ECU that integrates and controls the drive system of the engine.

[0015] In the following description and in drawings such as FIG. 1, ECUs 3, 4, 5, 6, and 7 may be referred to as ADA ECU 3, meter ECU 4, navigation ECU 5, body ECU 6, and engine ECU 7, respectively. Also, in FIG. 1, only ECUs 3 to 7, which are some of the domain ECUs mounted on the vehicle 2, are illustrated, but actually, there are also domain ECUs other than these. For other domain ECUs not shown, communication is relayed by the relay device 1 in the same manner as ECUs 3 to 7.

[0016] The cloud application 8 corresponds to various cloud services realized by a data center or the like provided outside the vehicle 2. ECUs 3 to 7 and the cloud application 8 are all nodes connected to the relay device 1 and correspond to a plurality of connected nodes. These ECUs 3 to 7 and the cloud application 8 corresponding to the plurality of connected nodes are configured to perform request-reply type information acquisition communication.

[0017] In the following description, the connection node that sends a request to request information acquisition may be referred to as the request source node, and the connection node that returns a reply including the information requested by the request source node to the request source node when receiving the request may be referred to as the request destination node. As its basic operation, the relay device 1 executes the following relay operation. That is, when the relay device 1 receives a request sent from the request source node, it relays the request to the request destination node, and when it receives a reply sent from the request destination node, it relays the reply to the request source node.

[0018] The relay device 1 includes a storage unit 11, a communication unit 12, a control unit 13, and the like. The storage unit 11 is composed of various storage devices such as a ROM and a RAM, and can store a reply. Note that as the storage unit 11, it is also possible to use a storage device provided separately for storing various data other than the reply. The storage unit 11 is a large-capacity storage device having a storage capacity large enough to store at least the reply sufficiently. The communication unit 12 is a communication interface that communicates with the ECUs 3 to 7 and the cloud application 8 via a network port provided in the relay device 1.

[0019] The control unit 13 has a configuration including a CPU capable of software operation, for example. The control unit 13 includes functional blocks such as a storage processing unit 14, a determination processing unit 15, and a relay processing unit 16. These functional blocks are realized by executing a computer program stored in a non-transitory physical storage medium by the CPU included in the control unit 13 and executing the processing corresponding to the computer program, that is, realized by software. Note that at least a part of each functional block may be realized by hardware.

[0020] When the memory processing unit 14 relays a reply sent from the request destination node to the request source node, it executes a memory process of storing the reply in the memory unit 11. Further, when executing the memory process, if a reply corresponding to the same request as the relayed reply is already stored in the memory unit 11, the memory processing unit 14 deletes the stored reply.

[0021] When the determination processing unit 15 relays a request sent from the request source node to the request destination node, it executes a determination process of determining whether a corresponding reply corresponding to the relay target request exists among the replies stored in the memory unit 11. Note that the relay target request is a request to be relayed, and the corresponding reply is a reply corresponding to the relay request. When a corresponding reply exists, the relay processing unit 16 executes a return process of returning the corresponding reply stored in the memory unit 11 to the request source node as a reply to the relay target request without sending the relay target request to the request destination node.

[0022] In the above configuration, the requests exchanged between the connected nodes and received by the relay device 1 have a data structure as shown in FIG. 2, for example. That is, the request includes a request key. The request key is a character string representing information requested by the request source node and is uniquely determined for the information to be acquired. Specifically, the request key is, for example, GPS position information, cloud application status, trunk door lock status, headlight status, and the like.

[0023] In this case, depending on the content of the request key, the request destination node to which the request key is sent is uniquely determined. For example, when the request key is the cloud application status, the request destination node to which the request including the request key is sent is the cloud application 8. Also, for example, when the request key is the trunk door lock status, the request destination node to which the request including the request key is sent is the body ECU 6.

[0024] In the above configuration, the reply sent by the relay device 1 during the communication between the connected nodes has a data structure as shown in, for example, FIG. 3. That is, the reply includes a request key and reply data. The request key is a character string corresponding to the request key of the request, and is uniquely determined for the information provided by the request destination node. The reply data is the information provided by the request destination, and as its data format, various formats such as, for example, a character string, a numerical value, and binary can be adopted. For example, when the request key is "trunk door lock status", the reply data is data such as "Locked" or "Unlocked".

[0025] The stored data obtained by storing the reply relayed by the relay device 1 in the storage unit 11 in the above configuration has a data structure as shown in, for example, FIG. 4. That is, the stored data includes a request key and reply data, similar to the reply.

[0026] As shown in FIG. 5, the relay device 21 communicates with the connected nodes that are the ECUs 3 to 7 and the cloud application 8, and performs the following input and output of data. That is, during relaying, when a request is input from the connected node Na that is the request source node, the relay device 21 outputs the request to the connected node Nb that is the request destination node. Also, during the relay process, when a reply is input from the connected node Nb, the relay device 21 outputs the reply to the connected node Na.

[0027] At this time, the relay device 21 stores the reply input from the connection node Nb in the storage unit 11. The storage of the reply is in a form of overwriting and storing the old stored data including the same request key. However, when the relay device 21 retrieves the stored data which is the corresponding reply from the storage unit 11 without relaying the request, no input / output is performed with respect to the connection node Nb.

[0028] Next, the flow of processing related to communication relayed by the relay device 1 with the above configuration will be described with reference to FIG. 6. Note that the relay device 1 repeatedly executes processing with the content as shown in FIG. 6, that is, request-reply relay processing, at a predetermined cycle. First, in step S101, the relay device 1 receives a request transmitted from the request source node. After the execution of step S101, the process proceeds to step S102.

[0029] In step S102, it is determined whether there is a reply including a request key that matches the request key included in the relay target request which is the received request, among the stored data stored in the storage unit 11, that is, the corresponding reply. That is, step S102 is a processing step corresponding to the above-described determination processing. Here, if there is no corresponding reply in the storage unit 11, "NO" is obtained in step S102, and the process proceeds to step S103. In step S103, the relay target request is transmitted to the request destination node. That is, step S103 is a processing step corresponding to the relay processing for relaying the request.

[0030] After the execution of step S103, steps S104 to S106 are executed in this order. In step S104, the relay device 1 receives a reply returned from the request destination node. In step S105, the reply received in step S104 is stored in the storage unit 11 as stored data. That is, step S105 is a processing step corresponding to the above-described storage processing. In step S106, the reply received in step S104 is returned to the request source node. After the execution of step S106, this processing ends.

[0031] On the other hand, if there is a corresponding reply in the memory unit 11, it becomes "YES" in step S102 and proceeds to step S107. In step S107, the stored data corresponding to the corresponding reply is retrieved from the memory unit 11. After the execution of step S107, it proceeds to step S108. In step S108, the stored data corresponding to the corresponding reply retrieved in step S107 is returned to the request source node as a reply corresponding to the relay target request. After the execution of step S108, this process ends.

[0032] Next, the operation of the relay device 1 when communication is performed between the connected nodes having the above configuration will be described along with specific examples shown in FIGS. 7 and 8. Note that the specific examples shown in FIGS. 7 and 8 represent communication when the meter ECU 4 acquires the trunk door lock status from the body ECU 6. Also, in FIGS. 7 and 8 and the like, illustration of components unnecessary for the operation description is omitted.

[0033] [1] When the relay device relays communication and returns a reply As shown in FIG. 7, when the relay device 1 receives a request including a request key representing the "trunk door lock status" transmitted from the meter ECU 4, it determines whether the stored data in the memory unit 11 can be returned as a reply, that is, executes the above-described determination process. In this case, it is assumed that there is no corresponding reply in the memory unit 11. Therefore, the relay device 1 transfers the request as it is to the body ECU 6 which is the request destination node.

[0034] After that, when the relay device 1 receives a reply corresponding to the request key from the body ECU 6 which is the request destination node, it relays the reply to the meter ECU 4 which is the request source node. At this time, the relay device 1 stores the relayed reply in the memory unit 11 as stored data, that is, executes the above-described storage process.

[0035] When the relay device returns a reply without relaying communication As shown in FIG. 8, when the relay device 1 receives a request including a request key representing the "trunk door lock status" transmitted from the meter ECU 4, it determines whether the stored data in the storage unit 11 can be returned as a reply, that is, executes the above-described determination process. In this case, it is assumed that there is a corresponding reply in the storage unit 11. Therefore, the relay device 1 retrieves the stored data stored in the storage unit 11 and transfers the stored data as a reply to the meter ECU 4, which is the request source node, that is, executes the above-described return process. In this case, the body ECU 6, which is the request destination node, does not execute any operations related to communication.

[0036] According to the present embodiment described above, the following effects can be obtained. According to the above configuration, in a case where a plurality of connection nodes issue the same request to another connection node, the relay device 1 does not transfer the same communication data to the same destination a plurality of times. Specifically, the relay device 1 does not transfer the same request to the same request destination node a plurality of times. As a result, the communication traffic between the relay device 1 and the request destination node is reduced, and the processing load on the request destination node is reduced. Therefore, according to the present embodiment, an excellent effect of reducing the communication load between the connection nodes and the processing load on the connection node that is the request destination can be obtained.

[0037] In the above configuration, when the memory processing unit 14 executes memory processing, if a reply corresponding to the same request as the relayed reply is stored in the memory unit 11, the stored reply is deleted. In this way, when the relay device 1 relays replies corresponding to the same request multiple times, only the latest data among the multiple replies remains in the memory unit 11, and the old data is deleted. Therefore, according to the above configuration, the storage capacity of the memory unit 11 can be effectively utilized. As a result, it is not necessary to use a memory unit 11 with an unnecessarily large storage capacity, and the manufacturing cost of the relay device 1 can be reduced accordingly.

[0038] (Second Embodiment) Hereinafter, the second embodiment will be described with reference to FIGS. 9 to 23. As shown in FIG. 9, the relay device 21 of this embodiment is different from the relay device 1 of the first embodiment shown in FIG. 1 in that it includes a control unit 22 instead of the control unit 13. The control unit 22 is different from the control unit 13 in that it includes a memory processing unit 23 instead of the memory processing unit 14, and a relay processing unit 24 instead of the relay processing unit 16.

[0039] When the memory processing unit 23 executes memory processing, it attaches and stores a reply time, which is the time corresponding to the time when the reply was relayed, that is, the time when the relay device 1 received the reply, to the reply. When the elapsed time from the reply time of the corresponding reply to the current time is within a predetermined allowable elapsed time, the relay processing unit 24 executes a return process. When the elapsed time of the corresponding reply exceeds the allowable elapsed time, the relay processing unit 24 executes a relay process of transmitting the relay-corresponding request to the request destination node. In this specification, the allowable elapsed time may be referred to as AT.

[0040] In this way, the relay device 21 determines whether the stored data stored in the storage unit 11 is valid based on AT. It can be said that the stored data determined to be valid by the determination based on AT is data that guarantees a certain level of freshness. Then, the relay device 21 can return only the stored data determined to be valid to the requesting node as a corresponding reply.

[0041] AT includes AT-Client which is the elapsed tolerance time specified by the requesting node at the time of request, AT-Service which is the elapsed tolerance time specified in advance by the destination node for a specific request, and AT-Default which is the specified elapsed tolerance time of the destination node. In the following description and drawings, AT-Client, AT-Service, and AT-Default may be abbreviated as AT-C, AT-S, and AT-D respectively.

[0042] AT-C is the time set individually for each request transmitted by the requesting node. The requesting node is configured to attach AT-C to the request when transmitting the request. AT-S is the time set individually for each piece of information requested by the request. AT-D is the time set individually for each destination node.

[0043] As shown in FIG. 10, the relay device 21 has the setting parameter of AT-D input in the configuration executed at the time of device startup. AT-D represents the valid time of the reply data defined for each connected node. The setting parameter of AT-D input in this way is stored in the storage unit 11. Note that the setting parameter of AT-D may be stored in a storage device different from the storage unit 11 in which the stored data that is the corresponding reply is stored.

[0044] AT-D is specifically set based on the following concept. For example, when the relay device 21 needs to provide the information provided by the body ECU 6, that is, the reply data, with an accuracy within 10 ms, the AT-D corresponding to the body ECU 6 is set to 10 ms. In this way, for example, for the reply provided by a connection node with relatively high real-time requirements such as the body ECU, the period during which the stored data becomes valid when stored in the storage unit 11 is set short. Also, in this way, for example, for the reply provided by a connection node with relatively low real-time requirements such as a cloud application, the period during which the stored data becomes valid when stored in the storage unit 11 is set long.

[0045] As shown in FIG. 11, the relay device 21 communicates with the connection nodes that are the ECUs 3 to 7 and the cloud application 8, and in addition to the input and output of data similar to the relay device 1, performs the following input and output of data. That is, during the parameter setting process, the relay device 21 receives the setting parameter of AT-S from the connection node Nb that is the request destination node. AT-S represents the valid time of the reply data specified by the request destination node that returns the reply data. The setting parameter of AT-S input in this way is stored in the storage unit 11. Note that the setting parameter of AT-S may be stored in a storage device different from the storage unit 11 in which the stored data that is the corresponding reply is stored.

[0046] The AT-S is specifically set based on the following concept. For example, when it is necessary to provide the trunk door lock status of the vehicle 2 to the request source node with an accuracy within 10 ms, the AT-S of the trunk door lock status is set to 10 ms. In this way, for example, for a reply corresponding to a request key with relatively high required real-time performance such as the headlight status, the period during which the stored data becomes valid when stored in the storage unit 11 is set short. Also, in this way, for example, for a reply corresponding to a request key with relatively low required real-time performance such as GPS position information, the period during which the stored data becomes valid when stored in the storage unit 11 is set long.

[0047] In the above configuration, the setting parameters of the AT-D set in the relay device 21 during configuration have a data structure as shown in FIG. 12. That is, the setting parameters of the AT-D are such that the connection node and the AT-D are associated. Also, in the above configuration, the setting parameters of the AT-S notified to the relay device 21 during parameter setting processing have a data structure as shown in FIG. 13. That is, the setting parameters of the AT-S are such that the request key and the AT-S are associated.

[0048] In the above configuration, the requests exchanged between the connection nodes and received by the relay device 21 have a data structure as shown in FIG. 14, for example. That is, the request includes a request key and an AT-C. The AT-C represents the valid time of the reply data specified by the request source node that sends the request. The AT-C is specifically set based on the following concept. For example, when the meter ECU 4 that sends the request wants to acquire the trunk door lock status of the vehicle 2 with an accuracy within 10 ms, the AT-C in that request is set to 10 ms. Note that the AT-C in the request is optional.

[0049] In the above configuration, the stored data obtained by saving the reply relayed by the relay device 21 in the storage unit 11 has a data structure as shown in FIG. 15, for example. That is, the stored data includes a request key, reply data, and a reply time. The reply time is time data corresponding to the time when the reply was relayed, that is, the time when the relay device 21 received the reply.

[0050] In the above configuration, the management table stored in the storage unit 11 has data as shown in FIG. 16, for example. That is, AT-D and AT-S are stored in the management table. As described above, AT-D is set at the time of configuration, and AT-S is set at the time of parameter setting processing. The set parameters of AT-S notified by the connection node are dynamically registered in the management table as AT-S. The management table of AT-D has the connection node and the value of AT-D associated with each other.

[0051] Specifically, the value of AT-D of the cloud application 8 is 1000 ms, the values of AT-D of the ADA SECU 3, the meter ECU 4, and the navigation ECU 5 are 100 ms, and the value of AT-D of the body ECU 6 is 10 ms. The management table of AT-S has the request key and the value of AT-S associated with each other. Specifically, the value of AT-S of the GPS position information is 100 ms, the value of AT-S of the cloud application status is 1000 ms, the value of AT-S of the trunk door lock status is 50 ms, and the value of AT-S of the headlight status is 20 ms.

[0052] The connection nodes, which are the ECUs 3 to 7 and the cloud application 8, are configured to notify the relay device 21 of the set parameters of AT-S corresponding to the reply provided by themselves. Such notification can be transmitted at an arbitrary timing. When the relay device 21 receives such notification, it reflects the received set parameters of AT-S in the above-described management table at any time.

[0053] Next, the parameter setting process executed by the relay device 21 with the above configuration will be described with reference to FIG. 17. Note that the relay device 21 is configured to repeatedly execute the parameter setting process with the content as shown in FIG. 17 at a predetermined cycle. First, in step S201, the relay device 21 receives the AT-S setting parameters notified from the connected node. After the execution of step S201, the process proceeds to step S202. In step S202, the AT-S setting parameters received in step S201 are registered in the management table. After the execution of step S202, this process ends.

[0054] Next, the flow of the process related to the communication relay executed by the relay device 21 with the above configuration will be described with reference to FIGS. 17 and 18. Note that the relay device 21 is configured to repeatedly execute the process with the content as shown in FIG. 17, that is, the request-reply relay process, at a predetermined cycle. The relay process of the present embodiment shown in FIG. 17 is different from the relay process of the first embodiment shown in FIG. 6 in that steps S201 and S202 are added.

[0055] In the relay process of the present embodiment, when there is a corresponding reply in the storage unit 11, it becomes "YES" in step S102 and the process proceeds to step S201. In step S201, the AT setting process is executed. The AT setting process is a process for setting any one of AT-D, AT-S, and AT-C as the AT to be used in the determination of step S202, and has the content as shown in FIG. 18.

[0056] As shown in FIG. 18, when the AT setting process is started, first, step S301 is executed. In step S301, it is determined whether the received request is provided with AT-C. Here, when the received request is provided with AT-C, it becomes "YES" in step S301 and the process proceeds to step S302. In step S302, AT-C is set as the AT. On the other hand, when the received request is not provided with AT-C, it becomes "NO" in step S301 and the process proceeds to step S303.

[0057] In step S303, it is determined whether the information requested by the received request, that is, whether the AT-S corresponding to the request key included in the received request exists in the management table. Here, if the AT-S corresponding to the request key included in the received request exists in the management table, step S303 results in "YES" and proceeds to step S304. In step S304, the AT-S is set as the AT. On the other hand, if the AT-S corresponding to the request key included in the received request does not exist in the management table, step S303 results in "NO" and proceeds to step S305. In step S305, the AT-D is set as the AT. After the execution of step S305, the process returns.

[0058] When returning from the AT setting process, the process proceeds to step S107, and the saved data corresponding to the corresponding reply is retrieved from the storage unit 11. After the execution of step S107, the process proceeds to step S202. In step S202, it is determined whether the saved data retrieved in step S107 is valid using the AT set in step S201. This determination is made based on whether the following equation (1) is satisfied. Here, let Tr be the reply time included in the saved data and Tc be the current time. Tr < Tc - AT …(1)

[0059] When the above equation (1) is satisfied, since the elapsed time from the reply time Tr of the saved data to the current time Tc is within the AT, it can be determined that the saved data is valid. Also, when the above equation (1) is not satisfied, since the elapsed time from the reply time Tr of the saved data to the current time Tc exceeds the AT, it can be determined that the saved data is invalid.

[0060] Here, when the above (1) is satisfied, "YES" is obtained in step S202, and the process proceeds to step S108. The stored data corresponding to the corresponding reply retrieved in step S107 is returned to the request source node as a reply corresponding to the relay target request. On the other hand, when the above (1) is not satisfied, "NO" is obtained in step S202, and the process proceeds to step S103, where the relay target request is transmitted to the request destination node. After the execution of step S103, steps S104 to S106 are sequentially executed. After the execution of step S106 or S108, this process ends.

[0061] Next, the operation of the relay device 21 when communication is performed between the connected nodes having the above configuration will be described along with specific examples shown in FIGS. 20 to 23. Note that the specific examples shown in FIGS. 20 to 23 represent communication when the meter ECU 4 acquires the trunk door lock status from the body ECU 6.

[0062] [1] When the relay device relays communication and returns a reply As shown in FIG. 20, when the relay device 21 receives a request including a request key representing "trunk door lock status" transmitted from the meter ECU 4, it determines whether the stored data in the storage unit 11 can be returned as a reply. In this case, it is assumed that there is no valid corresponding reply in the storage unit 11. Therefore, the relay device 21 transfers the request as it is to the body ECU 6, which is the request destination node.

[0063] Thereafter, when the relay device 21 receives a reply corresponding to the request key from the body ECU 6, which is the request destination node, it relays the reply to the meter ECU 4, which is the request source node. At this time, the relay device 21 stores the relayed reply in the storage unit 11 as stored data after adding the reply time, that is, executes the above-described storage process.

[0064] [2] When the relay device does not relay communication and returns a reply using the AT-C As shown in FIG. 21, when the relay device 21 receives a request including a request key representing the "trunk door lock status" transmitted from the meter ECU 4, it determines whether AT-C is attached to the request. When AT-C is attached to the request, it determines whether the stored data in the storage unit 11 can be returned as a reply using AT-C.

[0065] In this case, it is assumed that there is a corresponding reply in the storage unit 11 and the elapsed time from the reply time of the corresponding reply to the current time is within the value of AT-C. Therefore, the relay device 21 retrieves the stored data stored in the storage unit 11 and transfers the stored data as a reply to the meter ECU 4, which is the request source node, that is, executes the above-described return process. In this case, the body ECU 6, which is the request destination node, does not execute any operations related to communication.

[0066] [3] When the relay device returns a reply using AT-S without relaying communication As shown in FIG. 22, when the relay device 21 receives a request including a request key representing the "trunk door lock status" transmitted from the meter ECU 4, it determines whether AT-C is attached to the request. When AT-C is not attached to the request, the relay device 21 determines whether AT-S corresponding to the request key included in the request exists in the management table.

[0067] If the AT-S corresponding to the request key exists in the management table, it is determined whether the stored data in the storage unit 11 can be returned as a reply using the AT-S. In this case, it is assumed that there is a corresponding reply in the storage unit 11 and the elapsed time from the reply time of the corresponding reply to the current time is within the value of the AT-S. Therefore, the relay device 21 retrieves the stored data stored in the storage unit 11 and transfers the stored data as a reply to the meter ECU 4 which is the request source node, that is, executes the above-described return process. In this case, the body ECU 6 which is the request destination node does not execute any operation related to communication.

[0068] [4] When the relay device returns a reply using the AT-D without relaying the communication As shown in FIG. 23, when the relay device 21 receives a request including a request key representing the "trunk door lock status" transmitted from the meter ECU 4, it determines whether the AT-C is attached to the request. If the AT-C is not attached to the request, the relay device 21 determines whether the AT-S corresponding to the request key included in the request exists in the management table. If the AT-S corresponding to the request key does not exist in the management table, it is determined whether the stored data in the storage unit 11 can be returned as a reply using the AT-D.

[0069] Note that which value among the plurality of AT-Ds existing in the management table is used is determined according to the request destination node. In this case, since the request destination node is the body ECU 6, the AT-D corresponding to the body ECU 6 is used. And in this case, it is assumed that there is a corresponding reply in the storage unit 11 and the elapsed time from the reply time of the corresponding reply to the current time is within the value of the AT-D. Therefore, the relay device 21 retrieves the stored data stored in the storage unit 11 and transfers the stored data as a reply to the meter ECU 4 which is the request source node, that is, executes the above-described return process. In this case, the body ECU 6 which is the request destination node does not execute any operation related to communication.

[0070] According to the present embodiment described above, in addition to the effects similar to those of the first embodiment, the following effects can be obtained. In the above configuration, when the memory processing unit 23 executes memory processing, it stores by attaching a reply time to the reply. When the elapsed time from the reply time of the corresponding reply to the current time is within a predetermined AT, the relay processing unit 24 executes a return process, and when the elapsed time of the corresponding reply exceeds AT, the relay processing unit 24 executes a relay process of transmitting a relay corresponding request to the request destination node. That is, in the above configuration, the relay processing unit 24 determines whether the corresponding reply is valid using AT, executes a return process when the corresponding reply is valid, and executes a relay process when the corresponding reply is invalid.

[0071] In this way, when the relay device 21 returns the stored data corresponding to the corresponding reply stored in the storage unit 11 to the request source node without relaying the communication, the freshness of the corresponding reply can be guaranteed at a certain level. That is, according to the above configuration, when the relay device 21 returns the stored data corresponding to the corresponding reply stored in the storage unit 11 to the request source node without relaying the communication, the real-time property of the corresponding reply can be ensured at a desired level.

[0072] AT includes AT-D which is a time individually set for each request destination node, AT-S which is a time individually set for each piece of information requested by a request, and AT-C which is a time individually set for each request transmitted by the request source node. When the relay device 21 determines the validity of the corresponding reply using AT-D, the real-time property of a predetermined level for each connection node can be guaranteed for the corresponding reply returned to the request source node.

[0073] Also, when the relay device 21 determines the validity of the corresponding reply using AT-S, the request destination node can specify the level of real-time performance guaranteed for the corresponding reply sent back to the request source node. Further, when the relay device 21 determines the validity of the corresponding reply using AT-C, the request source node can specify the level of real-time performance guaranteed for the corresponding reply sent back to the request source node each time a request is transmitted.

[0074] Among AT-D, AT-S, and AT-C, AT-C is the time defined in the most detail for each piece of information requested by the request, followed by AT-S which is the time defined in detail, and AT-D is the time defined in the broadest manner. Therefore, in this case, regarding AT-D, AT-S, and AT-C, the priority used for the determination of validity is that AT-C is the highest, AT-S is the second highest, and AT-D is the lowest. By doing so, it becomes possible to preferentially use the AT defined in detail for each piece of information requested by the request among each AT to determine the validity of the corresponding reply, and thus it is possible to more surely guarantee the desired level of real-time performance of the corresponding reply.

[0075] (Other Embodiments) Note that the present invention is not limited to the embodiments described above and shown in the drawings, and can be arbitrarily modified, combined, or extended without departing from the gist thereof. The numerical values and the like shown in the above embodiments are examples and are not limited thereto. The present invention can be applied not only to the relay devices 1 and 21 used in the communication system of the vehicle 2, but also to relay devices in general that relay communication among a plurality of connected nodes performing request-reply type information acquisition communication.

[0076] Although the present disclosure has been described in accordance with the embodiments, it is understood that the present disclosure is not limited to such embodiments or structures. The present disclosure also includes various modifications and variations within the equivalent scope. In addition, various combinations and forms, and further other combinations and forms including only one element, more than one element, or less than one element thereof, are also within the scope and spirit of the present disclosure.

[0077] The control unit and its method described in the present disclosure may be implemented by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and its method described in the present disclosure may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the control unit and its method described in the present disclosure may be implemented by one or more dedicated computers constituted by a combination of a processor and a memory programmed to execute one or more functions and a processor constituted by one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

Description of Reference Numerals

[0078] 1, 21... Relay device, 3 - 7... ECU, 8... Cloud application, 11... Storage unit, 14, 23... Storage processing unit, 15... Judgment processing unit, 16, 24... Relay processing unit.

Claims

1. In a relay device that relays communication between a plurality of connection nodes (3 to 8) performing request - reply type information acquisition communication, when the connection node that transmits a request for requesting information acquisition is defined as a request source node, and the connection node that returns a reply including the information requested by the request source node to the request source node when receiving the request is defined as a request destination node, a storage unit (11) capable of storing the reply; a storage processing unit (14, 23) that, when relaying the reply sent from the request destination node to the request source node, executes a storage process of storing the reply in the storage unit; a determination processing unit (15) that executes a determination process of determining whether or not there is a corresponding reply that is the reply corresponding to the relay target request, which is the request to be relayed, among the replies stored in the storage unit when relaying the request sent from the request source node to the request destination node; a relay processing unit (16, 24) that, when the corresponding reply exists, executes a return process of returning the corresponding reply stored in the storage unit to the request source node as the reply for the relay target request without transmitting the relay target request to the request destination node; comprising: when executing the storage process, the storage processing unit (23) is configured to attach a reply time, which is a time corresponding to the time when the reply is relayed, to the reply and store it; the relay processing unit (24) determines whether or not the corresponding reply is valid based on whether or not the elapsed time from the reply time of the corresponding reply to the current time is within a predetermined allowable elapsed time; when it is determined that the elapsed time of the corresponding reply is within the allowable elapsed time and the corresponding reply is valid, the return process is executed; when it is determined that the elapsed time of the corresponding reply exceeds the allowable elapsed time and the corresponding reply is not valid, a relay process of transmitting the relay target request to the request destination node is executed. The elapsed allowable time includes an AT-D which is a time individually set for each destination node of the request, an AT-S which is a time individually set for each piece of information requested by the request, and an AT-C which is a time individually set for each request transmitted by the source node of the request. When transmitting the request, the source node of the request is configured to attach the AT-C to the request. A relay device in which priorities for determining whether or not the corresponding reply is valid are defined for the AT-D, the AT-S, and the AT-C.

2. The relay device according to claim 1, wherein when executing the storage process, the storage processing unit deletes the stored reply if the reply corresponding to the same request as the relayed reply is stored in the storage unit.

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