JP2010273297A - Intermediate server device, transmission server device, communication system, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate server device for attaining communication quality improvement and communication resource saving in an overall communication system, a transmission server device, the communication system and a communication method. <P>SOLUTION: There are included a transmission server device 12, a receiving server device 16, and an intermediate server device A13 which relays a request signal and a response signal between the transmission server device 12 and the receiving server device 16. The intermediate server device A13 includes a fault monitor and control section 23 for obtaining a fault state of the receiving server device, and an HTTP signal transmitting/receiving section 20 for receiving the request signal from the transmission server device 12 and transmitting a signal instructing retransmission of the request signal or a signal of transmission disability to the transmission server device 12 as the response signal based on the fault state of the receiving server device 16. The transmission server device 12 includes an HTTP signal transmitting/receiving section 17 for performing request signal retransmission processing to the intermediate server device A13 in accordance with the fault state of the receiving server device 16 reported from the intermediate server device A13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an intermediate server device, a transmission server device, a communication system, and a communication method.

  In conventional communication systems and communication methods, various methods are known as methods for monitoring communication abnormalities between server devices, such as monitoring by regular ping, connection monitoring, monitoring by presence / absence of signal response, and use of a routing protocol. When an abnormality of the communication destination server apparatus is detected by each monitoring method, it is possible to avoid call loss by taking measures based on blockage or detouring by itself. In addition, in a communication system in which the server configuration is multistage due to the presence of an intermediate server device on the route to the destination server by using a routing protocol, the state of the receiving server device not directly connected to the transmitting server device is indicated. It is possible to collect call routing information and avoid call loss such as detour measures at the transmission server device. (For example, see Non-Patent Documents 1 to 4)

C. Hedrick, Routing Information Protocol, IETF RFC1058, [online], June 1988, IETF, [Search May 7, 2009], Internet <URL: http://www.ietf.org/rfc/rfc1058.txt ? number = 1058) J. Moy, OSPF Version 2, IETF RFC1583, [online], March 1994, IETF, [Search May 7, 2009], Internet <URL: http://www.ietf.org/rfc/rfc1583.txt ? number = 1583) F. Baker, Editor, Requirements for IP Version 4 Routers, IETF RFC1812, [online], June 1995, IETF, [Search May 7, 2009], Internet <URL: http://www.ietf.org/ rfc / rfc1812.txt? number = 1812) G. Malkin RIP Version 2, IETF RFC 2453, [online], November 1998, IETF, [Search May 7, 2009], Internet <URL: http://www.ietf.org/rfc/rfc2453.txt? number = 2453)

  However, in the communication system and the communication method described above, monitoring by periodic ping is effective only between directly connected servers, and is not directly connected as in the communication system via the intermediate server device. In some cases, it was not effective for the server configuration. In the above-described method, there is a concern that a call loss may occur due to the transmission server device continuously sending a signal to the reception server device even though the state of the reception server device is abnormal, so high reliability is required. In such a communication system, it is not always sufficient, and it may lead to a decrease in communication reliability.

  In addition, by using the above routing protocol, it is possible to some extent to know the state of the receiving server device in the multistage server configuration. That is, it is considered that the routing information of the IP layer is exchanged by the routing protocol, the failure state in the physical layer or the IP layer of the receiving server device is grasped, and the transmitting server device is operated according to the situation. However, the level that can be relieved by the routing protocol is only the “IP layer”, and it is impossible to grasp the application layer. That is, when there is no abnormality in the physical layer or IP layer and an abnormality in the upper signal protocol has occurred, the transmission server device sends a signal to the reception server device as in the above problem, and a call loss occurs. There was a problem.

  In addition, even if the receiving server device in a multistage server configuration is expected to recover, such as a failure for a certain period of time (such as Failover), and the sending server device can hope for call relief by taking measures such as signal transmission retry, the above-mentioned In the method using the above routing protocol, it is difficult to accurately grasp the failure state (the state of the upper protocol) of the receiving server device, but only to grasp the state of the physical layer or the IP layer. There was a problem of losing.

  As described above, in the conventional communication system and communication method, it has been required to improve communication quality in the entire communication system and to save communication resources.

  Accordingly, an object of the present invention is to provide an intermediate server device, a transmission server device, a communication system, and a communication method that can solve the above-described problems and can improve communication quality and save communication resources in the entire communication system. .

  An intermediate server device according to the present invention is an intermediate server device that relays a request signal and a response signal between a transmission server device and a reception server device, and a failure state acquisition unit that acquires a failure state of the reception server device; A request signal receiving means for receiving a request signal from the transmission server device, and a response signal indicating a request signal retransmission instruction signal or a transmission disabled signal to the transmission server device based on a failure state of the reception server device Response signal transmitting means for transmitting as:

  According to the intermediate server device of the present invention, when the receiving server device is in a failure state, the failure state of the receiving server device is acquired by the failure state acquiring unit, and the request signal from the transmitting server device is acquired by the request signal receiving unit. When the reception process is performed, the response signal transmission means can transmit a request signal retransmission instruction signal, a transmission disabled signal, or the like as a response signal to the transmission server device based on the failure state of the reception server device. . As a result, the transmitting server device can grasp the status of the receiving server device, so that call rescue can be performed by resending the request signal in accordance with the status of the receiving server device, or the request If the signal cannot be relieved even if the signal is retransmitted, the resources of the transmission server device can be saved by not performing the retransmission. In this way, it is possible to monitor the state of the receiving server device that is not directly connected to the transmitting server device in the communication system, and to grasp the application level, and to perform a call loss by operating according to the state of the receiving server device. It can be avoided autonomously. As described above, according to the intermediate server device according to the present invention, the transmission server device can take an optimal request signal transmission method according to the state of the reception server device. Communication resources can be saved.

  Further, in the intermediate server device according to the present invention, the response signal transmission means responds to the transmission server device with a request signal retransmission instruction signal or a transmission impossible signal according to the severity or type of failure of the reception server device. It is preferable to transmit as a signal. As a result, an instruction can be given to the transmission server device according to the state of the reception server device. For example, when the reception server device has failed for a certain time (such as Failover), the intermediate server device prompts a retransmission request. Since the call can be relieved by transmitting the signal to the transmission server device, the reliability of communication can be improved.

  The transmission server device according to the present invention comprises request signal retransmission means for performing a request signal retransmission process on the intermediate server device in accordance with the failure state of the receiving server device notified from the intermediate server device described in claim 1. It is characterized by providing.

  According to the transmission server device according to the present invention, the request signal retransmission means can perform call recovery by retransmitting the request signal in accordance with the state of the reception server device, or the request signal retransmission. If it cannot be remedied by performing the transmission, resources of the transmission server device can be saved by not performing retransmission. In this way, it is possible to monitor the state of the receiving server device that is not directly connected to the transmitting server device in the communication system, and to grasp the application level, and to perform a call loss by operating according to the state of the receiving server device. It can be avoided autonomously. As described above, according to the transmission server device according to the present invention, it is possible to adopt an optimal request signal transmission method according to the state of the reception server device, so that communication quality is improved and communication resources are saved in the entire communication system. Can be achieved.

  In the transmission server device according to the present invention, it is preferable that the request signal retransmission process is performed for a plurality of different intermediate server devices. Thereby, in the communication abnormality between the intermediate server device and the receiving server device, when the cause of the abnormality is in the intermediate server device, the transmission server device transmits a retry signal to the intermediate server device installed in a plurality of units, Compared with a communication method that makes a retransmission request to the same or a single intermediate server device, the reliability of communication can be further improved.

  In the transmission server device according to the present invention, it is preferable that the retransmission interval and the number of retransmissions are variably controlled in the request signal retransmission process. As a result, depending on the severity of the failure of the receiving server device, the number of retransmissions can be increased / decreased or the retransmission interval can be varied to flexibly change the optimal conditions for maintaining communication quality and securing communication resources. It becomes possible.

  A communication system according to the present invention is a communication system including a transmission server device, a reception server device, and an intermediate server device that relays a request signal and a response signal between the transmission server device and the reception server device. The apparatus has a failure state acquisition unit for acquiring a failure state of the reception server device, a request signal reception unit for receiving a request signal from the transmission server device, and a transmission server device based on the failure state of the reception server device. Response signal transmitting means for transmitting a request signal retransmission instruction signal or a transmission disabled signal as a response signal, and the transmission server device responds to the failure status of the reception server device notified from the intermediate server device. And a request signal retransmission means for performing a request signal retransmission process on the intermediate server device.

  According to the communication system of the present invention, when the receiving server device is in a failure state, the failure state acquiring unit acquires the failure state of the receiving server device, and the request signal receiving unit receives the request signal from the transmitting server device. When the reception processing is performed, the response signal transmission unit can transmit a request signal retransmission instruction signal, a transmission disabled signal, or the like as a response signal to the transmission server device based on the failure state of the reception server device. As a result, the transmission server device can grasp the state of the reception server device, and the request signal retransmission means of the transmission server device can perform call relief by retransmitting the request signal in accordance with the state of the reception server device. If the request signal cannot be relieved even if the request signal is retransmitted, the resources of the transmission server device can be saved by not performing the retransmission. In this way, it is possible to monitor the state of the receiving server device that is not directly connected to the transmitting server device in the communication system, and to grasp the application level, and to perform a call loss by operating according to the state of the receiving server device. It can be avoided autonomously. As described above, according to the communication system according to the present invention, it is possible for the transmission server device to adopt an optimal request signal transmission method according to the state of the reception server device. Resources can be saved.

  A communication method according to the present invention is a communication method using an intermediate server device that relays a request signal and a response signal between a transmission server device and a reception server device, wherein the intermediate server device is in a failure state of the reception server device. A failure state acquisition step for acquiring the request signal, a request signal reception step for the intermediate server device to receive and process a request signal from the transmission server device, and the intermediate server device to the transmission server device based on the failure state of the reception server device. A response signal transmission step for transmitting a request signal retransmission instruction signal or a transmission impossible signal as a response signal, and the transmission server device according to the failure status of the reception server device notified from the intermediate server device A request signal retransmission step for performing a request signal retransmission process on the server device.

  According to the communication method of the present invention, when the receiving server device is in a failure state, the intermediate server device acquires the failure state of the receiving server device in the failure state obtaining step, and the intermediate server device is in the request signal receiving step. When receiving the request signal from the transmission server device, the intermediate server device in the response signal transmission step, based on the failure state of the reception server device, the request signal retransmission instruction signal or the transmission impossible signal Etc. can be transmitted as a response signal. As a result, the transmission server apparatus can grasp the state of the reception server apparatus, and the transmission server apparatus can perform call relief by retransmitting the request signal in accordance with the state of the reception server apparatus in the request signal retransmission step. If the request signal cannot be relieved even if the request signal is retransmitted, the resources of the transmission server device can be saved by not performing the retransmission. In this way, it is possible to monitor the state of the receiving server device that is not directly connected to the transmitting server device in the communication system, and to grasp the application level, and to perform a call loss by operating according to the state of the receiving server device. It can be avoided autonomously. As described above, according to the communication method according to the present invention, it is possible for the transmission server device to adopt an optimal request signal transmission method according to the state of the reception server device. Resources can be saved.

  According to the intermediate server device, the transmission server device, the communication system, and the communication method according to the present invention, it is possible to improve communication quality and save communication resources in the entire communication system.

It is a figure which shows the block configuration of the communication system which concerns on embodiment of this invention. It is a sequence diagram for demonstrating the flow of the control processing by the communication system which concerns on embodiment of this invention. It is a sequence diagram for demonstrating the flow of the other control processing of the communication system which concerns on embodiment of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an intermediate server device, a transmission server device, a communication system, and a communication method according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

  FIG. 1 is a diagram showing a configuration of a communication system 10 according to an embodiment of the present invention. The communication system 10 has a function of exchanging a request signal and a response signal between the transmission server device 12 and the reception server device 16 by relaying with the intermediate server devices A13 and B13 to n13. As shown in FIG. 1, the communication system 10 includes a transmission server device 12, a plurality of intermediate server devices A13, B13 to n13, and a reception server device 16, and the server devices are connected to each other via a network. Has been. Each server device has a function of transmitting and receiving information request signals and response signals. Each server device is physically a CPU, a main storage RAM and ROM, an auxiliary storage device such as a hard disk, an input device such as a keyboard and a mouse as input devices, an output device such as a display, a data transmission / reception device such as a network card It is comprised as a computer system containing the communication module etc. which are.

  The transmission server device 12 includes an HTTP signal transmission / reception unit (request signal retransmission unit) 17, an HTTP control unit 18, and a retry control unit 19. The HTTP signal transmission / reception unit 17 has a function of performing transmission of an information request signal and reception of a response signal on the transmission server device 12 using an HTTP signal. Further, the HTTP signal transmission / reception unit 17, based on the retry signal from the retry control unit 19, according to the failure state of the reception server device 16 notified from the intermediate server devices A 13, B 13 to n 13, the intermediate server devices A 13, B 13 to It has a function of performing a request signal retransmission process for n13.

  The HTTP control unit 18 has a function of decoding the status code of the HTTP signal received by the HTTP signal transmission / reception unit 17.

  The retry control unit 19 has a function of controlling the number of retries and the retry interval of the request signal and registering the number of retries and the retry interval. As a result of the status code being decoded by the HTTP control unit 18, the retry control unit 19 determines that the HTTP signal transmission / reception unit 17 is in accordance with the registered maximum number of retries and the retry interval. It has a function of transmitting a retry signal via the. In addition, the maximum number of retries and the retry interval set in the retry control unit 19 are set to variable values so that the time can be set after estimating the recovery time of the temporary failure of the receiving server device 16.

  The intermediate server device A13 includes an HTTP signal transmission / reception unit (request signal reception unit, response signal transmission unit) 20, a signal transmission / reception unit 21, an HTTP control unit 22, a failure monitoring control unit (failure state acquisition unit) 23, and a failure management DB 24. Configured. The intermediate server apparatuses B13 to n13 have the same configuration, and a plurality of intermediate server apparatuses B13 to n13 can be installed (one can be used).

  The HTTP signal transmission / reception unit 20 receives and processes an HTTP request signal from the transmission server device 12 in the intermediate server device A13 and relays it to the reception server device 16, or receives a response signal from the reception server device 16 and transmits it to the transmission server. It has a function of relaying to the device 12. The HTTP signal transmission / reception unit 20 has a function of returning an HTTP signal response to the transmission server device 12 in accordance with the failure state of the reception server device 16 acquired by the failure monitoring control unit 23. Further, the HTTP signal transmission / reception unit 20 has a function of transmitting a request signal retransmission instruction signal or a transmission disabled signal as a response signal to the transmission server device 12 according to the severity or type of failure of the reception server device 16. Have. The types of abnormalities include hardware failures, memory failures, process failures, maintenance such as file replacement due to function addition, and the like.

  The signal transmission / reception unit 21 has a function of relaying a request signal response signal to the reception server device 16, and also has a function of performing protocol conversion when the reception server device 16 and the transmission server device 12 use different protocols. Yes.

  The HTTP control unit 22 has a function of setting a status code to be added to the HTTP response signal to the transmission server device 12 in the intermediate server device A13. Further, the failure monitoring control unit 23 has a function of monitoring the line normality with the receiving server device 16 and acquiring a failure state. The failure monitoring control unit 23 has a function of determining that the state of the receiving server device 16 is a failure when a line abnormality is detected, and registering the state of the receiving server device as a failure state in the failure management DB 24. The detection of line abnormality includes, for example, health check by periodic ping to the receiving server device 16, monitoring of physical ports connected to the receiving server device (basic functions such as NW devices), application level with the receiving server device 16 ( Health check by HTTP message etc.). The failure management DB 24 is a database that holds the receiving server device state.

  The reception server device 16 includes a signal transmission / reception unit 25. The signal transmission / reception unit 25 has a function of performing a request signal reception and response signal transmission process in the reception server device 16, and uses the same protocol (other than HTTP) with the intermediate server devices A13 and B13 to n13. Works.

  The HTTP signal transmission / reception unit 17, the HTTP control unit 18, the retry control unit 19, the HTTP signal transmission / reception unit 20, the signal transmission / reception unit 21, the HTTP control unit 22, the failure monitoring control unit 23, the failure management DB 24, and the signal transmission / reception unit 25 are By reading predetermined computer software on hardware such as CPU and RAM, the communication module, input device, and output device are operated under the control of the CPU, and data is read from and written to the RAM and auxiliary storage device. Realized by things.

  Next, with reference to FIG. 2, the communication method by the communication system 10 which concerns on embodiment of this invention is demonstrated. FIG. 2 is a sequence diagram for explaining the flow of control processing of the communication system 10 according to the embodiment of the present invention. FIG. 2 shows an example of a signal transmission / reception operation at the time of failure of the reception server device 16. In FIG. 2, a case where the transmission server device 12 and the reception server device 16 are relayed by a plurality of intermediate server devices A13, B13 to n13 will be described. Although only one intermediate server device is possible, it is preferable to use a plurality of intermediate server devices in order to obtain an effect when a failure factor described later is present on the intermediate server device side.

  As shown in FIG. 2, when the receiving server device 16 has a failure (such as Failover), the failure monitoring control unit 23 of the intermediate server devices A13 and B13 to N13 detects a line error (TCP) with the receiving server device 16. The connection management at the layer is detected (step S101). Next, the failure monitoring controller 23 determines that the state of the receiving server device 16 is a failure, sets the state of the receiving server device 16 as “failure”, and registers it in the failure management DB 24 (step S102: failure state acquisition step) ).

  The HTTP signal transmission / reception unit 17 of the transmission server device 12 transmits an HTTP Request (information request) to the intermediate server device A13 for relaying to the reception server device 16 at the start of communication, and the HTTP signal transmission / reception unit of the intermediate server device A13. 20 receives an HTTP Request (information request) (step S103: request signal reception step). At that time, the HTTP control unit 22 makes an inquiry to the failure monitoring control unit 23 as to whether or not the state of the receiving server device 16 is “failure” (step S104). If the state of the receiving server device 16 is “failure”, the HTTP control unit 22 sets “500” in the HTTP status code (step S105). Thereafter, the HTTP signal transmission / reception unit 20 returns “Status Code: 500” as an HTTP Response (information request response) to the transmission server device 12 (step S106: response signal transmission step).

  The HTTP signal transmission / reception unit 17 of the transmission server device 12 receives the HTTP Response, and the HTTP control unit 18 decodes the status code (step S107). When the status code is 500, the HTTP control unit 18 determines that the reception server device 16 is in a failure state, and the HTTP signal transmission / reception unit 17 retries HTTP request transmission according to the retry interval set in the HTTP retry control unit 19. (Step S108: Request signal retransmission step). This process is performed when 20 seconds have elapsed since the reception of HTTP Response. At this time, the intermediate server device of the transmission destination is an intermediate server device B13 other than the intermediate server device A13 that has received the HTTP Response.

  The retry count and retry interval are managed by the retry control unit 19 of the transmission server device 12. The retry control unit 19 sets the retry interval (information request response timer) and the number of retries after estimating the time to recover the state of the receiving server device 16 for the retry of the HTTP request transmission of the transmitting server device 12. In the present embodiment, the retry interval is set to 20 seconds and the retry count is set to 10 times, and communication is possible without a call loss for a temporary failure of 20 seconds × 10 times = 200 seconds.

  The HTTP signal transmission / reception unit 20 of the intermediate server device B13 receives the retry of the HTTP Request transmission from the transmission server device 12 of S108, and the HTTP control unit 22 performs the process α configured by the processes of S104 and S105 (Step S108). S109). Thereafter, the HTTP signal transmission / reception unit 20 returns “Status Code: 500” as an HTTP Response (information request response) to the transmission server device 12 (step S110: response signal transmission step).

  On the other hand, in the transmission server device 12, as long as the reception server device 16 is not recovered and the reception server device state held in the failure management DB 24 of the intermediate server devices A13 and B13 to n13 remains “failure”, the HTTP signal Although the transmission / reception unit 17 repeats retry transmission, the retry control unit 19 of the transmission server device 12 manages the number of retries each time retry transmission is performed. Specifically, the retry control unit 19 increments the number of retries managed every time retry transmission is performed (step S111). If retry transmission is performed to the intermediate server device B13 and the processing of S109 to S111 is performed, then retry transmission is performed to intermediate server devices other than the intermediate server devices A13 and B13, and then retry transmission is performed once thereafter. The retry transmission is sequentially performed to the intermediate server devices other than those performed. Each time a retry is performed, the processing of S109 and S110 is performed in the intermediate server device that has performed the retry transmission, and the processing of S111 is performed in the transmission server device 12. Also, the transmission server device 12 ends the retry transmission when the number of retries reaches a specified value (maximum number of retries).

  On the other hand, when the receiving server device 16 recovers from a temporary failure (in this embodiment, the Failover completion time is set to 180 seconds), the failure monitoring control unit 23 of the intermediate server devices A13 and B13 to B13 detects line state recovery. (Connection recovery at the TCP layer) (step S112). Next, the failure monitoring control unit 23 determines that the state of the receiving server device 16 is normal, sets the state of the receiving server device 16 to “normal”, and registers it in the failure management DB 24 (step S113).

  Thereafter, the HTTP signal transmitting / receiving unit 17 of the transmission server device 12 transmits an HTTP Request retry signal to the intermediate server device n13 (step S114: request signal retransmission step). When the retry signal of S114 is received, the HTTP control unit 22 of the intermediate server device n13 inquires of the failure monitoring control unit 23 about the state of the reception server device 16 (step S115). If it is determined in S115 that the state of the receiving server device 16 is “normal”, the signal transmitting / receiving unit 21 of the intermediate server device n13 transmits an information request to the receiving server device 16 (step S116). When the signal transmission / reception unit 25 of the reception server device 16 receives the information request of S116, the signal transmission / reception unit 25 returns an information request response to the transmission server device 12 via the intermediate server device n13 according to the content (step S117, step S118). When the process of S118 ends, the control process shown in FIG. 2 ends.

  In the control process shown in FIG. 2, when the receiving server device 16 is in a temporary failure state (such as Failover), the intermediate server device A13 (if there are a plurality of intermediate server devices, any one of the intermediate server devices A13 to A13). The transmission server device 12 returns a signal prompting the retry to the transmission server device 12, so that the transmission server device 12 follows the setting value of the maximum number of retries, the retry interval estimated from the temporary failure factor of the reception server device 16, Call relief can be achieved by performing retry transmission to the receiving server device 16. Further, considering the case where the cause of the failure is in the intermediate server device A13, a retry is performed to a different intermediate server device by monitoring the line state between the intermediate server devices A13, B13 to n13 and the receiving server device 16. As a result, compared to a method of retrying the same or single intermediate server device, call relief can be performed more reliably.

  Next, another control process of the communication system 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sequence diagram for explaining the flow of another control process of the communication system according to the embodiment of the present invention. FIG. 3 shows a case where a normal response cannot be transmitted due to a factor other than the failure due to the state of the receiving server device 16 and a normal response cannot be expected even if a retry is performed. This shows the control processing when the intermediate server apparatus A13 notifies that. In FIG. 3, an example in which the intermediate server device A13 is installed as the intermediate server device will be described (however, a plurality of devices may be installed).

  As shown in FIG. 3, as the start of communication, the HTTP signal transmission / reception unit 17 of the transmission server device 12 transmits an HTTP Request (information request) to the intermediate server device A13 for relaying to the reception server device 16 (step S202). : Request signal receiving step). Next, the signal transmitting / receiving unit 21 of the intermediate server device A13 transmits an information request to the receiving server device 16 (step S203).

  At that time, if the receiving server device 16 has a failure (system congestion or the like) in which a normal response cannot be expected even after retrying (step S201), the signal transmission / reception unit 25 of the receiving server device 16 has system congestion. A signal to that effect (information request response “congestion”) is returned to the intermediate server device A13, the signal transmitting / receiving unit 21 of the intermediate server device A13 receives the information request response in S203, and the failure monitoring control unit 23 receives the information request response. The state of the server device 16 is acquired (step S204: failure state acquisition step). The system congestion is assumed when the CPU usage rate or traffic congestion is equal to or higher than a threshold value (before reaching a level at which transmission and reception cannot be performed at all).

  Since the signal acquired in S204 is a response indicating that the system is congested, the HTTP control unit 22 sets “503” in the HTTP status code (step S205), and the HTTP signal transmission / reception unit 20 transmits the transmission server device. HTTP Response (Status Code: 503) is returned to 12 (step S206: response signal transmission step).

  The HTTP signal transmission / reception unit 17 of the transmission server device 12 receives the HTTP Response, and the HTTP control unit 18 interprets the status code and grasps the state of the reception server device 16 (step S207). If the status code is 503, it is determined that the receiving server device 16 is in a system congestion state and call remedy cannot be performed even if retry transmission is performed, and the retry is not performed (step S208). When the process of S208 ends, the control process shown in FIG. 3 ends. In the process illustrated in FIG. 3, the retry control unit 19 of the transmission server device 12, the failure monitoring control unit 23 of the intermediate server device A13, and the failure management DB 24 are not necessarily required.

  In the process shown in FIG. 3, whether or not to request a retry is transmitted by using a plurality of HTTP status codes indicating the state of the receiving server device 16 in the signal returned from the intermediate server device A13 to the transmitting server device 12. When the server apparatus 12 makes a decision and cannot be saved even by retry transmission (system congestion or the like), the transmission server apparatus 12 can save resources without performing retry transmission. is there.

  As described above, according to the communication system 10, the transmission server device 12, and the intermediate server devices A13 and B13 to n13 according to the present embodiment, when the reception server device 16 is in a failure state, the failure monitoring control unit 23 performs the reception server. When the failure state of the device 16 is acquired and the request signal from the transmission server device 12 is received by the HTTP signal transmission / reception unit 20, the HTTP signal transmission / reception unit 20 determines that the transmission server device is based on the failure state of the reception server device 16. 12, a request signal retransmission instruction signal, a transmission impossible signal, or the like can be transmitted as a response signal. Thus, since the transmission server device 12 can grasp the state of the reception server device 16, the HTTP signal transmission / reception unit 17 performs call relief by retransmitting the request signal in accordance with the state of the reception server device 16. If the request signal cannot be relieved even if the request signal is retransmitted, the resources of the transmission server device 12 can be saved by not performing the retransmission. In this way, the state of the receiving server device 16 that is not directly connected in the communication system 10 can be monitored and grasped up to the application level, and call loss can be autonomously performed by performing operations according to the state of the receiving server device 16. Can be avoided. As described above, since the transmission server device 12 can take an optimum request signal transmission method according to the state of the reception server device 16, it is possible to improve communication quality and save communication resources in the entire communication system. It becomes.

  Further, in the intermediate server devices A13 and B13 to n13 according to the present embodiment, the HTTP signal transmission / reception unit 20 instructs the transmission server device 12 to retransmit the request signal according to the severity or type of failure of the reception server device 16. A signal or a signal that cannot be transmitted can be transmitted as a response signal. As a result, it is possible to give an instruction to the transmission server device 12 according to the state of the reception server device 16. For example, when the reception server device 16 has failed for a certain period of time (such as Failover), the intermediate server device A 13, Since B13 to n13 transmit a signal prompting a retransmission request to the transmission server device 12, call relief can be achieved, so that communication reliability can be improved.

  In the transmission server device 12 according to the present embodiment, the request signal retransmission process is performed for a plurality of different intermediate server devices A13, B13 to n13. Thereby, in the communication abnormality between the intermediate server device and the receiving server device 16, when the cause is in the intermediate server device, the transmission server device 12 sends a retry signal to the intermediate server devices A13, B13 to n13 installed in a plurality of units. By transmitting, it is possible to further improve the reliability of communication compared to a communication method that makes a retransmission request to the same or a single intermediate server device.

  In the transmission server device 12 according to the present embodiment, the retransmission interval and the number of retransmissions are variably controlled in the request signal retransmission process. As a result, the number of retransmissions can be increased or decreased according to the severity of the failure of the receiving server device 16, or the retransmission interval can be varied to flexibly change to optimal conditions for maintaining communication quality and securing communication resources. Is possible.

  Further, according to the communication method according to the present embodiment, when the receiving server device 16 is in a failure state, the intermediate server devices A13, B13 to n13 acquire the failure state of the receiving server device 16 in the failure state acquisition step S102. If the intermediate server apparatuses A13, B13 to n13 receive the request signal from the transmission server apparatus 12 in the request signal reception steps S103 and S202, the intermediate server apparatuses A13 and B13 to the response signal transmission steps S106, S110, and S206. Based on the failure state of the receiving server device 16, the n 13 can transmit a request signal retransmission instruction signal, a transmission impossible signal, or the like as a response signal to the transmitting server device 12. Thereby, the transmission server device 12 grasps the state of the reception server device 16, and the transmission server device 12 retransmits the request signal in accordance with the state of the reception server device 16 in request signal retransmission steps S 108 and S 114. Relieving can be performed, or if the request signal cannot be relieved even if it is retransmitted, resources of the transmission server device 12 can be saved by not retransmitting. In this way, the state of the receiving server device that is not directly connected in the communication system 10 can be monitored and grasped up to the application level, and call loss is made autonomous by performing operations according to the state of the receiving server device 16. Can be avoided. As described above, since the transmission server device 12 can take an optimum request signal transmission method according to the state of the reception server device 16, it is possible to improve communication quality and save communication resources in the entire communication system. It becomes.

  The present invention is not limited to the embodiment described above. For example, the transmission server device 12 and the reception server device 16 described above can be interchanged. In other words, the receiving server device 16 becomes the request source, and the server / client relationship can be reversed. However, at that time, the receiving server device 16 needs to mount an HTTP signal transmission / reception unit for retry control with the intermediate server device.

  DESCRIPTION OF SYMBOLS 10 ... Communication system, 12 ... Transmission server apparatus, A13, B13-n13 ... Intermediate server apparatus, 16 ... Reception server apparatus, 17 ... HTTP signal transmission / reception part (request signal resending means), 20 ... HTTP signal transmission / reception part (request signal reception) Means, response signal transmission means), 23... Fault monitoring control unit (failure state acquisition means).

Claims (7)

An intermediate server device that relays a request signal and a response signal between a transmission server device and a reception server device,
Failure status acquisition means for acquiring the failure status of the receiving server device;
Request signal receiving means for receiving and processing a request signal from the transmission server device;
Response signal transmitting means for transmitting a request signal retransmission instruction signal or a transmission impossible signal as a response signal to the transmission server device based on a failure state of the reception server device. Intermediate server device.   The response signal transmission means transmits a request signal retransmission instruction signal or a transmission impossible signal as a response signal to the transmission server device according to the severity or type of failure of the reception server device. The intermediate server device according to claim 1.   A transmission server comprising request signal retransmission means for performing a request signal retransmission process on the intermediate server device according to a failure state of the receiving server device notified from the intermediate server device according to claim 1 apparatus.   The transmission server apparatus according to claim 3, wherein the request signal retransmission process is performed on a plurality of different intermediate server apparatuses.   4. The transmission server apparatus according to claim 3, wherein in the request signal retransmission process, the retransmission interval and the number of retransmissions are variably controlled. A communication system including a transmission server device, a reception server device, and an intermediate server device that relays a request signal and a response signal between the transmission server device and the reception server device,
The intermediate server device
Failure status acquisition means for acquiring the failure status of the receiving server device;
Request signal receiving means for receiving and processing a request signal from the transmission server device;
Response signal transmission means for transmitting a request signal retransmission instruction signal or a transmission impossible signal as a response signal to the transmission server device based on a failure state of the reception server device,
The transmission server device
A communication system comprising request signal retransmission means for performing request signal retransmission processing on the intermediate server device in accordance with a failure state of the receiving server device notified from the intermediate server device. A communication method using an intermediate server device that relays a request signal and a response signal between a transmission server device and a reception server device,
A failure state acquisition step in which the intermediate server device acquires a failure state of the receiving server device;
A request signal receiving step in which the intermediate server device receives and processes a request signal from the transmission server device;
A response signal transmission step in which the intermediate server device transmits a request signal retransmission instruction signal or a transmission impossible signal as a response signal to the transmission server device based on a failure state of the reception server device;
The transmission server device includes a request signal retransmission step of performing a request signal retransmission process on the intermediate server device according to a failure state of the receiving server device notified from the intermediate server device. Communication method.

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