JP7258468B2 - Communication system, gateway device and communication method - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to communication systems, gateway devices, and communication methods.

In software development in recent years, a method of building a system by preparing multiple small-scale services called microservices and bundling them with an API gateway has been adopted.

In such an approach, each service is developed separately and runs in different environments. In addition, since each service has a different purpose, there are cases where multiple servers are used for each service, and service users (software developers, etc.) select (designate) and use the desired service when connecting to the service. There is a need to. For example, selecting a desired server service from high-performance, expensive servers and low-performance, low-cost servers, or selecting a desired server service from servers divided into test and production purposes. A case of selecting is conceivable.

Conventionally, Amazon Web Services (referred to as "AWS"), which provides a platform for using applications on the cloud, has an application programming interface gateway (hereinafter referred to as "API gateway"), which is a relay device between clients and servers (services). ”) has a communication destination switching function for switching the communication destination of each API according to the stage such as testing or production (see, for example, Non-Patent Document 1).

In addition, for example, there is a technique of automatically switching communication destinations by combining some of the settings of a plurality of communication patterns (see, for example, Patent Document 1), and when a specific server cannot be communicated with, an alternative server is used. Communication settings can be easily made.

Amazon API Gateway: https://aws.amazon.com/jp/api-gateway/

JP 2013-196460 A

However, the conventional technology described above has the following problems.
In the case of the conventional technology disclosed in Patent Document 1, a software developer needs to manually combine communication patterns of communication destinations to set communication destinations, and setting work is required each time, which incurs setting costs.

As in recent software development, when an API gateway is used to bundle services provided by APIs of multiple servers, it is necessary to manually combine and set communication patterns for a large number of APIs. Configuration costs would be higher.

Further, in the conventional technique disclosed in Non-Patent Document 1, it is necessary to individually specify the communication destination for each API by manual operation when setting the stage. The number of required stages may increase in a multiplicative manner according to the number of services, and even with this technology, setting work for each API is required each time the number of stages is increased, so the cost for setting work will increase. there is a possibility.

The problem to be solved by the present invention is that the API gateway relays a request from a client and passes it to a server for processing, thereby reducing the manual work of setting communication destinations in providing services to client users. To provide a communication system, a gateway device, and a communication method capable of providing a user with an optimum service at any given time while maintaining the same.

The gateway device of the embodiment includes an environmental parameter acquisition section, a specification information storage section, an evaluation condition storage section, a stage determination section, a server parameter acquisition section, a communication destination selection section, and a communication processing section. The environment parameter acquisition unit acquires system environment parameters that can be detected by the gateway device. The specification information storage unit stores specification information including microservice information realized by each server and an application program (API) operating on each server, and location information of each server on the network. The evaluation condition storage unit stores a first evaluation condition (stage evaluation formula) for evaluating the stage in which the application program is running on each server, and whether or not the function of the server can process the request for each stage. A second evaluation condition (server evaluation formula) for The stage determination unit determines the current stage that satisfies the first evaluation condition based on the acquired environmental parameters of the system. The server parameter acquisition unit acquires server parameters obtained by converting functions existing in each server into real numbers. The communication destination selection unit selects communication destination server candidates that satisfy the second evaluation condition corresponding to the stage determined by the stage determination unit based on the acquired server parameters and specification information. The communication processing unit sequentially attempts communication with the server candidates selected by the communication destination selection unit.

It is a figure which shows the structure of the application system of embodiment. It is a figure which shows an example of a stage information table. It is a figure which shows an example of an API information table. It is a figure which shows an example of a server information table. It is a figure which shows an example of an environmental parameter table. It is a figure which shows an example of a server parameter table. 4 is a flow chart showing the overall operation of this application system; 4 is a flow chart showing the operation of determining the current stage in this application system; 4 is a flow chart showing an operation of determining a communication destination server in this application system; 4 is a flowchart showing communication operations in this application system;

Hereinafter, embodiments will be described in detail with reference to the drawings.
(embodiment)
FIG. 1 is a diagram showing the configuration of an application system in one embodiment of a communication system.

As shown in FIG. 1, the application system of the embodiment includes microservices MS_1 and MS_2 (hereinafter "service MS_1 , MS_2") and a client C1 as a client computer are connected via a network 1, an API gateway 2 is interposed between them as a gateway device, and communication between the servers 41 to 44 and the client C1 is performed by the API gateway. 2 is a relay network system.

Of the plurality of servers 41-44, servers 41 and 42 provide service MS_1. Assume that the server name of the server 41 is "1_1" and the server name of the server 42 is "1_2".

Of the plurality of servers 41-44, servers 43 and 44 provide service MS_2. Assume that the server name of the server 43 is "2_1" and the server name of the application server 44 is "2_2".

Each of the servers 41-44 that provide the services MS_1 and MS_2 has an application programming interface (hereinafter referred to as "API") as software or processing components that perform processing on the web.

The API is a Web-enabled program module that executes data processing in response to a processing request received from the client C1 through the API gateway 2. FIG.

An API is an interface program used by computer software components such as servers and clients to communicate with each other. A network 1 is a communication line including the Internet.

The servers 41 to 44, the client C1, and the API gateway 2 are computers having CPUs, memories, communication interfaces, etc. as hardware.

A software component such as a web browser capable of executing JavaScript (registered trademark) is installed in the client C1. The web browser can display input screens for various functions from the APIs of the servers 41 to 44 by accessing the servers 41 to 44 .

The input screen displays an input box for the operator of the client C1 to directly key-input text data (characters, etc.), such as for a questionnaire survey. The data entered in the input box is sent to the target API among the servers 41 to 44 via the network 1 and API gateway 2 and processed.

The API gateway 2 includes a storage unit 20, an environment parameter acquisition unit 27, a server parameter acquisition unit 28, a communication destination selection unit 29, a control unit 30, a communication management unit 31, an editing unit 34, as a functional configuration realized by the above hardware. and so on.

The storage unit 20 stores an evaluation condition table 21 as evaluation conditions, specification information tables 24 such as an API information table 22 and a server information table 23, an environment parameter table 25, a server parameter table 26, and the like. The API information table 22 stores specification information (see FIG. 3) of APIs that operate on the servers 41-44. The server information table 23 stores specification information (see FIG. 4) of the servers 41-44. The communication management section 31 has a communication processing section 32 and a communication error notification section 33 .

As shown in FIG. 2, the evaluation condition table 21 includes a stage evaluation formula (first evaluation condition), a server evaluation formula (second evaluation condition), and the like for evaluating the stage indicating the environment and situation of the entire system. identification information (stage ID) and each stage name. The stage evaluation formula is a logical formula for evaluating whether or not the item corresponds to the stage. An evaluation condition is whether or not a value obtained as a calculation result by substituting the acquired environmental parameter into this logical expression satisfies a preset threshold value.

For example, let Process=test be the discriminant of the stage that indicates that the implementation stage of the service is the test stage, and Process=prod be the discriminant of the stage that indicates that the service is in the production stage (operation stage). Also, the stage discriminant expressing that the current time is daytime is 1000<Time<2000. In this way, the determination result of the stage may be obtained as a real number (numerical value), as a binary value of "positive" or "no", or as a command.

The server evaluation formula is a calculation formula that serves as a reference for server evaluation in the relevant stage, and is set for each stage. After specifying the stage, the ranking of the server as a communication destination candidate is determined by the magnitude of the numerical value obtained as a calculation result by substituting the acquired server parameter into the calculation formula corresponding to the specified stage.

That is, the evaluation condition table 21 includes a stage evaluation formula for evaluating the stage in which the API is running on each server 41 to 44, and whether the functions of the servers 41 to 44 can process the request from the client C1 for each stage. It functions as an evaluation condition storage unit that stores a server evaluation expression for evaluating whether or not.

The specification information table 24 includes information (microservice ID) of microservices implemented by the servers 41 to 44 and APIs that operate on the servers 41 to 44, and location information of the servers 41 to 44 on the network 1 ( (location) is stored as a specification information storage unit.

For example, as shown in FIG. 3, the API information table 22 stores, for each API ID, the API name, which is the name of the API, and the microservice ID of the communication destination in association with each other.

As shown in FIG. 4, the server information table 23 stores the location (location information) of each server 41 to 44 on the network 1, the microservice ID, and the server name for each server ID.

The environment parameter acquisition unit 27 acquires system environment parameters detectable on the API gateway 2 side. The environment parameters are, for example, the current time (Time), time zone (Time zone), calendar (week, day), service implementation stage (Process: test stage (test) or production stage (prod)), this gateway 2 , and the total amount of usage of pay servers (total billing: Billing), which are uniquely determined for the entire system, and acquisition modules 27a to 27n are provided for each. Each acquisition module 27a to 27n is implemented so as to uniquely acquire these values in response to a request from the communication destination selection unit 29. FIG.

In addition, the value returned by the environment parameter acquisition unit 27 must indicate whether the result of substituting the stage evaluation formula corresponds to the current situation. is preferably a truth value (numerical value).

As shown in FIG. 5, the environment parameter table 25 stores a variable name and a value (parameter value) of the variable name corresponding to each environment parameter ID. The value of the variable name (parameter value) contains the value acquired by the environment parameter acquisition unit 27 . In this example, billing amount Billing and stage Process are used as variable names, but other variables include time, server total billing amount, server operation status, or API operation status running on the server. Conceivable.

The server parameter acquisition unit 28 acquires server parameters that represent the functions and performance of each of the servers 41 to 44 in real numbers. These server parameters are, for example, values (attribute information).

The server parameter acquisition unit 28 has a plurality of acquisition modules 28a-28n. Each of the acquisition modules 28a to 28n is provided for each parameter, such as a program for acquiring performance and a program for acquiring a usage fee (accounting amount), and parameters are acquired for the number of servers in use. be.

As shown in FIG. 6, the server parameter table 26 stores a variable name, its server ID, and the value of the variable name (parameter value) in association with each server parameter ID. A value obtained by the server parameter obtaining unit 28 is entered as the value of the variable name (parameter value). In this example, billing amount Billing and operation stage Version_newest are used as variable names.

The communication destination selection unit 29 functions as a stage determination unit that determines the current stage (test or production) that satisfies the stage evaluation formula based on the acquired environmental parameters of the system. Specifically, the communication destination selection unit 29 substitutes the environmental parameters into a plurality of different stage evaluation formulas (stage_1, stage_2, . . . ) set as evaluation conditions, evaluates each stage, , identify the stage with the best rating as the current stage.

Further, the communication destination selection unit 29 selects communication destination server candidates that satisfy the server evaluation formula corresponding to the determined stage based on the server parameters acquired by the server parameter acquisition unit 28 . More specifically, the communication destination selection unit 29 generates a list of communication destination candidate servers that satisfy the server evaluation formula, and assigns priority to the servers in order of the communication destination candidates with the best evaluation results in the generated list. It is passed to the communication processing section 32 through the control section 30 .

The control unit 30 performs control to relay an API request from the client C1 to a server (one of the servers 41 to 44) that is the request destination. Also, the control unit 30 controls the following units.

The communication management unit 31 receives the server list from the communication destination selection unit 29 through the control unit 30, and communicates with the server according to the server list. The communication processing unit 32 sequentially attempts communication with the server candidates (one of the servers 41 to 44) selected by the communication destination selection unit 29. FIG. At this time, the communication processing unit 32 attempts to communicate with the server in order of priority among the server IDs described in the delivered server list.

The communication processing unit 32 instructs the communication error notification unit 33 to return a communication error when the communication fails, that is, when a communication error occurs as a result of trying to communicate with all the candidate servers. The communication error notification unit 33 returns a communication error to the control unit 30 according to this instruction. Then, the control unit 30 returns a communication error to the client C1.

The editing unit 34 displays an editing screen for editing the contents of the evaluation condition table 21 on the administrator's PC by accessing from the administrator's PC, and can edit the contents of the evaluation condition table 21 on the editing screen. be.

The operation of the application system of this embodiment will be described below with reference to the flow charts of FIGS. 7 to 10. FIG. FIG. 7 is a flow chart showing the overall operation of this application system.

First, the processing operation from receiving an API request from the client C1 in the API gateway 2 to relaying the communication to the communication target server will be described with reference to the flowchart of FIG.

In the API gateway 2, the control unit 30 waits for an API request to be received from the client C1 (No in step S101 in FIG. 7, step S102), and when it receives an API request from the client C1 (FIG. 7 (Yes in step S101), the control unit 30 instructs the communication destination selection unit 29 to generate a list of communication destination server candidates (server list) (step S103).

At this time, the control unit 30 transmits request destination information indicating to which API the API request received from the client C1 is directed to the communication destination selection unit 29 . Request destination information is included in the API request.

The communication destination selection unit 29 receives an instruction from the control unit 30, and the environment parameters acquired by the environment parameter acquisition unit 27 (the time, the total billing amount of the server, the operation status of the server, the operation status of the API running on the server, etc.) ) to identify (determine) the current stage of the communication destination (step S104). The operation of specifying the stage will be described in detail later with reference to the flowchart of FIG.

Along with identifying the stage, the communication destination selection unit 29 substitutes the acquired server parameters into the server evaluation formula to evaluate the performance, state, and the like of the server.

The communication destination selection unit 29 stores the server ID of the server that satisfies the conditions of the identified stage, the location information of the server operating in that stage, and the API information used in the microservices in the specification information table 24 (server information table 23). and API information table 22), select server candidates that can be communication destinations using the read server information and API information, generate a server list of communication destination candidates, and pass it to the control unit 30 (step S105). The operation of selecting a communication destination server will be described in detail later with reference to the flowchart of FIG.

The control unit 30 passes the API request received from the client C1 and the server list of communication destination candidates generated by the communication destination selection unit 29 to the communication management unit 31 (step S106).

The communication management unit 31 executes communication with the servers in order from the highest priority server ID described in the server list passed from the control unit 30 (step S107), and sends the communication result obtained by the communication to the control unit. Return to 30.

The control unit 30 returns the communication result received from the communication management unit 31 to the client C1 (step S108).

The stage specifying operation of S104 will be described in detail with reference to the flowchart of FIG.
In this process, the communication destination selection unit 29 identifies (determines) the current stage using the stage evaluation formula included in the stage information read from the evaluation condition table 21 .

In this case, the communication destination selection unit 29 first reads the stage evaluation condition, that is, the stage evaluation formula of the evaluation condition table 21 in FIG. environmental parameters are requested (step S202).

The environmental parameter acquisition unit 27 acquires environmental parameters using the acquisition modules 27 a to 27 n (step S 203 ) and returns them to the communication destination selection unit 29 .

When the communication destination selection unit 29 receives the environment parameters acquired by the environment parameter acquisition unit 27, the communication destination selection unit 29 applies the received environment parameters to all stage evaluation formulas (stage IDs "stage_1", "stage_2", ... stage IDs "stage_4"). and evaluate the current stage of the server for each stage (step S204).

Then, among those evaluated by each stage evaluation formula, the one with the best evaluation (specifically, if the evaluation result is correct for a conditional formula, or if it is a function formula, one with a high numerical value) is assigned to that server. The current stage is determined, that is, the stage is specified (step S205).

Here, the variable Billing and the variable Process in the stage evaluation formula of the evaluation condition table 21 of FIG. 2 correspond to each environmental parameter, and the value of the acquired environmental parameter is substituted into the evaluation formula. For example, for the variable Blling and the variable Process, if the acquired environment parameters are "1500" and "test", the evaluation formula for the stage ID "stage_1" is "No", the evaluation formula for the stage ID "stage_2" is "Positive", The evaluation formula for stage ID "stage_3" is "fail", and the evaluation formula for stage ID "stage_4" is "fail". Determine as the current stage.

Note that the evaluation formula shown here is just an example, and in addition to the above conditional formula (selection formula), it may be expressed by, for example, a polynomial formula using variables (F1 (X1, X2, . . . Xn), etc.). By substituting the acquired environmental parameters into the variables X1, X2, . Among these, the stage with the largest real number of evaluation results is specified (determined) as the current stage.

The operation of selecting the communication destination server in S105 will be described in detail with reference to the flow chart of FIG.
In this process, the communication destination selection unit 29 reads the evaluation condition of the server from the evaluation condition table 21, that is, the server evaluation formula of the evaluation condition table 21 of FIG. 2 (step S301).

Subsequently, the communication destination selection unit 29 requests all server parameters from the server parameter acquisition unit 28 (step S302).

The server parameter acquisition unit 28 that has received this request acquires the corresponding server parameters using the acquisition modules 28a to 28n (step S303).

The values returned by the acquisition modules 28a to 28n of the server parameter acquisition unit 28 to the communication destination selection unit 29 are evaluated by substituting them into the server evaluation formula (see FIG. 2) read by the communication destination selection unit 29, similarly to the environment parameters. (compared with a threshold), preferably a real number. However, when representing a server that cannot be communicated with, an exception value is used.

The communication destination selection unit 29 receives the server parameters acquired by the server parameter acquisition unit 28 from the server parameter acquisition unit 28, and applies the received server parameters to the server evaluation formula included in the stage of the stage ID determined in the process of S104. Then, the evaluation value is calculated and stored (step S304).

The server evaluation formula used here is the server evaluation formula corresponding to the stage ID "stage2" determined in the process of FIG. 8, that is, "-billing+version_newest".

If the server parameter acquisition result is the value of the server parameter table 26 as shown in FIG. 1000+1="-999", the calculation result (evaluation value) of the server 42(1_2) is -10+1="-9", the calculation result (evaluation value) of the server 43(2_1) is 0+1 ="1", and the calculation result (evaluation value) of the server 44 (2_2) is 0+exception="exception".

By substituting the server parameters acquired in this way for each variable of the server evaluation formula, the evaluation calculation at the stage is performed, and a real number is calculated as the evaluation result of each server. However, if the evaluation result is an exceptional value like the calculation result (evaluation value) of the server 44(2_2), the server determines that communication is impossible.

The communication destination selection unit 29 acquires the server IDs of the connection destination candidates having the requested API and their locations from the specification information table 24, and creates a server list of connection destination candidates corresponding to the server IDs and their locations. is generated (step S305).

Here, first, the microservice ID to be communicated with the API ID included in the request is obtained from the API information table 22 . Subsequently, the communication destination selection unit 29 acquires the server ID and its location (location information of the server on the network 1) included in the microservice of the acquired microservice ID from the server information table 23, and establishes a connection based on these. Generate a server list of candidate destinations.

The communication destination selection unit 29 assigns a priority to each server ID in the generated server list of connection destination candidates (ranks the server ID by assigning a number starting from 1 in descending order of the evaluation value) (step S306). to the control unit 30 (step S307). A server with an exceptional value in the evaluation result is determined to be incapable of communication and is excluded from the list. In the above evaluation result, the server 41(1_1), the server 42(1_2), and the server 43(2_1) except for the server 44(2_2) are listed on the server list from the calculation result (evaluation value).

The communication operation of S107 will be described in detail with reference to the flow chart of FIG.
In the communication management unit 31, the communication processing unit 32 selects the server ID with the highest priority from the communication destination candidate server list included in the information (communication destination candidate server list, API request, etc.) received from the control unit 30. Select and execute communication with the server (step S401 in FIG. 10).

Here, if the communication is successful (No in step S402), the communication processing unit 32 terminates the communication with the server and returns the communication result received from the server to the control unit 30 (step S403).

On the other hand, if communication fails (Yes in step S402), the communication processing unit 32 excludes the server ID of the server with which communication failed from the server list of communication destination candidates (step S404).

After the exclusion, the communication processing unit 32 checks whether the server ID of the communication destination server remains in the server list of communication destination candidates (step S405).

As a result of checking the server list of communication destination candidates, if the server ID of the communication destination server does not remain in the server list of communication destination candidates (No in step S405), the communication processing unit 32 notifies the communication error notification unit 33 of the communication error. and the communication error notification unit 33 returns a communication error to the control unit 30 according to this instruction (step S406).

If the server ID of the communication destination server remains in the server list (Yes in step S405), the communication processing unit 32 selects the server with the next highest evaluation after the communication attempt from among the server IDs remaining in the list. The server ID of the selected server is selected (step S407), and communication is re-executed with the server having the selected server ID (step S408).

Thus, according to the application system of this embodiment, when the API gateway 2 receives an API request from the client C1, the API gateway 2 relays the communication to the API of the server in accordance with the API request. Get the server parameters, first substitute the obtained environment parameters into the stage evaluation formula to determine the current stage, then substitute the obtained server parameters into the server evaluation formula corresponding to the determined current stage to select a server to communicate with. In other words, the server that will be the relay destination for communication is automatically selected according to the current situation, so software developers no longer need to manually specify the relay destination server according to the situation. Cost can be reduced.

In addition, the API gateway 2 often manages information of a large number of APIs, and it is necessary to set communication patterns and the like for connection destinations for each API. In the embodiment, it is not necessary to set a communication pattern for each API, and it is sufficient to prepare two evaluation formulas corresponding to assumed situations, one for stage evaluation and one for server evaluation, thereby reducing the setting cost. be able to.

In this application system, the current stage and communication destination server are automatically selected without being specified by the user, and all API communication destinations are appropriately switched according to the usage environment and usage status of the server. , the setting work of the communication pattern for that purpose becomes unnecessary, and when developing software that bundles services using the APIs of a plurality of servers 41 to 44 using the API gateway 2, manual setting work is reduced, Total cost can be reduced.

While embodiments of the invention have been described, the embodiments have been presented by way of example and are not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. The embodiments shown here and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

In the above embodiment, in the API gateway 2, the control unit 30 receives requests from the client C1 and distributes them to the respective servers 41 to 44. In addition, the API gateway 2 may be provided with several APIs for each service. Alternatively, the request from the client C1 may be temporarily accepted by the API of the API gateway 2, and the API may distribute the request to the servers 41 to 44 that provide the corresponding service.

Further, as a specific example of selecting a server according to the stage evaluation result, in a case where the installation locations of the servers 41 to 44 are scattered in different areas such as "Osaka" and "Tokyo", The environmental parameter acquisition unit 27 acquires disaster occurrence information indicating that a disaster has occurred in the Kanto area such as "Tokyo", "Chiba", and "Kanagawa" from, for example, a disaster prevention site server, and selects a communication destination for the disaster occurrence information. 29, and the communication destination selection unit 29 calculates the score of the disaster area using a preset function from the location information (environmental parameters) included in the disaster occurrence information, The degree of influence on service provision is evaluated, and if the degree of influence in the Kanto region is high, the request from the client C1 may be distributed to a server in "Osaka" that provides the same kind of service.

In the above embodiment, each component of the API gateway 2 is realized by a program installed in a storage such as a hard disk device of a computer. Alternatively, the functions of the present invention may be realized by the computer by causing the computer to read the program from the electronic medium. Examples of electronic media include recording media such as CD-ROMs, flash memories, removable media, and the like. Furthermore, it may be realized by distributing and storing the constituent elements in different computers connected via a network, and by communicating between the computers that operate each constituent element.

41 to 44 application server (server) C1 client 2 API gateway 20 storage unit 21 evaluation condition table 22 API information table 23 server information table 24 specification information table 25 Environmental parameter table 26 Server parameter table 27 Environmental parameter acquisition unit 28 Server parameter acquisition unit 29 Communication destination selection unit 30 Control unit 31 Communication management unit 32 Communication processing unit 33 Communication error notification part.

Claims (9)

A gateway device for relaying a request to a destination server in a system in which a client and a plurality of servers are connected via a network and relaying a request from the client to the destination server,
an environment parameter acquisition unit that acquires an environment parameter indicating an environment of the entire system that can be detected by the gateway device;
A specification information storage unit storing specification information including information on microservices realized by each server of the plurality of servers and application programs running on each server, and location information of each server on the network. and,
Using a first evaluation condition having a stage evaluation formula that gives a judgment value for determining a stage indicating the operation of the application program on each server using the environment parameters, and using server parameters that are real numbers representing the functions that exist in each server. an evaluation condition storage unit storing a second evaluation condition having a server evaluation formula that gives an evaluation value for evaluating the function of each server for each stage specified by the determination value;
a stage determination unit that determines the current stage of the request destination server based on a determination value obtained by applying the acquired environment parameter of the system to the stage evaluation formula;
a server parameter acquisition unit that acquires the server parameters of each server;
a communication destination selection unit that selects candidates for the request destination server based on the evaluation value obtained by applying the acquired server parameter to the server evaluation formula corresponding to the current stage and the specification information;
and a communication processing unit that sequentially attempts communication with the server candidates selected by the communication destination selection unit. 2. The gateway device according to claim 1, wherein said environmental parameters include any one of the operation stage or production stage of the service, time, time period, calendar, amount of data to be relayed, and billing amount of pay server. 2. The gateway device according to claim 1, wherein said server parameter includes either a billing amount or a performance value set for each server. 2. The gateway apparatus according to claim 1, wherein said first evaluation condition is whether or not a value obtained as a result of calculation by substituting said environment parameter into said stage evaluation formula satisfies a preset threshold value. 2. The gateway device according to claim 1, wherein said server evaluation formula of said second evaluation condition is a calculation formula for server evaluation set corresponding to the determined current stage. The communication destination selection unit
generating a list of communication destination candidate servers using the second evaluation condition, assigning priority to the server in order of communication destination candidates with good evaluation results in the list, and passing the server to the communication processing unit;
The communication processing unit
2. The gateway device according to claim 1, wherein communication is attempted in the order of priority candidates in the delivered server list. The stage determination unit
2. The gateway device according to claim 1, wherein said environmental parameters are substituted into said plurality of stage evaluation formulas set as evaluation conditions, each stage is evaluated, and a stage with a good evaluation result is specified as a current stage. In a communication system comprising a client, a plurality of servers, and a gateway device connected via a network, wherein the gateway device relays a request from the client to a destination server,
The gateway device
an environment parameter acquisition unit that acquires an environment parameter indicating an environment of the entire communication system that can be detected by the gateway device;
A specification information storage unit storing specification information including information on microservices realized by each server of the plurality of servers and application programs running on each server, and location information of each server on the network. and,
Using a first evaluation condition having a stage evaluation formula that gives a judgment value for determining a stage indicating the operation of the application program on each server using the environment parameters, and using server parameters that are real numbers representing the functions that exist in each server. an evaluation condition storage unit storing a second evaluation condition having a server evaluation formula that gives an evaluation value for evaluating the function of each server for each stage specified by the determination value;
a stage determination unit that determines the current stage of the request destination server based on a determination value obtained by applying the acquired environmental parameter of the communication system to the stage evaluation formula;
a server parameter acquisition unit that acquires the server parameters of each server;
a communication destination selection unit that selects candidates for the request destination server based on the evaluation value obtained by applying the acquired server parameter to the server evaluation formula corresponding to the current stage and the specification information;
and a communication processing unit that sequentially attempts communication with the server candidates selected by the communication destination selection unit. A communication method using a gateway device for relaying a request from a client to a destination server in a system in which a client and a plurality of servers are connected via a network and relaying the request from the client to the destination server,
The gateway device
Acquiring an environment parameter indicating an environment of the entire system detectable by the gateway device;
storing specification information including information on microservices realized by each of the plurality of servers and application programs running on each of the servers, and location information of each of the servers on the network;
Using a first evaluation condition having a stage evaluation formula that gives a judgment value for determining a stage indicating the operation of the application program on each server using the environment parameters, and using server parameters that are real numbers representing the functions that exist in each server. a second evaluation condition having a server evaluation formula that gives an evaluation value for evaluating the function of each server for each stage specified by the determination value;
determining the current stage of the request destination server based on a determination value obtained by applying the acquired environment parameter of the system to the stage evaluation formula;
obtaining server parameters for each of said servers;
selecting candidates for the request destination server based on the evaluation value obtained by applying the acquired server parameter to the server evaluation formula corresponding to the current stage and the specification information;
A communication method that sequentially tries to communicate with selected server candidates.

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