KR101665852B1 - Method and apparatus for providing service discovery, and computer readable medium for the same - Google Patents

Abstract

The present invention relates to a service search providing method and apparatus and a computer-readable recording medium. According to the present invention, there is provided a method comprising: discovering a service host among host devices on a network; Transmitting a probe packet to the service host; And receiving a response message corresponding to the transmitted probing packet from the service host. According to the present invention, consumption of computing resources of IoT objects can be minimized.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for providing a service search, and a recording medium readable by a computer.

The present invention relates to a service search providing method and apparatus, and a computer readable recording medium.

The development of various IT devices has increased the efficiency of people's work so that more work can be accomplished in a short time. However, it is becoming increasingly difficult for an individual to achieve something by diversifying and complicating the tasks that people need to do.

This led to the emergence of an intentional community in which people with the same goals were grouped together to influence community culture. In addition, in Switzerland and the United States, there is an increasing number of living spaces that seek to maximize economic efficiency through the sharing of residential living such as cohousing. But. The limitations of physical constraints in forming an intrinsic community exist as difficult challenges to overcome.

However, it may be possible to form and utilize various intentional communities in artificially gathered areas such as apartments in high density countries such as Korea, but there is a problem that there are still physical limitations.

Therefore, we propose a service search providing technology that can provide improved control based on the generalization of various IoT.

The present invention aims at solving all of the above problems.

It is another object of the present invention to find various requirements arising in daily life of users and to provide services suited to the situation.

It is another object of the present invention to provide a technique for assisting a community of various people living in a plurality of smart homes.

It is another object of the present invention to support the interaction between users and IoTs made up of devices capable of self-determination with computing ability.

In order to accomplish the objects of the present invention as described above and achieve the characteristic effects of the present invention described below, the characteristic structure of the present invention is as follows.

According to an embodiment, there is provided a method of providing a service search, comprising: discovering a service host among host devices on a network; Transmitting a probe packet to the service host; And receiving a response message corresponding to the transmitted probing packet from the service host.

According to another embodiment of the present invention, there is provided a service search providing method comprising: analyzing a received response message using service metadata; And recognizing a service type provided from a service host using the analyzed response message; As shown in FIG.

According to yet another embodiment, in the method of providing a service search, the step of discovering a service host may include identifying a dummy host among the host devices on the network to find a service host excluding the dummy host .

According to another embodiment of the present invention, in the method of providing a service search, the transmitting of the probing packet may include transmitting a probing packet generated using a network packet in which mutual agreement of protocols of the service host is unnecessary .

In another aspect of the present invention, there is provided a method of providing a service search, wherein the probing packet includes a request for obtaining predetermined information from the service host.

According to another embodiment of the present invention, in the service search providing method, the step of transmitting the probing packet may include transmitting the probing packet by optimizing the order of the probing packets to be transmitted considering the search time and resource consumption .

According to another embodiment of the present invention, in the method of providing a service search, the analyzing of the response message may include analyzing service information matched with the service host among the databases built on knowledge of the service and the protocol, And analyzing the response message.

According to another embodiment of the present invention, in the service search providing method, the database may include a database constructed using information including at least one of a behavior, a property, and an update direction for each protocol of a service host.

According to another embodiment of the present invention, in the service search providing method, the step of recognizing the service type may include determining service type information to be queried in response to the analyzed response message to recognize a service type .

In another aspect of the present invention, the step of recognizing the service type includes recognizing a service type as information obtained by repeating the process of determining the service characteristic information using a decision tree can do.

According to an embodiment of the present invention, there is provided a service search and provision apparatus comprising: a service host discovery unit for discovering a service host among host devices on a network; A probing packet transmitter for transmitting a probing packet to the service host; And a response message receiver for receiving a response message corresponding to the transmitted probing packet from the service host; . ≪ / RTI >

According to another embodiment of the present invention, there is provided a service search and provision apparatus, comprising: a response message analyzer for analyzing the received response message using service metadata; And a service type recognition unit for recognizing a service type provided from a service host using the analyzed response message; As shown in FIG.

According to another embodiment, the service host discovery unit may include a dummy host among the host devices on the network to discover the service host excluding the dummy host.

According to another embodiment, the probing packet transmitting unit may include transmitting a probing packet generated using a network packet in which mutual agreement of protocols of the service host is unnecessary.

According to another embodiment, the probing packet may include a packet designed to acquire predetermined information from the service host.

According to another embodiment of the present invention, the probing packet transmitter may include transmitting the probing packet by optimizing the order of the probing packets to be transmitted considering the search time and resource consumption.

According to another embodiment, the response message analyzing unit may analyze the response message by extracting characteristics of service information and host information matched with the service host among databases constructed based on knowledge of services and protocols can do.

According to another embodiment, the database may include a database constructed using information including at least one of a behavior, a property, and an update direction for each protocol of a service host.

According to another embodiment, the service type recognition unit may include determining service type information to be queried in response to the analyzed response message to recognize a service type.

According to another embodiment of the present invention, the service type recognizing unit may include recognizing a service type as information obtained by repeating the process of determining the service characteristic information using a decision tree.

In the computer-readable recording medium according to the embodiment, the computer-readable recording medium may include a program recorded thereon for executing the method according to any one of claims 1 to 10.

The present invention can find various requirements arising in daily life of users and provide services according to the situation. Therefore, the present invention has an effect of providing a technique for assisting a community of various people living in a plurality of smart homes.

The present invention can support the interaction between users and IoT, which is composed of devices capable of self-determination with computing ability. Therefore, the present invention has the effect that it is possible to search for surrounding services in a lightweight manner that minimizes consumption of computing resources of IoT objects.

1 is a conceptual diagram illustrating a service search providing method according to an exemplary embodiment of the present invention.
FIG. 2 illustrates a service search providing method according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating a service search providing method according to an exemplary embodiment of the present invention.
4 illustrates a service search providing method according to an embodiment of the present invention.
FIG. 5 illustrates a service search providing method according to an embodiment of the present invention.
6 is a block diagram illustrating a service search and provision apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram illustrating a service search providing method according to an exemplary embodiment of the present invention.

Referring first to FIG. 1, an overall system according to an exemplary embodiment of the present invention may include an Internet of Things (IoT) device and a service host. Of course, there may be a dummy host on the network. The service search providing apparatus may discovery the first service host through the third service host, but may not identify the first dummy host and the second dummy host in some cases. As a matter of course, at least one of the first to third service hosts may be an IoT device.

According to one embodiment, the service discovery providing apparatus can identify and retrieve the service independently of the standard SDP. First, in order to discover a service existing in the Smart IoT environment without using the SDP, the service search providing device can first discover existence of all the host devices existing on the network. At this time, the service search providing apparatus can select a dummy host, which is devices for not interacting with ordinary users such as a general PC, a network gateway, a personal server, etc. in addition to a service providing device on the network. In addition, the service search providing apparatus may have knowledge of dummy hosts for performing the sorting operation and perform identification of the dummy host in the information gathering process.

In addition, according to one embodiment, after discovering the existence of a service host, the service search providing apparatus can recognize what service is provided from the host without using the standard SDP. For example, the service discovery providing apparatus can design a network packet (probing) that can universally extract information from the target hosts even when there is no mutual agreement of the protocols.

In addition, according to an embodiment, the service search and provision apparatus can exchange various probing packets in order to grasp a target service. At this time, the service search providing and receiving apparatuses may communicate with each other through the network, and many of the IoT devices as the service search and providing apparatus have limited computing resources. For example, the service discovery providing apparatus may minimize the time and resources consumed to identify the service by optimizing the order of the probing packets to be exchanged, as the case may be.

In addition, according to an embodiment, the service search and provision apparatus can refer to a database as a built-in knowledge base that becomes a basis for various decision-making processes by having overall knowledge of services and protocols. Of course, the service search providing apparatus may refer to an external database as a knowledge base or refer to a database constructed in the service search providing apparatus. In addition, the service search providing apparatus may construct a database as a knowledge base, as the case may be.

According to one embodiment, the response message obtained in the process of exchanging the probing packet may contain a lot of information about the target service and the host. At this time, the service search providing apparatus can refer to the data information of the database in order to acquire basic knowledge information about how a certain probing packet is to extract a characteristic and how the characteristic can be extracted from the response message. As a matter of course, the service search providing apparatus may construct a database by acquiring basic knowledge information on how a probing packet is to extract a characteristic and how the characteristic can be extracted from the response message.

According to one embodiment, in some cases, the knowledge base may be defined at an abstract level to encompass the behavior and characteristics of the various protocols and future directions of updates.

FIG. 2 illustrates a service search providing method according to an exemplary embodiment of the present invention.

According to one embodiment, the service search providing apparatus is designed so that three core modules are designed to perform functions, and can perform service discovery and identification independently of SDP through interaction. For example, the service search providing apparatus may include a Probing Scheme module, a Decision Algorithm module, and a Knowledge Base module, as the case may be. In addition, the probing structure module, the decision algorithm module, and the knowledge base module may comprise at least one of a processor, a memory, a data transceiver, an electronic circuit, an electric circuit, an integrated circuit, an electronic device, . At this time, the decision algorithm module can optimize the probing sequence.

Referring to FIG. 2, it can be seen how the three core modules of the probing structure module, the decision algorithm module, and the knowledge base module interact with each other in the service search and supply apparatus.

In step S201, the service search providing apparatus can provide a host IP on a network found through ARP host scanning as an input value of a Decision Algorithm module.

In step S202, the service search providing apparatus exchanges probing packets in the order presented by a Decision Algorithm module using a Decision Algorithm module for the target IP, Can be collected.

In step S203, the service search providing apparatus may send a request to the probing scheme module to transmit a probing packet for a certain service characteristic in the Decision Tree, using an algorithm (Decision Algorithm) module.

In step S204, the service search providing apparatus can exchange the probing packet corresponding to the characteristic transferred to the target host with the target host by using the Probing Scheme module.

In step S205, the service search providing apparatus may return a response message to the Decision Algorithm module using the Probing Scheme module.

In step S206, the service search providing apparatus can use the Decision Algorithm module to find out how to analyze the response message from the Knowledge Base module.

In step S207, the service search providing apparatus can determine the service characteristics to be queried in the following order.

According to one embodiment, the service search and provision apparatus can repeat the steps of the above steps to determine which service type is based on the collected information.

3 is a flowchart illustrating a service search providing method according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the service search providing method performed by the service search providing apparatus may include the following steps.

In step S301, the service search providing apparatus can discover a service host among host devices on the network. At this time, the service search providing apparatus can identify a dummy host among the host devices on the network and find a service host excluding the dummy host.

In step S302, the service search providing apparatus can transmit the probing packet to the service host. Specifically, the service search and provision apparatus can transmit a probing packet generated by using a network packet in which mutual agreement of protocols of a service host is unnecessary. At this time, the probing packet may be a packet designed to acquire predetermined information from the service host. In addition, the service search providing apparatus can transmit the probing packet by optimizing the order of the probing packets to be transmitted considering the search time and resource consumption.

In step S303, the service search providing apparatus can receive a response message corresponding to the probing packet transmitted from the service host.

In step S304, the service search providing apparatus can analyze the response message received using the service metadata. Specifically, the service search providing apparatus can analyze the response message by extracting characteristics of the service information and the host information matching the service host in the database constructed based on the knowledge of the service and the protocol. At this time, the database may be a database constructed using information including at least one of a behavior, a property, and an update direction for each protocol of the service host.

In step S305, the service search providing apparatus can recognize the service type provided from the service host using the analyzed response message. Specifically, the service search providing apparatus can recognize the service type by determining the service characteristic information to be queried in response to the analyzed response message. Also, the service search providing apparatus may recognize the service type as information obtained by repeating the process of determining the service characteristic information using the decision tree.

4 illustrates a service search providing method according to an embodiment of the present invention.

According to one embodiment, the service search providing apparatus may include a probing scheme module. The service search providing apparatus can define the API of the probing packets and the format of the response message using the Probing Scheme module.

For example, the service search providing apparatus can receive a host IP and port as basic input values of each probing packet using a probing scheme module, and return a JSON formatted packet as a response message. At this time, there may be 'probetime' as to how much time is taken as information to be basically included in the response message, and 'type' as to what kind of probe. Further, the service search providing apparatus can provide the other items to the developer to arbitrarily add and edit according to the service characteristics to be grasped.

According to an embodiment, when designing a probing packet according to a service characteristic, a service search providing and providing apparatus may know which combination of characteristics makes services distinguish from each other. For example, the service search providing apparatus obtains information on the interaction of the IETF / W3C standard service protocol and the IoT devices, analyzes characteristics that services have in common, Can obtain information on the characteristics that can be obtained only by exchanging the information. Of course, the service search providing apparatus may acquire information about features that can be obtained only by exchanging basic packets regardless of SDP from the outside.

According to one embodiment, the service search provisioning device can provide six probing packets designed to extract six service characteristics from the target host, as can be seen with reference to Table 1 below.

Referring to Table 1, according to one embodiment, the CONNECT probe is the most basic probing packet and can be designed to check whether or not a destination host is connected. This can be the most essential probing packet for selecting dummy hosts. Also, even if the host does not operate any service, the service search providing apparatus can receive a response message having a value of 'false' from the host.

Also, according to one embodiment, the HTTP Probe may be used for extracting manufacturer information, which may be considered the core of service identification. HTTP is a lingua franca that is being used by many smart devices today, and the service discovery provider from the majority of IoT devices can get a response.

Also, according to one embodiment, since the popularity of HTTPS greatly affects the popularity of HTTPS, the design of HTTPS Probe enables information on the certificate issuer of the service to be grasped.

Also, according to one embodiment, the DNS Probe can be designed to extract it because the Domain Name is useful information that directly or indirectly reveals the characteristics of the service and the information of the owner.

Also, according to one embodiment, the WHOIS Probe can be designed to obtain more information, such as contacts, for the service owner.

Also, according to one embodiment, the Favicon Probe can be designed to extract it because Favicon is the W3C standard and is universal information used by most web browsers and smart device platforms to reflect the nature of the service .

According to one embodiment, the service search providing apparatus may include a Decision Algorithm module. The service search providing apparatus can minimize the time and resources consumed to grasp the service by optimizing the order of the probing packets to be exchanged by using the Decision Algorithm module.

According to one embodiment, the service search providing apparatus may use the ID3 algorithm as a Decision Tree algorithm, as the case may be. For example, the service search providing apparatus can construct a decision tree based on the information gain (information gain) that can be calculated using the frequency of the characteristics of the following learning sample data using ID3. In some cases, the service search providing apparatus may use equations (1) and (2).

At this time, H (S) may be a statistical entropy of S given data set. Also, X may be a set of service types and p (x) may be a ratio of each service type. Also, A is a service characteristic to be checked, and T can be a target service.

The service search providing apparatus compares IGs with respect to all service characteristics at the time of tree construction, and can determine the service characteristics that provide the most IGs as decision nodes. In addition, the service search and provision apparatus can complete a well-balanced decision tree that minimizes the depth through this process. At this time, since one probe packet is exchanged for each service characteristic node, the service search and provision apparatus can minimize the depth of the tree, balance the number of probing packets to be exchanged, and reduce the completion time .

According to one embodiment, the service search providing apparatus may perform the service search providing method, including the following steps, as the case may be.

In step (1), the service search providing apparatus can select a route characteristic that can cause a right service identification with a minimum probe message exchange. At this time, the route characteristic can be selected based on knowledge base and decision algorithm.

In step (2-1), the service search providing apparatus can query the corresponding probe for the selected characteristic.

In step (2), the service search providing apparatus can send a query for the probe to the target service host in order to extract the property value from the response message. At this time, the knowledge base may indicate in the response message which characteristics can be extracted by the probe and a certain characteristic. For example, it can be a regular expression.

In step (3), based on the probe, the service search provisioning device may select the next probe that can execute or conclude that there is one (or zero) service remaining in the candidate set. If a new probe is selected, it may move to step (2), as the case may be.

In step (4), if the service is identified, the service discovery providing device may request the downloadable SDP adapter store to the appropriate SDP adapter so that the user device knows how to start the actual interaction.

At this time, it can be assumed that the resource-limited smart object provides at least one SDP that interacts with others. In addition, the service discovery providing apparatus may determine a corresponding SDP and download a specific SDP adapter from the storage, considering a service ID (ID) that can be mapped to specific SDPs, if the target service is identified.

FIG. 5 illustrates a service search providing method according to an embodiment of the present invention.

According to one embodiment, a knowledge base module is a module for collecting information on how an IoT device, which is a service host, can be a manufacturer, what kind of a service is, It can be the basis for decision making in service identification process, including information on knowledge.

For example, a knowledge base module may include information about various knowledge, such as how probes meta-data responds to probing packets, and the like. In some cases, the knowledge base module may include information on the most essential knowledge in the system design of the service search providing apparatus.

Referring to FIG. 5, we can see some of the core parts of the knowledge base. Also, knowledge base can be designed through ontology.

6 is a block diagram illustrating a service search and provision apparatus according to an embodiment of the present invention.

6, the service search providing apparatus 600 includes a service host discovery unit 610, a probing packet transmitting unit 620, a response message receiving unit 630, a response message analyzing unit 640, (650). At this time, the service search providing apparatus 600 may be a computing device such as, but not limited to, a tablet PC, a smart phone, and a wearable device. In addition, the service search providing apparatus 600 may be configured to include at least one of a processor, a memory, a data transceiver, an electronic circuit, an electric circuit, an integrated circuit, an electronic device, and a magnetic device. The service host discovery unit 610, the probing packet transmitting unit 620, the response message receiving unit 630, the response message analyzing unit 640, and the service type recognizing unit 650 may, A decision algorithm module, and a knowledge base module. The service host discovery unit 610, the probing packet transmitting unit 620, the response message receiving unit 630, the response message analyzing unit 640 and the service type recognizing unit 650 may be a processor, a memory, a data transceiver, But is not limited to, at least one of a circuit, an electric circuit, an integrated circuit, an electronic device, and a magnetic device.

The service host discovery unit 610 may discover a service host among the host devices on the network. At this time, the service host discovery unit 610 can identify the dummy host among the host devices on the network and find the service host excluding the dummy host.

The probing packet transmitter 620 can transmit the probing packet to the service host.

Specifically, the probing packet transmitter 620 can transmit a probing packet generated using a network packet in which mutual agreement of protocols of a service host is unnecessary. At this time, the probing packet may be a packet designed to acquire predetermined information from the service host.

In addition, the probing packet transmitting unit 620 may transmit the probing packet by optimizing the order of the probing packets to be transmitted considering the search time and resource consumption.

The response message receiving unit 630 can receive a response message corresponding to the probing packet transmitted from the service host.

The response message analysis unit 640 can analyze the response message received using the service metadata. Specifically, the response message analyzer 640 can analyze the response message by extracting characteristics of the service information and host information matched with the service host among the databases constructed based on the knowledge of the service and the protocol. At this time, the database may be a database constructed using information including at least one of a behavior, a property, and an update direction for each protocol of the service host.

The service type recognizing unit 650 can recognize the service type provided from the service host using the analyzed response message. At this time, the service type identification unit 650 can recognize the service type by determining service characteristic information to be queried in response to the analyzed response message.

Also, the service type identification unit 650 may recognize the service type as information obtained by repeating the process of determining the service characteristic information using the decision tree.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced. Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (19)

A service search providing method,
Discovering a service host among host devices on the network;
Transmitting a probe packet to the service host;
Receiving a response message corresponding to the transmitted probing packet from the service host;
Analyzing the received response message using service information matched to the service host; And
Determining service characteristic information to be queried in response to the analyzed response message, and recognizing a service type provided from the service host
Lt; / RTI >
Wherein the probing packet is a packet designed to obtain predetermined information from the service host,
Wherein the transmitting the probing packet comprises:
Transmitting a probing packet in consideration of a search time and a consumption of resources,
The step of recognizing the service type comprises:
Determining a service type by using information obtained by repeating the process of determining the service characteristic information using a decision tree,
Wherein the decision tree utilizes statistical entropy. delete The method according to claim 1,
Wherein the discovering of the service host comprises:
Identifying a dummy host among the host devices on the network to find a service host excluding the dummy host. The method according to claim 1,
Wherein the transmitting the probing packet comprises:
And transmitting a probing packet generated using a network packet to which mutual agreement of protocols of the service host is unnecessary. delete delete The method according to claim 1,
The step of analyzing the response message comprises:
Analyzing response messages by extracting characteristics of service information and host information matched with the service host among databases constructed based on knowledge of services and protocols,
Wherein,
A service search providing method, which is a database constructed using information including at least one of a behavior, a property, and an update direction for each protocol of a service host. delete delete A service search providing apparatus comprising:
A service host discovery unit for discovering a service host among host devices on the network;
A probing packet transmitter for transmitting a probing packet to the service host;
A response message receiver for receiving a response message corresponding to the transmitted probing packet from the service host;
A response message analyzer for analyzing the received response message using service information matched with the service host; And
Determining a service characteristic information to be queried in response to the analyzed response message, and recognizing a service type provided from the service host;
Lt; / RTI >
Wherein the probing packet is a packet designed to obtain predetermined information from the service host,
Wherein the probing packet transmitting unit transmits the probing packet in consideration of the search time and resource consumption,
The service type determination unit recognizes the service type using information obtained by repeating the process of determining the service characteristic information using a decision tree,
Wherein the decision tree uses statistical entropy. delete 11. The method of claim 10,
The service host discovering unit,
Wherein a service host excluding the dummy host is identified by identifying a dummy host among the host devices on the network. 11. The method of claim 10,
Wherein the probing packet transmitter comprises:
And transmits a probing packet generated using a network packet in which mutual agreement of protocols of the service host is unnecessary. delete delete 11. The method of claim 10,
Wherein the response message analyzer comprises:
Analyzing response messages by extracting characteristics of service information and host information matched with the service host among databases constructed based on knowledge of services and protocols,
Wherein,
Wherein the service providing server is constructed using information including at least one of a behavior, a property, and an update direction for each protocol of a service host. delete delete A computer-readable recording medium having recorded thereon a program for executing the method according to any one of claims 1, 3, 4, and 7.

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