KR20170126641A - System and method for providing internet of things service to support private networks - Google Patents

Abstract

The present invention relates to a system and a method for providing an IoT service in a private network. The system and method for providing an IoT service supporting a private network comprises: an IoT server which provides an application to search an IoT service to a user terminal, and provides an IoT service URI corresponding to the IoT service searched from the user terminal, to the user terminal; and an internet proxy which is searched through the IoT service URI from a user terminal, receives IoT service request information transmitted from the user terminal, and transmits the IoT service request information to an IoT gateway providing an IoT service in accordance with the IoT service URI. The IoT gateway is connected to at least one IoT device, is configured on a private network, and transmits the information to an IoT device corresponding to the IoT service request information transmitted from the IoT proxy.

Description

TECHNICAL FIELD [0001] The present invention relates to an Internet service providing system and method for supporting a private network,

The present invention relates to a system and method for providing Internet services for objects in a private network.

In general, IP (Internet Protocol version 4) can not allocate IP to all terminals, resulting in IP shortage. Dynamic Host Configuration Protocol (DHCP) and Network Address Translator (NAT) are used in order to solve IP shortage in IPv4. DHCP leases IP to the terminal for a certain period of time, and retrieves the used IP to solve the IP shortage phenomenon. NAT provides a public IP address to the network, while terminals belonging to the network use the private IP address and use public IP only when connecting to the Internet. As described above, a network using a private IP is referred to as a private network, and a terminal inside a private network can not confirm presence or directly access the terminal from the Internet (i.e., outside).

On the other hand, Internet of Things (IoT) refers to a network of objects, people, and services for creating, collecting, sharing, and utilizing information by connecting objects, people, and space to the Internet. These objects can be used to share information in various fields such as healthcare, remote meter reading, smart home, and smart car, as well as household appliances and electronic devices through the Internet.

The Object Internet Platform is a platform for implementing the Internet of things, and functions to connect objects to the Internet and provide services to utilize them. These objects Internet platforms can be classified into P / M / S / D-platform. Specifically, the P-platform represents a platform for registering and retrieving object Internet devices, and the M-platform (Mash up-platform) represents data of object Internet devices as information, Platform represents a platform for registering and retrieving an application related to a matter Internet device, and a D-platform (device-platform) represents a platform for controlling the connection of objects to the Internet (P / M / S), which is a platform for interworking with other objects Internet platform (P / M / S).

However, the existing Internet platform is implemented considering IPv6. Accordingly, in order to support the IPv4 private network, a separate hardware switch or an application has to be added, or a virtual private network must be established by an expert. In addition, the object Internet service refers to a service that accesses and uses easily regardless of the user's location through a common interface by providing the functions of objects as a web service (WS: Web service). However, There was a limit to the impossibility of access.

Korean Patent Laid-Open Publication No. 2015-0107951 (entitled " Security System and Method for Internet of Things Interworking with Wireless Network "

An object of the present invention is to provide a system and a method for supporting a private network to enable communication from an external terminal to a terminal inside a private network, thereby providing the object Internet service.

In order to solve the above-mentioned problems, the object Internet service providing system supporting the private network of the present invention provides an application for browsing the object internet service to the user terminal, and provides an object Internet service corresponding to the object internet service retrieved from the user terminal. An object Internet server for providing a service URI to the user terminal; And transmits the object Internet service request information to the object Internet gateway, which receives the object Internet service request information transmitted from the user terminal and is provided through the object Internet service URI from the user terminal and provides the object Internet service according to the object Internet service URI Wherein the object Internet gateway is connected to at least one object Internet device and configured on the private network and transmits the object Internet device to the object Internet device corresponding to the object Internet service request information transmitted from the object Internet proxy, do.

In addition, the Internet proxy of the object receives the Internet service request information using the port forwarding of the web service, removes the Internet proxy address of the object from the Internet service URI of the object, and transmits the ID of the Internet gateway of the object to the Internet service To the private IP address of the object Internet gateway corresponding to the request information.

In addition, the object Internet server includes a Planet-platform for registering and retrieving object Internet devices, a Mash up-platform for processing data of objects Internet devices and controlling objects Internet devices, Can be interfaced with the Store- platform for registering and searching.

In addition, the object Internet gateway may be implemented using an Open Service Gateway Initiative (OSGi), and may include a component for communicating with the object Internet device connected to the object Internet gateway.

In addition, the Object Internet Gateway can be connected to the Device-Platform for linking the Internet device to the Internet, which is connected to the Object Internet gateway through the Internet proxy, and interworking with the Planet-platform, Mashup-platform and Store-platform.

According to another aspect of the present invention, there is provided a method for providing an object Internet service supporting a private network, comprising the steps of: providing an application for searching a object Internet service to a user terminal; Providing the object Internet service URI corresponding to the object Internet service retrieved from the user terminal to the user terminal by the object Internet server; Receiving object Internet service request information through the object Internet service URI transmitted from the user terminal by the object Internet proxy; Transmitting the object Internet service request information to the object Internet gateway providing the object Internet service by the object Internet proxy; And sending the object Internet service request information to the object internet device corresponding to the object internet service request information by the object internet gateway, wherein the object internet gateway is connected to the at least one object internet device and configured on the private network .

The step of receiving the object Internet service request information through the object Internet service URI is performed by receiving the object internet service request information using the port forwarding of the web service and the object Internet proxy address is removed from the object internet service URI And changing the ID of the object Internet gateway to the private IP address of the object Internet gateway corresponding to the object Internet service request information in the object Internet service URI.

According to the object Internet service providing system and method for supporting the private network according to the embodiment of the present invention, it is possible to access and use the object Internet service existing in the private network through the external terminal, Or a virtual private network.

In addition, according to the object Internet service providing system and method for supporting a private network according to an embodiment of the present invention, an object Internet proxy, which is an SW gateway for providing a object Internet service in a private network, The Internet gateway provides the Internet access to the objects through the Internet gateway.

1 is a block diagram of a system for providing an Internet service of objects supporting a private network according to an embodiment of the present invention.
2 is a block diagram of an Internet server according to an embodiment of the present invention.
3 is a block diagram of an object Internet proxy according to an embodiment of the present invention.
4 is a block diagram of an object Internet gateway according to an embodiment of the present invention.
FIG. 5 is a conceptual diagram illustrating an operation of an Internet gateway according to an embodiment of the present invention. Referring to FIG.
6 is a diagram for explaining a method for supporting a private Internet according to an embodiment of the present invention.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Hereinafter, a system and method for providing a matter-of-concern Internet service 10 supporting a private network according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a system for providing a matter-of-interest Internet service 10 supporting a private network according to an embodiment of the present invention. 1, the object Internet service providing system 10 according to an embodiment of the present invention includes an object Internet server 100, a object Internet proxy 200, a object Internet gateway 300, 400). The object Internet gateway 300 and the object Internet device 400 may exist in a private network and the object Internet gateway 300 may be connected to the Internet through the object Internet proxy 200. [

As shown in FIG. 1, at least one object Internet gateway 300 may be included in the private network, and at least one object Internet device 400 may be connected to each object Internet gateway 300. In addition, the object Internet server 100 and the user terminal 500 can also communicate with the object Internet proxy 200 by accessing the Internet network.

The object Internet server 100 can configure and manage the object Internet domain using the object Internet proxy 200 and manage the object Internet gateway 300 and the user. At this time, the object Internet server 100 can manage service bundles and communication components in a Maven Repository format, and can process monitoring of the object Internet gateway 300 and the object Internet proxy 200. [ Also, the object Internet server 100 can be interworked with the M-platform, the S-platform, and the P-platform among the object Internet platforms.

FIG. 2 is a block diagram of an object Internet server 100 according to an embodiment of the present invention. 2, the object Internet server 100 according to an exemplary embodiment of the present invention may operate on a Java Virtual Machine (JVM) 110 and may include a heartbeat server 120, a JMS broker 130, The HTTP client 140, the object Internet service client 150, the server storage 160, the monitoring unit 170, and the object Internet service web application providing unit 180. Hereinafter, the configuration and operation of the object Internet server 100 will be described in more detail with reference to FIG.

The heartbeat server 120 receives public IP from the object Internet proxy 200 and receives a heartbeat, which is data for confirming the current state.

The JMS broker 130 is a message broker that receives a topic message (MQTT, JMS) transmitted from the object Internet gateway 300 and the object Internet proxy 200.

The HTTP client (HTTP client) 140 is an HTTP client for invoking the object Internet service.

The object Internet service client (object Internet service client, 150) is a web service (WS) client for calling the object Internet service.

The server repository 160 may be a Maven Repository for easily managing and distributing Internet service bundles and communication components.

The monitoring unit 170 monitors the object Internet service and the object Internet gateway 300, and represents a monitoring tool for managing the object Internet service, the gateway and the user.

Object Internet Service Web Application 180 is a function that provides an application that enables a user to use the object Internet service through the Internet (browser).

Specifically, the user can search for a desired object Internet service through an application provided through the object Internet service web application providing unit 180. That is, when the user searches for the object Internet service through the user terminal 500, the object Internet service web application provider 180 may provide the object internet service URI corresponding to the relevant object internet service to the user terminal. Accordingly, the user terminal 500 can search for the object Internet proxy 200 to which the object Internet device corresponding to the object Internet service is connected based on the object Internet service URI, Service request information can be transmitted.

Referring back to FIG. 1, the object Internet proxy 200 receives the object Internet service request information requested by the private IP address using port forwarding, and then transmits the requested object Internet service to the corresponding object Internet service To the object Internet gateway 300 which provides the object information.

At this time, the object Internet proxy 200 receives data (i.e., object Internet service request information) transmitted from a specific port using port forwarding through a network address translator (NAT) device. Then, the object Internet proxy 200 transmits the object Internet service request information to the corresponding object Internet gateway 300 using the HTTP URI. At this time, the object Internet proxy 200 can store simple information composed only of the ID and IP of the object Internet gateway. For reference, a URI may include a Uniform Resource Locator (URL) and a Uniform Resource Name (URN).

3 is a block diagram of an object Internet proxy 200 according to an embodiment of the present invention. As shown in FIG. 3, the object Internet proxy 200 according to an exemplary embodiment of the present invention can be operated on a Java virtual machine (Java VM) 210 to support various OSs. The object Internet proxy 200 according to an exemplary embodiment of the present invention includes an MQTT broker 220, a first web application server 230, a heartbeat 240, a gateway manager 250, and an HTTP proxy 260 And the like. Hereinafter, the configuration and operation of the object Internet proxy 200 will be described in more detail with reference to FIG.

The MQTT broker (MQTT Broker) 220 receives the topic message transmitted from the object Internet gateway 300. Here, the Message Queue Telemetry Transport (MQTT) is a protocol for machine to machine / object Internet. It uses a broker-based publish / subscribe method instead of an HTTP request / response method. . At this time, the MQTT can operate on the TCP / IP protocol like HTTP.

The first web application server 230 functions to drive an HTTP proxy servlet.

The heartbeat 240 generates data (i.e., heartbeat) for confirming the public IP and the status of the object Internet proxy 200, and transmits the data to the object Internet server 100.

The gateway manager 250 stores the object Internet gateway information (i.e., ID, IP information, etc.) and status information (resource status, service status, etc.) transmitted as topic messages in a proxy map, To the server (100).

The HTTP proxy (HTTP Proxy) 260 can confirm the URI of the received object Internet service request and then deliver the object Internet service request information to the object Internet gateway 300 that provides the object Internet service.

The object Internet proxy 200 searches the object Internet gateway 300 corresponding to the selected object Internet service through the user terminal 500 and transmits the object Internet service request information to the relevant object Internet gateway 300 can do. At this time, the object Internet proxy 200 can transfer the object Internet service request information to the object Internet gateway 300 through a method of converting the object Internet service URI. Specifically, the object Internet proxy 200 removes the object Internet proxy address from the object Internet service URI, and transmits the ID of the object Internet gateway from the object Internet service URI to the private IP address of the object Internet gateway corresponding to the object Internet service request information . The description thereof will be referred to again with reference to FIG. 6, so that further explanation is omitted.

1, the object Internet gateway 300 is implemented using an Open Service Gateway Initiative (OSGi) to send a communication component (service bundle) to various objects (i.e., the object Internet device 400) on the object Internet to provide. That is, as shown in FIG. 1, the object Internet gateway 300 connects the object Internet devices 400 using a bundle. These bundles and components can be easily managed and distributed using Java Archive (JAR) files. For example, service bundles and communication components can be managed using a Maven repository (eg Nexus), and bundles can be downloaded and distributed using the Maven repository URI.

For reference, OSGi is an open Java-based service platform as a standard for standard connection of Internet devices such as home information appliances and security systems. In other words, OSGi is an open Java Enterprise System (JES) -based gateway software, and it can provide multiservice to devices and facilities regardless of platform and application software. In particular, OSGi is an open network technology that accommodates various wired and wireless network technologies such as Bluetooth, HAVi, home PNA, home RF, USB, and VESA. At this time, OSGi provides management and connection functions for all products (ie all things available as Internet devices), such as set-top boxes, cable modems, routers, alarm systems, power management systems, do.

In addition, the object Internet gateway 300 interfaces with the object Internet platform using a common interface (e.g., SOAP, RESTful) and interworks with the D-platform.

For reference, Simple Object Access Protocol (SOAP) is a communication protocol for invoking data services on other computers based on XML and HTTP. Most SOAP servers that support SOAP are accessible from the Web and can run in a variety of programming languages. Representational State Transfer (REST) is also used as a web service that exchanges data using HTTP and XML. There are many ways to implement Web services, and RESTful supports REST and is used in Web applications.

4 is a structural diagram of an object Internet gateway 300 according to an embodiment of the present invention. And FIG. 5 is a conceptual diagram for explaining the operation of the object Internet gateway 300 according to an embodiment of the present invention. 4, the object Internet gateway 300 according to an exemplary embodiment of the present invention includes a monitoring agent 330, a device manager 340, a component 350, a device 360, a second web application server 350, An Internet service provider 370, and an object Internet service provider 380. Hereinafter, the configuration and operation of the object Internet gateway 300 will be described in more detail with reference to FIGS.

First, the object Internet gateway 300 may be operated on a Java virtual machine (Java VM) 310 to support various OSs as shown in FIG. At this time, the object Internet gateway 300 provides a variety of communication components and operates based on the OSGi 320 to facilitate management and distribution of the service bundle.

The monitoring agent 330 collects status information (i.e., ID, IP, resource, etc.) of the object Internet gateway 300 and service status information (i.e., status information of the object Internet device) 200 or the object Internet server 100.

A device manager (340) manages the newly added object Internet devices and services.

Components 350 provide various communication components such as TCP, UDP, HTTP, and Bluetooth. That is, the component 350 is a configuration for communication between the object Internet devices 400 connected to the object Internet gateway 300.

The device 360 connects the object Internet device 400 using the component 350 to provide the object Internet service through the connected object Internet devices 400. [

The second web application server 370 allows the function of the connected object Internet device 400 to be provided as the object Internet service. For reference, the second web application server 370 is a middleware (software engine) for executing an application through a user's computer or a user terminal via HTTP on the Internet. In the second web application server 370, And to provide Internet services for objects.

Object Internet Service (Object Internet Services, 380) implements and provides the functions of connected Internet devices as SOAP (RESTful). Through the structure of the object Internet gateway 300 described above, the object Internet gateway 300 performs the operations shown in FIG.

Specifically, as shown in FIG. 5, the developed object Internet service bundle is registered in the object Internet repository (Object Internet Repository). At this time, the object Internet repository to which the object Internet service bundle is registered may be the server storage unit 160 of the object Internet server 100. Accordingly, the object Internet gateway 300 can download the object Internet service bundle from the server storage unit 160 of the object Internet server 100 and distribute the communication component using the Maven repository URI. And the object Internet gateway 300 is requested to register the object Internet service through the object Internet management tool.

As described above, since the object Internet service providing system 10 supporting the private network according to the embodiment of the present invention provides the object Internet service using WS (i.e., HTTP), port forwarding for the 80 port is processed And transmits the external object Internet service request to the object Internet proxy 200. [ For reference, port 80 is a port of a web server for HTTP service, usually a promised port. At this time, the object Internet proxy 200 can confirm the HTTP URI (Uniform Resource Identifier) and deliver the service request to the object Internet gateway 300 that provides the object Internet service.

6 is a diagram for explaining a method for supporting a private Internet according to an embodiment of the present invention. 6, a description will be given of an example in which a user is provided with a matter Internet service through a method of providing a matter Internet service supporting a private network according to an embodiment of the present invention. Hereinafter, the same elements as those described above will be omitted.

First, a step of providing an application to the user terminal 500 by the object Internet server 100 so that the object Internet service can be searched can be performed. At this time, the user can search for a necessary object Internet service from the object Internet server 100 through the user terminal 500. When the user terminal 500 searches for the required object Internet service from the object Internet server 100, the information about the found object Internet service is transmitted to the object Internet server 100.

Thereafter, the object Internet server 100 analyzes the data stored in the server storage unit to find the object Internet service URI corresponding to the object Internet service retrieved from the user terminal 500, and transmits the retrieved object Internet URI to the user terminal 500 have.

This is because the object Internet server 100 manages the domain information of the object Internet proxies 200 as object Internet domain information. That is, the object Internet server 100 is provided with object Internet service information for each object Internet proxy 200, including IDs of the object internet gateways 301 and 302 and object internet And manages service information. Here, the first and second Internet gateways 301 and 302, that is, the Internet gateways in the private network, may be connected to at least one of the Internet devices.

Thereafter, the user terminal 500 transmits the object Internet service request information to the object Internet proxy 200 using the URI of the received object Internet service. That is, the step of receiving the object Internet service request information through the object Internet service URI transmitted from the user terminal by the object Internet proxy 200 is performed. At this time, the object Internet proxy 200 receives the object Internet service request of the user terminal 500 through the public IP, and receives the data (i.e., the object Internet service request) transmitted to the specific pod using the port forwarding.

At this time, the ID of the object Internet proxy 200 is set, and the ID of the object Internet proxy 200 is registered and managed as the object Internet domain information in the object Internet server 100. The object Internet proxy 200 has a public IP address and is connected to the first object Internet gateway 301 and the second object internet gateway 302 in the example of FIG. Private IP can be assigned. That is, in the example shown in FIG. 6, the object Internet proxy 200 manages and manages IDs and private IPs for the object Internet gateways 301 and 302 as gateway information.

Thereafter, the object Internet proxy 200 transmits the object Internet service request information transmitted from the user terminal 500 to the object Internet gateway for providing the corresponding service, so that the object Internet service is provided. In this example, it is assumed that a corresponding one of the two Internet gateways 301 and 302 is connected to the second Internet gateway 302. In this case, the object Internet proxy 200 may transmit the object Internet request information transmitted from the user terminal 500 to the second object internet gateway 302 to which the object Internet device providing the desired service is connected.

Here, the object Internet proxy 200 can transfer the object Internet service request information to the second object Internet gateway 302 through the method of converting the object Internet service URI. That is, as shown in FIG. 6, the object Internet proxy 200 removes the object Internet proxy address from the object Internet service URI of the user terminal 500, and then converts the ID of the object Internet gateway to the IP address Can be performed.

For example, if the object Internet service URI requested by the user terminal 500 to the object Internet proxy 200 is "http: //121.166.81.xx:8080/c89bf82adfe04965b12681b621a423fe:8181/ServiceOfThings", the object Internet proxy 200 ) Removes the object Internet proxy address "121.166.81.xx: 8080" and converts it to "http: // c89bf82adfe04965b12681b621a423fe: 8181 / ServiceOfThings. Thereafter, the object Internet proxy 200 converts the ID of the second object Internet gateway 302 into the IP address in the converted address, thereby converting the object Internet URI to "http://192.168.0.2:8181/ServiceOfThings" . Accordingly, the object Internet service request information can be transmitted to the second object Internet gateway 302.

Thereafter, a process of transmitting the object Internet service request information to the object Internet device corresponding to the object Internet service request information by the second object Internet gateway 302 may be performed.

The object Internet service providing system and method for supporting a private network according to an embodiment of the present invention may be realized in the form of a recording medium including instructions executable by a computer such as a program module executed by a computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes any information delivery media, including computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transport mechanism.

While the methods and systems of the present invention have been described in connection with specific embodiments, some or all of those elements or operations may be implemented using a computer system having a general purpose hardware architecture.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

10: Internet service delivery system
100: Things Internet Server 200: Things Internet Proxy
300: Things Internet Gateway 400: Things Internet Devices
500: user terminal

Claims (8)

An object Internet service providing system for supporting a private network,
An object Internet server providing an application that enables a user terminal to search for a thing Internet service, and providing the object internet service URI corresponding to the object internet service retrieved from the user terminal to the user terminal; And
The object Internet service providing method according to claim 1, further comprising: receiving, from the user terminal, the object Internet service request information retrieved from the object Internet service URI, transmitted from the user terminal, and providing the object Internet service according to the object internet service URI, An object Internet proxy for communicating service request information,
The object Internet gateway comprises:
Wherein the at least one Internet service provider is connected to at least one of the object internet devices and is configured on the private network and transmits the object internet service to the object internet device corresponding to the object internet service request information transmitted from the object internet proxy. The method according to claim 1,
The object Internet proxy comprises:
Receiving the object Internet service request information using port forwarding of the web service,
Wherein the object internet proxy address is removed from the object Internet service URI and the ID of the object Internet gateway is changed from the object Internet service URI to the private IP address of the object Internet gateway corresponding to the object internet service request information, Internet Service Providing System. The method according to claim 1,
The object Internet server comprises:
A Planet-platform for registering and retrieving objects Internet devices, a Mash up-platform for processing and providing data of objects Internet devices and controlling objects Internet devices, and for registering and retrieving applications related to devices Store-platform, which is connected to a private Internet service providing system that supports private network. The method of claim 3,
The object Internet gateway comprises:
And a component for communicating with the object Internet device connected to the object Internet gateway is implemented using an Open Service Gateway Initiative (OSGi). 5. The method of claim 4,
The object Internet gateway comprises:
And a device-platform for interfacing with the Planet-platform, the Mashup-platform, and the Store-platform, wherein the object Internet device connected to the object Internet gateway is connected to the Internet via the object Internet proxy. Internet Service Providing System. A method for providing Internet service for objects supporting a private network,
Providing an application to the user terminal by the object Internet server so that the object Internet service can be searched;
Providing the object Internet service URI corresponding to the object Internet service retrieved from the user terminal to the user terminal by the object Internet server;
Receiving object Internet service request information from the object Internet proxy through the object Internet service URI transmitted from the user terminal;
Transmitting the object Internet service request information to the object Internet gateway providing the object Internet service by the object Internet proxy; And
And transmitting the object Internet service request information to the object Internet device corresponding to the object Internet service request information by the object Internet gateway,
Wherein the object Internet gateway is connected to at least one object Internet device and is configured on a private network. The method according to claim 6,
The step of receiving the object Internet service request information through the object Internet service URI is performed by receiving the object Internet service request information using the port forwarding of the web service,
Removing the object Internet proxy address from the object Internet service URI and changing the ID of the object Internet gateway from the object Internet service URI to the private IP address of the object Internet gateway corresponding to the object Internet service request information A method for providing Internet service for objects supporting a private network. The method according to claim 6,
The object Internet server comprises:
A Planet-platform for registering and retrieving objects Internet devices, a Mash up-platform for processing and providing data of objects Internet devices to control objects Internet devices, and a Store-Platform for registering and retrieving applications associated with devices The method comprising the steps of:

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