Do IoT Yourself! - 사물 간의 연결을 위한 Open API

사물 간의 연결을 위한 Open API

IoT Web Service Dev. – 사물 간의 연결을 위한 Open API

Sensing

• 주변 상황 정보

획득과 실시간

전달

Network

• 사물과 인터넷

간의 연결

Service

• 수집된 정보의

가공, 처리,

융합

Security


■아두이노 소개 – Open source H/W

– sparkfun™ starker kit for Redboard

■가변 저항으로 LED 색깔 바꾸기 구현 – Soft potentiometer 이용

■온도 센서 구현 – 실시간 온도 정보를 serial port로 출력하기


■ Get the source code: http://goo.gl/V5HJzo

http://goo.gl/V5HJzo

http://goo.gl/V5HJzo



Security

Sensing

• 주변 상황 정보

획득과 실시간

전달

Network

• 사물과 인터넷

간의 연결

Service

• 수집된 정보의

가공, 처리 융합


■ Web Service Development of IoT using

Node.JS and MySQL

Serial comm.

Open API

※ Covers at day 2


■ Server-side application development

platform with JavaScript

– Google’s chrome JavaScript engine (V8) 기반

– Event handling I/O Framework

• Non-blocking I/O

• 단일 스레드 이벤트 루프를

통한 높은 처리성능


■사이트에서 설치 (http://nodejs.org/)

http://nodejs.org/

http://nodejs.org/


■설치가 완료된 이후, console에서 node 실행

■ REPL (Read Eval Print Loop)에서 코드 입력

– console.log(‘Hello, Node.JS ‘ + process.version)

■화면에 메시지와 함께 버전을 출력

■ Crtl+c를 두번 입력해서 REPL 종료


■가장 많이 사용하는 Node.js 웹 개발 프레임워크

■ Express 생성기 설치

– npm install –g express-generator

■ Express 템플릿 생성

– express DIoTY

■템플릿 폴더로 이동하여

관련 모듈 설치

– cd DIoTY; npm install


■ Open Source Relational

Database Management System (RDBMS)

– 세계에서 가장 많이 쓰이는 DB

• 다양한 웹 사이트 및 웹 애플리케이션에서 사용 중

– Apache web server, PHP, Tomcat 등과 연계해서 사용.

– 현재 Oracle에 인수


■사이트에서 community version 설치

– Windows 계열

• http://dev.mysql.com/downloads/windows/installer/5.6.html

http://dev.mysql.com/downloads/windows/installer/5.6.html




■ ‘mysql –u{id} –p{password}’ 로 로그인하면 설치

완료

– 오류 발생 시 ‘mysql 설치’로 googling해서 원인 해결


■ Reading or Writing or Both


■ GETing or POSTing


■ Client protocol: – {GET | PUT | POST | DELETE …} {URI} HTTP/1.1

{HTTP headers, e.g. Accept:, User-Agent:, Host:, …} {body – any representation}

■ Server protocol: – HTTP/1.1 {200 OK | 404 Not Found | …}

{HTTP headers, e.g. Content-Length:, Content-Type:, …} {body – any representation}

HTTP header

empty line

body


■ Representation

– Content-Type header describes media type of the body.

<?xml version="1.0" encoding="UTF-8"?>

<xml>

<Person firstName=“John” lastName=“Smith” alive>

<age>25</age>

<height scale=“cm”>167.6</height>

<address>

<streetAddress> 21 2nd Street</streetAddress>

<city>New York</city>

<state>NY</state>

<postalCode>10021-3100</postalCode>

</address>

<phoneNumbers> … <phoneNumbers>

<children></children>

<spouse></spouse>

</Person>

</xml>

<!doctype html>

<html>

<head>

</head>

<body>

<header>

John Smith

</header>

<div role=‘main’>

<p>age: 25</p>

<p>height: 167.cm</p>

<p>address:<br/>

21 2nd Street, New York,

NY 10021-3100

</p>

</div>

</body>

</html> [HTML] [XML] [JSON]


■ Clients request, Server responses

client

요청

server

응답

client

요청

응답

응답

요청

C

S

C

C

C

C

C

C

C


■ Sensing or actuating within things over internet


■ IoT requests, IoT responses

IoT

요청

IoT

응답

IoT

요청

응답

응답

요청 IoT

IoT

IoT

IoT

IoT

IoT

IoT

IoT

IoT



■ Sets of technologies that enable websites to

interact with each other by using REST, SOAP,

JavaScript and other web technologies.

– wikipedia (http://en.wikipedia.org/wiki/Open_API)

■ Open API 예

http://en.wikipedia.org/wiki/Open_API

http://en.wikipedia.org/wiki/Open_API


■ REST: REpresentational State Transfer

– from R. T. Fielding’s dissertation

• resources and their state transfer by HTTP standard protocol.

Resource

[client] [server]

Resource

GET

update

state

Resource

Resource PUT, POST, DELETE

Resource


■ Retrieving resources

– Request:

• GET /api/resources HTTP/1.1

Accept: application/json

…

– Response:

• HTTP/1.1 200 OK

Content-Type: application/json

…

{ “resources” : [ {“id” : “…”,

“name” : “…” }, … ]

}

Operation HTTP command

Retrieve GET

Create POST

Update PUT

Delete DELETE


■ Create new resource

– Request:

• POST /api/resources HTTP/1.1


{ “resource” : {“name” : “newbie”

} }

– Response:

• HTTP/1.1 201 Created

{ “resource” : {“id”: “1”, “name” : “newbie” } }


Retrieve GET

Create POST

Update PUT

Delete DELETE


■ Update a resource

– Request:

• PUT /api/resources/1 HTTP/1.1


{ “resource” : {“name” : “intermediate”

} }

– Response:

• HTTP/1.1 202 Accepted


Retrieve GET

Create POST

Update PUT

Delete DELETE


■ Delete a resource

– Request:

• DELETE /api/resources/1 HTTP/1.1

Accept: application/json

– Response:

• HTTP/1.1 200 OK


Retrieve GET

Create POST

Update PUT

Delete DELETE


List

information

API state

diagram

Magic

string

elimination

Design

media type

& profile

API

implement

& billboard

URL

■ Design procedure

– Excerpt from the book “RESTful Web API”

• By Leonard Richardson, Mike Amundsen and Sam Ruby


■ List all the pieces of information for a

temperature sensor

– a list of sensors

• a thermometer, …

a collection of temperatures

» a temperature

date published

unit of measure (e.g. 섭씨 (C), 화씨 (K))

» the latest temperature

• a switch

turn on or off


■ derives state diagram and eliminates all

magic strings

a list of

sensors

a thermo-

meter (switch)

sensor

(safe)

Turn on or off

(unsafe, idempotent*)

a list of

temperatures

temperature (datePublished)

(unitOfMeasure)

latest

(safe)

temperatures

(safe) *Idempotent: the result of a

successful performed

request is independent of

the number of times it is

executed.


■ Design media type for representation

– application/json (without semantic descriptor)


■ API implementation & billboard URL

– Describes a request and responses briefly.

• Considers success condition and various error conditions

e.g. 200 OK on success, 500 Internal Server Error on error, …

– Billboard URL: /api

Action Request Response codes*

Retrieve sensors GET /api/sensors 200, 500

Retrieve a sensor GET /api/sensors/:id 200, 404, 500

Switch a sensor on/off PUT /api/sensors/:id 202, 404, 406, 500

Retrieve temperatures GET /api/sensors/:id/temperatures 200, 404, 500

Retrieve latest temp. GET /api/sensors/:id/temperatures/latest 200, 404, 500

* http://en.wikipedia.org/wiki/List_of_HTTP_status_codes

http://en.wikipedia.org/wiki/List_of_HTTP_status_codes




■ DB schema 만들기

– MySQL console로 로그인 후 temps DB 및 schema 생성

mysql -u root -p Enter password: mysql> CREATE DATABASE temps; mysql> USE temps;

Mysql> CREATE TABLE tempData ( tempId int(11) AUTO_INCREMENT NOT NULL, tempDate datetime NOT NULL, tempCelsius decimal(4,2) NOT NULL, constraint tempData_PK primary key (tempId) );

tempData

int tempId (public key)

datetime tempDate

decimal tempCelsius


■ DB schema 확인

– SQL 기본 질의 구문인 “SELECT {property name} FROM

{table name} WHERE {query condition}” 사용

mysql> select * from tempData; +--------+---------------------+-------------+ | tempId | tempDate | tempCelsius | +--------+---------------------+-------------+ +--------+---------------------+-------------+ 0 rows in set (0.11 sec) mysql>


■ mysql 모듈 설치 (npm install mysql)

■ Node.JS에서 DB에 데이터 쓰기 var mysql = require('mysql'); var connection = mysql.createConnection({ host: 'localhost', user: 'root', password: ‘{password here}', database: 'temps' }); connection.connect(); connection.query('insert into tempData(tempDate, tempCelsius) values(?, ?)', [new Date(), 10.01], function(err, rows, cols) { if (err) throw err; console.log(rows); }); connection.end();


■ Node.JS에서 DB에 읽어오기

var mysql = require('mysql'); var connection = mysql.createConnection({ host: 'localhost', user: 'root', password: '{password here}', database: 'temps' }); connection.connect(); connection.query('select * from tempData', function(err, rows, cols){ if (err) throw err; console.log(rows); }); connection.end();


■ serialport 모듈 설치 (npm install serialport)

■ Redboard와 PC 연결 후 해당 {COM port} 입력

var serialPort = require('serialport'); var sp = new serialPort.SerialPort('{your COM port here}', { baudrate: 19200, parser: serialPort.parsers.readline('\n') }); sp.on('open', function () { console.log('serial opened.'); sp.on('data', function (data) { try { data = new String(data).trim(); console.log(data + ' degree'); } catch (e) { console.error('ERROR: ' + e.name); } }); });


■ Express로 생성한 폴더의 app.js 열기

■파일 마지막 줄 위에 아래 코드 삽입

■ node app 실행

■ Browser로 http://localhost:3000/ 접속

// create http server at port 3000 var http = require('http'); http.createServer(app).listen(3000, function () { console.log("Express server listening on port 3000"); }); module.exports = app; // end of code line.

http://localhost:3000/

http://localhost:3000/


■ Retrieve sensors

var express = require('express'); var router = express.Router(); var sensorsObj = { "sensors": [{ "type": "thermometer", "id": "thermometer1", "switch": "off" }] }; /* GET api/sensors listing. */ router.get('/sensors', function (req, res) { res.writeHead(200, { "Content-Type": "application/json" }); res.end(JSON.stringify(sensorsObj)); }); module.exports = router;


■ Retrieve a sensor

/* GET api/sensors/:id */ router.get('/sensors/:id', function (req, res) { try { var id = req.params.id; // search the sensor in the sensors var sensorObj = findSensor(id); if (sensorObj == null) { throw new Error('404'); } res.writeHead(200, { "Content-Type": "application/json" }); res.end(JSON.stringify(sensorObj)); } catch (err) { // return error code here res.sendStatus(err.message); } });


■ Switch a sensor on/off /* PUT api/sensors/:id */ router.put('/sensors/:id', function (req, res) { try { // search the sensor in the sensors var sensorObj = findSensor(req.params.id); if (sensorObj == null) { throw new Error('404'); } if (!req.is('application/json')) { throw new Error('406'); } var sensorModified = req.body; if (!sensorModified.switch == null) { throw new Error('406'); } sensorObj.switch = sensorModified.switch; if (sensorObj.switch == 'on') { serialToDb(true); } else { serialToDb(false); } res.sendStatus(202); } catch (err) { res.sendStatus(err.message); } });


■ Retrieve temperature list

/* GET api/sensors/:id/temperatures */ router.get('/sensors/:id/temperatures', function (req, res) { try { // omitted:search the sensor in the sensors var tempList = getTemperatureList(function (tempList) { var temps = { temperatures: tempList }; res.writeHead(200, { "Content-Type": "application/json" }); res.end(JSON.stringify(temps)); },queries); } catch (err) { res.sendStatus(err.message); } });


■ Retrieve the latest temperature

/* GET api/sensors/:id/temperatures/latest */ router.get('/sensors/:id/temperatures/latest', function (req, res) { try { var id = req.params.id; // search the sensor in the sensors var tempList = getLatestTemperature(function (temp) { var tempObj = { temperatures: temp }; res.writeHead(200, { "Content-Type": "application/json" }); res.end(JSON.stringify(tempObj)); }); res.sendStatus(err.message); } });


■ Chrome browser에 Advanced REST Client 설치

– Open API의 동작을 간단하게 테스트 가능


■ JavaScript API Development

– How to invoke open API with AJAX

■ Web Application Development

– HTML5 basics

– Don’t reinvent the wheel! reuses the open source.

– Data visualization with google open API

■ Postmortem


■ HTTP 프로토콜 관련

– 개요: http://ko.wikipedia.org/wiki/HTTP

– 헤더 유형:

http://en.wikipedia.org/wiki/List_of_HTTP_header_fields

– 응답 코드:


■ REST API 관련

– 개요: http://ko.wikipedia.org/wiki/REST

– 설계 절차: http://webofthink.tistory.com/19

http://ko.wikipedia.org/wiki/HTTP








http://ko.wikipedia.org/wiki/REST



http://webofthink.tistory.com/19

http://webofthink.tistory.com/19


■ Node.JS 관련

– Node.JS API: http://nodejs.org/documentation/api/

– Express API: http://expressjs.com/api.html

– mysql API: https://github.com/felixge/node-mysql/

– serialport API: https://github.com/voodootikigod/node-

serialport

■ MySQL 관련

– MySQL 설치: http://blog.daum.net/bang2001/91

– SQL 문법: http://ko.wikipedia.org/wiki/SQL

http://nodejs.org/documentation/api/

http://nodejs.org/documentation/api/

http://expressjs.com/api.html

http://expressjs.com/api.html

https://github.com/felixge/node-mysql/




https://github.com/voodootikigod/node-serialport




http://blog.daum.net/bang2001/91

http://ko.wikipedia.org/wiki/SQL

Software

Do IoT Yourself! - 사물 간의 연결을 위한 Open API