Creating a Simple IoT Project

cem akpolat
Dec 22, 2021 · 11 min read

Introduction

In this tutorial a simple IoT project is presented. It is composed of simulated sensor, services, database, web api and a web application. First a quick start is introduced to directly dive in the code, afterwards a real use case scenario is followed. In order to realize the use case, the required system architecture and system componets are presented. Finally, the potential improvement posilibities are explained. To have a short overview, the table of contents is given below. If your interest is only one of it, you can directly focus on the related section, however, I recommend to read all tutorial.

  1. Quick Start
  2. Use Case
  3. System Architecture
  4. Required Technologies
  5. System Components
  • MQTT Broker Configuration
  • IoT Data Model Design
  • Simulated IoT Sensor Implementation
  • Data Processing&Observer Service Implementation
  • Data Storing&Requesting Service Implementation
  • User Web Interface Implementation
  • Predictive Maintenance Service Implementation (TODO)

6. Future Works

Quick Start

All project components are dockerized and docker-compose solves all dependency issues among them. To run the project, call simply the following commands:

Use Case

A smart factory environment is composed of many simple and complex devices that owns diverse features. The harmonization of all these features necessitates an IoT platform that unifies distinguished data models ranging from devices to human actor. The well known topic and crucial aspect of the smart factories is to predict beforehand when a device will be broken, since the whole production chain can severely be affected from a broken device in the system, and this may lead to stopping the complete system, which is not desired due to the cost and user perspectives. In order to prevent this kind of issues, a predictive maintenance system should be introduced to foresee when a device will be damaged, and it has to be replaced. To visualize such a use-case, we assume that a temperature sensor embedded in the production line is continuously monitored in a factory environment. All data retrieved from this sensor to the backend services for further analysis. Based on the observation analysis, the possibility of having a broken device is predicted. In the following section, only the data aggregation and visualization parts are implemented. The predictive maintenance module will be later integrated in the rest of the system.

System Architecture

The realization of this idea can be performed via a small IoT setup presented below.

Required Technologies

  • Communication Protocols: MQTT, HTTP, Websocket
  • Programming Language: C#, JavaScript, TypeScript, Python
  • Database: MongoDB
  • Container Tech: Docker
  • Machine Learning Algorithm: LSTM, … (TODO)
  • Development Environment: Mac OSX Catalina
  • .NET 5: Install from this link https://docs.microsoft.com/en-us/dotnet/core/install/macos

System Components

MQTT Broker

The data distribution among all other components are carried out via MQTT broker. In this project, the selected mqtt-broker is customized image based on the mosquitto-eclipse broker toke/mosquitto, because the websocket communication is enabled in this image, which is required for the user interface.

Technical View You can test the broker with the following command line:

docker run -ti -p 127.0.0.1:1883:1883 -p 9001:9001 toke/mosquitto

The easiest way to test the broker either run a simple python script or using a tool such as MQTT.fx. For python libraries, you can check this link: https://github.com/emqx/MQTT-Client-Examples/tree/master/mqtt-client-Python3

IoT Data Model

An IoT data model abstracts the features of an IoT sensor and allow its communication with other sensors or devices. We (me and other colleagues) described an IoT model in https://ieeexplore.ieee.org/document/8767276 and implemented it in https://github.com/GT-ARC/chariot-apis. In this tutorial, a very simplified version of this model is utilized. Two classes, namely, IoTEntity and Property belonging to the IoTEntity are implemented with the limited features. This model covers only the primive devices, for a complex device, it is recommended to utilize the whole library.

Common-API

The desired approach of using an IoT data model is to describe it under a common-api folder and enable its integration by other projects. Even this approach is possible and described how to do in common-api/README.md file, it is not considered in this tutorial.

Temperature Sensor/Service (Producer):

Sensor simulates a temperature service that generates randomly temperature values and sends it through MQTT communication protocol to the broker as a publisher. The service simulating device first transmits data and then stops for a while in a continous loop. The behavior of the simulation can be easily modified using the App.config file.

Technical View

  • create a project called iotservice:

dotnet new console --name iotservice

  • add the following libraries that are required for the mqtt connection, a better logging, the json-to-from-object convertor (POJO) and processing the configuration file.
  • App.config: Create an App.config file and edit it as follow. The brokerUrl can be replaced with localhost if it will tested seperately. The first three parameters are the standard mqttp parameters, the rest defines how the simulator should send the data to the mqtt broker. Below, waiting_daruratio represents the data transmission frequency, while sim_mode_changing_duration indicates how much time the broker should pause, i.e. no data transmission. The last parameter shows the sensor UUID, which differs this sensor from others.
  • Classes: Simulator class describes how often a random value should be generated and transmitted, and then pause. It can be extended and controlled from another script through the app.config file
  • Run the program to see how it works. The minimum requirements for the test is to have an mqtt broker and a tool that can behave as subscriber. Both are given in the MQTT-Broker section.

dotnet run

  • Dockerize: The docker file describes how the project will be dockerized, i.e. copying the files, restoring the app, building/publishing the program as a release. Notice that the multi-state build is applied in order to keep docker container small and efficient. Multi-state docker building works simply as follows: the requirement on the first image will not moved to the second image, so that the images will kept small sized. Please the docker-compose section, where the references to this topic are given.

Data Processing&Observer Service (Temperature Observer Service / Data Consumer)

This module consumes the data sent from the temperature sensor and process it. The actual service sends all received objects to the MQTT broker as well as error messages if any message is received for a while.

Technical View

dotnet new console --name iotservice

  • App.config: Same structure as in iotsensor.
  • Classes: Consumer.cs file is the main class and initiates to receive the messages using Servies/MQTTConnection object and seperatly listens in a distinct loop for understanding whether the messages can be received in a max amount of time, if not the a message is sent to the broker reporting this issue.
  • Run the program to see how it works. The minimum requirements for the test is to have an mqtt broker and a tool that can behave as publisher. Both are given in the MQTT-Broker section.

dotnet run

  • Dockerize: Same structed as in iotsensor.

Mongo Database

One of the project goals is to make the data persistent in a database. In this project, the mongodb is chosen to save the data. For the aforementioned use-ase any kind of database either sql or no-sql would fulfill the requirements. Another reason to select the mongodb is the availability of welld structured and written tutorials and documents in this link https://docs.microsoft.com/en-us/aspnet/core/tutorials/first-mongo-app?view=aspnetcore-5.0&tabs=visual-studio or many other links.

Technical View

  • Configuration: All database configurations are written in the docker-compose file. If the intention is to test it locally, the image can be initiated via docker with the configuration parameters givne in the docker-compose file.
  • mongodb-settings/mongo-init.js: Whenever the mongo database is started, it calls this javascript script and creates a database with the name iotworld, user root and pwd universe. These parameters must be given

Data Storing&Requesting Service

All sensor data is directly stored in the mongo database and the swagger interface enables to fetch and visualize the stored data from the database. The view of the swagger interface is depicted below.

Technical View

dotnet new webapi --name datastore

  • Add the following libraries: The libraries are necessary for interacting with the mongodb database, communicating via MQTT broker, a better logging and supporting swagger.
  • appsettings.json: This file is automatically created and it is also a configuration file like App.config, just the notations are in JSON rather than XML. Three configuration blocks are available: 1) Logging config, 2) Database settings such as user name, password and database name, these can be directly passed from the docker-compose, 3) mqtt settings provided by the docker-compose. If the goal is to test only this component, modify the the brokerUrl address such as localhost or another url address.
  • launchsettings.json: This file is also created and it includes the launch settings. Two parameters are important, applicationUrl should be similar what is written in docker-compose file. The initial configuration has localhost:5000 as a value. ASPNETCORE_ENVIRONMENT is also important and must be given in docker-compose. Otherwise the swagger interface cannot be accesed.
  • Classes:

Controller/IoTEntityController.cs is a typical rest class, which enables user to send/receive the request/response. In case of need, this rest interface can be extended.

Domain/* classes shows the structure how the data will be stored in the mongodb.

Models/* classes are used to convert the Json messages to the classic objects, which are shown also in other examples

Services/* supports the classes direct interaction with the database using IoTService and mqtt connection via MQTTConnection. The IoT object in JSON lands in the MQTTConnection object, converted to Entity object and then stored in the mongodb using IoTService object

Startup.cs class behaves like main initiater, adds all required app configuration, append new classes such as IoTservice and initiate the MQTT connection.

User Web Interface

The visualization of the aggeregated data is mostly more satisfying for end users and the purpose of this component is exactly to focus on a web application that has only two views aimint at depicting the sensor data and showing the log messages. With these minor requirements a web project can be easily created by using any kind of javascript framework ranging from jquery, angular, vue to reactjs. In this application, the angular is selected and one of the complete dashboard example, namely, coreuihttps://coreui.io/angular/, is taken as a base for the development. The reason is to have a solid code structure that allows to extend the features if required. A free version of the coreui dashboard can be accessed via https://coreui.io/angular/demo/free/2.11.1/#/dashboard.

The implemented user interfaces are demonstrated below:

Technical View

As mentioned above the app is constructed on the free vesion of (coreui/angular)[https://coreui.io/angular/] implemented via he angular framework. All additional subcomponents are removed to make a simplified code structure.

  • The instruction of coreui angular template is already explained in https://github.com/coreui/coreui-free-angular-admin-template. By applying them, the web app can be easily executed and accessed via http://localhost:4200
  • Remove all unnecessary files, for this project all views are removed.
  • Install ngx-mqtt module required for interacting via MQTT
  • update mqtt configuration in `app.module.ts`
  • if it is not added automatically import { IMqttMessage, MqttModule, IMqttServiceOptions } from "ngx-mqtt";
  • add mqtt configs and pass the config inside the ngmodule
  • create a service that observes mqtt topics and inform an angular component when its message comes, ../app/services/event.mqtt.service.ts
  • create two components:1 )sensor/device data visualization, 2) showing log data on a view
  • views/device: consumes EventMQTTService, parses incoming json data and update the chartjs line graph
  • views/logs:consumes EventMQTTService, parses incoming json data and update the log data table.
  • update app/containers/default-layout/_nav.ts to access the modules on the navigation panel.
  • update the app-routing.module.ts to load the app components. The default selected module is devices component.
  • The upper given route structure is indeed pretty complext and for this application might be seen unnecessary, however, if you plan to extend it, it is great to see how a feature can be easily added here. All routes are listed in a single file.
  • npm start or ng serve will directly build and run the web app if any issue appears, the app can be reached via localhost:4200

Predictive Maintenance (TODO)

An autonomous smart factory necessitates to detect the errorness or the possibility of having a failure at devices. The predictive maintenance service aims at aggregating the data from the sensors and predict whether the device behaves normal based on the historical data. This component will be added as a future work.

Future Works

  • (short term)Complete a predictive maintenance app using Python and an existing project, and inform the user web interface in case of having a failure.
  • Extend IoT Data Model
  • Add UUID to each sensor via App.config
  • Add UUID to be subscribed or published to services or devices in App.config.
  • Find solutions for Single Point of Failures such as more than a MQTT Broker, multipe database, etc.
  • Improve user web interface, be able to display all devices in the dashboard.
  • Extend the controller functionalities in the datastore

Nerd For Tech

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cem akpolat

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Nerd For Tech

NFT is an Educational Media House. Our mission is to bring the invaluable knowledge and experiences of experts from all over the world to the novice. To know more about us, visit https://www.nerdfortech.org/.