General

This repository contains the source code of three applications:

• DeviceSimulator
• LoggerService
• ApiGateway

Applications Start Sequence

1. LoggerService
2. ApiGateway
3. DeviceSimulator

Environment

The system has been build to run a single system because all communication goes to localhost.

Prerequisites

The following software has to be install to build and run all applications:

• Java 1.8
• Maven 3.6.1
• node.js v12.1.0 including npm
• protoc 3.7.1

The mentioned versions are those used during development.

Technology

The following table lists the technologies and frameworks used to develop the applications

Application	Language	Framework	Dependencies	Remarks
DeviceSimulator	Java		org.json	pure Java
ApiGateway	Java	Spring Boot	spring-boot-starter-webflux
			spring-boot-starter-test
			reactor-test
			protobuf-java
			protobuf-maven-plugi
			spring-boot-maven-plugin
			build-helper-maven-plugin
LoggerService	JavaScript	node.js	google-protobuf
			dgram
			winston

LoggerService

The application LoggerService is a node.js application. Its use case is to receive binary Google Protocol Buffer messages sent over the UDP protocol, deserialize these received messages and log them into a log file located in the folder path/to/LoggerService/logs.

Install Packages & Run

To install necessary npm package and start the application open a terminal and execute the following commands inside the folder path/to/LoggerService:

npm install
node server.js

ApiGateway

The ApiGateway is an application acting as a gateway receiving requestand to to pass them on to the LoggerService. Its main use case in addition to pass all incoming requests on to the LoggerService is to translate/convert received JSON payload to Google Protocol Buffer format. The communication protocol also changes from HTTP to UDP.

Build

The project ApiGateway is a Maven project. To build the project open a terminal and execute the following command inside the folder path/to/ApiGateway:

mvn clean install

Run

The application can then be started by executing the following command inside the folder path/to/ApiGateway:

java -jar target/ApiGateway-0.0.1-SNAPSHOT.jar

DeviceSimulator

The DeviceSimulator is an application for testing the ApiGateway and the LoggerService. It simulates 20 devices each sending HTTP POST request with a JSON payload to the ApiGateway.

Build

The project DeviceSimulator is a Maven project. To build the project open a terminal and execute the following command inside the folder path/to/DeviceSimulator:

mvn clean install

Run

The application can then be started by executing the following command inside the folder path/to/DeviceSimulator:

java -jar target/DeviceSimulator-0.0.1-SNAPSHOT-jar-with-dependencies.jar