Integration and Building REST APIs

Complete source code is available here to download: Attach:advera.zip

• This session is based on the Spring platform
• Spring is not just a Java-based framework, but an ecosystem with family of Spring projects https://spring.io/projects/
  • Spring Boot is one of the Spring projects used to create a micro Service.

Setting up the development environment

• These instructions are explained in this video

Install Java

• Verify the version of Java installed: java --version. If you don't get any result or any suggestions to install, then follow the below steps:

1. Update the package repository: sudo apt update
2. Install Java RE: sudo apt install default-jre
3. Install Default JDK (Java 11): sudo apt install default-jdk
   • If you have multiple version of Java installed on your system, you can decide which one is the default one.
     • First, run this sudo update-alternatives --config java command to show all the installed version of Java on your computer
     • The choices are represented by numbers, select the number that's mapped to Java 11

Install Spring Boot

• SDK Manager (sdkman): curl -s "https://get.sdkman.io" | bash
• Spring Boot CLI: sdk install springboot

Build Automation Tools:

• Gradle: sudo snap install gradle --classic
  • Upgrade Gradle:
    • Add this PPA repository: sudo add-apt-repository spa:cwchien/gradle
    • Download package information from all configured sources: sudo apt-get update
    • Upgrade Gradle: sudo apt upgrade gradle

Create Spring Boot Application

• Terminal:
• You can choose one of these option to create your Spring Boot Application.
  • Gradle based project: spring init --build=gradle --dependencies=web your_project_name
    • ...with multiple dependencies: spring init --build=gradle --dependencies=web,h2,data-jpa your_project_name
    • Here is a full list of dependencies
  • Maven based project: spring init --dependencies=web your_project_name
• VS Code:
• IntelliJ IDEA (Ultimate):
• Browser (Online):
  • You can also visit https://start.spring.io, an easy way to generate a template for Spring Boot project.

Run Spring Boot Applications

• Gradle:
  • Build: gradle build
  • Run: gradle bootRun
• Maven: mvn spring-boot:run

Deploy Spring Boot Application (Gradle) to Heroku

• Create system.properties file in project root folder:
  • Add Java runtime version and save it: java.runtime.version=11
• Create Procfile in project root folder:
  • Add the web process type and save it: web: java -jar build/libs/Your-Project-Name-0.0.1-SNAPSHOT.jar
• Add default port number:
  • Open Your-Project-Name/src/main/resources/application.properties and add server.port=${PORT:5000}, save, and start deploying.

PostgreSQL

• Refresh local package index: sudo apt update
• Install: sudo apt install postgresql postgresql-contrib
  • Start: sudo systemctl start postgresql.service
  • Check Status: sudo systemctl status postgresql.service
  • Stop: sudo systemctl stop postgresql.service
  • Restart: sudo systemctl restart postgresql.service
• Login: sudo -i -u postgres OR sudo -u postgres psql
• Create a New User: sudo -u postgres createuser --interactive
  • Login with new role:
    • Add user: sudo adduser user_name
    • Login: sudo -u user_name psql
• Create a Database: createdb database_name OR sudo -u postgres createdb database_name
• List Databases: \l
• Change Database: \c database_name
• Show Database Tables: \dt
• To reset the password if you have forgotten:
• Login without a password:
  • sudo -u user_name psql db_name e.g. sudo -u postgres psql postgres
  • ALTER USER user_name WITH PASSWORD 'new_password';

• We recommend pgAdmin4 if you prefer to use a GUI tool for PostgreSQL administration.

1. Part 1: Initial Scenario
2. Part 2: Building API
3. Part 3: Testing API