*5 Tasks for today: 4Feb* ✅ 1. Get clear basic understanding of Framework & APIs. ✅ 2. Code Hello World API using Spring Boot. ✅ 3. Use ChatGPT to generate CalculationController with add, sub, mul methods ✅ 4. Experiment with your 1st Spring Boot app ✅ 5. Understand DNS mappings (Domain, IP, Port) ====================== *1. Get clear basic understanding of Framework & APIs.* * Building web app using plan core java vs with technologies (servlets/jsps) vs frameworks(Spring/Spring boot) * https://spring.io/ Spring used for building: Microservices|Reactive|Cloud|Webapp|Serverless|Even driven|Batch. * Spring Boot is given as a "Project" by Spring Team. https://spring.io/projects/spring-boot * Spring Boot is build on top of core Spring framework. * Provides rapid application development. * 2 major features of Spring Boot is "starters" & "autoconfiguration" Clarity on APIs * Understand that its mostly preferred to develop & deploy frontend(FE) app separately & backend(BE) app separately. * FE connects with backend via APIs. * The APIs on web environment are called as WebAPIs or Webservices. * There are multiple standards of API development, REST, JsonRS, SOAP, gRPC, GraphQL. * The commonly used one across multiple projects is RestAPIs. =============================== *2. Code Hello World API using Spring Boot.* * Setup Eclipse STS: https://spring.io/tools * Maven would be available along with your Eclipse installation * Refer below quick start guide to build app. https://spring.io/quickstart * You don't need to know what the annotations are, or how to code these, just think logically, and build application & test it. Just make it work. * Create your demo project from https://start.spring.io/ * Java, Maven, Spring Boot: 3.4.2, jar, java 17, Web dependency * Download & extract the demo project into your local workspace folder. * Launch IDE on the workspace /ws/ide * Import the demo.zip using "Import Existing Maven Project" * Create DemoController by taking reference from https://spring.io/quickstart * Use basic maven commands to run the spring boot application clean, package, clean package, clean spring-boot:run * Ensure "Tomcat started on port 8080" in console Test the application from browser by below 2 urls: http://localhost:8080/hello http://localhost:8080/hello?name=Amazing ============================ *3. Use ChatGPT to generate CalculationController with add, sub, mul methods* Just experiment with ChatGPT, set code in IDE test from browser ============================ *4. Experiment with your 1st Spring Boot app* * Refer to the LIVE session for details actions. Experiment & build confidence on all of below points: * Try to start same demo app, 2 times. And check port error. * Stop the previous demo app using terminate button from IDE. * Stop the demo app using commands to identify which process occupies 8080, and then end the task. Use IDE netstat -ano | findstr :8080 * Strongly under how below maps to the functional method that you write. http://:/ * Write a PostMapping method & try to call from browser. Check error. * Debug in browser, right click => inspect option, network tab. Check 405 error * Setup Postman, to test Post method call. * Explore "empty cache & hard reload" of browser * Add devtools maven dependency to pom.xml. Your changes should reflect automatically. * Add SonarQube support in your IDE. ============================= *5. Understand DNS mappings (Domain, IP, Port)* * In DNS, we map domain name to IP of server * default port for http is 80, https is 443 * If you use http://google.com, it maps as http://:80 * If you use https://google.com, it maps as http://:443 * You can check which IPs are mapped to domain using nslookup nslookup google.com