🔒 Step-by-Step HTTPS Request Flow in Spring Boot

1. 🔐 HTTPS Client Request

• A browser or REST client (like Postman) sends a secure HTTPS request:
  https://yourdomain.com/api/data
• The request is encrypted using TLS/SSL.

2. 🌐 SSL Termination (Optional)

• In production, SSL is usually terminated by a:
  • Reverse proxy (e.g., Nginx, Apache)
  • Load balancer (e.g., AWS ELB)
• These forward the request as HTTP to Spring Boot (if configured).

🔁 In a local dev setup, Spring Boot can directly handle HTTPS using an embedded Tomcat server and a keystore.

3. 🛡️ Spring Boot Embedded Server

• Spring Boot runs with Tomcat, Jetty, or Undertow.
• If SSL is enabled in application.properties, the server listens on port 443 (or custom):

4. 🧭 DispatcherServlet

• Spring Boot uses the DispatcherServlet as the front controller.
• It intercepts all HTTP(S) requests and routes them through the Spring MVC framework.

5. 📍 Handler Mapping

• Spring scans your controllers (@RestController, @Controller) and maps URLs to methods via annotations:
  • @GetMapping, @PostMapping, etc.
  • Or @RequestMapping

6. 🧠 Controller Method Execution

• The matching controller method is invoked.
• Spring handles:
  • Parameter binding (e.g., @RequestParam, @PathVariable)
  • Validation (if enabled)
  • Deserialization (e.g., @RequestBody → Java object)

7. 🧰 Business Logic & Services

• Controller delegates to service classes (@Service) and repositories (@Repository).
• Optional features like:
  • Database access (via JPA)
  • Caching
  • Transaction management
  • Exception handling

8. 📦 Response Serialization

• The response (typically a Java object or String) is:
  • Converted to JSON (via Jackson)
  • Or rendered as HTML (if @Controller + view engine)

9. 🔙 Return Through DispatcherServlet

• The response is returned to DispatcherServlet, then to the embedded server.

10. 🔐 Encrypted HTTPS Response

• The response is encrypted with SSL and sent back to the client securely.

🔁 Visual Flow

✅ Summary