Step 1: Receiving the HTTPS Request

When a client, such as a web browser or mobile application, submits an HTTPS request to a Spring Boot application, it first interacts with the embedded web server. Spring Boot supports various web servers like Tomcat, Jetty, and Undertow, which can be configured to handle incoming requests.

The web server's role includes decrypting the HTTPS request. HTTPS, which stands for Hypertext Transfer Protocol Secure, enhances HTTP by incorporating encryption via SSL (Secure Sockets Layer) or TLS (Transport Layer Security). This ensures that the data exchanged between the client and server remains encrypted and secure from potential eavesdroppers.

Step 2: Request Filtering

Before reaching the core business logic, the request passes through various filters that can perform tasks such as authentication, logging, request modification, and CORS handling. Spring Boot offers a comprehensive set of filters, and developers can create custom filters to meet specific requirements.

For instance, let's assume we have a basic authentication filter that checks for a valid token. If the request holds a valid token, it proceeds; if not, it is rejected.

@Component

public class AuthenticationFilter implements Filter {

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

HttpServletRequest httpRequest = (HttpServletRequest) request;

String authToken = httpRequest.getHeader("Authorization");

if ("ValidToken123".equals(authToken)) {

chain.doFilter(request, response);

} else {

HttpServletResponse httpResponse = (HttpServletResponse) response;

httpResponse.setStatus(HttpServletResponse.SC_UNAUTHORIZED);

}

}

}

Step 3: Dispatching the Request

After successfully passing through the filters, the request is dispatched to the appropriate controller. Spring Boot utilizes the @Controller or @RestController annotations to define controllers, mapping each request to the corresponding method based on the URL and HTTP method (GET, POST, etc.) specified in the request. This mapping is typically achieved using the @RequestMapping annotation or its variants like @GetMapping and @PostMapping.

For example, a request for /products is directed to the relevant controller. Here’s a simple controller that handles requests to /products.

@RestController

@RequestMapping("/products")

public class ProductController {

@GetMapping

public ResponseEntity<List<Product>> getAllProducts() {

List<Product> products = productService.findAll();

return ResponseEntity.ok(products);

}

}

Step 4: Business Logic Execution

Within the controller, a specific method manages the request, incorporating the application’s business logic. This is where the request is processed, data may be fetched or updated in the database, and a response is generated.

For instance, the getAllProducts method executes business logic to retrieve a list of products, potentially involving a database query or a call to another service.

@Service

public class ProductService {

public List<Product> findAll() {

return Arrays.asList(new Product("Laptop", 999.99), new Product("Smartphone", 499.99));

}

}

Step 5: Response Creation

Once the business logic has been executed, a response is prepared. In a @RestController, the return value of the controller method is automatically converted into JSON or XML format, thanks to Spring Boot’s built-in message converters. This response is then sent back to the client.

For example, Spring Boot automatically serializes the list of products into a JSON response, which is handled by the HttpMessageConverters. Assuming the Product class looks like this:

public class Product {

private String name;

private double price;

// Constructor, getters, and setters omitted for brevity

}

The JSON response might resemble the following:

[

{

"name": "Laptop",

"price": 999.99

},

{

"name": "Smartphone",

"price": 499.99

}

]

Step 6: Sending the HTTPS Response

The response travels back through the embedded web server, which encrypts the data using the same SSL/TLS protocol to ensure secure information transit. Ultimately, the client receives the HTTPS response, decrypts it, and processes the data.

For example, the JSON response from Step 5 is sent back to the client via a secure HTTPS channel. The embedded web server encrypts the response data using SSL/TLS, ensuring security during transit. The client's browser or application receives the encrypted data, decrypts it, and processes the JSON response.