REST API: This refers to any API that adheres to the principles of REST (Representational State Transfer). REST is an architectural style with constraints like statelessness, uniform interface, and resource-based interactions. Technically, an API can claim to be a REST API even if it doesn’t fully comply with all REST principles.
RESTful API: This term is used to describe APIs that strictly follow REST principles and are more closely aligned with RESTful design. Essentially, a RESTful API is a "better-behaved" REST API. It emphasizes proper implementation of REST constraints, including statelessness, resource representation via URLs, and the use of standard HTTP methods.
To simplify, all RESTful APIs are REST APIs, but not all REST APIs are RESTful.
REST - Point to point HTTP communication, not reliable, URL directly references the resource being accessed and message can be of any formats - only HTTP
JAX-RS - uses annotations like @Path, @GET, @POST, @PUT, @Consumes, @Produces and @Provider
SOAP - distributed communication, reliable, WSDL-XSD - contract based where WSDL will be registered in UDDI and standard XML message communication between WS client and server. - HTTP and SMTP
JAXB - API to marshal JAVA objects to XML and unmarshal it + Java web services development pack
Testing WS - Add the WS component in web.xml -> WS will be added to WS servlet. Now, we can test the WS using localhost.
WASAxis2Servlet is the servlet class name for WS.
WSDL Basic Parts - Definition, Type, Interface, Service, Endpoint, Message
WSDL minor parts - wsdl:definitions, types, message, part, portType, operation, input, output, binding, body, service, port
XSD parts - xsd:types, schema, element, complexType, sequence, element
UDDI - Universal Definition Discovery and Integration
. Set Up Your Project
2. Create a REST Controller
Use the @RestController annotation to define a RESTful controller. Here's an example:
java
@RestController
@RequestMapping("/api/users")
public class UserController {
@GetMapping("/{id}")
public User getUserById(@PathVariable Long id) {
// Logic to fetch a user by ID
return userService.getUserById(id);
}
@PostMapping
public User createUser(@RequestBody User user) {
// Logic to create a new user
return userService.saveUser(user);
}
@PutMapping("/{id}")
public User updateUser(@PathVariable Long id, @RequestBody User user) {
// Logic to update a user
return userService.updateUser(id, user);
}
@DeleteMapping("/{id}")
public void deleteUser(@PathVariable Long id) {
// Logic to delete a user
userService.deleteUser(id);
}
}
3. Key Annotations
@RestController: Combines @Controller and @ResponseBody to return JSON/XML responses.
@RequestMapping: Maps a base URL for the controller.
@GetMapping, @PostMapping, @PutMapping, @DeleteMapping: Handle specific HTTP methods.
@RequestBody: Binds the body of a request to an object.
@PathVariable: Binds a variable in the URL to a method parameter.
4. Handle Data
Spring Boot uses Jackson to handle JSON serialization and deserialization, ensuring that objects are converted seamlessly.
5. Database Integration (Optional)
Add spring-boot-starter-data-jpa for working with databases.
Configure the application.properties file for database connection details.
Use Spring Data JPA for CRUD operations.
6. Run and Test
7. Advanced Features
Validation: Use @Valid and validation annotations like @NotNull or @Size.
Exception Handling: Use @ControllerAdvice and @ExceptionHandler to provide meaningful error responses.
Security: Add spring-boot-starter-security for authentication and authorization
