Best Practices

This section shows some best practices for using @HttpExchange.

Contract-Driven Development

@HttpExchange also provides server endpoints, just like @RequestMapping. This makes it ideal for defining interface contracts and supporting contract-driven development.

Project structure:

.
├── order-service
│   ├── order-api
│   └── order-server
└── user-service
    ├── user-api
    └── user-server

order-api

@HttpExchange("/orders")
public interface OrderApi {
    @GetExchange("/by_user/{userId}")
    List<OrderDTO> getOrdersByUserId(@PathVariable("userId") String userId);
}

order-server

@RestController
public class OrderApiImpl implements OrderApi {

    @Autowired
    private UserApi userApi;

    @Override
    public List<OrderDTO> getOrdersByUserId(String userId) {
        UserDTO user = userApi.getUser(userId);
        if (user.getStatus() == INACTIVE) {
            throw new UserInactiveException();
        }
        // Ignore the implementation
    }
}

user-api

@HttpExchange("/users")
public interface UserApi {
    @GetExchange("/{id}")
    UserDTO getUser(@PathVariable("id") String id);
}

user-server

@RestController
public class UserApiImpl implements UserApi {
    @Override
    public UserDTO getById(String id) {
        // Ignore the implementation
    }
}