Monolithic vs SOA vs Microservices
Monolithic Architecture:
- Monolithic architecture involves a single unified codebase that contains all the functionalities of an application. All components (e.g., user interface, business logic, data access) are tightly integrated and deployed together as one unit.
- Characteristics:
- Single codebase
- Tight coupling between components
- Single deployment unit
- Shared database

Table of Contents
Advantages:
- Simpler to develop and test initially
- Easier to deploy and manage as a single unit
- Performance can be optimized in a single environment
Disadvantages:
- Scalability issues (cannot scale components independently)
- Hard to maintain as the codebase grows
- Any change requires redeploying the entire application
Java Example:
Syntax
```java
// User Management
public class UserService {
public User getUserById(String id) {
// Logic to get user by ID
}
}
// Product Catalog
public class ProductService {
public Product getProductById(String id) {
// Logic to get product by ID
}
}
// Order Processing
public class OrderService {
public Order createOrder(Order order) {
// Logic to create order
}
}
// Main Application
public class ECommerceApplication {
public static void main(String[] args) {
// Start the application
}
}
```
Service-Oriented Architecture (SOA):
- SOA is a design pattern where software components (services) provide functionalities to other components over a network. Services are loosely coupled and communicate through well-defined interfaces.
- Characteristics:
- Loose coupling between services
- Interoperability through standard protocols (SOAP, REST)
- Reusability of services
- Discoverability of services
Advantages:
- Scalability and flexibility
- Easier maintenance and updating of services
- Interoperability across different platforms and technologies
Disadvantages:
- Complexity in design and management
- Performance overhead due to network communication
- Security concerns across service boundaries
Java Example:
Syntax
```java
@WebService
public class UserService {
@WebMethod
public User getUserById(String id) {
return new User(id, "John Doe", "john.doe@example.com");
}
}
@WebService
public class ProductService {
@WebMethod
public Product getProductById(String id) {
return new Product(id, "Laptop", 1000.0);
}
}
@WebService
public class OrderService {
@WebMethod
public Order createOrder(String userId, String productId) {
UserService userService = new UserService();
User user = userService.getUserById(userId);
ProductService productService = new ProductService();
Product product = productService.getProductById(productId);
return new Order("1", user, product, new Date());
}
}
```
Microservices Architecture:
- Microservices architecture is a variant of SOA, where the application is decomposed into smaller, independent services. Each microservice is self-contained and focuses on a specific business functionality.
- Characteristics:
- Fine-grained services
- Independent deployment and scalability
- Decentralized data management
- Lightweight communication (usually HTTP/REST)
Advantages:
- High scalability and flexibility
- Independent development, deployment, and scaling of services
- Resilience (failure of one service doesn’t affect others)
Disadvantages:
- Complexity in managing numerous services
- Increased network latency and communication overhead
- Challenges in maintaining data consistency
Java Example:
Syntax
```java
// User Service
@SpringBootApplication
@RestController
public class UserServiceApplication {
public static void main(String[] args) {
SpringApplication.run(UserServiceApplication.class, args);
}
@GetMapping("/users/{id}")
public User getUserById(@PathVariable String id) {
return new User(id, "John Doe", "john.doe@example.com");
}
}
// Product Service
@SpringBootApplication
@RestController
public class ProductServiceApplication {
public static void main(String[] args) {
SpringApplication.run(ProductServiceApplication.class, args);
}
@GetMapping("/products/{id}")
public Product getProductById(@PathVariable String id) {
return new Product(id, "Laptop", 1000.0);
}
}
// Order Service
@SpringBootApplication
@RestController
public class OrderServiceApplication {
public static void main(String[] args) {
SpringApplication.run(OrderServiceApplication.class, args);
}
@Autowired
private RestTemplate restTemplate;
@GetMapping("/orders")
public Order createOrder(@RequestParam String userId, @RequestParam String productId) {
User user = restTemplate.getForObject("http://localhost:8081/users/" + userId, User.class);
Product product = restTemplate.getForObject("http://localhost:8082/products/" + productId, Product.class);
return new Order("1", user, product, new Date());
}
@Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
```