What is Microservice Architecture and Why is it Preferred?

What is Microservice Architecture?

Microservice architecture is an architectural approach used in the modern software world to create flexible, scalable, and manageable systems. An application consists of small services that work independently of each other. Each microservice encapsulates its own functionality, manages its own data independently, and can be deployed separately.
The simplest answer to the question “What is microservice architecture?” is that the system is modularized by breaking it into small and independent components (services). These services communicate with each other through methods like REST API, gRPC, or RabbitMQ.

Monolithic Architecture vs. Microservice Architecture

Limitations of Monolithic Structure

In monolithic architecture, all functions are grouped under a single application. Although this structure can be advantageous for small projects, over time it may lead to code complexity, maintenance challenges, and deployment problems. For instance, a change in the user management module would require recompiling and redeploying the entire application.

Advantages of Microservice Architecture

• Independent Development: Each service can be developed by different teams.
• Technology Independence: One service can be developed with .NET Core, another with Java.
• Easy Scalability: Only the required services can be scaled.
• Fast Deployment (CI/CD): Independent deployment of services ensures continuity.
• Fault Isolation: When one service fails, only that service is affected, not the whole system.

Disadvantages of Microservice Architecture

• Distributed System Complexity: Communication, monitoring, logging, and debugging between services can be complex.
• Data Consistency: Managing data per service requires eventual consistency instead of ACID compliance.
• Requires DevOps and CI/CD Culture: Managing microservices requires advanced automation systems.

Microservice Architecture Sample Project (C#/.NET Core)

1. Project Scenario
A microservice named “ProductService” will be an independent module that manages the product list. It will communicate with other services (OrderService, UserService, etc.) via API.

2. Folder Structure:

ProductService/
│
├── Denetleyiciler/
│   └── ProductController.cs
├── Modeller/
│   └── Product.cs
├── Hizmetler/
│   └── ProductService.cs
├── Arayüzler/
│   └── IProductService.cs
├── Program.cs
├── Startup.cs
├── appsettings.json

3. Product.cs

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}

4. IProductService.cs

public interface IProductService
{
    IEnumerable<Product> GetAll();
    Product GetById(int id);
    void Add(Product product);
}

5. ProductService.cs

public class ProductService : IProductService
{
    private readonly List<Product> _products = new();

    public IEnumerable<Product> GetAll() => _products;

    public Product GetById(int id) => _products.FirstOrDefault(p => p.Id == id);

    public void Add(Product product) => _products.Add(product);
}

6. ProductController.cs

[ApiController]
[Route("api/[controller]")]
public class ProductController : ControllerBase
{
    private readonly IProductService _productService;

    public ProductController(IProductService productService)
    {
        _productService = productService;
    }

    [HttpGet]
    public IActionResult GetAll() => Ok(_productService.GetAll());

    [HttpPost]
    public IActionResult Add(Product product)
    {
        _productService.Add(product);
        return Created("", product);
    }
}

7. Dockerfile

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
WORKDIR /app
COPY . .
ENTRYPOINT ["dotnet", "ProductService.dll"]

Conclusion and Recommendations

Microservice architecture is an excellent choice for high-traffic, high-growth-potential projects where modularity is essential. However, it is not suitable for every project. Monolithic architecture is still valid for small and simple applications.

• Key Considerations for a Successful Microservice Transition:
• Knowledge of Domain Driven Design (DDD)
• Setting up a CI/CD pipeline
• Centralized logging and monitoring (Elastic Stack, Grafana, Prometheus)
• Usage of API Gateway and Service Discovery