How can a monolithic application be broken into separate microservices?

Breaking down a monolithic application into microservices is a phased process that includes the following steps:

1. Analyzing the current monolith: identify main business functions and module boundaries.
2. Defining services: isolate logically independent components that can operate autonomously.
3. Separating the database: where possible, divide data by services to avoid a shared database.
4. Creating APIs for interaction: define protocols (e.g., REST, gRPC) for communication between services.
5. Gradually migrating functionality: migrate parts of the code from the monolith to separate services step by step.
6. Organizing infrastructure: set up CI/CD, orchestration (e.g., Kubernetes), monitoring.

Example in C# — creating a simple REST API using ASP.NET Core for one of the microservices:

[ApiController]
[Route("api/[controller]")]
public class OrdersController : ControllerBase
{
    [HttpGet("{id}")]
    public IActionResult GetOrder(int id)
    {
        // Logic to get the order
        return Ok(new { Id = id, Product = "Sample" });
    }
}