tcc/ASP.NET/Controllers/SimulationController.cs

using Microsoft.AspNetCore.Mvc;
using ProtoBuf;
using System.IO;

namespace TCC.Controllers
{
    [ApiController]
    [Route("simulation")]
    public class SimulationController : ControllerBase
    {
        public SimulationController()
        {
        }

        [HttpGet("harmonic-progression")]
        public async Task<IActionResult> GetHarmonicProgression([FromQuery] int n)
        {
            double sum = 0;
            for (int i = 1; i <= n; i++)
            {
                sum += 1.0f / i;
            }

            return Ok(sum);
        }

        [HttpGet("json")]
        public async Task<IActionResult> GetJsonResponse()
        {
            return Ok(new { message = "Hello World!" });
        }

        [HttpPost("protobuf")]
        public async Task<IActionResult> PostProtobuf()
        {
            HelloWorld cliente;
            byte[] response;
            using (var stream = Request.BodyReader.AsStream())
            {
                cliente = ProtoBuf.Serializer.Deserialize<HelloWorld>(stream);
            }

            using (var stream = new MemoryStream())
            {
                ProtoBuf.Serializer.Serialize(stream, cliente);
                response = stream.ToArray();
            }

            await Response.Body.WriteAsync(response, 0, response.Length);
            return new EmptyResult();
        }
    }

    [ProtoContract()]
    public class HelloWorld
    {
        [ProtoMember(1)]
        public string Message { get; set; }
    }

}