Using RabbitMQ in ASP.net core IHostedService - .net-core

Question

I am facing a problem that would like help.
I am developing a background process that will be listening to a queue in rabbitmq server.
It is OK if I run it in a .net core console application. However I would like to do it in a more elegant way such as web service (which has given me a lot of trouble where it does not work when installed) or an IIS hosted web application.
I face a problem of Scoped Service when I try to host the service (IHostedService) in .net core web application.
The code below is working fine in a console application. How can make it run as an IHostedService in a .net core web application.
What am I supposed to change.
Your help is appreciated.
CODE:
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using PaymentProcessor.Models;
using Microsoft.Extensions.Configuration;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using RabbitMQ.Client;
using RabbitMQ.Client.Events;
using Microsoft.EntityFrameworkCore;
namespace PaymentProcessor
{
public class PaymentProcessingService : HostedService
{
IConfiguration configuration;
private EntitiesContext claimsContext;
private string connectionString;
private string HostName = "";
private string UserName = "";
private string Password = "";
private static int MaxRetries;
private IConnectionFactory factory;
private IConnection connection;
private IModel channel;
public PaymentProcessingService(IConfiguration configuration)
{
this.configuration = configuration;
this.connectionString = configuration.GetConnectionString ("StagingContext");
claimsContext = new EntitiesContext(connectionString);
HostName = this.configuration.GetValue<string>("Settings:HostName");
UserName = this.configuration.GetValue<string>("Settings:UserName");
Password = this.configuration.GetValue<string>("Settings:Password");
MaxRetries = this.configuration.GetValue<string>("Settings:MaxRetries").ConvertTo<int>();
}
protected override async Task ExecuteAsync(CancellationToken cancellationToken)
{
connect:
factory = new ConnectionFactory { HostName = HostName, UserName = UserName, Password = Password };
try
{
connection = factory.CreateConnection();
channel = connection.CreateModel();
channel.ExchangeDeclare("payment_rocessing_exchange", "topic");
channel.QueueDeclare("payment_processing_queue", true, false, false, null);
channel.QueueBind("payment_processing_queue", "payment_processing_exchange", "processing");
var queueArgs = new Dictionary<string, object>
{
{ "x-dead-letter-exchange", "payment_processing_exchange" },
{"x-dead-letter-routing-key", "processing_retry"},
{ "x-message-ttl", 10000 }
};
channel.ExchangeDeclare("payment_rocessing_exchange", "topic");
channel.QueueDeclare("payment_processing_retry_queue", true, false, false, queueArgs);
channel.QueueBind("payment_processing_retry_queue", "payment_processing_exchange", "processing_retry", null);
channel.ExchangeDeclare("payment_processing_exchange", "topic");
channel.QueueDeclare("payment_processing_error_queue", true, false, false, null);
channel.QueueBind("payment_processing_error_queue", "payment_processing_exchange", "processing_error", null);
channel.ExchangeDeclare("payment_processing_exchange", "topic");
channel.QueueDeclare("payment_integration_queue", true, false, false, null);
channel.QueueBind("payment_integration_queue", "payment_processing_exchange", "integration", null);
channel.BasicQos(0, 1, false);
var consumer = new EventingBasicConsumer(channel);
consumer.Received += (model, ea) =>
{
var message = ea.Body.DeSerializeText();
try
{
var saveBundle = JObject.Parse(message);
var msg = (dynamic)((dynamic)saveBundle).Message;
string referenceNo = (string)msg.ReferenceNo;
var parameters = new[]
{
new SqlParameter
{
DbType = DbType.String,
ParameterName = "ReferenceNo",
Value =referenceNo
}
};
var result = claimsContext.Database.ExecuteSqlCommand("dbo.PaymentReferencesProcessSingle #ReferenceNo", parameters);
IBasicProperties props = channel.CreateBasicProperties();
props.Persistent = true;
props.ContentType = "text/plain";
props.DeliveryMode = 2;
channel.BasicPublish("payment_processing_exchange", "integration", props, (new MessageEnvelope { RetryCounts = 0, Message = JObject.FromObject(new { ReferenceNo = referenceNo }) }).Serialize());
}
catch (Exception ex)
{
MessageEnvelope envelope = JsonConvert.DeserializeObject<MessageEnvelope>(message);
if (envelope.RetryCounts < MaxRetries)
{
int RetryCounts = envelope.RetryCounts + 1;
MessageEnvelope messageEnvelope = new MessageEnvelope { RetryCounts = RetryCounts, Message = envelope.Message };
var data = messageEnvelope.Serialize();
channel.BasicPublish("payment_processing_exchange", "processing_retry", null, data);
}
else
{
var data = envelope.Serialize();
channel.BasicPublish("payment_processing_exchange", "processing_error", null, data);
}
}
finally
{
channel.BasicAck(ea.DeliveryTag, false);
}
};
channel.BasicConsume(queue: "payment_processing_queue", autoAck: false, consumer: consumer);
}
catch (Exception ex)
{
Thread.Sleep(10000);
goto connect;
}
}
}
}
and then
services.AddScoped<IHostedService, PaymentProcessingService>();

Answer 1

As Dekim mentioned a service should be registered.
Please have a look on an example I created on GitHub.
Program.cs looks like this:
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System.Threading.Tasks;
namespace Core
{
internal class Program
{
static async Task Main(string[] args)
{
await new HostBuilder()
.ConfigureServices((hostContext, services) =>
{
services.AddHostedService<ServiceRabbitMQ>(); // register our service here
})
.RunConsoleAsync();
}
}
}

Answer 2

Because the IHostedService requires the creation of a special scope according to the documentation.
From the Microsoft documentation cited in the above answer :
No scope is created for a hosted service by default.
Consider using : services.AddHostedService<MyHostedService>();