无法使用公共交通将消息发布到 rabbitmq

Question

I am trying to implement simple pub/sub using MassTransit and RabbitMq. I am using dot net version 4.8 to implement it. I have created 2 console application projectss (each for pub and sub) I am unable to publish messages to queue via MassTransit but I can send and receive messages if I directly use RabbitMq.CLient nuget.

Please find my Publisher and Subscriber classes below: Publisher.cs:

using System;
using Contracts;
using MassTransit;
using MassTransit.Log4NetIntegration.Logging;

namespace Publisher
{
    internal class Send
    {
        public static void Main(string[] args)
        {
            SendMessage();
        }

        private static async void SendMessage()
        {
            //Log4NetLogger.Use();
            for (var i = 0; i < 10000; i++)
            {
                IBusControl busControl = null;
                try
                {
                    busControl = Bus.Factory.CreateUsingRabbitMq(sbc =>
                    {
                        sbc.Host(new Uri("rabbitmq://localhost"), h =>
                        {
                            h.Username("guest");
                            h.Password("guest");
                        });
                    });
                    busControl.Start();
                    var message = new ValueEntered
                    {
                        Value = $"Message {i}"
                    };

                    // The below call is not pushing messages. No Exception to is found.
                    await busControl.Publish(message);

                    Console.WriteLine($"Published [x] : {message} [at] {DateTime.Now:u}");
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
                finally
                {
                    busControl?.Stop();
                }
            }
        }
    }
}

Subscriber.cs:

using System;
using System.Threading;
using MassTransit;
using MassTransit.Log4NetIntegration.Logging;

namespace Subscriber
{
    internal class Receive
    {
        public static void Main(string[] args)
        {
            ReceiveMessage();
        }

        private static void ReceiveMessage()
        {
            //Log4NetLogger.Use();
            IBusControl busControl = null;
            try
            {
                busControl = Bus.Factory.CreateUsingRabbitMq(busFactoryConfigurator =>
                {
                    busFactoryConfigurator.Host(new Uri("rabbitmq://localhost"), h =>
                    {
                        h.Username("guest");
                        h.Password("guest");
                    });

                    busFactoryConfigurator.ReceiveEndpoint("value-events-listener", e =>
                    {
                        e.Consumer<ValueConsumer>();
                    });
                });
                busControl.Start();
                while (true)
                {
                    Thread.Sleep(5000);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }
            finally
            {
                busControl?.Stop();
            }
        }
    }
}

Contract used:

namespace Contracts
{
    public class ValueEntered
    {
        public string Value { get; set; }
    }
}

Consumer:

using System;
using System.Threading.Tasks;
using Contracts;
using MassTransit;
using Newtonsoft.Json;

namespace Subscriber
{
    public class ValueConsumer : IConsumer<ValueEntered>
    {
        public Task Consume(ConsumeContext<ValueEntered> context)
        {
            return Task.Run(() =>
            {
                Console.WriteLine($"Received [x] {JsonConvert.SerializeObject(context)} [at] {DateTime.Now:u}");
            });
        }
    }
}

Packages installed:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Automatonymous" version="5.1.1" targetFramework="net48" />
  <package id="GreenPipes" version="4.0.0" targetFramework="net48" />
  <package id="log4net" version="2.0.8" targetFramework="net48" />
  <package id="MassTransit" version="7.1.8" targetFramework="net48" />
  <package id="MassTransit.Log4Net" version="5.5.6" targetFramework="net48" />
  <package id="MassTransit.RabbitMQ" version="7.1.8" targetFramework="net48" />
  <package id="Microsoft.Bcl.AsyncInterfaces" version="1.1.1" targetFramework="net48" />
  <package id="Microsoft.Extensions.Logging.Abstractions" version="2.1.1" targetFramework="net48" />
  <package id="NewId" version="3.0.3" targetFramework="net48" />
  <package id="Newtonsoft.Json" version="11.0.2" targetFramework="net48" />
  <package id="Newtonsoft.Json.Bson" version="1.0.1" targetFramework="net48" />
  <package id="RabbitMQ.Client" version="6.2.1" targetFramework="net48" />
  <package id="System.Buffers" version="4.5.1" targetFramework="net48" />
  <package id="System.Diagnostics.DiagnosticSource" version="4.7.1" targetFramework="net48" />
  <package id="System.Memory" version="4.5.4" targetFramework="net48" />
  <package id="System.Numerics.Vectors" version="4.5.0" targetFramework="net48" />
  <package id="System.Reflection.Emit" version="4.7.0" targetFramework="net48" />
  <package id="System.Reflection.Emit.Lightweight" version="4.7.0" targetFramework="net48" />
  <package id="System.Reflection.Extensions" version="4.3.0" targetFramework="net48" />
  <package id="System.Runtime.CompilerServices.Unsafe" version="4.5.3" targetFramework="net48" />
  <package id="System.Runtime.Loader" version="4.3.0" targetFramework="net48" />
  <package id="System.Threading.Channels" version="4.7.1" targetFramework="net48" />
  <package id="System.Threading.Tasks.Extensions" version="4.5.4" targetFramework="net48" />
  <package id="System.Threading.ThreadPool" version="4.3.0" targetFramework="net48" />
  <package id="System.ValueTuple" version="4.5.0" targetFramework="net48" />
  <package id="System.Xml.ReaderWriter" version="4.3.1" targetFramework="net48" />
</packages>

After subscriber starts, Exchanges and Queues are created successfully, but still I am unable to push messages. Kindly help me out.

Answer 1

You probably need to start by learning how async/await works in C#. You expect a method, which returns a Task to do something without awaiting it, it will never happen. The task never gets started unless it's awaited.

Producer:

namespace Publisher
{
    class Program
    {
        public static async Task Main(string[] args)
        {
            var bus = Bus.Factory.CreateUsingRabbitMq(sbc =>
            {
                sbc.Host(new Uri("rabbitmq://localhost"), h =>
                {
                    h.Username("guest");
                    h.Password("guest");
                });
            });
            await bus.Start();
            await Task.WhenAll(Enumerable.Range(0, 100).Select(i =>
            {
                var message = new ValueEntered { Value = $"Message {i}" };
                return bus.Publish(message);
            }));
            await bus.Stop();
        }
    }
}

Consumer:

namespace Subscriber
{
    class Program
    {
        public static async Task Main(string[] args)
        {
            var bus = Bus.Factory.CreateUsingRabbitMq(cfg =>
            {
                cfg.Host(new Uri("rabbitmq://localhost"), h =>
                {
                    h.Username("guest");
                    h.Password("guest");
                });

                cfg.ReceiveEndpoint("value-events-listener", e =>
                {
                    e.Consumer<ValueConsumer>();
                });
            });
            await bus.Start();
            Console.WriteLine("Waiting for messages...");
            Console.ReadLine();
            await bus.Stop();
        }
    }

    public class ValueConsumer : IConsumer<ValueEntered>
    {
        public Task Consume(ConsumeContext<ValueEntered> context)
        {
            Console.WriteLine($"Received [x] {JsonConvert.SerializeObject(context)} [at] {DateTime.Now:u}");
            return Task.CompletedTask;
        }
    }
}