In Memory¶

This tutorial will get you from zero to up and running with In Memory and MassTransit.

Prerequisites¶

This example requires a functioning installation of the .NET Runtime and SDK (at least 6.0).

Install the Templates¶

MassTransit includes project and item templates simplifying the creation of new projects. Install the templates by executing the command below in the console. A video introducing the templates is available on YouTube.

dotnet new install MassTransit.Templates

Create the Project¶

To create a service using MassTransit, create a worker via the Command Prompt.

$ dotnet new mtworker -n GettingStarted
$ cd GettingStarted
$ dotnet new mtconsumer

Use the ForkForward Cargo Packages¶

The templates come from the MassTransit project, and the worker they create references the original MassTransit packages. Open GettingStarted.csproj, remove every PackageReference whose name starts with MassTransit, and add ForkForward Cargo instead:

$ dotnet remove package MassTransit
$ dotnet add package ForkForward.Cargo --prerelease

The code stays the same: the namespace is still MassTransit. See Moving from MassTransit 8 for the names of the other packages.

Project Overview¶

When you open the project you will see that you have 1 class file.

Program.cs is the standard entry point and here we configure the host builder.

Create a Contract¶

Create a Contracts folder in the root of your project, and within that folder create a file named GettingStarted.cs with the following contents:

namespace GettingStarted.Contracts;
public record GettingStarted() 
{
    public string Value { get; init; }
}

Add a Background Service¶

In the root of the project add Worker.cs

namespace GettingStarted;

using System;
using System.Threading;
using System.Threading.Tasks;
using Contracts;
using MassTransit;
using Microsoft.Extensions.Hosting;

public class Worker : BackgroundService
{
    readonly IBus _bus;

    public Worker(IBus bus)
    {
        _bus = bus;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            await _bus.Publish(new GettingStarted { Value = $"The time is {DateTimeOffset.Now}" }, stoppingToken);

            await Task.Delay(1000, stoppingToken);
        }
    }
}

Register the Service¶

In Program.cs at the bottom of the ConfigureServices method add

services.AddHostedService<Worker>();

Create a Consumer¶

Create a Consumers folder in the root of your project, and within that folder create a file named GettingStartedConsumer.cs with the following contents:

namespace GettingStarted.Consumers;

using System.Threading.Tasks;
using Contracts;
using MassTransit;
using Microsoft.Extensions.Logging;

public class GettingStartedConsumer :
    IConsumer<GettingStarted>
{
    readonly ILogger<GettingStartedConsumer> _logger;

    public GettingStartedConsumer(ILogger<GettingStartedConsumer> logger)
    {
        _logger = logger;
    }

    public Task Consume(ConsumeContext<GettingStarted> context)
    {
        _logger.LogInformation("Received Text: {Text}", context.Message.Value);
        return Task.CompletedTask;
    }
}

Run the Project¶

$ dotnet run

The output should have changed to show the message consumer generating the output (again, press Control+C to exit).

Building...
info: MassTransit[0]
      Configured endpoint Message, Consumer: GettingStarted.MessageConsumer
info: MassTransit[0]
      Bus started: loopback://localhost/
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /Users/chris/Garbage/start/GettingStarted
info: GettingStarted.MessageConsumer[0]
      Received Text: The time is 3/24/2021 12:02:01 PM -05:00
info: GettingStarted.MessageConsumer[0]
      Received Text: The time is 3/24/2021 12:02:02 PM -05:00