.NET Aspire Messaging With RabbitMQ & MassTransit

.NET Aspire, Microsoft's cloud-native stack, redefines how we approach distributed applications. With RabbitMQ & MassTransit, it's a powerful combination. Let's harness the potential of .NET Aspire, RabbitMQ & MassTransit to build resilient, cloud-native messaging architectures.

Ensure you have:
- Latest .NET SDK
- Visual Studio 2022 Preview

From Visual Studio Installer, install .NET Aspire SDK (Preview) by navigating to: Modify -> Individual Components -> .NET Aspire SDK (Preview)

Visual Studio Individual Components Installer Window

Update .NET Aspire Workload:

Update the .NET Aspire workload via terminal with the following commands:

From a terminal, run the following commands to update the .NET Aspire workload,

dotnet workload update
dotnet workload install aspire

Create a New .NET Aspire Starter Application:

Start with a fresh .NET Aspire Starter Application.

Using Visual Studio to Create a .NET Aspire Starter Application

Update Existing Apps:

For existing .NET Aspire apps, after installing the latest workload, update all .NET Aspire package references to: 9.0.0-preview.2.24162.2. If you prefer .NET 8, then update to 8.0.0-preview.4.24156.9
For example, update package references in the AspireMessaging.AppHost.csproj file for Aspire.Hosting.

<PackageReference Include="Aspire.Hosting" Version="9.0.0-preview.2.24162.2" />

Adding RabbitMQ Dependency:

Add a RabbitMQ resource to the application. It bootstraps a container used for local development. Also add the resource reference to two other projects,

var messaging = builder.AddRabbitMQ("RabbitMQConnection");

var apiService = builder.AddProject<Projects.AspireMessaging_ApiService>("apiservice")
    .WithReference(messaging);

builder.AddProject<Projects.AspireMessaging_Web>("webfrontend")
    .WithReference(cache)
    .WithReference(apiService)
    .WithReference(messaging);

Program.cs

Your appsettings.json file should contain a RabbitMQConnection property,

"ConnectionStrings": {
  "RabbitMQConnection": "amqp://guest:guest@localhost:5672"
}

Message Contract Library:

Add a new .NET Class Library e.g. AspireMessaging.Contracts, which will contain the message contract classes. Add a simple record for messaging,

namespace AspireMessaging.Contracts
{
    public record MessageContract
    {
        public Guid Id { get; init; } = Guid.NewGuid();

        public DateTime CreationDate { get; init; } = DateTime.UtcNow;

        public string Message { get; init; } = "";
    }
}

MessageContract.cs

Add the class library as project dependency to ApiService and Web.

Installing MassTransit:

Add the MassTransit.RabbitMQ package to both ApiService and Web using Nuget

<PackageReference Include="MassTransit.RabbitMQ" Version="8.1.3" />

builder.Services.AddMassTransit(x =>
{
    x.SetKebabCaseEndpointNameFormatter();

    x.UsingRabbitMq((context, cfg) =>
    {
        var configuration = context.GetRequiredService<IConfiguration>();
        var host = configuration.GetConnectionString("RabbitMQConnection");
        cfg.Host(host);
        cfg.ConfigureEndpoints(context);
    });
});

Program.cs

The .NET Aspire RabbitMQ component supports Microsoft.Extensions.Configuration. It loads the RabbitMQClientSettings from configuration.

Publishing Message:

In the _Imports.razor component of the Web project, add using statement for MassTransit and the AspireMessaging.Contracts project references,

@using MassTransit
@using AspireMessaging.Contracts

_Imports.razor

Replace content of the Home.razor with the following,

@page "/"
@rendermode InteractiveServer
@inject IBus Bus

<PageTitle>Home</PageTitle>

<button class="btn btn-primary mt-4" @onclick="DispatchMessage">Publish Hello, world!</button>

@code {
    private async Task DispatchMessage()
    {
        await Bus.Publish(new MessageContract
        {
            Message = "Hello, world!"
        });
    }
}

Home.razor

Consuming Message:

In the ApiService project, add a class for consuming a message published using the MessageContract class,

using AspireMessaging.Contracts;
using MassTransit;
using System.Diagnostics;

namespace AspireMessaging.ApiService
{
    public class HelloWorldMessageConsumer : IConsumer<MessageContract>
    {
        public async Task Consume(ConsumeContext<MessageContract> context)
        {
            Debug.WriteLine($"Received: {context.Message.Message}");
            await Task.CompletedTask;
        }
    }
}

builder.Services.AddMassTransit(x =>
{
    x.SetKebabCaseEndpointNameFormatter();
    x.AddConsumer<HelloWorldMessageConsumer>();

    x.UsingRabbitMq((context, cfg) =>
    {
        var configuration = context.GetRequiredService<IConfiguration>();
        var host = configuration.GetConnectionString("RabbitMQConnection");
        cfg.Host(host);
        cfg.ConfigureEndpoints(context);
    });
});

Program.cs

Test It Out Yourself:

Download the repository from the link below,

https://github.com/fiyazbinhasan/AspireMessaging

Run the Aspire project and from the home page of the Web, click on the Publish Hello, world! button,
In Visual Studio's Output panel, you should see the debug message,

Output