.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)

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.

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);

• 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; } = "";
    }
}

• 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" />

• Register MassTransit service in both ApiService and Web projects,

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);
    });
});

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

• 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!"
        });
    }
}

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;
        }
    }
}

• Register this consumer with MassTransit service,

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);
    });
});

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,