Mercurio

A library to make RabbitMQ integration in .NET microservices seamless

Introduction

Mercurio provides RabbitMQ integration with common implementation of Messaging Client. This common implementation of messaging client reduce the need of code duplication on microservices implementation that requires to interacts with RabbitMQ.
It also eases the setup of ConnectionFactory and also to register multiple ConnectionFactory setup, using the IRabbitMqConnectionProvider.

Mercurio follows RabbitMQ best practices by encouraging connection reuse and channel pooling per named connection. Instead of creating new connections for every operation—which is inefficient and discouraged by RabbitMQ—it provides a shared, thread-safe mechanism to lease and reuse channels from a limited pool tied to a single registered connection. This improves performance, resource management, and aligns with RabbitMQ's recommendations for production-grade messaging systems.

See channel reuse and connection management for more details on the implementation.

Examples

Dependency Injection Registration

```csharp var serviceCollection = new ServiceCollection();

serviceCollection.AddRabbitMqConnectionProvider() .WithRabbitMqConnectionFactoryAsync("Primary", _ => { var connectionFactory = new ConnectionFactory() { HostName = "localhost", Port = 5432 };

    return Task.FromResult(connectionFactory);
})
.WithRabbitMqConnectionFactory("Secondary", _ =>
{
    var connectionFactory = new ConnectionFactory()
    {
        HostName = "localhost",
        Port =  5433
    };

    return connectionFactory;
})
.WithSerialization();

var serviceProvider = serviceCollection.BuildServiceProvider(); var connectionProvider = serviceProvider.GetRequiredService(); var primaryConnection = await connectionProvider.GetConnectionAsync("Primary"); ```

📦 Message Serialization

Mercurio uses a flexible and extensible serialization system that supports multiple formats and allows format-specific resolution at runtime.

By default, Mercurio registers System.Text.Json-based serializers and deserializers. However, you can register custom implementations or support additional formats like MessagePack.

Serialization is configured using .WithSerialization() in your service registration:

csharp services .AddRabbitMqConnectionProvider() .WithSerialization(builder => builder .UseDefaultJson() // Registers JsonMessageSerializerService that uses System.Text.Json as default serializer .UseMessagePack<YourMessagePackSerializer>(asDefault: false)); // Optional additional format

Under the hood, serialization is format-aware:

• Each format (e.g., Json, MessagePack) is keyed by SupportedSerializationFormat and is transported in the 'content type' header.
• A central SerializationProviderService handles resolution of serializers and deserializers.
• The default format (usually Json) is mapped to the special key Unspecified.

The following interfaces drive the system:

• IMessageSerializerService – used to serialize outgoing messages.
• IMessageDeserializerService – used to deserialize incoming messages.
• ISerializationProviderService – allows resolving serializers and deserializers for a given format.

All registered services are added via IServiceCollection using Microsoft.Extensions.DependencyInjection’s keyed services.

🔧 Default Behavior

If .WithSerialization() is called without configuration, Mercurio will:

• Register JsonMessageSerializerService for both serializer and deserializer interfaces.
• Use SupportedSerializationFormat.Json as the default.
• Register a fallback mapping under SupportedSerializationFormat.Unspecified.

🔄 Format Resolution

Serialization and deserialization for a given format can be resolved at runtime via:

csharp var serializer = serializationProvider.ResolveSerializer(SupportedSerializationFormat.Json); var deserializer = serializationProvider.ResolveDeserializer(SupportedSerializationFormat.MessagePack);

MessageClientService

A base implementation of a MessageClientService is available. It defines base behavior to push and listen after messages on queue and exchange.
Following example expects to have a connection registered, the service registered as IMessageClientBaseService into the service collection and will use Direct Exchange.

Push Message

csharp var messageClientService = serviceProvider.GetRequiredService<IMessageClientBaseService>(); var exchangeConfiguration = new DirectExchangeConfiguration("DirectQueue", "AnExchange", "SomeRouting"); await messageClientService.PushAsync("RegisteredConnection","A message to be sent",exchangeConfiguration);

Listen After Message

csharp var messageClientService = serviceProvider.GetRequiredService<IMessageClientBaseService>(); var exchangeConfiguration = new DirectExchangeConfiguration("DirectQueue", "AnExchange", "SomeRouting"); var messageObservable = await messageClientService.ListenAsync<string>("RegisteredConnection", exchangeConfiguration); messageObservable.Subscribe(message => Console.WriteLine(message));

Integration Tests

Before running any integration tests, it is required to have a running instance of RabbitMQ.
Please use this following command to run it : sh docker run -d --name mercurio -p 15672:15672 -p 5672:5672 rabbitmq:4-management

Code Quality

Nuget

The Mercurio library is released as NuGet package and available from nuget.org.

Software Bill of Materials (SBOM)

As part of our commitment to security and transparency, this project includes a Software Bill of Materials (SBOM) in the associated NuGet packages. The SBOM provides a detailed inventory of the components and dependencies included in the package, allowing you to track and verify the software components, their licenses, and versions.

Why SBOM?

• Improved Transparency: Gain insight into the open-source and third-party components included in this package.
• Security Assurance: By providing an SBOM, we enable users to more easily track vulnerabilities associated with the included components.
• Compliance: SBOMs help ensure compliance with licensing requirements and make it easier to audit the project's dependencies.

You can find the SBOM in the NuGet package itself, which is automatically generated and embedded during the build process.