Asynchronous messaging patterns for .NET applications. Covers Wolverine and MassTransit, outbox pattern, saga and choreography, and broker configuration for RabbitMQ and Azure Service Bus. Load this skill when implementing event-driven communication, background processing, module-to-module messaging, or when the user mentions "Wolverine", "MassTransit", "message bus", "RabbitMQ", "Azure Service Bus", "event", "publish", "consumer", "outbox", "saga", "integration event", "queue", or "pub/sub".
Wolverine is the recommended default — MIT licensed, combines mediator + messaging in one library with built-in outbox, saga support, and convention-based handlers. MassTransit is an alternative but requires a commercial license from v9.
Outbox pattern for reliability — Always use the transactional outbox to ensure messages are published only when the database transaction succeeds.
Choreography for simple flows, saga for complex — If a workflow has 2-3 steps, use event choreography. If it has compensating actions or complex state, use a saga.
Messages are contracts — Put message types in a shared contracts project. Keep them as simple records with primitive types.
Patterns
Wolverine Setup
// Program.cs
builder.Host.UseWolverine(opts =>
{
// Auto-discover handlers from this assembly
opts.Discovery.IncludeAssembly(typeof(Program).Assembly);
