Fire and Forget

Fire-and-forget dispatches a command to exactly one handler with no return value. Unlike notifications, there is no fan-out — one handler, one operation.

Differences from Requests and Notifications

	IRequest<T>	INotification	IFireAndForget
Handlers	1	N	1
Response	TResponse	None	None
Pipeline	Yes	Yes	Yes
Use case	Query/Command	Domain events	Background ops

Defining Fire-and-Forget Commands

public record SendAuditLogCommand(
    string UserId,
    string Action,
    string Resource) : IFireAndForget;

Implementing the Handler

public class SendAuditLogHandler : IFireAndForgetHandler<SendAuditLogCommand>
{
    private readonly IAuditRepository _auditRepository;

    public SendAuditLogHandler(IAuditRepository auditRepository)
    {
        _auditRepository = auditRepository;
    }

    public async Task Handle(SendAuditLogCommand command, CancellationToken ct)
    {
        await _auditRepository.LogAsync(new AuditEntry
        {
            UserId = command.UserId,
            Action = command.Action,
            Resource = command.Resource,
            Timestamp = DateTimeOffset.UtcNow
        }, ct);
    }
}

Dispatching

Use Dispatch to send a fire-and-forget command:

await _mediator.Dispatch(new SendAuditLogCommand(
    userId: currentUser.Id,
    action: "CreateOrder",
    resource: $"orders/{orderId}"));

Common Use Cases

• Audit logging — record user actions without blocking the main flow
• Cache invalidation — invalidate a cache entry asynchronously
• Telemetry — send metrics or traces to external systems
• Webhook dispatch — fire a webhook notification

tip

If you need multiple handlers to react to the same event, use INotification instead. Fire-and-forget is for single-handler side effects.

Pipeline Support

Fire-and-forget commands go through the full pipeline just like requests:

// A dispatch behavior that logs all fire-and-forget operations
public class AuditDispatchBehavior<TDispatch> : IPipelineBehavior<TDispatch>
    where TDispatch : IFireAndForget
{
    public async Task Handle(TDispatch dispatch, Func<Task> next, CancellationToken ct)
    {
        Console.WriteLine($"[Dispatch] {typeof(TDispatch).Name}");
        await next();
    }
}

// Register it
config.AddDispatchBehavior<AuditDispatchBehavior<MyFireAndForget>>();
// Or open-generic:
config.AddBehavior(typeof(IPipelineBehavior<>), typeof(AuditDispatchBehavior<>));