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INotificationBehavior

Namespace: RA.Utilities.Dispatcher.Abstractions

INotificationBehavior<TNotification> lets you inject cross-cutting concerns around notification handler execution — retry, logging, metrics — per handler, independently of every other handler for the same notification.

📦 Type Definition​

public interface INotificationBehavior<in TNotification> where TNotification : INotification
{
    ValueTask<Result> HandleAsync(
        TNotification notification,
        NotificationHandlerDelegate next,
        CancellationToken cancellationToken);

    ValueTask<Result> HandleAsync<TContext>(
        TNotification notification,
        NotificationHandlerContextDelegate<TContext> next,
        PipelineContext<TContext> context,
        CancellationToken cancellationToken)
        where TContext : class, new()
        => HandleAsync(notification, () => next(context), cancellationToken); // default implementation
}

🎯 How It Works​

Each notification handler gets its own behavior pipeline. When Publish fans out to N handlers, each handler is wrapped in its own chain of INotificationBehavior<TNotification> instances, composed in registration order (outermost first). A behavior can:

  • Do work before and after — e.g., log at start and finish.
  • Retry — catch a failed result and re-run the inner pipeline (NotificationRetryBehavior).
  • Measure — time the inner pipeline and warn on slow handlers (NotificationMetricsBehavior).
  • Prevent a single handler from completing — by not calling next() — but it can never stop the other handlers from running.

🚀 Custom Behavior Example​

public class AuditBehavior<TNotification> : INotificationBehavior<TNotification>
    where TNotification : INotification
{
    public async ValueTask<Result> HandleAsync(
        TNotification notification, NotificationHandlerDelegate next, CancellationToken cancellationToken)
    {
        Result result = await next();
        _auditLog.Record(typeof(TNotification).Name, result.IsSuccess);
        return result;
    }
}

🔧 Registration​

Closed (non-generic) behaviors are auto-registered by the source generator under their interface. Generic behaviors must be registered explicitly:

builder.Services
    .AddNotification<OrderPlaced>()
    .AddDecoration<AuditBehavior<OrderPlaced>>();

🔗 Related​