INotificationBehavior

Namespace: RA.Utilities.Feature.Abstractions

The INotificationBehavior interface defines a pipeline behavior that can be applied to the processing of an INotification. It allows you to wrap the execution of INotificationHandlers to apply cross-cutting concerns.

🎯 Purpose

The primary purpose of INotificationBehavior is to create a "middleware" pipeline for notifications. This allows you to encapsulate logic that should run for every notification without duplicating code in every INotificationHandler.

When a notification is published, it can be passed through a pipeline of one or more INotificationBehavior implementations before it reaches the actual handlers. This allows you to execute logic both before and after the notification handlers are invoked.

Common use cases include:

• Logging: Logging the start and end of a notification's processing.
• Error Handling: Wrapping the execution of all handlers in a global try-catch block.
• Performance Monitoring: Measuring the time it takes for all handlers to complete.

⚙️ How It Works

A class that implements INotificationBehavior<TNotification> must define a HandleAsync method. This method receives the notification and a next delegate. The next delegate represents the invocation of the actual INotificationHandler(s) for that notification.

A behavior can:

1. Execute code before calling await next().
2. Execute code after await next() has completed.

This "wrapping" capability is what makes it a powerful tool for handling cross-cutting concerns in an event-driven architecture.

🚀 Usage Example

A common use case is to create a logging behavior to trace the flow of notifications through the system.

using Microsoft.Extensions.Logging;
using RA.Utilities.Feature.Abstractions;
using RA.Utilities.Feature.Models;

public class LoggingNotificationBehavior<TNotification> : INotificationBehavior<TNotification>
    where TNotification : INotification
{
    private readonly ILogger<LoggingNotificationBehavior<TNotification>> _logger;

    public LoggingNotificationBehavior(ILogger<LoggingNotificationBehavior<TNotification>> logger)
    {
        _logger = logger;
    }

    public async Task HandleAsync(TNotification notification, NotificationHandlerDelegate next, CancellationToken cancellationToken)
    {
        var notificationName = typeof(TNotification).Name;

        _logger.LogInformation("Handling notification {NotificationName}...", notificationName);

        // This calls the actual INotificationHandler(s)
        await next();

        _logger.LogInformation("Notification {NotificationName} handled.", notificationName);
    }
}

🧠 Summary

In summary, INotificationBehavior provides a clean, reusable way to add common logic to your event handling pipeline, keeping your individual notification handlers focused on their specific business logic.