Innovabit.DotNet.Interceptors.Notifications.Abstractions 1.0.0.96

Innovabit.DotNet.Interceptors.Notifications.Abstractions

Send notifications when an intercepted method throws, for the Innovabit.DotNet.Interceptors suite. This is the base package; add a channel (...Notifications.Slack and/or ...Notifications.Email) to actually deliver them.

What it provides

• [NotifyOnException] — dispatch a notification when a method (or any method of a class) throws.
• INotifier — a delivery channel abstraction (Slack, e-mail, ...).
• IExceptionNotificationHandler / ExceptionNotificationHandler<TException> — build the message per exception type, with a generic fallback for System.Exception.
• INotificationDispatcher — picks the most specific handler and fans the message out to every matching channel.
• Templates — AddTemplates() plus template sources (code, files, embedded resources) so the wording lives outside the code, with a channel specific variant per notifier.
• INotificationSender — send a notification (templated or not) on demand, outside the exception pipeline.

Install

dotnet add package Innovabit.DotNet.Interceptors.Notifications.Abstractions

Usage

services.AddInterceptors()
    .AddNotifications()
    .AddSlack(o => o.WebhookUrl = "https://hooks.slack.com/services/XXX/YYY/ZZZ")
    .AddHandler<TimeoutExceptionNotificationHandler>();

public class OrderService : IOrderService
{
    [NotifyOnException]                       // notify (all channels) then re-throw
    public Task PlaceAsync(Order order) { ... }
}

[NotifyOnException] supports Rethrow, Severity, Channels, ExceptionTypes and Template. Register a handler for a concrete exception type by deriving from ExceptionNotificationHandler<TException>; the most specific match wins, falling back to the handler for System.Exception.

Templates

Move the wording out of the code and give every channel its own version — a rich HTML e-mail and a one-line Slack message out of the same failure:

services.AddInterceptors()
    .AddNotifications()
    .AddTemplates(o => o.DefaultTemplateName = "house-style")
    .AddTemplatesFromDirectory("Templates")   // {name}[.{channel}].{txt|html}
    .AddTemplatesFromAssembly()               // embedded resources
    .AddTemplate("order-failed",              // ... or in code
        title: "Order failed in {{ Member }}",
        body: "{{ ExceptionMessage }} at {{ OccurredAt:yyyy-MM-dd HH:mm }}");

[NotifyOnException(Template = "order-failed")]
public Task PlaceAsync(Order order) { ... }

Templates/order-failed.Email.html:

<h1>{{ ExceptionType }}</h1>
<p>{{ ExceptionMessage }}</p>

The built-in renderer substitutes {{ Path }} placeholders (dotted paths, an optional :format specifier, HTML-encoded in HTML templates). Add Innovabit.DotNet.Interceptors.Notifications.Templating.Scriban when the wording needs conditionals, loops or filters.

The model of an exception notification exposes Exception, Method, TargetType, Arguments, OccurredAt, Severity and the shortcuts ExceptionType, ExceptionMessage, StackTrace, Member and MachineName.

Sending on demand

The same channels and templates are available outside the exception pipeline:

public class WelcomeService(INotificationSender sender)
{
    public Task WelcomeAsync(Customer customer)
        => sender.SendTemplateAsync("welcome", new { customer.Name, customer.OrderId });
}

Unlike the exception dispatcher — which swallows channel failures so a broken mail server never changes how a method fails — an explicit send attempts every channel and throws an AggregateException with whatever went wrong.

Part of

The Innovabit.DotNet.Interceptors suite — github.com/Innovabit/dotnet-interceptors.