Notifications — Multi-Channel Email, SMS & Push Engine

Granit.Notifications is a multi-channel notification engine built on a fan-out pattern. A single INotificationPublisher.PublishAsync() call fans out to every registered channel (InApp, Email, SMS, WhatsApp, Mobile Push, SignalR, SSE, Web Push, Zulip) after filtering through user preferences. Delivery attempts are recorded in an immutable audit trail (ISO 27001). By default, notifications dispatch via an in-process Channel<T> — add Granit.Notifications.Wolverine for durable outbox-backed dispatch with exponential backoff retry.

Package structure

• DirectoryGranit.Notifications/ Core: fan-out engine, InApp channel, definitions, entity tracking

  • Granit.Notifications.EntityFrameworkCore EF Core persistence (all stores)
  • Granit.Notifications.Endpoints Minimal API REST endpoints
  • Granit.Notifications.Wolverine Durable outbox dispatch via IMessageBus
  • DirectoryGranit.Notifications.Email/ Email channel abstraction (Keyed Services)

    • Granit.Notifications.Email.Smtp MailKit SMTP provider
    • Granit.Notifications.Email.AzureCommunicationServices Azure Communication Services email
    • Granit.Notifications.Email.Scaleway Scaleway TEM email provider
    • Granit.Notifications.Email.SendGrid SendGrid email provider
  • DirectoryGranit.Notifications.Sms SMS channel abstraction (Keyed Services)

    • Granit.Notifications.Sms.AzureCommunicationServices Azure Communication Services SMS
    • Granit.Notifications.Sms.AwsSns AWS SNS SMS provider
  • Granit.Notifications.WhatsApp WhatsApp Business API channel
  • Granit.Notifications.Brevo Unified Brevo provider (Email + SMS + WhatsApp)
  • DirectoryGranit.Notifications.MobilePush/ Mobile push abstraction + token store

    • Granit.Notifications.MobilePush.GoogleFcm Firebase Cloud Messaging provider
    • Granit.Notifications.MobilePush.AzureNotificationHubs Azure Notification Hubs push
    • Granit.Notifications.MobilePush.AwsSns AWS SNS Platform Application push
  • Granit.Notifications.SignalR Real-time SignalR channel + Redis backplane
  • Granit.Notifications.WebPush W3C Web Push (VAPID, RFC 8030)
  • Granit.Notifications.Sse Server-Sent Events channel (.NET 10)
  • Granit.Notifications.Twilio Twilio SMS + WhatsApp provider
  • Granit.Notifications.Zulip Zulip chat integration

Package	Role	Depends on
Granit.Notifications	Fan-out engine, InApp channel, definitions, entity tracking	Granit.Guids, Granit.Timing, Granit.QueryEngine
Granit.Notifications.EntityFrameworkCore	EF Core stores (all entities + mobile push tokens)	Granit.Notifications, Granit.Notifications.MobilePush, Granit.Persistence
Granit.Notifications.Endpoints	Minimal API endpoints (inbox, preferences, subscriptions, followers)	Granit.Notifications, Granit.Notifications.MobilePush, Granit.Validation, Granit.Http.ApiDocumentation
Granit.Notifications.Wolverine	Durable outbox-backed dispatch via IMessageBus	Granit.Notifications, Granit.Wolverine
Granit.Notifications.Email	Email channel abstraction, Keyed Services resolution	Granit.Notifications
Granit.Notifications.Email.Smtp	MailKit SMTP provider (Keyed Service "Smtp")	Granit.Notifications.Email
Granit.Notifications.Email.AzureCommunicationServices	Azure Communication Services email provider (Keyed Service "AzureCommunicationServices")	Granit.Notifications.Email
Granit.Notifications.Email.Scaleway	Scaleway TEM email provider (Keyed Service "Scaleway")	Granit.Notifications.Email
Granit.Notifications.Email.SendGrid	SendGrid email provider (Keyed Service "SendGrid")	Granit.Notifications.Email
Granit.Notifications.Brevo	Unified Brevo provider (Email + SMS + WhatsApp)	Granit.Notifications.Email, Granit.Notifications.Sms, Granit.Notifications.WhatsApp
Granit.Notifications.Sms	SMS channel abstraction, Keyed Services resolution	Granit.Notifications
Granit.Notifications.Sms.AzureCommunicationServices	Azure Communication Services SMS provider (Keyed Service "AzureCommunicationServices")	Granit.Notifications.Sms
Granit.Notifications.Sms.AwsSns	AWS SNS SMS provider (Keyed Service "AwsSns")	Granit.Notifications.Sms
Granit.Notifications.WhatsApp	WhatsApp Business API channel	Granit.Notifications
Granit.Notifications.MobilePush	Mobile push abstraction + device token store	Granit.Notifications
Granit.Notifications.MobilePush.GoogleFcm	Firebase Cloud Messaging (FCM HTTP v1 API)	Granit.Notifications.MobilePush
Granit.Notifications.MobilePush.AzureNotificationHubs	Azure Notification Hubs push provider (Keyed Service "AzureNotificationHubs")	Granit.Notifications.MobilePush
Granit.Notifications.MobilePush.AwsSns	AWS SNS Platform Application push provider (Keyed Service "AwsSns")	Granit.Notifications.MobilePush
Granit.Notifications.SignalR	Real-time SignalR channel + Redis backplane	Granit.Notifications
Granit.Notifications.WebPush	W3C Web Push (VAPID, RFC 8030/8291/8292)	Granit.Notifications
Granit.Notifications.Sse	Server-Sent Events channel (.NET 10 native SSE)	Granit.Notifications
Granit.Notifications.Twilio	Twilio SMS + WhatsApp provider (Keyed Service "Twilio")	Granit.Notifications.Sms, Granit.Notifications.WhatsApp
Granit.Notifications.Zulip	Zulip Bot API chat integration	Granit.Notifications

Dependency graph

graph TD
    N[Granit.Notifications] --> G[Granit.Guids]
    N --> T[Granit.Timing]
    N --> Q[Granit.QueryEngine]

    NEF[Granit.Notifications.EntityFrameworkCore] --> N
    NEF --> MP[Granit.Notifications.MobilePush]
    NEF --> P[Granit.Persistence]

    NE[Granit.Notifications.Endpoints] --> N
    NE --> MP
    NE --> V[Granit.Validation]
    NE --> AD[Granit.Http.ApiDocumentation]

    NW[Granit.Notifications.Wolverine] --> N
    NW --> W[Granit.Wolverine]

    EM[Granit.Notifications.Email] --> N
    SMTP[Granit.Notifications.Email.Smtp] --> EM
    ACSEM[Granit.Notifications.Email.AzureCommunicationServices] --> EM
    SCW[Granit.Notifications.Email.Scaleway] --> EM
    SG[Granit.Notifications.Email.SendGrid] --> EM
    BR[Granit.Notifications.Brevo] --> EM
    BR --> SMS[Granit.Notifications.Sms]
    BR --> WA[Granit.Notifications.WhatsApp]

    SMS --> N
    ACSSMS[Granit.Notifications.Sms.AzureCommunicationServices] --> SMS
    SNSSMS[Granit.Notifications.Sms.AwsSns] --> SMS
    TW[Granit.Notifications.Twilio] --> SMS
    TW --> WA
    WA --> N
    MP --> N
    FCM[Granit.Notifications.MobilePush.GoogleFcm] --> MP
    ANH[Granit.Notifications.MobilePush.AzureNotificationHubs] --> MP
    SNSMP[Granit.Notifications.MobilePush.AwsSns] --> MP
    SR[Granit.Notifications.SignalR] --> N
    WP[Granit.Notifications.WebPush] --> N
    SSE[Granit.Notifications.Sse] --> N
    ZU[Granit.Notifications.Zulip] --> N

Setup

Production (Wolverine + EF Core)

[DependsOn(typeof(GranitNotificationsWolverineModule))]
[DependsOn(typeof(GranitNotificationsEntityFrameworkCoreModule))]
public class AppModule : GranitModule
{
    public override void ConfigureServices(ServiceConfigurationContext context)
    {
        // EF Core persistence (replaces in-memory defaults)
        context.Builder.AddGranitNotificationsEntityFrameworkCore(
            opts => opts.UseNpgsql(context.Configuration
                .GetConnectionString("Notifications")));

        // Email channel via SMTP
        context.Services.AddGranitNotificationsEmail(opts => opts.Provider = "Smtp");
        context.Services.AddGranitNotificationsEmailSmtp();

        // SignalR real-time channel with Redis backplane
        context.Services.AddGranitNotificationsSignalR(
            context.Configuration.GetConnectionString("Redis")!);

        // Notification endpoints
        context.Services.AddGranitNotificationsEndpoints();
    }

    public override void OnApplicationInitialization(ApplicationInitializationContext context)
    {
        context.App.MapGranitNotifications();
        context.App.MapHub<NotificationHub>("/hubs/notifications");
    }
}

Development (in-memory)

[DependsOn(typeof(GranitNotificationsModule))]
public class AppModule : GranitModule { }

In-memory stores, in-process Channel<T> dispatch. No database, no outbox. Notifications are lost on crash — suitable for development only.

With Brevo (Email + SMS + WhatsApp)

// One provider for three channels
context.Services.AddGranitNotificationsBrevo();
context.Services.AddGranitNotificationsEmail(opts => opts.Provider = "Brevo");
context.Services.AddGranitNotificationsSms(opts => opts.Provider = "Brevo");
context.Services.AddGranitNotificationsWhatsApp(opts => opts.Provider = "Brevo");

{
  "Notifications": {
    "Brevo": {
      "ApiKey": "vault:secret/data/brevo#api-key",
      "DefaultSenderEmail": "[email protected]",
      "DefaultSenderName": "Clinic Portal",
      "DefaultSmsSenderId": "CLINIC"
    }
  }
}

Building your own *.Notifications package

Modules that emit user-facing events (export ready, payment succeeded, quota exceeded…) ship a sibling Granit.{Module}.Notifications package wiring the event to the fan-out engine and providing the email templates. The notifications package conventions page documents the canonical file layout, the Wolverine handler shape, the <title>-tag subject extraction, the JSON-array *Display companion gotcha, the manifest pinning test, and the embedded-vs-DB template override mechanics.