Rask.Outbox 0.20.0

Rask.Outbox

A transactional outbox for Rask.Data entities — durable, crash-safe domain-event delivery on the app's own database, with no broker or Redis.

• Mark a domain event IOutboxEvent and it's written to an OutboxMessage table in the same transaction as the change that raised it — so an event is never lost, and never fires for a change that rolled back.
• A background OutboxProcessor polls the table and publishes each message through Rask.Cqrs (IDispatcher.PublishAsync) — at-least-once, with retries and an attempt count.
• Published messages are purged after RetentionPeriod (default 7 days) so the table doesn't grow forever. Dead letters are never purged — they have no ProcessedAt for the predicate to match.
• Metrics on the Rask.Outbox meter: processed / failed / dead-lettered counters, a duration histogram, and pending / dead-letter gauges. rask.outbox.deadletters is the one to alert on.
• A source generator registers every IOutboxEvent type for reflection-free lookup on the drain path.

Use

public sealed record OrderPlaced(Guid Id) : IOutboxEvent;   // raised on your Entity

// Program.cs
builder.Services.AddRaskCqrs();
builder.Services.AddRaskData(o => o.DispatchDomainEventsInProcess = false); // the outbox owns delivery
builder.Services.AddRaskOutbox<AppDbContext>(o => o.PollInterval = TimeSpan.FromSeconds(5));

builder.Services.AddDbContextFactory<AppDbContext>((sp, o) => o
    .UseSqlite("Data Source=app.db")
    .AddInterceptors(sp.GetServices<ISaveChangesInterceptor>()));

// AppDbContext.OnModelCreating
modelBuilder.AddRaskOutbox(); // maps the OutboxMessage table

db.SaveChanges() now writes an OutboxMessage row for each IOutboxEvent the entity raised, in the same transaction; the processor drains and publishes them just after commit. Any INotificationHandler<OrderPlaced> reacts — the same handler works whether events are delivered in-process (Rask.Data) or via the outbox.

Server-side. The processor is a hosted BackgroundService and the store is your EF Core database (SQLite by default). Part of the Rask framework. MIT licensed.