Freakout.MsSql

Freakout

📤 Just a general outbox thing

Why? Because "outbox" is closer to your chosen type of persistence (SQL Server, Postgres, etc.) than to anything else.

Which types of persistence does it support?

1. Microsoft SQL Server (for when you're working with Microsoft.Data.SqlClient and SqlConnection)

and that's it for now. 😅

How?

First, enable Freakout in your app:

services.AddFreakout(new MsSqlFreakoutConfiguration(connectionString));

It will register a couple of things, e.g. a background worker that will poll the outbox for pending commands. AddFreakout can only be called once.

Then, add your handlers:

services.AddCommandHandler<RecalculateClaimSummaryCommandHandler>();
services.AddCommandHandler<SendEmailCommandHandler>();
services.AddCommandHandler<PublishRebusEventCommandHandler>();

which will of course be resolved from the container, each in their own service scope.

Now it's fully configured - what's missing is putting something in the outbox.

Since this example is for SQL Server, and we're pretending to be working with Microsoft.Data.SqlClient and SqlConnection, it's natural to provide the outbox functionality as an extension method to DbTransaction. This way, your code can do stuff like this:

await using var connection = new SqlConnection(_connectionString);
await connection.OpenAsync();

await using var transaction = await connection.BeginTransactionAsync();

// do your own work with connection+transaction here
// (...)

// possibly call this bad boy a couple of times
await transaction.AddOutboxCommandAsync(new PublishRebusEventCommand(
	Event: new JournalEntryAdded(Id: journalEntryId)
));

// do more of your own work
// (...)

// commit it all atomically
await transaction.CommitAsync();

which in this case would result in publishing a couple of JournalEntryAdded events using Rebus.

Btw. a command handler to do this could look like this:

public class PublishRebusEventCommandHandler(IBus bus) : ICommandHandler<PublishRebusEventCommand>
{
	public Task HandleAsync(PublishRebusEventCommand command, CancellationToken token) => bus.Publish(command.Event);
}

and that would be it.