Vulthil.Messaging.Inbox.Relational

Relational Entity Framework Core implementation of IIdempotencyStore for Vulthil.Messaging.Inbox. Gives transactional exactly-once consumer processing on relational databases: the inbox marker and the consumer's business writes commit in a single transaction, so a redelivered message is never processed twice.

When to use

• You use Vulthil.Messaging.Inbox and persist with EF Core against a relational provider (PostgreSQL, SQL Server, MySQL, SQLite)

It relies on relational transactions, so it does not support the EF Core Cosmos provider — Cosmos needs a separate store with a different (effectively-once) mechanism.

Pattern

• Your DbContext implements ISaveInboxMessages and maps InboxMessage
• The store opens an ambient transaction; the consumer's SaveChanges flushes into it without committing
• The marker and the consumer's writes commit together; a consumer exception rolls both back

Usage

public sealed class AppDbContext(DbContextOptions<AppDbContext> options)
    : DbContext(options), ISaveInboxMessages
{
    public DbSet<InboxMessage> InboxMessages => Set<InboxMessage>();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
        => modelBuilder.ApplyRelationalInbox();
}

builder.Services.AddRelationalInbox<AppDbContext>();

The consumer and the store must resolve the same scoped DbContext instance (the default with AddDbContext). Add an EF Core migration for the InboxMessage table as you would for any entity. See the Inbox Pattern article for details.