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Outbox Registration

Once your components are ready, wire them up in your application using the fluent EventPublisherBuilder chain.

Registration Patterns​

Minimal Setup (Custom Store)​

For non-EF Core backends or custom implementations:

builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>()
    .WithStore<MyOutboxMessageStore>()
    .WithFactory<OrderOutboxMessageFactory>();

Minimal Setup (EF Core Integration)​

Use DbOutboxMessage directly when no extra columns are needed:

builder.Services
    .AddEventPublisher()
    .AddOutbox<DbOutboxMessage>()   // use the built-in entity as-is
    .WithEntityFramework()
    .WithFactory<DbOutboxMessageFactory>();

Or with a subclass when you need application-specific columns:

builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>()  // OrderOutboxMessage : DbOutboxMessage
    .WithEntityFramework()
    .WithFactory<OrderOutboxMessageFactory>();

Convenience Method​

The AddEntityFrameworkOutbox method combines outbox and EF registration:

builder.Services
    .AddEventPublisher()
    .AddEntityFrameworkOutbox(opts => opts.UseSqlServer(connectionString))
    .WithFactory<OrderOutboxMessageFactory>();

With Inline Options​

Configure outbox options inline during registration:

builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>(options =>
    {
        options.ChannelName = "outbox";
    })
    .WithStore<MyOutboxMessageStore>()
    .WithFactory<OrderOutboxMessageFactory>();

OutboxPublishOptions​

PropertyTypeDefaultDescription
ChannelNamestringnullLogical name for the outbox channel

Note: OutboxPublishOptions inherits from EventPublishOptions and currently adds no outbox-specific properties. It exists as a dedicated type so that future releases can introduce outbox-only settings without a breaking change.

Bound from Configuration​

Register options from appsettings.json:

builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>("Events:Outbox")
    .WithStore<MyOutboxMessageStore>()
    .WithFactory<OrderOutboxMessageFactory>();

Configuration File​

{
  "Events": {
    "Outbox": {
      "ChannelName": "outbox"
    }
  }
}

Complete Registration with Relay and Transport​

Same-Process Deployment​

When the relay runs inside the same application host:

builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>()
    .WithEntityFramework(opts => opts.UseSqlServer(connectionString))
    .WithFactory<OrderOutboxMessageFactory>()
    .WithRelay(relay =>
    {
        relay.Interval     = TimeSpan.FromSeconds(15);
        relay.MaxBatchSize = 100;
    })
    .AddRabbitMq(opts =>
    {
        opts.ConnectionString = "amqp://guest:guest@localhost:5672";
        opts.ExchangeName     = "events";
    });

Important: Calling .WithRelay(…) automatically sets EventPublisherOptions.ThrowOnErrors = true via a post-configuration callback. This ensures transport errors surface to the relay service so it can correctly mark messages as Failed.

Configuration-Bound Equivalent​

builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>("Events:Outbox")
    .WithEntityFramework(opts => opts.UseSqlServer(connectionString))
    .WithFactory<OrderOutboxMessageFactory>()
    .WithRelay("Events:OutboxRelay")
    .AddRabbitMq("Events:RabbitMq");
{
  "Events": {
    "Outbox": {
      "ChannelName": "outbox"
    },
    "OutboxRelay": { 
      "Interval": "00:00:15", 
      "MaxBatchSize": 100 
    },
    "RabbitMq": { 
      "ConnectionString": "amqp://...", 
      "ExchangeName": "events" 
    }
  }
}

Cross-Process Deployment​

For larger deployments, run the relay as a dedicated worker process:

Main Application (Publisher Only)​

Registers only the outbox channel — no relay, no transport:

// Main application Program.cs
builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>()
    .WithEntityFramework(opts => 
        opts.UseSqlServer(builder.Configuration.GetConnectionString("Shared")));

Relay Worker (Separate Process)​

Registers repository, factory, relay, and transport — but not the outbox channel:

// Relay worker Program.cs
builder.Services
    .AddEventPublisher()
    .AddOutbox<OrderOutboxMessage>()
    .WithEntityFramework(opts =>
        opts.UseSqlServer(builder.Configuration.GetConnectionString("Shared")))
    .WithFactory<OrderOutboxMessageFactory>()
    .WithRelay(relay =>
    {
        relay.Interval     = TimeSpan.FromSeconds(10);
        relay.MaxBatchSize = 200;
    })
    .AddRabbitMq(opts =>
    {
        opts.ConnectionString = "amqp://guest:guest@rabbitmq:5672";
        opts.ExchangeName     = "events";
    });

Benefits of Cross-Process Deployment​

BenefitDescription
Independent scalingScale relay workers without scaling the main application
Isolated failuresRelay crashes don't affect the main application
Dedicated resourcesRelay can run on different hardware/infrastructure
Simplified deploymentUpdate relay logic without redeploying the main application

Combining Outbox with Other Channels​

The outbox channel participates in the same fan-out as any other channel. You can mix the outbox with direct transport channels:

builder.Services
    .AddEventPublisher()
    // Guaranteed, async delivery for all events via outbox
    .AddOutbox<OrderOutboxMessage>()
        .WithEntityFramework(opts => opts.UseSqlServer(connectionString))
        .WithFactory<OrderOutboxMessageFactory>()
        .WithRelay(r => r.Interval = TimeSpan.FromSeconds(20))
    // Direct delivery for high-priority events
    .AddWebhooks(opts =>
    {
        opts.ChannelName   = "priority-webhook";
        opts.EndpointUrl   = "https://partner.example.com/events";
        opts.SigningSecret = "s3cr3t";
    });

Use Named Channels to route specific event types to specific channels.