JerrettDavis · JerrettDavis · May 20, 2026 · May 20, 2026
@@ -44,28 +44,33 @@ The example uses `InMemoryBackplaneTransport` for deterministic tests. A product
 The demo now starts from a host builder, which is the shape a production application would usually expose from its composition root:
 
 ```csharp
-await using var host = await BackplaneHost.Create()
-    .UseTransport(() => transport)
-    .UseOutbox(outbox)
-    .UseIdempotencyStore(idempotency)
-    .MapCommand<SubmitOrder, BackplaneOrderAccepted>(
-        static (message, _) => message.Payload.CustomerTier == CustomerTier.Vip,
-        "orders.priority")
-    .MapDefaultCommand<SubmitOrder, BackplaneOrderAccepted>("orders.standard")
-    .ReceiveEndpoint("orders.standard", endpoint =>
-        endpoint.HandleCommand<SubmitOrder, BackplaneOrderAccepted>(services.AcceptStandardOrderAsync))
-    .ReceiveEndpoint("billing-service", endpoint =>
-        endpoint.Subscribe<BackplaneOrderSubmitted>("orders.submitted", services.CapturePaymentAsync))
-    .ReceiveEndpoint("notification-service", endpoint =>
-    {
-        endpoint.Subscribe<PaymentDeclined>("payments.declined", services.NotifyPaymentDeclinedAsync);
-        endpoint.Subscribe<ShipmentScheduled>("shipments.scheduled", services.NotifyShipmentScheduledAsync);
-    })
+await using var host = await GeneratedBackplaneTopology.Configure(
+        BackplaneHost.Create()
+            .UseTransport(() => transport)
+            .UseOutbox(outbox)
+            .UseIdempotencyStore(idempotency),
+        services)
     .BuildAsync(cancellationToken);
 ```
 
 `BackplaneHost` owns the bus, typed client, transport, endpoint subscriptions, outbox, idempotency store, and topology metadata. Application code uses `host.Client`, while advanced integrations can still reach the lower-level `host.Bus`.
 
+The generated topology comes from declarative attributes on a partial class:
+
+```csharp
+[GenerateBackplaneTopology(typeof(BackplaneDemoServices), HostBuilderType = typeof(BackplaneHostBuilder))]
+[BackplaneRequestReply(typeof(SubmitOrder), typeof(BackplaneOrderAccepted), "orders.priority", nameof(BackplaneDemoServices.AcceptPriorityOrderAsync), PredicateMethodName = nameof(IsVipOrder))]
+[BackplaneRequestReply(typeof(SubmitOrder), typeof(BackplaneOrderAccepted), "orders.standard", nameof(BackplaneDemoServices.AcceptStandardOrderAsync))]
+[BackplaneSubscription(typeof(BackplaneOrderSubmitted), "orders.submitted", "billing-service", nameof(BackplaneDemoServices.CapturePaymentAsync))]
+public static partial class GeneratedBackplaneTopology
+{
+    private static bool IsVipOrder(Message<SubmitOrder> message, MessageContext context)
+        => message.Payload.CustomerTier == CustomerTier.Vip;
+}
+```
+
+The same host builder also remains fluent, so applications can mix generated, reviewed topology with environment-specific transport, outbox, idempotency, and observability wiring.
+
 ## Request/Reply
 
 The client exposes a typed request/reply API:
@@ -118,7 +123,9 @@ BackplaneHost.Create()
 The tests assert that:
 
 - Standard orders route to `orders.standard` and VIP orders route to `orders.priority`.
+- The generated topology registers request/reply routes and publish/subscribe endpoints.
 - The host builder configures transport, outbox, idempotency, endpoint topology, and the typed client surface.
+- The example can be imported through `IServiceCollection` with `AddMessagingBackplaneFacadeExample`.
 - Duplicate commands replay the original response and do not duplicate outbox side effects.
 - Published events fan out to independent services.
 - Every event is recorded in the outbox before transport dispatch.

@@ -72,6 +72,7 @@ PatternKit includes a Roslyn incremental generator package (`PatternKit.Generato
 | [**Saga**](messaging.md#generated-saga) | Typed process-manager transition factories | `[GenerateSaga]` |
 | [**Mailbox**](messaging.md#generated-mailbox) | Serialized in-process inbox factories | `[GenerateMailbox]` |
 | [**Reliability Pipeline**](messaging.md#generated-reliability-pipeline) | Idempotent receiver, inbox, and outbox factories | `[GenerateReliabilityPipeline]` |
+| [**Backplane Topology**](messaging.md#generated-backplane-topology) | Request/reply routes and publish/subscribe endpoint topology | `[GenerateBackplaneTopology]` |
 
 ## Quick Reference
 
@@ -165,6 +166,12 @@ public static partial class OrderMailbox { }
 [GenerateReliabilityPipeline(typeof(AcceptOrder), typeof(string), typeof(OrderAccepted))]
 public static partial class OrderReliability { }
 
+// Backplane topology - generated request/reply and pub/sub host wiring
+[GenerateBackplaneTopology(typeof(OrderBackplaneServices), HostBuilderType = typeof(OrderBackplaneHostBuilder))]
+[BackplaneRequestReply(typeof(SubmitOrder), typeof(OrderAccepted), "orders", nameof(OrderBackplaneServices.AcceptAsync))]
+[BackplaneSubscription(typeof(OrderSubmitted), "orders.submitted", "audit-service", nameof(OrderBackplaneServices.AuditAsync))]
+public static partial class OrderBackplane { }
+
 // Routing slip - generated ordered itinerary factory
 [GenerateRoutingSlip(typeof(Order))]
 public static partial class OrderSlip { }

@@ -1,6 +1,6 @@
 # Messaging Generators
 
-PatternKit includes nine messaging-oriented source generators:
+PatternKit includes ten messaging-oriented source generators:
 
 - <xref:PatternKit.Generators.Messaging.GenerateDispatcherAttribute> for source-generated mediator dispatchers.
 - <xref:PatternKit.Generators.Messaging.GenerateMessageEnvelopeAttribute> for required message-envelope contracts.
@@ -11,6 +11,7 @@ PatternKit includes nine messaging-oriented source generators:
 - <xref:PatternKit.Generators.Messaging.GenerateSagaAttribute> for typed saga/process-manager factories.
 - <xref:PatternKit.Generators.Messaging.GenerateMailboxAttribute> for serialized in-process inbox factories.
 - <xref:PatternKit.Generators.Messaging.GenerateReliabilityPipelineAttribute> for idempotent receiver, inbox, and outbox factories.
+- <xref:PatternKit.Generators.Messaging.GenerateBackplaneTopologyAttribute> for compile-time request/reply and publish/subscribe host topology.
 
 Use these generators when the message topology is known at compile time and should remain explicit, AOT-friendly, and validated by the compiler. They generate factories and fluent builders; they do not discover handlers from assemblies at runtime and they do not replace brokers, durable queues, or workflow engines.
 
@@ -235,6 +236,33 @@ Example files:
 - `src/PatternKit.Examples/Messaging/ReliabilityExample.cs`
 - `test/PatternKit.Examples.Tests/Messaging/ReliabilityExampleTests.cs`
 
+## Generated Backplane Topology
+
+`[GenerateBackplaneTopology]` wires request/reply routes and publish/subscribe endpoints into a `BackplaneHostBuilder` from declarative attributes:
+
+```csharp
+using PatternKit.Generators.Messaging;
+using PatternKit.Messaging;
+
+[GenerateBackplaneTopology(typeof(OrderBackplaneServices), HostBuilderType = typeof(OrderBackplaneHostBuilder))]
+[BackplaneRequestReply(typeof(SubmitOrder), typeof(OrderAccepted), "orders.priority", nameof(OrderBackplaneServices.AcceptPriorityAsync), PredicateMethodName = nameof(IsPriority))]
+[BackplaneRequestReply(typeof(SubmitOrder), typeof(OrderAccepted), "orders.standard", nameof(OrderBackplaneServices.AcceptStandardAsync))]
+[BackplaneSubscription(typeof(OrderSubmitted), "orders.submitted", "billing-service", nameof(OrderBackplaneServices.CapturePaymentAsync))]
+public static partial class OrderBackplane
+{
+    private static bool IsPriority(Message<SubmitOrder> message, MessageContext context)
+        => message.Payload.CustomerTier == CustomerTier.Vip;
+}
+```
+
+The generated `Configure` method applies content-router request routes before default routes, registers command handlers, and registers topic subscriptions. It keeps broker infrastructure application-owned: the caller still supplies the transport, outbox, idempotency store, service object, and host-builder type used at the composition root.
+
+Example files:
+
+- `src/PatternKit.Examples/Messaging/BackplaneFacadeDemo.cs`
+- `test/PatternKit.Examples.Tests/Messaging/BackplaneFacadeDemoTests.cs`
+- `test/PatternKit.Generators.Tests/BackplaneTopologyGeneratorTests.cs`
+
 ## Generated Saga
 
 `[GenerateSaga]` emits a process-manager factory from typed transition methods:
@@ -276,6 +304,7 @@ Example source:
 | `PKSG001`-`PKSG004` | Saga | Non-partial host, missing transitions, invalid transition signatures, or invalid completion checks. |
 | `PKMB001`-`PKMB005` | Mailbox | Non-partial host, missing handler, invalid handler signatures, or invalid configuration. |
 | `PKRP001`-`PKRP005` | Reliability Pipeline | Non-partial host, missing handler, invalid handler/key selector signatures, or invalid configuration. |
+| `PKBT001`-`PKBT005` | Backplane Topology | Non-partial host, missing topology, invalid route/subscription signatures, or duplicate default routes. |
 
 ## Related Runtime Patterns
 
@@ -285,3 +314,4 @@ Example source:
 - [Saga / Process Manager](../patterns/messaging/saga.md)
 - [Mailbox](../patterns/messaging/mailbox.md)
 - [Idempotent Receiver, Inbox, and Outbox](../patterns/messaging/reliability.md)
+- [Messaging Backplane Facade](../examples/messaging-backplane-facade.md)
@@ -55,8 +55,8 @@ The source of truth is `PatternKitPatternCatalog` in `src/PatternKit.Examples/Pr
 | Messaging Reliability | Idempotent Receiver | `IdempotentReceiver<TPayload, TResult>` | Reliability pipeline generator |
 | Messaging Reliability | Inbox | `InboxProcessor<TPayload, TResult>` | Reliability pipeline generator |
 | Messaging Reliability | Outbox | `InMemoryOutbox<TPayload>` and dispatcher contracts | Reliability pipeline generator |
-| Enterprise Integration | Request-Reply | Messaging backplane facade example | Tracked in [#214](https://github.com/JerrettDavis/PatternKit/issues/214) |
-| Enterprise Integration | Publish-Subscribe | Messaging backplane facade example | Tracked in [#214](https://github.com/JerrettDavis/PatternKit/issues/214) |
+| Enterprise Integration | Request-Reply | Messaging backplane facade example | Backplane topology generator |
+| Enterprise Integration | Publish-Subscribe | Messaging backplane facade example | Backplane topology generator |
 | Application Architecture | CQRS | Mediator/dispatcher command-query split | Dispatcher generator |
 
 ## Research Baselines

@@ -2,7 +2,7 @@
 
 PatternKit source generators remove repetitive registration code for explicit enterprise integration patterns. They do not scan assemblies implicitly; each generated factory is opt-in through attributes on a partial type.
 
-Use generators when routes, recipient lists, splitter/aggregator contracts, routing-slip steps, saga transitions, or mailbox inbox policies are static enough to validate at compile time and you want AOT-friendly factories without reflection.
+Use generators when routes, recipient lists, splitter/aggregator contracts, routing-slip steps, saga transitions, mailbox inbox policies, or request/reply and publish/subscribe host topology are static enough to validate at compile time and you want AOT-friendly factories without reflection.
 
 ## Generated Content Router
 
@@ -79,6 +79,8 @@ Mailbox generation is documented in [Mailbox](mailbox.md). It discovers one `[Ma
 
 Reliability helpers also have a generated path through `[GenerateReliabilityPipeline]`, which emits idempotent receiver, inbox, and outbox factories while keeping durable storage implementation owned by the application.
 
+Backplane topology generation is documented in [Messaging Generators](../../generators/messaging.md#generated-backplane-topology). It discovers `[BackplaneRequestReply]` and `[BackplaneSubscription]` declarations on a partial topology type and emits a public `Configure` method for wiring the declared host-builder type at the application composition root.
+
 ## Diagnostics
 
 | ID | Meaning |
@@ -96,13 +98,15 @@ Reliability helpers also have a generated path through `[GenerateReliabilityPipe
 | `PKRS001`-`PKRS003` | Routing-slip generator validation. |
 | `PKSG001`-`PKSG004` | Saga generator validation. |
 | `PKMB001`-`PKMB005` | Mailbox generator validation. |
+| `PKBT001`-`PKBT005` | Backplane topology generator validation. |
 
 ## Troubleshooting
 
 - Make the generated host type `partial`.
 - Keep route, step, and saga methods `static`; generated factories reference them directly.
 - Use `nameof(PredicateMethod)` in `[ContentRoute]` and `[RecipientListRecipient]` so renames remain compile-time safe.
 - Use unique route and recipient names and orders. Content routers are first-match, and recipient lists are ordered fan-out, so ambiguous ordering should fail at build time.
+- Use one default request/reply route per request type in generated backplane topology; predicate routes are emitted before defaults so first-match routing stays deterministic.
 - Ensure generated code builds under nullable enabled; the tests compile generated examples with Release settings.
 
 ## API
@@ -121,6 +125,9 @@ Reliability helpers also have a generated path through `[GenerateReliabilityPipe
 - <xref:PatternKit.Generators.Messaging.MailboxHandlerAttribute>
 - <xref:PatternKit.Generators.Messaging.MailboxErrorHandlerAttribute>
 - <xref:PatternKit.Generators.Messaging.MailboxEventSinkAttribute>
+- <xref:PatternKit.Generators.Messaging.GenerateBackplaneTopologyAttribute>
+- <xref:PatternKit.Generators.Messaging.BackplaneRequestReplyAttribute>
+- <xref:PatternKit.Generators.Messaging.BackplaneSubscriptionAttribute>
 - <xref:PatternKit.Messaging.Routing.ContentRouter`2>
 - <xref:PatternKit.Messaging.Routing.RecipientList`1>
 
@@ -130,3 +137,5 @@ Reliability helpers also have a generated path through `[GenerateReliabilityPipe
 - `test/PatternKit.Examples.Tests/Messaging/ContentRouterGeneratorExampleTests.cs`
 - `src/PatternKit.Examples/Messaging/RecipientListGeneratorExample.cs`
 - `test/PatternKit.Examples.Tests/Messaging/RecipientListGeneratorExampleTests.cs`
+- `src/PatternKit.Examples/Messaging/BackplaneFacadeDemo.cs`
+- `test/PatternKit.Examples.Tests/Messaging/BackplaneFacadeDemoTests.cs`
@@ -409,7 +409,7 @@ public static IServiceCollection AddResilientCheckoutMailboxesExample(this IServ
     public static IServiceCollection AddMessagingBackplaneFacadeExample(this IServiceCollection services)
     {
         services.AddSingleton(new MessagingBackplaneFacadeExample(BackplaneFacadeDemo.RunAsync));
-        return services.RegisterExample<MessagingBackplaneFacadeExample>("Messaging Backplane Facade", ExampleIntegrationSurface.GenericHost | ExampleIntegrationSurface.Messaging | ExampleIntegrationSurface.ExternalInfrastructure | ExampleIntegrationSurface.DependencyInjection);
+        return services.RegisterExample<MessagingBackplaneFacadeExample>("Messaging Backplane Facade", ExampleIntegrationSurface.GenericHost | ExampleIntegrationSurface.Messaging | ExampleIntegrationSurface.SourceGenerator | ExampleIntegrationSurface.ExternalInfrastructure | ExampleIntegrationSurface.DependencyInjection);
     }
 
     public static IServiceCollection AddPrototypeGameCharacterFactoryExample(this IServiceCollection services)