Part 6: HTTP push subscriptions

Expose generated HTTP subscription discovery and custom event routes

The HTTP subscription example shows DeliveryMode.Http for applications that use normal HTTP ingress or reverse proxies.

Define a routed handler

[DaprTopic(
    "pubsub",
    "invoices",
    Delivery = DeliveryMode.Http,
    Route = "api/events/invoices")]
public sealed class InvoiceProcessingHandler : ITopicHandler<InvoiceGenerated>
{
    public Task<TopicResponseAction> HandleAsync(
        InvoiceGenerated invoice,
        TopicContext context,
        CancellationToken cancellationToken)
    {
        return Task.FromResult(
            invoice.TotalAmount <= 0
                ? TopicResponseAction.Drop
                : TopicResponseAction.Success);
    }
}

Map the generated routes

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddDaprMessaging();

var app = builder.Build();
app.MapDaprMessaging();
app.Run();

The generated mapping exposes GET /dapr/subscribe for Dapr to discover subscriptions and maps POST /api/events/invoices for the topic’s CloudEvents. The route is generated from the Route property; it does not need a separate controller or action.

Run with the application’s HTTP port:

dapr run --app-id http-subscriber-example --app-port 5000 `
  --dapr-grpc-port 50001 -- dotnet run

Inspect the generated manifest with curl http://localhost:5000/dapr/subscribe.

Test HTTP delivery

The unit tests invoke the invoice handler directly for valid, zero, and negative amounts. The integration tests use the test application and a real Dapr sidecar to verify subscription discovery and HTTP push delivery. This lets the test cover route mapping and CloudEvent dispatch without coupling business-rule tests to ASP.NET hosting.

dotnet test examples\Messaging\06-HttpSubscription\HttpSubscription.Example06.Tests\HttpSubscription.Example06.Tests.csproj

Next

Last modified September 13, 2026: Updated documentation to include tutorial documentation going through implementation, unit and integration testing for Dapr.Messaging (8c51cf06b)