Named activity source registration

Use named registration when you want multiple logical activity sources in the same application and resolve them explicitly with keyed services.

Register a named activity source

using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();

services.AddNamedActivitySource("orders");

This registers:

• keyed System.Diagnostics.ActivitySource with the name orders
• keyed IActivitySource<T> that resolves to that same named ActivitySource

Register an instrumentation scope version

Pass version to identify the instrumentation scope version:

services.AddNamedActivitySource("orders", version: "1.2.3");

The keyed source exposes Version == "1.2.3". The existing overload without a version remains supported and keeps an empty-string version.

Resolve the named activity source in consumers

using Cratis.Traces;
using Microsoft.Extensions.DependencyInjection;

public class OrderService([FromKeyedServices("orders")] IActivitySource<OrderService> activitySource)
{
}

IActivitySource<T> remains available as a non-keyed service as well, where the underlying source name defaults to typeof(T).FullName. Per-type sources are not subscribed by default; explicitly subscribe the source name in your telemetry provider, or use a named source that your provider subscribes to.

Registration boundaries

The name is both the diagnostics source name and the dependency-injection key. Use the same string when registering, resolving, and configuring your telemetry provider. A null, empty, or whitespace-only name is rejected. Different names create separate singleton sources; typed consumers resolved with the same key share the underlying activity source even when their generic type arguments differ.

Registration uses TryAddKeyedSingleton. Registering the same name again does not replace its existing services, so choose the version on the first registration rather than trying to update it with a later call. Registration alone does not configure an exporter or subscribe a telemetry provider.

See also

• Overview — typed traces APIs and usage
• Roslyn — generate instrumentation methods
• Named meters — configure the other diagnostics signal