Bsft.Correlation.Http 2.1.0

Bsft.Correlation.Http

The outbound half of the Bsft.Correlation family: an HttpClient delegating handler that attaches the X-Correlation-Id of the current scope to every request it sends, so the next service continues the same trace instead of starting its own.

Install

dotnet add package Bsft.Correlation.Http

Requires Bsft.Correlation.Abstractions (pulled transitively) and Microsoft.Extensions.DependencyInjection.Abstractions for the entry point. No further Bsft packages, and no ASP.NET Core: this package is deliberately referenceable from a Blazor WebAssembly front end, a console tool or an integration-test client, and a test pins that closure. A host that also serves requests takes Bsft.Correlation, which references this package and registers the handler for you.

Register

services.AddBsftCorrelationHttp();

services.AddHttpClient<IBillingServiceClient, BillingServiceClient>()
    .AddHttpMessageHandler<CorrelationIdDelegatingHandler>();

Register it per client rather than globally, and only on clients that reach your own services. The handler attaches the header to whatever the client sends, a request following a redirect to another host included. The identifier is not a credential, but it says how a deployment traces itself, and a third party has no business reading that.

Nothing else is required. AddBsftCorrelationHttp() registers the handler and nothing more — it does not supply an ICorrelationContext, because where the ID comes from differs per host: a server gets it from AddBsftCorrelation() and its inbound middleware, a client registers its own implementation. The call is idempotent, so a host that calls AddBsftCorrelation() (which calls this) and this method itself still ends up with one handler registration.

Configure

Validation: none — there is nothing to configure and therefore nothing that can be misconfigured.

Extend

ICorrelationContext — declared in Bsft.Correlation.Abstractions, it is what the handler reads the outgoing ID from and the only seam involved. Bsft.Correlation supplies the request-scoped implementation for a server; a client that mints or receives its ID some other way implements the interface itself. CorrelationIdDelegatingHandler is sealed.

Documentation

Topic page: docs/correlation.md. Conventions: docs/package-conventions.md.