[Blazor] Communicate with a circuit instance from outside of the circuit

[javiercn]

The other piece of feedback we've received in this area involves how to communicate information to a given circuit from outside of the context of the circuit. This involves passing information during "circuit" startup and while the circuit is running. We might be able to create some documentation to specifically define how these pattern should work or streamline it in our default implementation.

[garrettlondon1]

Regarding passing information during "circuit" startup, @javiercn, one area I am not clear on is the CircuitHandler custom implementation.

Am I correct in saying that overriding OnCircuitOpenedAsync in your own custom CircuitHandler, is the only safe way of getting data from HttpContext and putting it inside of the circuits scoped services (not the scoped services of the http side)?

• CircuitHandler OnCircuitOpenedAsync
  namespace Microsoft.AspNetCore.Components.Server.Circuits;

In old Blazor Server apps I think there was a way of doing it through _Host.cshtml razor page, but now with Blazor Web, that no longer exists