Supporting custom Authentication for SubscriptionServiceClient.Search and SubscriptionServiceClient.UpdateResults

[jezzsantos]

In practice, making a call to the remote subscription endpoints like:

• GET /webhooks/subscriptions/search and
• PUT /webhooks/subscriptions/history

is going to need some kind of authentication (i.e. session, token etc) for the remote service to authorize (based upon the WebhookFeature.SecureRelayRoles configuration).

If these endpoints are secured, then calls to SubscriptionServiceClient are going to need to support custom authentication in some way.

[jezzsantos]

Perhaps, we could simply provide a handler that will be called if a 401 is received, where the developer can put some code to perform the authentication first, and then it retries again, and this time fails.
(similar to ServiceClientBase)

i.e.

            container.Register<ISubscriptionService>(x => new SubscriptionServiceClient(appSettings)
            {
                ServiceClientFactory = x.Resolve<IEventServiceClientFactory>(),
                OnAuthenticationRequired = (serviceclient) =>
                {
                    //Do the required authN (to the remote SubscriptionService with another client instance)
                    // then set the cookies or bearertoken on the serviceclient
                },
            });