What is the proper HTTP response to send for requests that require SSL/TLS

Question

I\'m designing an RESTful API where some calls are public over HTTP, and some require an API key and encryption over HTTPS. I\'m deliberating on what response code should b

Answer 1

I cannot say if this is broadly accepted by HTTP clients, but speaking strictly RFC, the server should respond with:

HTTP/1.1 426 Upgrade Required
Upgrade: TLS/1.0, HTTP/1.1
Connection: Upgrade

Source:
http://tools.ietf.org/html/rfc2817#section-4.2