From technotes.googlecode.com:
This document describes a Transport Layer Security (TLS) extension for application layer protocol negotiation. This allows the application layer to negotiate which protocol should be performed over the secure connection. The Next Protocol Negotiation extension (NPN) is currently used to negotiate the use of SPDY as an application level protocol on port 443, and to perform SPDY version negotiation.
Tagged: #google #protocols #server #strings