6. TLSTLS TCPTCP BrowserBrowser HTTP/2HTTP/2 TLSTLS TCPTCP ServerServer HTTP/2HTTP/2

7. HTTP/2 over clear text (HTTP:// Scheme) Negotiate TCP connection Client sends request over HTTP 1.1 Server sends HTTP 1.1 response and includes an UPGRADE header Client sends 2 nd request over HTTP 1.1, includes UPGRADE header Server sends 101 – Switching Protocols with response Client send HTTP/2 setting frame… HTTP/2 over TLS (HTTPS:// Scheme) Negotiate TCP connection TLS Client Hello contains ALPN Extension with h2, HTTP 1.1 TLS Server Hello contains ALPN Extension with h2 TLS completes Client sends HTTP/2 Settings Frame…

8. HTTP/1.1 – Request = Connection HTTP/2 – Request = Stream … Streams look like TCP connections to IIS/ASP.NET apps Each request required dedicated TCP connectionTCP connection can have multiple streams (requests) Responses come in order per connectionResponses can come out of order, server can optimize Each connection requires setup + slow startNo connection setup for new streams, no slow start Application sees “connections”Streams are represented as “connections” to apps

9. Idle Open Half- Closed (local) Half- Closed (local) Half- Closed (remote) Half- Closed (remote) Closed Reserved (local) Reserved (local) Reserved (remote) Reserved (remote)

10. :path: / accept-encoding: gzip,deflate user-agent: :authority: … Static Table :authority: www.example.com Dynamic Table :method: GET :scheme: http :path: / :authority: www.example.com Lit- Index Name Value (Huffman-encoded string)

12. GET /index.aspx GET /style.css GET /logo.png GET /script.js App calls new IIS/ASP API with desired request headers Creates new request in http.sys pipeline, delivered to app as if client made request Push Promise /style.css /logo.png /script.js

14. iXHR Windows.Web.HTTP WWA Internet Explorer Spartan WebView IIS ASP.NET Web OC.NET WinHTTP Legacy Web Platforms