Spec finalised late in 2015.
Supercedes some previous protocols such as SPDY.
Multiple streams multiplexed on a single connection.
Header compression as standard.
Browsers: Chrome, IE11, Firefox
Servers: Jetty (9.3), nginx (1.9.5)
Others: haproxy
HTTP/2 specifies both TLS and cleartext usage
TLS usage uses ALPN for protocol negotiation, on Java this needs bootclasspath hackage
Jetty supports a non-standard upgrade mechanism for cleartext
Browsers will not support HTTP/2 over cleartext
Jetty HTTP client already available
Connection-level ping might negate need for TCP keepalive required for Abacus