HTTP-2
HTTP/2. RFC 7540 introduced binary multiplexing and header compression for web transport in 2015.
Definition
HTTP/2 is the second major version of HTTP, published as RFC 7540 in May 2015. It replaces HTTP/1.1 pipelining with binary stream multiplexing over a single TCP connection, adds HPACK header compression (RFC 7541), enables server push, and effectively requires TLS 1.2 or above. It is today used by every PEPPOL Access Point and most AS4 hubs.
Origin
HTTP/2 derives from SPDY, an experimental protocol published by Google in 2009 and adopted by Chrome and Firefox. The IETF httpbis WG started standardisation in November 2012 and published RFC 7540 in May 2015. RFC 9113 (June 2022) updates the specification to incorporate errata and clarifications. HTTP/2 is the foundation of AS4 transport and most modern EDI platform webhook APIs.
Example in context
A PEPPOL Access Point can receive dozens of e-invoices simultaneously on the same TLS 1.3 + HTTP/2 connection thanks to multiplexing. Each invoice becomes an independent HTTP stream identified by a Stream ID, and repeated headers (Host, User-Agent, Content-Type SOAP+XML) are compressed via HPACK. Latency gains compared to HTTP/1.1 are typically 30 to 60 % at equal load.