Web pages, dynamic or not, are resource intensive. Browsers typically open one or more TCP connections to an infrastructure to request resources. This motivated the Internet Engineering Task Force (IETF) to pursue a new protocol focused on network performance. In the process, other improvements were adopted. HTTP/2 is the latest generation of HTTP protocols. The main body of the new protocol was influenced and based on Google-sponsored SPDY.

HTTP/2 has several advantages over HTTP:

• Messages are binary instead of textual.

• Fully multiplexed, instead of ordered and blocking.

• Everything happens in one connection.

• Compressed headers.

• Infrastructure can proactively push information/resources not requested by clients.

• Two protocols for SSL/TLS negotiation: NPN and APLN. The Acquia platform uses OpenSSL 1.0.2g which supports both protocols.

Using the protocol and these features can reduce response time for websites.

Acquia supports HTTP/2 on its platform, with some exceptions. If you have a compliant HTTP/2 client, no configuration is required.

Unsupported features

Acquia’s HTTP/2 implementation doesn’t support the following features:

• Non-secure connections: TLS-protected requests are supported with HTTP/2 on Cloud Platform. Non-encrypted connections will always be served over HTTP/1.1.

• Elastic Load Balancers (ELB): Subscribers who have an ELB cannot use HTTP/2.

• Infrastructure Push

CDNs

If your website is behind a CDN which supports HTTP/2, such as Acquia Cloud Edge, it has HTTP/2 support. If your website is behind a CDN that doesn’t support HTTP/2, you won’t.

HTTP/2 support on Cloud Platform