IETF bakes Google's SPDY protocol into HTTP 2.0

Google's SPDY (speedy) protocol has been adopted by the Internet Engineering Task Force (IETF) for use in the forthcoming HTTP 2.0 standard.

Google developed SPDY as part of its ongoing efforts to speed up the Web. While its work to do so isn't entirely altruistic – a faster web means more users doing more on Google – the company released a comprehensive draft of the protocol.

The Chocolate Factory has outlined three main ways in which SPDY speeds things up, namely:

• SPDY allows client and server to compress request and response headers,which cuts down on bandwidth usage when the similar headers (e.g. cookies) are sent over and over for multiple requests.
• SPDY allows multiple, simultaneously multiplexed requests over a single connection, saving on round trips between client and server, and preventing low-priority resources from blocking higher-priority requests.
• SPDY allows the server to actively push resources to the client that it knows the client will need (e.g. JavaScript and CSS files) without waiting for the client to request them, allowing the server to make efficient use of unutilized bandwidth.

The IETF obviously likes those ideas, as the httpbis working group, which oversees HTTP, last week published a draft spec for HTTP 2.0 that integrates SPDY into the next version of HTTP.

The draft says today's HTTP standard “... causes several problems, including additional round trips for connection setup, slow-start delays, and connection rationing by the client, where it tries to avoid opening too many connections to any single server.”

Workarounds like HTTP pipelining, the draft says, aren't long-term fixes.

SPDY, by contrast, hurries things along nicely while also preserving current HTTP semantics, and “only replaces the way the data is written to the network.”

“SPDY introduces two layers of protocol,” the draft explains. “The lower layer is a general purpose framing layer which can be used atop a reliable transport (likely TCP) for multiplexed, prioritized, and compressed data communication of many concurrent streams.”

“The upper layer of the protocol provides HTTP-like semantics for compatibility with existing HTTP application servers.”

Google uses SPDY widely and has in the past said SPDY improves page load times by 15 per cent, and was designed to halve the time needed to load a page. The protocol has also found its way into Chrome, Opera, Firefox and Amazon's Silk browser, while Twitter has enabled its servers to 'do' SPDY.

The IETF's draft is worded in the usual very cautious language that makes it clear SPDY is a long way from being set in stone, but the discussion thread on the topic has not seen new comments on the protocol since mid-October. That could be a sign of general agreement that SPDY deserves its place in HTTP 2.0, or just a slow week in the forums.

In either case, it seems worth keeping an eye on the scheduled January 2013 meeting of the httpbis working group. ®