A Faster Future with HTTP/2

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A FASTER FUTURE WITH HTTP/2 By / Engineer @ , Heroku alum Blake Gentry @blakegentry Opendoor GoSF, April 2015

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HTTP/2 A QUICK INTRO

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WHY HTTP/2? Performance. End-user perceived latency Network and server resource usage More effective use of bandwidth

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WHAT DOES HTTP/2 CHANGE?

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What does HTTP/2 change? WHAT DOES HTTP/2 NOT CHANGE?

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HTTP/2 IS JUST LIKE HTTP/1.1* *SEMANTICALLY

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STUFF THAT DOESNT CHANGE Request methods Status codes URLs Other HTTP paradigms

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HTTP/2 == A NEW BINARY FRAMING LAYER FOR HTTP

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HTTP/2: MAIN IMPROVEMENTS Multiplexed streams (requests & responses) Header compression (HPACK) Secure TLS required-ish Less optional parts

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DOES IT MATTER?

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HTTP/2: ALL-NEW FEATURES

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GRACEFUL SHUTDOWN Peer can stop accepting new streams, yet finish old ones Enabled by the G O A W A Y frame Peer can stop accepting new streams, yet finish old ones Can be sent by either client or server Includes ID of last processed stream

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SERVER PUSH “Here, you'll need this too”

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STREAM PRIORITY Prioritize more important data streams DEPENDENCIES “B depends on A” WEIGHT “C is ½ as important as A”

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FLOW CONTROL Permission to send more data Credit-based scheme, 65k default Per-connection, and per-stream Applies only to DATA frames (message bodies)

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STREAM RESET “j/k, I don't need that” Cancel requests or pushes

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CHALLENGES

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HTTP/1.1 OPTIMIZATIONS HARMFUL TO HTTP/2 PERF Domain sharding Image sprites Inlining Asset concatenation

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OPTIMIZE FOR HTTP/1.1 OR HTTP/2? Decide when to switch OR optimize for both at the same time

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HTTP/2 IS ALREADY HERE! >9% usage in Firefox ( ) source Browser adoption will be extremely rapid.

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PUSH IS AWESOME, I'M GOING TO USE IT FOR EVERYTHING!

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SERVER PUSH NOT AS SIMPLE AS IT SEEMS When do we push? Which resources are needed? Does the client already have it cached? How to combine with resource hints?

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SERVER PUSH WHAT ELSE CAN WE PUSH? On 3XX, push the new resource Push additional API responses Push API dependencies for front-end apps ?

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STREAM PRIORITY What combination of weights and dependencies is optimal?

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HOW CAN WE MAKE THIS EASIER?

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WEB PERFORMANCE IS ALREADY COMPLICATED.

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THE GOOD NEWS: HTTP/2 GIVES US A LOT FOR FREE

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THE BAD NEWS: GETTING THE MOST OUT OF HTTP/2 WON'T BE EASY

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IF PERFORMANCE MATTERS, YOU CAN'T IGNORE HTTP/2

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LET'S MAKE IT EASIER.

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CDNs or reverse proxies that make these decisions for you Packages to figure out which resources should be pushed …or track which have already been pushed Perf. testing to determine optimal priorities …or which other optimizations are worthwhile

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GO IS THE PERFECT LANGUAGE FOR THIS

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WE'RE HIRING: Front-end Engineers (Angular) Data Engineers Data Scientists

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THANKS! Blake Gentry / @blakegentry

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REFERENCES , HTTP/2 Draft 17 HPACK Draft 11 HTTP/2 home page SPDY Whitepaper HTTP/2 Explained bradfitz/http2