HTTP/2

HTTP/2: How we got here and what to do now.

Transcript

1. HTTP/2 This one goes to eleven
2. Pages Today (via HTTP Archive)
4. The Quest for Parallelism
5. HTTP/1.0 - 1996 • A New Connection per Request ◦ Huge overhead ◦ 3 packets for setup ◦ 4 packets for termination
6. HTTP/1.1 - 1997 • Persistent Connections ◦ Reuse the connection for multiple requests ◦ However: One outstanding request at a time • Pipelined Connections ◦ Multiple outstanding requests at a time ◦ However: FIFO order, slow requests block others ◦ However: Never really works ▪ "it's recommended nobody uses pipelining” - Chromium Project
7. The Quest for Parallelism
8. Best Practices!
9. Reduce the Number of Requests • Fewer Bigger Files ◦ JS/CSS Concatenation ◦ Image Sprites / Fonts • Inline Assets ◦ Inline JS/CSS ◦ Data URI for Images / Fonts
10. Increase Parallelism • Domain Sharding ◦ Browsers open ~6 connections per domain ◦ Shard assets across multiple domains for even more parallelism
11. Best Practices?
12. Reduce the Number of Requests • Fewer Bigger Files ◦ Download and parse unnecessary content ◦ Increases cache churn • Inline Assets ◦ Prevents caching of assets
13. Increase Parallelism • Domain Sharding ◦ Each connection has its own overhead ◦ Each connection competes with the others ◦ Many sites over shard ▪ After 2 shards performance degrades
14. HTTP/2
16. Fully Multiplexed • One connection per domain • Multiple outstanding requests • Fully async, out of order delivery ◦ Slow requests don’t block others
17. Fully Multiplexed
18. Server Push • Server / CDN can “push” assets before the client requests • Example Strategy ◦ Server / CDN observes requests ◦ Builds dependency graph using referer header ◦ Server / CDN is able to push page dependencies
19. Other Improvements • Efficient Binary Protocol ◦ Much faster to parse than test base protocols • Compressed Headers ◦ This includes cookies which can be huge
20. Best Practices!
21. Best Practices! • No more concatenation ◦ No more cache churn issues ◦ Only download what is needed • No more inlining ◦ Better caching • No more domain sharding ◦ Better resource utilization
22. Getting Started
23. Can I Use It?
24. CDN Support