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HTTP/2 and web development practices
This document discusses HTTP/2 and improvements over HTTP/1.x including a binary format, multiplexing, stream priority, flow control, header compression, and server push. HTTP/2 aims to improve bandwidth utilization, reduce latency, and overcome head-of-line blocking which is an issue in HTTP/1.x. Developers need to rethink some HTTP/1.x best practices like resource concatenation for HTTP/2 while still optimizing performance through techniques such as reducing DNS lookups, using CDNs, caching, and minimizing HTTP requests.
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HTTP/2 and web development practices
- 1. HTTP/2 and webdevelopment practices Developing for H2
- 2. HTTP • HTTP/1.0 (RFC-1945– May 1996) • HTTP/1.1 (RFC-2068 – Jan 1997) • HTTP/2 (RFC-7540 – May 2015) https://www.ietf.org/download/rfc-index.txt
- 3. HTTP/1.x improvements • Persistentconnection (HTTP keep alive) • HTTP pipelining • Session state (cookies) • HTTP over TLS
- 4. Performance Issues • Bandwidthutilization • Resource consumption • High latency • Complex web design
- 5. Head-of-line blocking 1 outstandingtransaction per TCP connection
- 6. H1 best practice •Domain sharding • Resource concatenation • Spriting • Resource inlining
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- 11. H2 benefits • Binaryformat • Multiplexing – Stream priority – Flow control • Header compression • Server push • Mandatory encryption ??? • Opportunistic encryption
- 12. Header Compression • ~100 assets • ~1 / 2 Kb each (Cookies, Referer, etc.) • Multiple round trips to get them out
- 13. H2 benefits • Binaryformat • Multiplexing – Stream priority – Flow control • Header compression • Server push • Mandatory encryption ??? • Opportunistic encryption
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- 17. H2 benefits • Binaryformat • Multiplexing – Stream priority – Flow control • Header compression • Server push • Mandatory encryption ??? • Opportunistic encryption
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- 20. Conclusion: developing for H2 •Rethink resource concatenation • Undo some HTTP/1.x best practices • Keep doing – Reduce DNS Lookups – CDN – Caching – Minimize HTTP requests – Reduce Redirects
Editor's Notes
- #3 IETF Index: https://www.ietf.org/download/rfc-index.txt HTTP2: RFC-7540, RFC-7541, RFC-8164
- #4 HTTP pipelining: multiple serial requests over single TCP without waiting for the response
- #6 The “head-of-line blocking” is the phenomenon where effectively only one request can be outstanding on a connection at a time It has been fixed with HTTP pipelining, but it didn’t completely address the problem (a large or slow response can still block others behind it)
- #7 Domain Sharding – splits resources across subdomains to improve performance. Allow simultaneous resource download at any given time Concatenation – bundles several Javascript files into single minified Javascript file It Introduced numerous regressions: poor caching, unnecessary downloads, delayed execution With the concatenation we lose the caching benefit, because there is no granularity. Image Spriting - is a collection of images put into a single image
- #8 Inlining Images - uses data URI to embed image items. Inline images saves HTTP requests over externally referenced objects. Refer link for more details
- #11 Initial Google effort with a protocol called SPDY HTTP/2 was developed by the IETF’s HTTP Working Group, SPDY was gaining traction with implementers (like Mozilla and nginx), so it was chosen as the basis for HTTP/2 Core engineer at Google Mike Belshe and Roberto Peon, joined the H2 effort. Google deprecated the protocol and adopted H2
- #12 HTTP/1.x semantic is mantained (HTTP verbs, request/response schema, etc), but is not backwards compatible due to the binary format Binary format: binary protocols are more efficient to parse, more compact “on the wire”, and most importantly, they are much less error-prone Multiplexing address the HOL blocking Priority: The purpose of prioritization is to allow an endpoint to express how it would prefer its peer to allocate resources when managing concurrent streams. Flow control: ensures that streams on the same connection do not destructively interfere with each other. Encryption: is not mandatory, but major browser vendors implemented H2 over TLS. Opportunistic encryption: using TLS for HTTP URLs
- #13 Not uncommon to have multiple assets of several Kbs Conservative estimation
- #19 Opportunistic encryption: using TLS for HTTP URLs
- #20 To enable HTTP/2 on NginX