Http-2

What we need to know

@h6165

Abhishek Yadav

ரூபீ ப்ரோக்ராமர்

Co-organizer: Chennai.rb

HTTP-2

• History
• Technical details
• Affects on Rails
• What we can use

HTTP: History

• 1991: HTTP 0.9 - First documented version
• 1996: HTTP 1.0 (rfc-1945), work starts on HTTP 1.1 (rfc-2068)
• 1997, 1999: HTTP 1.1 release and improvements (RFC-2068, RFC-2616)
• 2007: HTTPbis working group starts work on revising HTTP 1.1
• 2012: First draft of SPDY published
• 2014: HTTPbis submits new spec
• 2015: HTTP-2 published. Google announces stopping support for SPDY

HTTP: History

• 1991: HTTP 0.9 - First documented version
• 1996: HTTP 1.0 (rfc-1945), work starts on HTTP 1.1 (rfc-2068)
• 1997, 1999: HTTP 1.1 release and improvements (RFC-2068, RFC-2616)
• 2007: HTTPbis working group starts work on revising HTTP 1.1
• 2012: First draft of SPDY published
• 2014: HTTPbis submits new spec
• 2015: HTTP-2 published. Google announces stopping support for SPDY

1989: Tim Berners Lee: First GET requests

1996: Browser wars

1996: 40-60 % browsers already on Http1.0

1998: Google founded

1997-2000: Dot Com Bubble

2004: Facebook founded

2004: Gmail launched

2007: Iphone released

2008: Android released

2005: Ruby on Rails-1

2011: Rails 3.1: asset pipeline

2000: Roy Fielding: REST

2008: Chrome launched

2008: HTML5 Draft-1

2014: HTML5 finalized

2013: Chrome-29: SPDY

2011: Websockets shipped

2013: Snowden: NSA

2014: India: Modi as PM: massive use of social media

HTTP: History

• 1991: HTTP 0.9 - First documented version
• 1996: HTTP 1.0 (rfc-1945), work starts on HTTP 1.1 (rfc-2068)
• 1997, 1999: HTTP 1.1 release and improvements (RFC-2068, RFC-2616)
• 2007: HTTPbis working group starts work on revising HTTP 1.1
• 2012: First draft of SPDY published
• 2014: HTTPbis submits new spec
• 2015: HTTP-2 published. Google announces stopping support for SPDY

1989: Tim Berners Lee: First GET requests

1996: Browser wars

1996: 40-60 % browsers already on Http1.0

1998: Google founded

1997-2000: Dot Com Bubble

2004: Facebook founded

2004: Gmail launched

2007: Iphone released

2008: Android released

2005: Ruby on Rails-1

2011: Rails 3.1: asset pipeline

2000: Roy Fielding: REST

2008: Chrome launched

2008: HTML5 Draft-1

2014: HTML5 finalized

2013: Chrome-29: SPDY

2011: Websockets shipped

2005-2015: China+India add 600 million users (450+180).

India is at 350million now 

HTTP: History: Conclusion

• HTTP 1.1 has been stable, and popular

• Internet has changed, has newer challenges

  • Majority users are on mobile

  • Privacy and security have become political

  • Governments are major stakeholders

• THe web must be efficient and secure

HTTP-2: Technical details

• HTTP is built on top of TCP

• A typical web page load in browser: 

  • ​Open TCP connection

  • Send the GET request

  • Receive HTML, parse it, start rendering it

  • Open new TCP connection for each asset referred in the html (asset: Javascript, CSS, image, font)

• Server sends data only when browser requests it (exception: Websockets)

• Every new connection creates a massive overheard

HTTP-2: Technical details

• Popular websites have hundreds of such requests

• Only upto 6 parallel connections are permitted per domain

HTTP-2: Technical details

• Concatenating JS and CSS  (Rails asset pipeline)

• Creating sprites from images

• Data inlining for images

• Domain Sharding: serving assets from different domains to parallelize

• Caching (Conditional GET, Etag etc)

• HTTP Pipelining

Optimizations to HTTP 1.1

HTTP-2: Technical details

• Connection multiplexing
• Server push

HTTP-2 Proposals

• Header compression
• Binary encoding

HTTP-2: Technical details

• There will be a single, long-lived TCP connection
• The connection will be duplex (TCP is)

HTTP-2 Proposals: connection multiplexing

HTTP-2: Technical details

• All assets can be sent over the same connection. No need to reconnect
• Server can push assets instead of waiting for client to ask
• Client can express preference for certain assets, and get them before others (stream prioritisation)

Connection multiplexing: possible impacts

And

• No need for any of the HTTP 1.1 optimisations - no need of asset-pipeline
• No need of Websockets (https://samsaffron.com/archive/2015/12/29/websockets-caution-required)

HTTP-2: Technical details

• Header compression will some some bandwidth. Little from developer point of view, more as a big picture
• Binary encoding will also make transport efficient. Developers will need more tools for debugging (like Wireshark)

Compression and encoding

• No need for any of the HTTP 1.1 optimisations - no need of asset-pipeline
• No need of Websockets

And

HTTP-2: Technical details

• Spec doesn't require HTTPS, but implementations do.
• All major browsers require TLS mandatorily with HTTP-2 

Impacts: HTTPS

HTTP-2: Today

• Implemented by all major browsers
  • Except Android browser

HTTP-2: Today

• Implemented by almost all major browsers
• Implemented by Apache and Nginx
• Supported by default on Cloudflare CDN (out assets are served with HTTP2)
  • Server push also announced recently:  https://blog.cloudflare.com/announcing-support-for-http-2-server-push-2/

HTTP-2: Today

In Rails world

• Rack is not HTTP-2 compatible
• So no Rack based frameworks can use it
• Some experimental work has been done. 

HTTP-2 experiments with Rack