http2

What is http?

HTTP is a protocol for data transfer on the internet used by the web browsers.

HTTP mainly sits on top of TCP, which provides reliable, error-checked delivery of the data between nodes on a network.

Hypertext Transfer Protocol

What is http2?

An update to http1.1, which is over 15 years old now.

An attempt to combat the growing size of websites, and speed up the web.

How?

1: Multiplexed

LIKE CRAMMING MULTIPLE BITS OF PAPER INTO A SINGLE ENVELOPE - The verge

HTTP/1.x:

Ordered and blocking. only one request can be outstanding on a connection at a time.

HTTP/2:

Multiple request and response messages to be in flight at the same time

Benefits

With HTTP/1, browsers would open up to 30 connections per website
( 4 - 6 per origin * multiple origins)

Could cause overflow by bypassing TCP congestion control and "stole" network resources from other applications.

Speed and reliability

2: Server Push

Benefits

"Server Push allows the server to avoid this round trip of delay by “pushing” the responses it thinks the client will need"

Speed!

3: Header Compression

The http header define the operating parameters of an HTTP transaction.

HTTP2 will compress the headers significantly 

"If you assume that a page has about 80 assets, and each request has 1400 bytes of headers, it takes at least 7-8 round trips to get the headers sent”

This is because of "TCP slow start", which is a mechanism for detecting the max transfer speed, but also limiting the size of the first round trips.

Mobile clients, which typically see round-trip latency of several hundred milliseconds, even under good conditions.

round trips?

From high performance browser networking

Benefits

Again.. speed!

When?

Formally approved, so at that point it is up to websites, hosting services and companies such as Google to implement the standard.

 

Google has already said that it’s current SPDY protocol will be withdrawn in favour of HTTP/2 in Chrome by early 2016.

It'll be fast

Conclusion

http://www.theguardian.com/technology/2015/feb/18/http2-speed-up-web-browsing-desktop-mobile

Text

http://http2.github.io/faq/

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By Bård Hovde

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