Learning HTTP/2
A Practical Guide for Beginners
Stephen Ludin and Javier Garza
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Learning HTTP/2
by Stephen Ludin and Javier Garza
Copyright © 2017 Stephen Ludin, Javier Garza. All rights reserved.
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June 2017: First Edition
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Revision History for the First Edition
2017-05-14: First Release
See http://oreilly.com/catalog/errata.csp?isbn=9781491962442 for release
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Preface
HTTP/2, also called h2 for simplicity, is a major revision of the HTTP
network protocol used by the World Wide Web, meant to improve the
perceived performance of loading web content.
Since HTTP/1.1 (h1) was approved in 1999, the web has changed significantly
from mostly text-based web pages that weighed a few kilobytes and included
less than 10 objects, to today’s media-rich websites that weigh on average
over 2 megabytes,
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and include an average of 140 objects. However, the HTTP
protocol used to deliver the web content did not change in the intervening
years, making room for a new industry of Web Performance experts who
specialize in coming up with workarounds to help the aging protocol load web
pages faster. People’s expectations for performance have changed too — while
in the late ’90s people were willing to wait up to seven seconds for a page to
load, a 2009 study by Forrester Research found that online shoppers expected
pages to load under two seconds, with a large share of users abandoning sites
where pages take over three seconds to load. A recent study by Google showed
that a even a delay of 400 milliseconds (the blink of an eye) will cause people
to search less.
That’s why h2 was created — a protocol that can better handle today’s
complex pages without sacrificing speed. HTTP/2’s adoption has been
increasing
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as more website administrators realize they can improve the
perceived performance of their websites with little effort.
We all use h2 every day — it powers some of the most popular sites like
Facebook, Twitter, Google, and Wikipedia — but many people don’t know
about it. Our goal is to educate you on h2 and its performance benefits, so you
can get the most out of it.
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