Http/2

Why Change HTTp?

The WEb Changed

HTTP/1.1 RFC is 15~ years old (June 1999)

Heavier

More Interactive

Mobile

Internet of Things

Performance

=

Attention

=

$$$

Eliminate Requests

Techniques

Spriting

Inlining

Concatenation

Sharding

these are technically

Indications that the underlying technology can be better

Hacks

How does http/1.1 work?

Why are requests so expensive?

1: HTTP/1.1 uses TCP poorly

HTTP flows are short & bursty,
TCP is built for long-lived flows

When your HTML needs a file, the client
opens a TCP connection to the server through HTTP.

The server responds, says, "yeah, here's the file," and starts sending chunks of the file until the client has the whole thing.

The client, after it has everything, says "thanks",

and closes the TCP connection.

2: TCP connections exhibit a slowstart when opened

This means every time a TCP connection is opened,
it takes a few packets until the TCP connection
has reached throughput peak.

Slow start exists to combat network congestion,

double-edged performance sword

TCP Slowstart

Typical requests per page

Late 2014: average of 90-100 @ 1.5mb

2010: average of 55-65 @ 600k

3: Browsers "guess"

State of the Art: Browsers allow 4-8 open,

active connections at a time.

TCP Head of Line Blocking

Networks become congested if more connections
are active (congestion control is your friend)

HTTP/1.1 isn't designed to identify what files are
important on the client end; very confusing about
where responsibilities lie.

So

HTTP/1.1 doesn't use TCP right

Because of that, TCP slowstart kicks in very often

And browsers need to make educated guesses
about a lot of stuff

WHAT IS HTTP/2?

Initially a Rewrite of RFC 2616 (HTTP/1.1)

Google did SPDY, brought it to the IETF, and it became

HTTP/2 (RFC 7540) as of May 15, 2015 (4+ years work)

For: Clarity, speed, cleanups, security, much more.

TECHNICAL goal

Take advantage of one TCP connection

backward incompatible

HOW DOES

HTTP/2

WORK?

The idea is everything is sent in one TCP connection

Everything should work like normal, but with
new features and behaviors

Features

Prioritization

Flow Control

Header Compression through HPAC

TLS will be mandatory

Questions?

Let's talk & drink beers!

William M. Riley: @bill_riley

Grain & Mortar: @grainandmortar

AIGA Nebraska: @AIGA_nebraska

Midwest Dev Chat: http://midwestdevchat.com

Midwest Design Chat: No site yet, ask me if you'd like to join!

Hubdia: @hubdia

Tapped: http://tappedapp.co

Http/2 (SPDY)

By bill_riley

Http/2 (SPDY)

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