HTTP2 & HPACK #pyfes 2013-11-30

HTTP2.0 & HPACK
based on draft-08
2013/11/30
#pyfes

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id: Jxck
github: Jxck
twitter: jxck_
about: http://jxck.io
blog: http://d.hatena.ne.jp/jxck
Love: music

Jack

History of HTTP
...
1996/ 5
1997/ 1
2009/11
...
2011/ 9
2012/ 8
2012/11
...
2013/ 7
...
2013/10
2013/11

HTTP/0.9
HTTP/1.0 (RFC 1945)
HTTP/1.1 (RFC 2068)
SPDY/1
WebSocket(RFC 6455)
HTTP/2.0 start
HTTP/2.0 (draft-00)
HPACK

(draft-00)

HPACK
(draft-04)
HTTP/2.0 (draft-08)

HTTP / 1.1
motivation

version

●
●
●
●

● HTTP/0.9
● HTTP/1.0
● HTTP/1.1

Sharing Documents
Over TCP
Text Base Protocol
Stateless

○ Keep-Alive
○ Pipelining

Req / Res on HTTP/1.1
Text Base Protocol
GET /index.html HTTP/1.1
Host: example.org
Accept: text/html

CLIENT

HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 35
<!DOCTYPE html>
<title>hello</title>

SERVER

HTTP ?
● Simple
○ text base, easy scaling etc
○ good for document sharing
○ but Good for Now ?

● now “Web” is
○
○
○
○

Plat Form (not only document sharing)
Ajax, WebSocket…
tons of JS, CSS, Images...
PC, Mobile, Tablet, TV, Game …

● needs
○ more speed
○ more efficiency
○ more secure

about HTTP2
● httpbis wg at IETF from 2012
● motivation
○ update HTTP/1.1
● version
○
○
○
○
○

draft-00 (copy of spdy/3)
...
draft-08 (2013/11/30 current)
...
RFC XXXX (2014 spring? bit.ly/130oZrZ)

SPDY or HTTP2.0 ?

SPDY/3

http2.0-00

SPDY/4

http2.0-01
http2.0-08

SPDY/n

??

http2.0

specs
● working on github !
○

https://github.com/http2/http2-spec

● draft
○

http://tools.ietf.org/wg/httpbis/draft-ietf-httpbis-http2/

● current (2013/8/28)
○

http://tools.ietf.org/html/draft-ietf-httpbis-http2-08

● ML
○

http://lists.w3.org/Archives/Public/ietf-http-wg/

○

https://www.ietf.org/mailman/listinfo/http-devops

HTTP/2.0 draft-08
●
●
●
●
●

Multiplexing (same as spdy)
Server Push (same idea as spdy)
ALPN / Upgrade
Binary Frames
HPACK

Starting HTTP2.0 (1/2 step)
● “http://”
○ Upgrade Header like websocket

● “https://”
○ ALPN (application layer protocol negotiation)
○ not NPN like spdy

● Known Supported
○ prior knowledge from DNS or so
○ may immediately send http2.0 frame

TLS-ALPN (Application Layer protocol negotiation)

Starting HTTP2.0 (2/2 step)
● sending connection header
○ make sure peer supports http2.0
○ with Magic Octets
505249202a20485454502f322e300d0a0d0a534d0d0a0d0a

invalid
Method PRI

PRI * HTTP/2.0
rnrn
SM
rnrn

2 new line
for parser

Frame Type
●
●
●
●
●
●
●
●
●
●

DATA
HEADERS
PRIORITY
RST_STREAM
SETTINGS
PUSH_PROMISE
PING
GOAWAY
WINDOW_UPDATE
CONTINUATION

HEADERS & DATA frame
HEADERS(stream_id=1)
+ END_STREAM
+ END_HEADERS
:method = GET
:scheme = https
:authority = example.org
:path = /index.html
accept = text/html

HEADERS(stream_id=1)

CLIENT

- END_STREAM
+ END_HEADERS
:status = 200
content-type = text/html
content-length = 35

DATA(stream_id=1)
+ END_STREAM
<!DOCTYPE html>
<title>hello</title>

SERVER

Server Push(1)
HEADERS

(stream_id=1)

+ END_STREAM
HTTP/1.1 200 OK
+ END_HEADERS
Content-Type: text/html
:method = GET
Content-Length: 123
:scheme = https
{binary data} example.org
:authority =
:path = /index.html
accept = text/html

CLIENT

PUSH_PROMISE

(stream_id=1)

+ END_PUSH_PROMISE
Promised-Stream-ID=2
:method = GET
:scheme = https
:authority = example.org
:path = /a.png

SERVER
PUSH
Request

Server Push(2)

HEADERS

CLIENT

- END_STREAM
+ END_HEADERS
:status = 200
:path = /a.png
content-type = image/png
content-length = 123

DATA

Browser
Cache

(stream_id=2)

(stream_id=2)

+ END_STREAM
{binary data}

PUSH
Respons

SERVER

Server Push(2)

HEADERS　(stream_id=1)
- END_STREAM
+ END_HEADERS
:status = 200
content-type = text/html
content-length = 33

CLIENT

Response
SERVER

DATA

(stream_id=1)

+ END_STREAM
<html>
<img src=”a.png”>
</html>

cache hit !!

HPACK (header compression)
● HTTP Header
○ Text Base
○ Long Name
○ Send multiple time

● SPDY compression
○ CRIME

● HPACK
○ send diff
○ using binary

Static Header Table
Index

Header Name

1

:authority

2

:method

3

Header Value

...

...

51

refresh

GET

52

retry-after

:method

POST

53

server

4

:path

/

54

set-cookie

5

:path

/index.html

55

strict-transport-security

6

:scheme

http

56

transfer-encoding

7

:scheme

https

57

user-agent

8

:status

200

58

vary

9

:status

500

59

via

...

...

...

60

www-authenticate

...

Huffman Code (Request)
sym
'a'
'b'
'c'
'd'
'e'
'f'
'g'
'h'
'i'
'j'
'k'
'l'
'm'
'n'
'o'

( 97)
( 98)
( 99)
(100)
(101)
(102)
(103)
(104)
(105)
(106)
(107)
(108)
(109)
(110)
(111)

MSB
|01000
|101111
|01001
|110000
|0001
|110001
|110010
|110011
|01010
|1110001
|1110010
|01011
|110100
|01100
|01101

len
[5]
[6]
[5]
[6]
[4]
[6]
[6]
[6]
[5]
[7]
[7]
[5]
[6]
[5]
[5]

hex
8
2f
9
30
1
31
32
33
a
71
72
b
34
c
d

LSB
[5]
[6]
[5]
[6]
[4]
[6]
[6]
[6]
[5]
[7]
[7]
[5]
[6]
[5]
[5]

Header Representation
● Indexed Header Representation
● Literal Header Representation
○ Literal Header without Indexing
○ Literal Header with Incremental Indexing

HPACK example (1/2)
63byte -> 16byte
Request Header
:method: GET
:scheme: http
:path: /
:authority: www.example.com

Static Table

Decoded Data
82 ADD index 2
87 ADD index 7
86 ADD index 6
04 8b db6d 883e 68d1 cb12 25ba 7f
ADD key at index 4
value “www.example.com”

1

:authority

2

:method

GET

3

:method

POST

Reference Set

4

:path

/

1

:authority

www.example.com

5

:path

/index.html

2

:path

/

6

:scheme

http

3

:scheme

http

7

:scheme

https

4

:method

GET

HPACK example (2/2)
87byte -> 8byte
Request Header
:method: GET
:scheme: http
:path: /
:authority: www.example.com
cache-control: no-cache

Decoded Data
1b 86 63 65 4a 13 98 ff
ADD key at index 27
value “cache-control: no-cache”

Static Table
1

:authority

2

:method

GET

Reference Set

3

:method

POST

1

cache-control

no-cache

4

:path

/

2

:authority

www.example.com

5

:path

/index.html

3

:path

/

6

:scheme

http

4

:scheme

http

7

:scheme

https

5

:method

GET

implementations
●
●
●
●
●
●
●
●
●
●
●
●
●

nghttp2
C
http2-katanaC#
node-http2
node.js
Mozilla
C++
http2-perl
Perl
iij-http2
node.js
Akamai GhostC++
Chromium
C++
Hasan's GFE
C++
Twitter
Java
Wireshark
C
http2-go
Go
http2
Haskell

see: https://github.com/http2/http2-spec/wiki/Implementations

nghttp2
● C implementation library
● nghttp
○ client cli tool
● nghttpd
○ file server
● nghttpdx
○ proxy

web frontend of nghttp2 => http2cat

HTTP2Cat (https://jxck.io/labs/http2cat)

books
● High Performance Browser Networking
○ by Ilya Grigorik(Google)

● Translate to Japanese ?
○ http://twitter.com/turky/status/406663190768914432

HTTP2 & HPACK #pyfes 2013-11-30

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