SPDY - Clean Slate HTTP

• About SPDYo What is SPDYo Goalso Features

• About HTTPo Simple HTTPo Pipelining for cuncurrencyo Pipelining doesn’t help

• SPDY in a nutshello Multiplexed Requestso Prioritized Requestso Compressed Headerso Server Push & Server Hint

About SDPY : What is SPDY

o An open networking protocolo Developed at Googleo Trademark of Google(not an acronym)o Started over 3 years agoo A protocol to Reduce latency

About SPDY: Goals

• Around 50%deduction in page load time

• Concurrent HTTP requests across a single TCP

• Reduce band width

About SPDY: Features

Always operates on Transport Layer Security (TLS).

• Transport Layer Security (TLS) is the next version of Secure Sockets Layer (SSL).

SPDY applies only to websites written with HTTPS.

SPDY - Clean Slate HTTP

•  About SPDYo What is SPDYo Motivationo Features

• About HTTPo Simple HTTPo Pipelining for cuncurrencyo Pipelining doesn’t help

• SPDY in a nutshello Multiplexed Requestso Prioritized Requestso Compressed Headerso Server Push & Server Hint

About Http: Simple Http

1 Open a connection

2 Send a request

3 Receive a response

4 Repeat request and response

5 Close the connection, and done

Single request per connection

About HTTP : Pipelining for cuncurrency

About Http: “Pipelining" doesn't help

• FIFO queue

• HOL(head of the line) block

• Additional round trips for connection setup

• Slow-start delays

• Waiting for the first response to be complete :

Performance Loss

Solution…

SPDY - Clean Slate HTTP

•  About SPDYo What is SPDYo Motivationo Features

• About HTTPo Simple HTTPo Pipelining for cuncurrencyo Pipelining doesn’t help

• SPDY in a nutshello Multiplexed Requestso Prioritized Requestso Compressed Headerso Server Push & Server Hint

SPDY in a nutshell

• One TCP connection

• Multiplexed

• Prioritized

• Headers compressed

• Server initiated stream

SPDY : Multiplexed requests

SPDY allows for unlimited concurrent streams over a single TCP connection

There is no limit to the number of requests that can be issued concurrently over a single SPDY connection

SPDY: Prioritized Requests

• Not all requests are equal!

• Allow clients to mark priority on each resource

• server best effort to deliver

SPDY: Compressed HeadersAverage request /response header: ~600bytesNo compression for headers in HTTP(redundant data)

Compressing the headers in SPDY: Save latency and bandwidth compared to HTTPFewer Packets and bytes transmission

Request Headers 1st 2nd

HTTP Request 686.2 636.4

SPDY Request 379.4 (55%) 68.6 (10%)

Response Headers 1st 2nd

HTTP Response 444.6 418.7

SPDY Response 202.0 (45%) 69.2 (17%)

Server push and server hint • Server Push: Server pushes a resource directly to the client without the

client asking for the resource.

Save 1 round-trip

It is wasteful, if the resource is in cache

• Server Hint: Server can notify the client of a resource that will be needed before the client can discover it.

Early discovery of critical resources

Allow cache validation

One round-trip between client and server

Results in Diagrams

Page Load Time as Latency Decreases

Page Load Time - Http vs SPDY

Thank you!Looking forward to a fantastic HTTP/2.0!

Resources:

• SPDY: An experimental protocol for a faster web• A Methodology to Derive SPDY’s Initial Dictionary for Zlib• The Chromium Project:SPDY Protocol• HTTP Pipelining