The new Cowboy

Le Cowboy nouveau est arrivé !

Loïc Hoguin - @lhoguin

Erlang Cowboy and Nine Nines Founder

The Cowboy guy

Fact 1

• I know you but I forgot your name or face, remind me!

Fact 2

• Not drinking alcohol, offer me a coke, not a beer!

Fact 3

• I forget my hat all the time. :(

The road so far

Beginnings

• Unsatisfied with existing solutions
• Wanted a mix of Webmachine and Misultin
  • With binaries
  • And dynamic "listeners"
  • And some icing on top
• First commit on March 7th 2011

Initial goals

• Binary
• Dynamic listeners
• Low latency and memory usage
• One Erlang process per connection
• Small codebase
• Clean Erlang code

Initial reactions

• Encouraging
• Community started growing slowly
• People started recommending Cowboy to others
• First Cowboy talk at EUC 2011 had a full room

Misultin's help

• Great project
• Still unmatched in usability
• Development stopped in favor of Cowboy
• Boosted Cowboy's adoption
• My thanks go to Roberto Ostinelli

The road to stable

• Few changes for about 6 months
• Spent a lot of time figuring things out
• Then spent a lot more time getting things done
• A few improvements remain to be done

Recent changes

Mascot

New goals

• Complete HTTP stack
• Complete support for the modern web
• Good documentation
• Stable version
• Target non-Erlang developers

New conventions

• Everything is a binary, including method and header names
• HTTP header names are lowercase
• cowboy_http_req -> cowboy_req
• cowboy_http_* -> cowboy_*

HTTP

• Improved HTTP/1.1 and HTTP/1.0 support
• Built-in response compression
• Built-in parsing of HTTP headers
• Much faster request body streaming code
• Properly detect socket close in long-polling

HTTP Req

• Normalized cowboy_req API
• Access: {Value, Req}
• Action: {Result, Req} | {Result, Value, Req} | {error, atom()}
• Modification: Req
• Question: boolean()

Websocket

• Fully passes the Autobahn test suite
• Much faster at processing frames
• Text frames now required to be valid UTF-8

REST

• Better error reporting
• PATCH method support
• Still experimental, no documentation
• Widely adopted by users

More powerful routing

• Routes must now be compiled
• Nicer string-based syntax
• Constraints: apply functions on bound values
• Allows distinguishing between these two:
  • /api/42/add
  • /api/blue/add

Middlewares

• Hook code at any point in request handling
• Replace routing or handling components of request processing
• Not WSGI
• WSGI: data centric, chain request, then reverse chain response
• Cowboy: chain of execution, only chain request, response happens at any point

Documentation

• Cowboy now has a guide!
• Still many improvements can be made
• Feedback needed

Focus on performance

Improvements

Testing in production

• Synthetic benchmarks don't help
• Most interesting results are under heavy load
• Users' production systems are the best benchmark
• The PROWESS Project might deliver benchmarking tools later on

NIFs and BIFs

• NIFs considered harmful
• BIFs can be harmful too!
• BIF doesn't mean "fast" or "scheduler friendly"

Example of BIFs killing scalability

• erlang:decode_packet/3
• binary:match/2
• lists:length/1
• ...

Performance tips

• Measure, measure, measure
• Don't assume something is faster, measure it
• Optimize the critical code path
• Don't waste your time on code that is rarely ran

Project status

Actively developed

• Cowboy is Nine Nines' main product
• Cowboy is the central project of a family
• Cowboy is key to Nine Nines' future SaaS solution

Popular

Many contributors

• Exponential growth
• More than 50 total contributors in 2 years
• Half of them over the past 9 months!
• 470+ total tickets
• 200+ total pull requests

Many success stories

• Kóði for realtime financial market data streaming
• 2600Hz in Kazoo, their telecom platform
• Heroku for Logplex, a high-performance, realtime system for log delivery
• Linden Lab for Versu, an interactive storytelling platform
• BLOOM for AdGear, their realtime ad bidding system

More success stories

• jtendo.com for a dynamic mobile provisioning system
• Tambur.IO for realtime web and mobile messaging PaaS
• Unison for realtime collaborative environment
• LeChat.im for their realtime team chat system
• Others: TV, Sports, Set-top boxes, ...

Success story template

• Service needs high-performance, realtime capabilities
• Service is using HTTP either directly or for inter-connecting systems
• Service needs a REST API and Websocket support
• Service may be used for web or mobile applications
• Bonus points for gaming related projects

Many open source projects

• Compatible web frameworks: Nitrogen, ChicagoBoss, axiom...
• Open source users:
  • RabbitMQ
  • LeoFS
  • Project-FiFo
  • Ybot
  • fipelines
  • Bigwig (needs a maintainer!)

Repository of Cowboy applications

• Chapter in the guide for listing Cowboy applications
• Please open pull requests to add your project

Related projects

Ranch

• Listener and acceptor code spin-off from Cowboy
• Supervises connections automatically
• Abstracts transport and protocol code
• Can be embedded into your own supervision tree

Bullet

• Cowboy handler
• Websocket-like behavior on all browsers
• Permanent connection, reconnects on failure

Farwest

• A mix of web framework and CMS
• Gives users autonomy to build and manage Erlang web applications
• First alpha version just released!
• Huge amount of development needed
• Bountysource.com Farwest fundraiser just started

LeoFS

• The Lion of storage systems
• Distributed file system compatible with Amazon S3 API
• Powered by Cowboy
• Focuses on high throughput instead of latency

Future works

Remaining API breaking changes

• Improved POST handling in REST
• Improved request body reading
• Removal of cowboy_req:peer_addr/1

Connections supervisor

• Duplicate work with 'max_connections' related monitors
• Overhead on creation and especially termination
• Custom supervisor can fill in both roles
• Makes other optimizations possible

SPDY

• Asynchronous, fully compressed, binary HTTP
• One process per connection + one process per request
• Same code for HTTP and SPDY requests
• Headers in SPDY are lowercase too, no conversion needed

Complete HTTP support

• Parsing code for all standard HTTP headers
• Allow users to build any HTTP compatible technology on top of Cowboy
• Support for Websocket extensions
• Support for SPDY based HTTP/2.0 when implementations come out

Version 1.0

• All of the above
• Stable API
• Fully documented
• Work won't stop there!

Getting help

Community support

• #ninenines on Freenode
• Mailing list on http://ninenines.eu

Consulting and commercial support

• Hourly remote or on-site consulting
• A la carte commercial support
  • Specific developments
  • System optimization
  • Code reviews
  • On-call support
  • For both Erlang and Cowboy

Getting involved

Contributing

• Tell me where you use Cowboy and for what
• Send me graphs showing how new Cowboy versions improve things
• Report bugs on Github
• Send patches, see CONTRIBUTING.md file

Sponsoring

• Gives you visibility
• Gives us a budget

The Cowboy book

• The Bible of writing web applications with Erlang and Cowboy
• Accessible by people who never programmed Erlang
• Goes into and explains advanced web development concepts
• Published online for free as it is written
• Hard-copy will be released when the book is completed

One more thing

Hello, Joe

• Cowboy will make an appearance in Programming Erlang 2nd Edition!

Contact info

• IRC: essen on #erlang or #ninenines on Freenode
• Twitter: @lhoguin
• Sales: contact@ninenines.eu