@Include { myslides }
@OverheadTransparencies
@Title {
A Cowboy quest for a modern web
}
@RunningTitle { cowboy }
@Author { Lo�c Hoguin }
@Institution {
Nine Nines
Dev:Extend
}
@DateLine { Erlang User Conference 2011 }
@InitialLanguage { English }
@PageOrientation { Landscape }
//
@Overhead
@Title { Why Cowboy? }
@Begin
@BulletList
@ListItem { Because guns are better than arrows }
@ListItem { It's all about the hat }
@EndList
@End @Overhead
@Overhead
@Title { History }
@Begin
@BulletList
@ListItem { First commit early March 2011 }
@ListItem { Mentioned on the Github blog two weeks later }
@ListItem { First beta early September 2011 }
@ListItem { First talk early November 2011 }
@EndList
@End @Overhead
@Overhead
@Title { Users and contributors }
@Begin
@BulletList
@ListItem { The etorrent project for its acceptor pool and web interface }
@ListItem { The sockjs-erlang project for a websocket and HTTP server }
@ListItem { Smarkets, Nivertech and other companies }
@ListItem { The "#erlounge" IRC folks }
@EndList
@End @Overhead
@Overhead
@Title { Cowboy's listeners }
@Begin
@BulletList
@ListItem { Cowboy isn't just an HTTP server }
@ListItem { Cowboy allows you to start your own listener
@BulletList
@ListItem { Essentially a transport and protocol-agnostic acceptor pool }
@ListItem { An acceptor pool is a pool of processes accepting connections }
@EndList
}
@ListItem { You can have as many listeners running side by side as you want }
@ListItem { Even listeners completely unrelated to the HTTP protocol }
@EndList
@End @Overhead
@Overhead
@Title { Transport handlers }
@Begin
@BulletList
@ListItem { Tiny wrappers around transport-related code
@BulletList
@ListItem { listen, accept, recv, send, setopts... }
@EndList
}
@ListItem { Works with any reliable transport
@BulletList
@ListItem { TCP, SSL }
@ListItem { Theorically also the UDP-based ENet }
@EndList
}
@EndList
@End @Overhead
@Overhead
@Title { Protocol handlers }
@Begin
@BulletList
@ListItem { Contains the protocol implementation }
@ListItem { Usually takes the form of a state machine }
@ListItem { gen_fsm can of course be used }
@ListItem { Only a "start_link/4" function is required }
@EndList
@End @Overhead
@Overhead
@Title { Acceptor loop }
@Begin
@BulletList
@ListItem { Wait for a connection }
@ListItem { Accept the connection
@BulletList
@ListItem { Start a request process }
@ListItem { Give the socket to that new process }
@ListItem { Inform the new process everything's ready }
@EndList
}
@ListItem { Check for max "#" of connections
@BulletList
@ListItem { Wait if this max is reached }
@EndList
}
@ListItem { Repeat }
@EndList
@End @Overhead
@Overhead
@Title { A pool of many acceptors }
@Begin
@BulletList
@ListItem { Idea taken from Mochiweb }
@ListItem { Having more than one acceptor process speeds things up }
@ListItem { Erlang processes are cheap }
@ListItem { Why not use 100 processes to accept connections? }
@EndList
@End @Overhead
@Overhead
@Title { Supervision }
@Begin
@BulletList
@ListItem { All processes started by a listener are supervised }
@ListItem { You don't need to worry about supervision! }
@ListItem { We're working on release upgrades }
@EndList
@End @Overhead
@Overhead
@Title { Connection pools }
@Begin
@BulletList
@ListItem { There are different kinds of connections }
@ListItem { Short-lived "request/response" should have a small max "#" }
@ListItem { Long-lived idle connections can have a much larger max }
@ListItem { Pools allow separating those connection types into two groups
@BulletList
@ListItem { Or more }
@EndList
}
@ListItem { You can add, move or delete connections from pools }
@ListItem { By default all connections are added to the pool named 'default' }
@EndList
@End @Overhead
@Overhead
@Title { Cowboy's HTTP server }
@Begin
@BulletList
@ListItem { Because all applications have their own HTTP interface }
@EndList
@End @Overhead
@Overhead
@Title { Initial design ideas }
@Begin
@BulletList
@ListItem { gen_fsm, lists }
@ListItem { Normal process, lists, with "[{active, once}]" }
@ListItem { Normal process, binary, with "[{active, once}]" }
@ListItem { Normal process, binary with "[{active, false}]" }
@ListItem { Normal process, binary, calling "erlang:decode_packet/3" directly }
@ListItem { We did want binary from the start but it required more custom code }
@EndList
@End @Overhead
@Overhead
@Title { Dispatch rules }
@Begin
@BulletList
@ListItem { Idea taken from Webmachine }
@ListItem { Matching hostname and path to HTTP handlers }
@ListItem { Partial matching allows binding "hostname/path" parts to variables }
@ListItem { If we had the rule "[<<\"users\">>, id, <<\"pics\">>]"
@BulletList
@ListItem { The path "/users/42/pics" would match }
@ListItem { "{id, 42}" would be added to the bindings }
@EndList
}
@ListItem { Entirely optional }
@EndList
@End @Overhead
@Overhead
@Title { HTTP handlers }
@Begin
@CD @F @Box paint { lightyellow } { @Verbatim {
-module(my_handler).
-export([init/3, handle/2, terminate/2]).
init(_TransportType, Req, _Opts) ->
{ok, Req, undefined_state}.
handle(Req, State) ->
{ok, Req2} = cowboy_http_req:reply(200, [], <<"Hi EUC!">>,
Req),
{ok, Req2, State}.
terminate(_Req, _State) ->
ok.
} }
@End @Overhead
@Overhead
@Title { HTTP request object }
@Begin
@BulletList
@ListItem { Retrieve the method, HTTP version, peer IP and port }
@ListItem { Retrieve the requested hostname and path }
@ListItem { Retrieve headers, query string values, bindings, cookies }
@ListItem { Semantically parse headers }
@ListItem { Read the body of the request }
@ListItem { Send a simple or a chunked reply }
@EndList
@End @Overhead
@Overhead
@Title { HTTP handler loops }
@Begin
@BulletList
@ListItem { Useful for long-polling or Event Source }
@ListItem { Receive messages from other processes and send back data }
@ListItem { Hibernate and timeouts support }
@EndList
@End @Overhead
@Overhead
@Title { HTTP handlers for long-polling }
@Begin
@CD @F @Box paint { lightyellow } { @Verbatim {
-module(my_loop_handler).
-export([init/3, info/3, terminate/2]).
init(_TransportType, Req, _Opts) ->
my_session_server:hello(),
{loop, Req, undefined_state, 60000, hibernate}.
info({my_session_server, Message}, Req, State) ->
{ok, Req2} = cowboy_http_req:reply(200, [], Message, Req),
{ok, Req2, State};
info(_Any, Req, State) ->
{loop, Req, State, hibernate}.
terminate(_Req, _State) -> ok = my_session_server:bye().
} }
@End @Overhead
@Overhead
@Title { Websocket support }
@Begin
@BulletList
@ListItem { Cowboy supports all Websocket protocol versions in use in web browsers }
@ListItem { New versions get added as soon as browsers start implementing them }
@ListItem { Cowboy's websocket interface should be future-proof }
@ListItem { Websocket connections are on a different pool than normal HTTP }
@EndList
@End @Overhead
@Overhead
@Title { Websocket handlers }
@Begin
@CD @F @Box paint { lightyellow } { @Verbatim {
-module(my_ws_handler).
-export([init/3, websocket_init/3, websocket_handle/3,
websocket_info/3, websocket_terminate/3]).
init(_TransportType, Req, _Opts) ->
{upgrade, protocol, cowboy_http_websocket}.
websocket_init(_TransportType, Req, _Opts) ->
Req2 = cowboy_http_req:compact(Req),
{ok, Req2, undefined_state, 60000, hibernate}.
%% ...
} }
@End @Overhead
@Overhead
@Title { Websocket handlers continued }
@Begin
@CD @F @Box paint { lightyellow } { @Verbatim {
%% ...
websocket_handle({text, Data}, Req, State) ->
{reply, {text, Data}, Req, State, hibernate};
websocket_handle(_Frame, Req, State) ->
{ok, Req, State, hibernate}.
websocket_info(_Info, Req, State) ->
{ok, Req, State, hibernate}.
websocket_terminate(_Reason, _Req, _State) ->
ok.
} }
@End @Overhead
@Overhead
@Title { REST handlers }
@Begin
@BulletList
@ListItem { Use Webmachine's decision flow diagram }
@ListItem { Not a rewrite, a new implementation }
@ListItem { Clean, readable code not requiring the diagram to be understood }
@EndList
@End @Overhead
@Overhead
@Title { Cowboy is clean code }
@Begin
@BulletList
@ListItem { Easy to understand, easy to debug }
@ListItem { No process dictionaries or other side effects }
@ListItem { No parameterized modules }
@ListItem { Use only documented "Erlang/OTP" features }
@EndList
@End @Overhead
@Overhead
@Title { Cowboy and OTP }
@Begin
@BulletList
@ListItem { All Cowboy processes are supervised }
@ListItem { OTP upgrades work (though improvements are coming) }
@ListItem { HTTP handlers are inspired by gen_servers
@BulletList
@ListItem { gen_server: client > api call > server }
@ListItem { http_handler: http client > http request > http handler }
@EndList
}
@EndList
@End @Overhead
@Overhead
@Title { Cowboy's performance }
@Begin
@BulletList
@ListItem { 500 000 concurrent websocket connections and beyond }
@EndList
@End @Overhead
@Overhead
@Title { Does performance matter? }
@Begin
@BulletList
@ListItem { It depends on your application }
@ListItem { It probably doesn't matter for 99% of the applications }
@ListItem { In HTTP, response latency is very important }
@ListItem { When handling many concurrent connections, memory usage matters }
@EndList
@End @Overhead
@Overhead
@Title { 1 process per connection }
@Begin
@BulletList
@ListItem { Other Erlang HTTP servers use 2 processes per connection }
@ListItem { Cowboy uses only 1 }
@ListItem { Saves a significant amount of memory }
@ListItem { Reduces latency thanks to reduced message passing }
@EndList
@End @Overhead
@Overhead
@Title { Low memory usage: binary }
@Begin
@BulletList
@ListItem { Big binaries are ref counted }
@ListItem { Small binaries are still smaller than lists }
@ListItem { Sub-binary optimizations helps reduce copying }
@EndList
@End @Overhead
@Overhead
@Title { Low memory usage: "cowboy_http_req:compact/1" }
@Begin
@BulletList
@ListItem { Removes everything unwanted from the Req object }
@ListItem { Lowers memory usage for long-running processes }
@ListItem { Works especially well with process hibernation }
@EndList
@End @Overhead
@Overhead
@Title { Requests per seconds }
@Begin
@BulletList
@ListItem { Not a good indicator of performance }
@ListItem { But a good indicator of a design's simplicity }
@ListItem { If "requests/s" lowers significantly between two commits, you've messed up }
@EndList
@End @Overhead
@Overhead
@Title { The Horse project }
@Begin
@BulletList
@ListItem { Continuous performance testing of the Cowboy project }
@ListItem { Will measure latency, CPU usage, memory usage... }
@ListItem { Will produce nice graphs to quickly notice drops and fix them }
@ListItem { Release expected for Q1 2012 }
@EndList
@End @Overhead
@Overhead
@Title { Cowboy's related projects }
@Begin
@BulletList
@ListItem { Because the core project should stay lightweight }
@EndList
@End @Overhead
@Overhead
@Title { Bullet handler }
@Begin
@BulletList
@ListItem { A "Socket.IO/SockJS" alternative }
@ListItem { Sets up an always connected streaming interface between JS and Erlang }
@ListItem { Uses Websocket by default, other methods when not available }
@ListItem { A single interface both client and server-side }
@ListItem { More work is needed on the JS side }
@EndList
@End @Overhead
@Overhead
@Title { cowboy_static handler }
@Begin
@BulletList
@ListItem { A static file handler by Magnus Klaar }
@ListItem { Using the sendfile code originally from Yaws }
@ListItem { Will be using the future REST support }
@ListItem { Available as a separate project }
@EndList
@End @Overhead
@Overhead
@Title { Bigwig: Spawnfest great winner }
@Begin
@BulletList
@ListItem { Spawnfest is an annual Erlang programming contest }
@ListItem { First edition took place in June 2011 }
@ListItem { They produced an awesome webtool replacement with many more features }
@ListItem { Got the IRCCloud guys interested in Cowboy }
@EndList
@End @Overhead
@Overhead
@Title { Farwest: a new kind of web development stack }
@Begin
@BulletList
@ListItem { Default administration panel
@BulletList
@ListItem { Setup your data }
@ListItem { Setup your views }
@ListItem { Write simple rules to route your data to your views }
@ListItem { Write simple rules to create forms and save the data }
@ListItem { Edit and reload any client and server-side code live }
@ListItem { Edit and reload the dispatch list live }
@ListItem { Git integration }
@EndList
}
@ListItem { NoSQL backend, nice development API and many plugins }
@ListItem { Beta expected for Q1 2012 }
@EndList
@End @Overhead
@Overhead
@Title { Cowboy's future }
@Begin
@BulletList
@ListItem { Because they aren't just figures of the past }
@EndList
@End @Overhead
@Overhead
@Title { Listener upgrades }
@Begin
@BulletList
@ListItem { We want to update the dispatch list on-the-fly }
@ListItem { We want to update most transport or protocol options }
@ListItem { Also allow adding or removing acceptors }
@EndList
@End @Overhead
@Overhead
@Title { Improved dispatcher }
@Begin
@BulletList
@ListItem { API will be improved }
@ListItem { Allow giving tokens as lists and not just binaries }
@ListItem { Hostname and path hierarchy will be added }
@ListItem { Might eventually switch to matchspecs for better performance }
@EndList
@End @Overhead
@Overhead
@Title { gen_event for request tracking and monitoring }
@Begin
@BulletList
@ListItem { Ad-hoc error and access logging }
@ListItem { Allows writing custom event handlers }
@ListItem { No cost when no handlers are defined }
@EndList
@End @Overhead
@Overhead
@Title { Multipart support }
@Begin
@BulletList
@ListItem { File upload support }
@ListItem { Convenience function
@BulletList
@ListItem { Save all files to temporary locations }
@ListItem { Return the paths along with the additional POST parameters }
@EndList
}
@ListItem { Streaming
@BulletList
@ListItem { Stream each parts individually }
@ListItem { Stream each parts' payload }
@EndList
}
@EndList
@End @Overhead
@Overhead
@Title { Aiming for full "HTTP/1.1" compliance }
@Begin
@BulletList
@ListItem { Support for all "HTTP/1.1" features }
@ListItem { Correct "HTTP/1.0" clients handling }
@ListItem { Semantic parsing of all header values }
@ListItem { Gzip compression enabled by default for replies }
@EndList
@End @Overhead
@Overhead
@Title { Up-to-date Websocket support }
@Begin
@BulletList
@ListItem { We are actively monitoring the Websocket draft changes }
@ListItem { Updated implementation usually supported within 7 days }
@ListItem { Interface shouldn't be changing anymore }
@EndList
@End @Overhead
@Overhead
@Title { Links }
@Begin
@BulletList
@ListItem { cowboy: "https://github.com/extend/cowboy" @ExternalLink { "https://github.com/extend/cowboy" } }
@ListItem { bullet: "https://github.com/extend/bullet" @ExternalLink { "https://github.com/extend/bullet" } }
@EndList
@DP
@BulletList
@ListItem { essen on "#erlounge" and "#erlang" on Freenode }
@ListItem { "@lhoguin" on Twitter }
@ListItem { Lo�c Hoguin on G+ }
@ListItem { "[email protected]" }
@EndList
@End @Overhead
@Overhead
@Title { Questions? }
@Begin
@BulletList
@ListItem { I won't shoot you for asking! }
@EndList
@End @Overhead
