|
@@ -31,207 +31,3 @@ Support
|
|
|
* Official IRC Channel: #ninenines on irc.freenode.net
|
|
|
* [Mailing Lists](http://lists.ninenines.eu)
|
|
|
* [Commercial Support](http://ninenines.eu/support)
|
|
|
-
|
|
|
-
|
|
|
-
|
|
|
-Old README (deprecated)
|
|
|
------------------------
|
|
|
-
|
|
|
-This and all following sections will be removed as soon as their
|
|
|
-equivalent appear in the Cowboy guide.
|
|
|
-
|
|
|
-Cowboy does nothing by default.
|
|
|
-
|
|
|
-Cowboy uses Ranch for handling connections, and provides convenience
|
|
|
-functions to start and stop Ranch listeners. The Ranch application
|
|
|
-must always be started before Cowboy. The crypto application must
|
|
|
-also be started.
|
|
|
-
|
|
|
-The `cowboy:start_http/4` function will handle HTTP connections
|
|
|
-using the TCP transport. Similarly, `cowboy:start_https/4` will
|
|
|
-handle HTTP connections using the SSL transport.
|
|
|
-
|
|
|
-You can start as many listeners as you need to. To allow this, you
|
|
|
-are required to give a name to your listeners. It is the first
|
|
|
-argument to the start functions. The name can be of any type.
|
|
|
-
|
|
|
-You can stop listeners using `cowboy:stop_listener/1`, giving it
|
|
|
-the name of the listener to be stopped.
|
|
|
-
|
|
|
-The following example demonstrates the startup of a very simple
|
|
|
-HTTP listener. It redirects all requests to the `my_handler`
|
|
|
-module.
|
|
|
-
|
|
|
-``` erlang
|
|
|
-application:start(crypto),
|
|
|
-application:start(ranch),
|
|
|
-application:start(cowboy),
|
|
|
-Dispatch = [
|
|
|
- %% {URIHost, list({URIPath, Handler, Opts})}
|
|
|
- {'_', [{'_', my_handler, []}]}
|
|
|
-],
|
|
|
-%% Name, NbAcceptors, TransOpts, ProtoOpts
|
|
|
-cowboy:start_http(my_http_listener, 100, [{port, 8080}],
|
|
|
- [{dispatch, Dispatch}]
|
|
|
-).
|
|
|
-```
|
|
|
-
|
|
|
-This is not enough though, you must also write the `my_handler`
|
|
|
-module to process the incoming HTTP requests. Of course Cowboy
|
|
|
-comes with predefined handlers for specific tasks but most of
|
|
|
-the time you'll need to write the handlers appropriate for your
|
|
|
-application.
|
|
|
-
|
|
|
-Following is an example of a "Hello World!" HTTP handler.
|
|
|
-
|
|
|
-``` erlang
|
|
|
--module(my_handler).
|
|
|
--export([init/3, handle/2, terminate/2]).
|
|
|
-
|
|
|
-init({tcp, http}, Req, Opts) ->
|
|
|
- {ok, Req, undefined_state}.
|
|
|
-
|
|
|
-handle(Req, State) ->
|
|
|
- {ok, Req2} = cowboy_req:reply(200, [], <<"Hello World!">>, Req),
|
|
|
- {ok, Req2, State}.
|
|
|
-
|
|
|
-terminate(Req, State) ->
|
|
|
- ok.
|
|
|
-```
|
|
|
-
|
|
|
-You can also write handlers that do not reply directly. Instead, such handlers
|
|
|
-will wait for an Erlang message from another process and only reply when
|
|
|
-receiving such message, or timeout if it didn't arrive in time.
|
|
|
-
|
|
|
-This is especially useful for long-polling functionality, as Cowboy will handle
|
|
|
-process hibernation and timeouts properly, preventing mistakes if you were to
|
|
|
-write the code yourself. A handler of that kind can be defined like this:
|
|
|
-
|
|
|
-``` erlang
|
|
|
--module(my_loop_handler).
|
|
|
--export([init/3, info/3, terminate/2]).
|
|
|
-
|
|
|
--define(TIMEOUT, 60000).
|
|
|
-
|
|
|
-init({tcp, http}, Req, Opts) ->
|
|
|
- {loop, Req, undefined_state, ?TIMEOUT, hibernate}.
|
|
|
-
|
|
|
-info({reply, Body}, Req, State) ->
|
|
|
- {ok, Req2} = cowboy_req:reply(200, [], Body, Req),
|
|
|
- {ok, Req2, State};
|
|
|
-info(Message, Req, State) ->
|
|
|
- {loop, Req, State, hibernate}.
|
|
|
-
|
|
|
-terminate(Req, State) ->
|
|
|
- ok.
|
|
|
-```
|
|
|
-
|
|
|
-It is of course possible to combine both type of handlers together as long as
|
|
|
-you return the proper tuple from init/3.
|
|
|
-
|
|
|
-Continue reading to learn how to dispatch rules and handle requests.
|
|
|
-
|
|
|
-Dispatch rules
|
|
|
---------------
|
|
|
-
|
|
|
-Cowboy allows you to dispatch HTTP requests directly to a specific handler
|
|
|
-based on the hostname and path information from the request. It also lets
|
|
|
-you define static options for the handler directly in the rules.
|
|
|
-
|
|
|
-To match the hostname and path, Cowboy requires a list of tokens. For
|
|
|
-example, to match the "ninenines.eu" domain name, you must specify
|
|
|
-`[<<"ninenines">>, <<"eu">>]`. Or, to match the "/path/to/my/resource"
|
|
|
-you must use `[<<"path">>, <<"to">>, <<"my">>, <<"resource">>]`. All the
|
|
|
-tokens must be given as binary.
|
|
|
-
|
|
|
-You can use the special token `'_'` (the atom underscore) to indicate that
|
|
|
-you accept anything in that position. For example if you have both
|
|
|
-"ninenines.eu" and "ninenines.fr" domains, you can use the match spec
|
|
|
-`[<<"ninenines">>, '_']` to match any top level extension.
|
|
|
-
|
|
|
-Finally, you can also match multiple leading segments of the domain name and
|
|
|
-multiple trailing segments of the request path using the atom `'...'` (the atom
|
|
|
-ellipsis) respectively as the first host token or the last path token. For
|
|
|
-example, host rule `['...', <<"ninenines">>, <<"eu">>]` can match both
|
|
|
-"cowboy.bugs.ninenines.eu" and "ninenines.eu" and path rule
|
|
|
-`[<<"projects">>, '...']` can match both "/projects" and
|
|
|
-"/projects/cowboy/issues/42". The host leading segments and the path trailing
|
|
|
-segments can later be retrieved through `cowboy_req:host_info/1` and
|
|
|
-`cowboy_req:path_info/1`.
|
|
|
-
|
|
|
-Any other atom used as a token will bind the value to this atom when
|
|
|
-matching. To follow on our hostnames example, `[<<"ninenines">>, ext]`
|
|
|
-would bind the values `<<"eu">>` and `<<"fr">>` to the ext atom, that you
|
|
|
-can later retrieve in your handler by calling `cowboy_req:binding/{2,3}`.
|
|
|
-
|
|
|
-You can also accept any match spec by using the atom `'_'` directly instead of
|
|
|
-a list of tokens. Our hello world example above uses this to forward all
|
|
|
-requests to a single handler.
|
|
|
-
|
|
|
-There is currently no way to match multiple tokens at once.
|
|
|
-
|
|
|
-Requests handling
|
|
|
------------------
|
|
|
-
|
|
|
-Requests are passed around in the Request variable. Although they are
|
|
|
-defined as a record, it is recommended to access them only through the
|
|
|
-cowboy_req module API.
|
|
|
-
|
|
|
-You can retrieve the HTTP method, HTTP version, peer address and port,
|
|
|
-host tokens, raw host, used port, path tokens, raw path, query string
|
|
|
-values, bound values from the dispatch step, header values from the
|
|
|
-request. You can also read the request body, if any, optionally parsing
|
|
|
-it as a query string. Finally, the request allows you to send a response
|
|
|
-to the client.
|
|
|
-
|
|
|
-See the cowboy_req module for more information.
|
|
|
-
|
|
|
-Websockets
|
|
|
-----------
|
|
|
-
|
|
|
-The Websocket protocol is built upon the HTTP protocol. It first sends
|
|
|
-an HTTP request for an handshake, performs it and then switches
|
|
|
-to Websocket. Therefore you need to write a standard HTTP handler to
|
|
|
-confirm the handshake should be completed and then the Websocket-specific
|
|
|
-callbacks.
|
|
|
-
|
|
|
-A simple handler doing nothing but sending a repetitive message using
|
|
|
-Websocket would look like this:
|
|
|
-
|
|
|
-``` erlang
|
|
|
--module(my_ws_handler).
|
|
|
--export([init/3]).
|
|
|
--export([websocket_init/3, websocket_handle/3,
|
|
|
- websocket_info/3, websocket_terminate/3]).
|
|
|
-
|
|
|
-init({tcp, http}, Req, Opts) ->
|
|
|
- {upgrade, protocol, cowboy_websocket}.
|
|
|
-
|
|
|
-websocket_init(TransportName, Req, _Opts) ->
|
|
|
- erlang:start_timer(1000, self(), <<"Hello!">>),
|
|
|
- {ok, Req, undefined_state}.
|
|
|
-
|
|
|
-websocket_handle({text, Msg}, Req, State) ->
|
|
|
- {reply, {text, << "That's what she said! ", Msg/binary >>}, Req, State};
|
|
|
-websocket_handle(_Data, Req, State) ->
|
|
|
- {ok, Req, State}.
|
|
|
-
|
|
|
-websocket_info({timeout, _Ref, Msg}, Req, State) ->
|
|
|
- erlang:start_timer(1000, self(), <<"How' you doin'?">>),
|
|
|
- {reply, {text, Msg}, Req, State};
|
|
|
-websocket_info(_Info, Req, State) ->
|
|
|
- {ok, Req, State}.
|
|
|
-
|
|
|
-websocket_terminate(_Reason, _Req, _State) ->
|
|
|
- ok.
|
|
|
-```
|
|
|
-
|
|
|
-Of course you can have an HTTP handler doing both HTTP and Websocket
|
|
|
-handling, but for the sake of this example we're ignoring the HTTP
|
|
|
-part entirely.
|
|
|
-
|
|
|
-As the Websocket protocol is still a draft the API is subject to change
|
|
|
-regularly when support to the most recent drafts gets added. Features may
|
|
|
-be added, changed or removed before the protocol gets finalized. Cowboy
|
|
|
-tries to implement all drafts transparently and give a single interface to
|
|
|
-handle them all, however.
|