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Add sub protocol behaviour
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fishcakez committed Feb 16, 2013
1 parent e3daf43 commit 6d67ad8
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3 changes: 2 additions & 1 deletion guide/handlers.md
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Expand Up @@ -41,7 +41,8 @@ Custom protocol upgrades
------------------------

The `my_protocol` module above will be used for further processing
of the request. It requires only one callback, `upgrade/4`.
of the request. It should use the `cowboy_sub_protocol` behaviour,
which requires only one callback, `upgrade/4`.

It receives the request object, the middleware environment, and
the handler this request has been routed to along with its options.
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1 change: 1 addition & 0 deletions src/cowboy_rest.erl
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Expand Up @@ -19,6 +19,7 @@
%% documentation available at http://wiki.basho.com/Webmachine.html
%% at the time of writing.
-module(cowboy_rest).
-behaviour(cowboy_sub_protocol).

-export([upgrade/4]).

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37 changes: 37 additions & 0 deletions src/cowboy_sub_protocol.erl
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@@ -0,0 +1,37 @@
%% Copyright (c) 2013, James Fish <[email protected]>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

%% @doc Behaviour for sub protocols.
%%
%% Only one function needs to be implemented, <em>upgrade/4</em>.
%% It receives the Req, the environment, the handler that the request has been
%% routed to and the handler's options. It acts exactly the same as a
%% middleware, so returns the same values a middleware's execute/2.
%%
%% Once the sub protocol has processed the request it should add the result
%% to the environment. This is done by adding the tuple {result, Value} to the
%% environment list. To continue handling requests on the current connection the
%% Value should be the atom ok. Any other value will prevent the processing of
%% subsequent requests.
%%
%% <em>upgrade/4</em> will be called when a handler's init/3 returns
%% {upgrade, protocol, Module}, where Module is the module of the sub protocol.
-module(cowboy_sub_protocol).

-callback upgrade(Req, Env, module(), any())
-> {ok, Req, Env}
| {suspend, module(), atom(), any()}
| {halt, Req}
| {error, cowboy_http:status(), Req}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
1 change: 1 addition & 0 deletions src/cowboy_websocket.erl
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Expand Up @@ -17,6 +17,7 @@
%% Cowboy supports versions 7 through 17 of the Websocket drafts.
%% It also supports RFC6455, the proposed standard for Websocket.
-module(cowboy_websocket).
-behaviour(cowboy_sub_protocol).

%% API.
-export([upgrade/4]).
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