Erlang web server support

Author: Matt Branton

.gitignore

@@ -1,3 +1,5 @@
 *~
 node_modules
 .DS_Store
+deps
+.rebar

README.md

@@ -52,6 +52,16 @@ go run server.go
 go get github.com/xyproto/algernon
 # or brew install algernon
 algernon server.lua
+
+```
+
+### Erlang
+
+```sh
+rebar get-deps
+rebar compile
+rebar shell
+application:ensure_all_started(server).
 ```
 
 And visit <http://localhost:3000/>. Try opening multiple tabs!

rebar.config

@@ -0,0 +1,7 @@
+{sub_dirs, ["apps/", "rel"]}.
+
+{deps_dir, ["deps"]}.
+{erl_opts, [debug_info, fail_on_warning]}.
+
+{deps, [{cowboy, "1.0.3", {git, "https://github.com/ninenines/cowboy.git", {tag, "1.0.3"}}},
+        {jiffy, ".*", {git, "git://github.com/davisp/jiffy.git"}}]}.

src/comment_handler.erl

@@ -0,0 +1,64 @@
+%% This file provided by Facebook is for non-commercial testing and evaluation
+%% purposes only. Facebook reserves all rights not expressly granted.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+%% FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+%% ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+%% WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+%%
+
+%% @doc POST echo handler.
+-module(comment_handler).
+
+-define(FilePath, "./comments.json").
+
+-export([init/3]).
+-export([handle/2]).
+-export([terminate/3]).
+
+init(_Transport, Req, []) ->
+	{ok, Req, undefined}.
+
+handle(Req, State) ->
+	{Method, Req2} = cowboy_req:method(Req),
+	HasBody = cowboy_req:has_body(Req2),
+	{ok, Req3} = maybe_comment(Method, HasBody, Req2),
+	{ok, Req3, State}.
+
+maybe_comment(<<"POST">>, true, Req) ->
+	{ok, PostVals, Req2} = cowboy_req:body_qs(Req),
+	comment(write_comments(read_comments(), PostVals), Req2);
+maybe_comment(<<"POST">>, false, Req) ->
+	cowboy_req:reply(400, [], <<"Missing body.">>, Req);
+maybe_comment(<<"GET">>, _, Req) ->
+	comment(read_raw_comments(), Req);
+maybe_comment(_, _, Req) ->
+	%% Method not allowed.
+	cowboy_req:reply(405, Req).
+
+comment(Comments, Req) ->
+	%% always return json
+	cowboy_req:reply(200, [
+		{<<"content-type">>, <<"application/json; charset=utf-8">>},
+		{<<"cache-control">>, <<"no-cache">>}
+	], Comments, Req).
+
+terminate(_Reason, _Req, _State) ->
+	ok.
+
+%% Private functions
+
+read_raw_comments() ->
+	{ok, F} = file:read_file(?FilePath),
+	F.
+
+read_comments() ->
+	jiffy:decode(read_raw_comments()).
+
+write_comments(Comments, NextComment) ->
+	C = jiffy:encode(Comments ++ [{NextComment}],
+					[force_utf8, pretty]),
+	ok = file:write_file(?FilePath, C),
+	C.

src/server.app.src

@@ -0,0 +1,14 @@
+{application, server,
+ [
+  {description, "React tutorial server"},
+  {vsn, "1"},
+  {registered, [server]},
+  {applications, [
+                  kernel,
+                  stdlib,
+                  crypto,
+                  cowboy,
+                  jiffy]},
+  {mod, { server_app, []}},
+  {env, []}
+ ]}.

src/server_app.erl

@@ -0,0 +1,41 @@
+%% This file provided by Facebook is for non-commercial testing and evaluation
+%% purposes only. Facebook reserves all rights not expressly granted.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+%% FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+%% ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+%% WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+%%
+%%
+%% @private
+-module(server_app).
+-behaviour(application).
+
+-export([start/2]).
+-export([stop/1]).
+
+start(_Type, _Args) ->
+	Port = default_port(os:getenv("PORT")),
+	Dispatch = cowboy_router:compile([
+		{'_', [
+			{"/api/comments", comment_handler, []},
+			{"/", cowboy_static, {file, "./public/index.html"}},
+			{"/[...]", cowboy_static, {dir, "./public",
+				[{mimetypes, cow_mimetypes, all}]}}
+		]}
+	]),
+	{ok, _} = cowboy:start_http(http, 10, [{port, Port}], [
+		{env, [{dispatch, Dispatch}]}
+	]),
+	server_sup:start_link().
+
+stop(_State) ->
+	ok.
+
+
+%% Utility
+
+default_port(false) -> 3000;
+default_port(N) -> N.

src/server_sup.erl

@@ -0,0 +1,21 @@
+%% @private
+-module(server_sup).
+-behaviour(supervisor).
+
+%% API.
+-export([start_link/0]).
+
+%% supervisor.
+-export([init/1]).
+
+%% API.
+
+-spec start_link() -> {ok, pid()}.
+start_link() ->
+	supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+%% supervisor.
+
+init([]) ->
+	Procs = [],
+	{ok, {{one_for_one, 10, 10}, Procs}}.