Add echo_handler module for Application Layer

example-app/cli.rb

@@ -6,8 +6,8 @@
 require 'websocket-eventmachine-client'
 require 'json'
 
-@ws_host = '127.0.0.1'
-@ws_port = '8085'
+@ws_host = ARGV[0]
+@ws_port = ARGV[1].to_i
 
 EM.run do
     ws = WebSocket::EventMachine::Client.connect(:uri => "ws://#{@ws_host}:#{@ws_port}/ws")
@@ -21,8 +21,7 @@
             "ts"        => ts,
             "action"    => "main/index.json",
             "query_str" => "",
-            "method"    => "GET",
-            "params"    => {},
+            "method"    => "GET"
         }
 
         puts "Sending..."

example-app/src/echo_get_app.erl

@@ -16,8 +16,8 @@ start(_Type, _Args) ->
 
 	Dispatch = cowboy_router:compile([
 		{'_', [
-			{"/ws", 	cowboy_websocket_rack_handler, 		[{path, Path}]},
-			{'_', 		cowboy_rack_handler, 				[{path, Path}]}
+			{"/ws", 	cowboy_websocket_rack_handler, 		[{path, Path}, {handler, echo_handler}]},
+			{'_', 		cowboy_rack_handler, 				[{path, Path}, {handler, echo_handler}]}
 		]}
 	]),
 	{ok, _} = cowboy:start_http(http, 100, [{port, 8085}], [

example-app/src/echo_handler.erl

@@ -0,0 +1,93 @@
+-module(echo_handler).
+-author('Konstantin Kiselyov, <kiseljovkn@gmail.com>').
+
+-export([
+	parse_message/1,
+	request_info_for_message/1,
+	encode_transport_response/2,
+	encode_rack_response/3
+]).
+
+%%% Application layer protocol
+
+-record(ra_protocol_message, {
+	unique = <<"">>,
+	ts = 0,
+	action = <<"">>,
+	method = <<"GET">>,
+	query_str = <<"">>,
+	params = {struct, []},
+	response = <<"{}">>
+}).
+
+if_undefined_then_value(X, Value) ->
+	case X of 
+		undefined -> Value;
+		_ -> X
+	end.
+
+parse_message(Message) ->
+	{struct, PropList} = mochijson2:decode(Message),
+
+	% extract parameters
+	Unique 	= if_undefined_then_value(proplists:get_value(<<"unique">>, PropList), <<"">>),
+	Ts 		= if_undefined_then_value(proplists:get_value(<<"ts">>, 	PropList), 0),
+	Action 	= if_undefined_then_value(proplists:get_value(<<"action">>, PropList), <<"">>),
+	Query 	= if_undefined_then_value(proplists:get_value(<<"query_str">>, PropList), <<"">>),
+	Method 	= if_undefined_then_value(proplists:get_value(<<"method">>, PropList), <<"GET">>),
+	Params 	= if_undefined_then_value(proplists:get_value(<<"params">>, PropList), {struct, []}),
+
+	% create result message
+	#ra_protocol_message{
+		unique = Unique, 
+		ts = Ts,
+		action = Action,
+		query_str = Query,
+		method = Method,
+		params = Params
+	}.
+
+request_info_for_message(ProtocolMessage) ->
+	RequestMethod = ProtocolMessage#ra_protocol_message.method,
+	Path = ProtocolMessage#ra_protocol_message.action,
+	QueryString = ProtocolMessage#ra_protocol_message.query_str,
+	ServerName = <<"localhost">>,
+	ServerPort = 8080,
+	{RequestMethod, Path, QueryString, ServerName, ServerPort}.
+
+encode_transport_response(Response, Message) ->
+	Unique 	= Message#ra_protocol_message.unique,
+	Ts 		= list_to_binary(integer_to_list(Message#ra_protocol_message.ts)),
+	Action 	= Message#ra_protocol_message.action,
+	Query 	= Message#ra_protocol_message.query_str,
+	Method 	= Message#ra_protocol_message.method,
+	Params 	= mochijson2:encode(Message#ra_protocol_message.params),
+
+	UniquePart 		= 	<<"\"unique\":", 	"\"", Unique/binary, "\"">>,
+	TsPart 			= 	<<"\"ts\":", 		Ts/binary>>,
+	ActionPart 		= 	<<"\"action\":", 	"\"", Action/binary, "\"">>,
+	QueryPart 		= 	<<"\"query_str\":", 	"\"", Query/binary, "\"">>,
+	MethodPart 		= 	<<"\"method\":", 	"\"", Method/binary, "\"">>,
+	ParamsPart 		= 	<<"\"params\":", 	Params/binary>>,
+	ResponsePart	= 	<<"\"response\":", 	Response/binary>>,
+
+	_Result = <<"{", 
+		UniquePart/binary, ",",
+		TsPart/binary, ",",
+		ActionPart/binary, ",",
+		QueryPart/binary, ",",
+		MethodPart/binary, ",",
+		ParamsPart/binary, ",",
+		ResponsePart/binary,
+	"}">>.
+
+encode_rack_response(Status, ResponseHeaders, ResponseBody) ->
+	StatusValue = list_to_binary(integer_to_list(Status)),
+	_ResponseHeadersValue = ResponseHeaders,
+	ResponseBodyValue = ResponseBody,
+	<<"{",
+		"\"status\":",  StatusValue/binary, ",",
+		% "\"headers\":\"",  ResponseHeadersValue/binary, "\",",
+		"\"body\":",  ResponseBodyValue/binary,
+	"}">>.
+