曾寫(xiě)過(guò)一篇使用XML實(shí)現IVR 。但當你要實(shí)現更復雜、更智能的業(yè)務(wù)邏輯時(shí)，你免不了跟數據庫或其它系統交互。我們曾用Ruby借助event_socket實(shí)現過(guò)比較復雜的功能，但當業(yè)務(wù)變得更加復雜時(shí)，我們使用Erlang重寫(xiě)了整個(gè)邏輯。
什么是 Erlang ?
Erlang是一種函數式編程語(yǔ)言，它天生支持高并發(fā)，高可靠性的編程。
為什么使用 Erlang ?
Erlang 最初就是設計用來(lái)編寫(xiě)電信程序的，它具有OTP（開(kāi)放電信平臺）庫，使用它可以很容易地實(shí)現FSM（有限狀態(tài)機）。
我們的PBX服務(wù)器運行在辦公室里，但當有電話(huà)進(jìn)來(lái)時(shí)它需要到國外的一臺服務(wù)器上取數據，并以此來(lái)選擇坐席。呼叫過(guò)程中，它也需要更新遠程的數據。我們使用HTTP與遠程服務(wù)器交互。如此長(cháng)距離的通信不僅會(huì )有很大的延時(shí)，而且經(jīng)常會(huì )失敗。FreeSWITCH本身有mod_http及mod_curl模塊，并且其它嵌入式腳本語(yǔ)言也都有HTTP支持，但我們認為Erlang會(huì )更加健壯。而且，通過(guò)使用Erlang的輕量級進(jìn)程，當一有電話(huà)進(jìn)來(lái)時(shí)，我們可以一邊啟動(dòng)IVR撥放歡迎詞，一邊spawn一個(gè)新進(jìn)程到遠程HTTP上取數據。當IVR運行到需要數據進(jìn)行決策時(shí)，絕大多數情況下這些數據已經(jīng)有了。即使獲取數據失敗，我們也可以以默認的方式進(jìn)行路由。這樣，客戶(hù)就不會(huì )感覺(jué)到任何延遲。
實(shí)現
我們使用mod_erlang_socket的outbound模式。當有電話(huà)進(jìn)來(lái)時(shí)，FreeSWITCH會(huì )通過(guò)dialplan立即把控制權交給Erlang。
<extension name="icall_fsm">
<condition field="destination_number" expression="^fsm$">
<action application="erlang" data="icall:fsm acd@192.168.1.27"/>
</condition>
</extension>
其中，Erlang程序acd運行在節點(diǎn)192.168.1.27上，FreeSWITCH會(huì )使用RPC調用執行icall:fsm()并在Erlang中啟動(dòng)一個(gè)有限狀態(tài)機，它接下來(lái)會(huì )控制呼叫流程，實(shí)現進(jìn)行狀態(tài)轉移，直到呼叫結束。并且，在呼叫過(guò)程中我們還通過(guò)db_pbx模塊與數據庫及遠程HTTP交互。Erlang實(shí)現的FSM代碼真的非常好看。
-module(icall).
-behaviour(gen_fsm).
-export([start/0, stop/0, fsm/1, init/1, welcome/2, handle_info/3, handle_event/3, terminate/3]).
-export([welcome_wait_playback/2, main_menu/2, main_menu_wait_dtmf/2, call_hst/2, call_sales/2, call_cc/2, call_extn/2,
call_cellphone/2, final_loop/2]).
-import(freeswitch_msg, [get_var/2, get_var/3, sendmsg/3]).
start() -> gen_fsm:start(icall_fsm, [], []).
stop() -> gen_fsm:send_all_state_event(self(), stop).
fsm(Ref) ->
{ok, NewPid} = ?MODULE:start(),
{Ref, NewPid}.
%% send a stop this will end up in "handle_event"
% stop() -> gen_fsm:send_all_state_event(hello, stopit).
%% -- interface end
% This initialisation routine gets called
init(State) ->
io:format("icall_fsm init ~p, PID: ~p~n", [State, self()]),
{ok, welcome, []}.
%% The state machine
welcome([], []) ->
{next_state, welcome, []};
% welcome(UUID, []) ->
% {next_state, welcome, [UUID]};
welcome({call, {event, [UUID | Data]}}, []) ->
CallerID = get_var("Channel-Caller-ID-Number", Data, "00000000"),
Pid = self(),
spawn(fun() -> fetch_cc_extn_from_crm(Pid, CallerID) end),
io:format("New call from [~p]~n", [CallerID]),
db_pbx:new_call(UUID, Data),
sendmsg(UUID, playback, "new_sales/1000.wav"),
{next_state, welcome_wait_playback, UUID}.
welcome_wait_playback({call_event, {event, [UUID | Data]} }, UUID) ->
Name = get_var("Event-Name", Data),
App = get_var("Application", Data),
error_logger:info_msg("welcome_wait_playback: Pid ~p: UUID ~p, Event ~p~n",[self(), UUID, Name]),
case Name of
"CHANNEL_EXECUTE_COMPLETE" when App =:= "playback" ->
NextState = route_time_condition(UUID),
gen_fsm:send_event(self(), UUID),
{next_state, NextState, UUID};
_ ->
{next_state, welcome_wait_playback, UUID}
end.
main_menu(UUID, UUID) ->
sendmsg(UUID, play_and_get_digits, "1 1 3 5000 # new_sales/1001.wav new_sales/9004.wav menu_number [1-5]"),
db_pbx:log(UUID, "MainMenu", ""),
gen_fsm:send_event(self(), {call_event, {event, [UUID]}}),
{next_state, main_menu_wait_dtmf, UUID}.
main_menu_wait_dtmf({call_event, {event, [UUID | Data]} }, UUID) ->
Name = get_var("Event-Name", Data),
App = get_var("Application", Data),
error_logger:info_msg("Pid ~p: UUID ~p, Event ~p, State: main_menu_wait_dtmf~n",[self(), UUID, Name]),
case Name of
"CHANNEL_EXECUTE_COMPLETE" when App =:= "play_and_get_digits" ->
MenuNumber = get_var("variable_menu_number", Data),
db_pbx:log(UUID, "MainMenu", MenuNumber),
case MenuNumber of
"1" ->
gen_fsm:send_event(self(), UUID),
{next_state, call_hst, UUID};
"5" ->
%<min> <max> <tries> <timeout> <terminators> <file> <invalid_file> <var_name> <regexp>
sendmsg(UUID, play_and_get_digits, "3 3 3 5000 # new_sales/2002.wav new_sales/9004.wav extn_number [68]\\d\\d"),
{next_state, call_extn, no_extn};
X when X == "2"; X == "3"; X == "4" ->
gen_fsm:send_event(self(), UUID),
{next_state, call_sales, UUID};
_ ->
sendmsg(UUID, playback, "new_sales/9003.wav"),
timer:sleep(5000),
sendmsg(UUID, hangup, ""),
{next_state, final_loop, UUID}
end;
_ ->
{next_state, main_menu_wait_dtmf, UUID}
end.
call_hst(UUID, UUID) ->
transfer(UUID, "fifo_hst"),
{next_state, final_loop, UUID}.
call_cellphone(UUID, UUID) ->
transfer(UUID, "fifo_cellphone"),
{next_state, final_loop, UUID}.
call_sales(UUID, UUID) ->
case get(cc_extn) of
undefined ->
transfer(UUID, "fifo_sales"),
db_pbx:log(UUID, "SalesFifo", ""),
{next_state, final_loop, UUID};
Extn ->
play_intransfer(UUID),
sendmsg(UUID, set, "ringback=${us-ring}"),
sendmsg(UUID, set, "continue_on_fail=true"),
sendmsg(UUID, set, "hangup_after_bridge=true"),
sendmsg(UUID, bridge, "user/" ++ Extn),
db_pbx:log(UUID, "CallCC", Extn),
{next_state, call_cc, Extn}
end.
call_cc({call_event, {event, [UUID | Data]} }, Extn) ->
Name = get_var("Event-Name", Data),
App = get_var("Application", Data),
error_logger:info_msg("Pid ~p: UUID ~p, Event ~p, Extn ~p~n",[self(), UUID, Name, Extn]),
case Name of
"CHANNEL_EXECUTE_COMPLETE" when App =:= "bridge" ->
HangupCause = get_var("variable_originate_disposition", Data),
DialedUser = get_var("variable_dialed_user", Data),
sendmsg(UUID, play_and_get_digits, "1 1 2 5000 # new_sales/8" ++ Extn ++
".wav new_sales/9004.wav cc_menu_number [12]"),
db_pbx:log(UUID, "CCFailure", HangupCause),
{next_state, call_cc, Extn};
"CHANNEL_EXECUTE_COMPLETE" when App =:= "play_and_get_digits" ->
CCMenuNumber = get_var("variable_cc_menu_number", Data),
case CCMenuNumber of
"1" -> sendmsg(UUID, transfer, "Playcell_" ++ Extn);
"2" -> sendmsg(UUID, transfer, "VM_" ++ Extn);
_ -> sendmsg(UUID, transfer, "Quit")
end,
{next_state, final_loop, UUID};
_ ->
{next_state, call_cc, Extn}
end.
call_extn({call_event, {event, [UUID | Data]} }, no_extn) ->
Name = get_var("Event-Name", Data),
App = get_var("Application", Data),
error_logger:info_msg("Pid ~p: UUID ~p, Event ~p, State: call_extn",[self(), UUID, Name]),
case Name of
"CHANNEL_EXECUTE_COMPLETE" when App =:= "play_and_get_digits" ->
Extn = get_var("variable_extn_number", Data),
db_pbx:log(UUID, "CallExtn", Extn),
gen_fsm:send_event(self(), UUID),
{next_state, call_extn, Extn};
_ ->
{next_state, call_extn, no_extn}
end;
call_extn(UUID, Extn) ->
io:format("Calling extn: ~p~n", [Extn]),
% sendmsg(UUID, set, "campon=true"),
sendmsg(UUID, set, "ringback=${us-ring}"),
sendmsg(UUID, set, "continue_on_fail=true"),
sendmsg(UUID, set, "hangup_after_bridge=true"),
DialString = "user/" ++ Extn,
sendmsg(UUID, bridge, DialString),
{next_state, call_cc, Extn}.
final_loop({call_event, {event, [UUID | Data]} }, UUID) ->
Name = get_var("Event-Name", Data),
error_logger:info_msg("final_loop Pid ~p: UUID ~p, Event ~p~n",[self(), UUID, Name]),
{next_state, final_loop, UUID};
final_loop(UUID, UUID) ->
{next_state, final_loop, UUID}.
handle_info({cc_extn, error}, State, Data) ->
{next_state, State, Data};
handle_info({cc_extn, Extn}, State, Data) ->
put(cc_extn, Extn),
io:format("Found CC Extn: ~p~n", [Extn]),
{next_state, State, Data};
handle_info(call_hangup, State, Args) ->
io:format("Hangup ~p ~p ~n", [State, Args]),
{stop, normal, State};
handle_info({E, {event, [UUID | Data]}} = Event, State, StateData) ->
Name = get_var("Event-Name", Data),
App = list_to_atom(get_var("Application", Data, "undefined")),
error_logger:info_msg("handle_info: ~p ~p ~p ~p~n~p~n",[self(), UUID, Name, State, StateData]),
case Name of
"CHANNEL_HANGUP_COMPLETE"->
db_pbx:hangup(UUID, Data),
% {next_state, final_loop, UUID};
{stop, normal, UUID};
"CUSTOM" ->
SubClass = get_var("Event-Subclass", Data),
Action = get_var("FIFO-Action", Data),
io:format("Fifo: ~p ~p~n", [SubClass, Action]),
case SubClass of
"fifo::info" when Action =:= "bridge-caller" ->
db_pbx:process(UUID, Data);
_ -> ok
end,
{next_state, State, StateData};
_ ->
List = [welcome, welcome_wait_playback, main_menu_wait_dtmf, call_cc, call_extn],
case lists:any(fun(Elem) -> Elem =:= State end, List) of
true ->
gen_fsm:send_event(self(), Event);
_ -> ok
end,
{next_state, State, StateData}
end;
handle_info(Info, State, Data) ->
io:format("Got Other Info: ~p ~p ~p ~n", [Info, State, Data]).
handle_event(stop, _StateName, StateData) ->
{stop, normal, StateData}.
terminate(normal, _StateName, _StateData) ->
io:format("Stop with reason: normal ~p ~p~n", [_StateName, _StateData]),
ok;
terminate(Reason, _StateName, _StateData) ->
io:format("Stop with reason: ~p ~p ~p~n", [Reason, _StateName, _StateData]),
ok.
%% private
route_time_condition(UUID) ->
case db_pbx:get_time_condition("sales_icall") of
{Action, Args} ->
case Action of
% "idp_acd:" ++ ErlAction ->
% Fun = list_to_atom(ErlAction),
% db_pbx:log(UUID, "TimeCondition", ErlAction ++ " " ++ Args),
% ?MODULE:Fun(UUID, Args);
Action ->
db_pbx:log(UUID, "TimeCondition", Action ++ " " ++ Args),
sendmsg(UUID, list_to_atom(Action), Args),
final_loop
end;
_ ->
{Date, {Hour, Min, _Sec}} = erlang:localtime(),
Weekday = calendar:day_of_the_week(Date),
route_work_time(UUID, Weekday, Hour, Min)
end.
route_work_time(UUID, Weekday, Hour, Min)
when Weekday > 5 andalso Hour > 10 andalso (Hour < 20 orelse ( Min < 30 andalso Hour < 21) ) ->
db_pbx:log(UUID, "Weekend", "10:00 - 20:30"),
main_menu;
route_work_time(UUID, Weekday, Hour, Min) when Hour > 9 andalso (Hour < 20 orelse (Min < 30 andalso Hour < 21 ))->
db_pbx:log(UUID, "Workday", "Weekend 9:00 - 20:30"),
main_menu;
route_work_time(UUID, _Weekday, Hour, Min) when (Hour > 21 orelse (Hour > 20 andalso Min > 30)) andalso Hour < 23 ->
db_pbx:log(UUID, "Time", "20:30 - 23:00"),
call_hst;
route_work_time(UUID, _Weekday, _Hour, _Min) ->
db_pbx:log(UUID, "NonWorktime", "Cellphone"),
call_cellphone.
transfer(UUID, Dest) ->
transfer(UUID, Dest, "XML", "new_sales").
transfer(UUID, Dest, Dialplan, Context) ->
sendmsg(UUID, transfer, Dest ++ " " ++ Dialplan ++ " " ++ Context).
play_intransfer(UUID) ->
sendmsg(UUID, playback, "new_sales/1002.wav"),
timer:sleep(3000).
fetch_cc_extn_from_crm(Pid, CallerID) ->
Extn = case helpers:http_fetch(?CRM_APP, "/voip/cdrs?caller_id=" ++ CallerID) of
{error, _} -> error;
Number -> Number
end,
Pid ! {cc_extn, Extn}.
