src/lwes.erl

   1 %%%
   2 %%% Light Weight Event System (LWES)
   3 %%%
   4 %%% Creating Events
   5 %%%   Event0 = lwes_event:new ("MyEvent"),
   6 %%%   Event1 = lwes_event:set_uint16 (Event0, "MyUint16", 25),
   7 %%%
   8 %%% Emitting
   9 %%%
  10 %%%   Channel = lwes:open (emitter, Ip, Port)
  11 %%%   ok = lwes:emit (Channel, Event1).
  12 %%%
  13 %%% Listening via callback
  14 %%%
  15 %%%   Channel = lwes:open (listener, Ip, Port)
  16 %%%   lwes:listen (Channel, Type, Fun, Accum).
  17 %%%
  18 %%%   Fun is called for each event
  19 %%%
  20 %%% Closing channel
  21 %%%
  22 %%%   lwes:close (Channel)
  23
  24 -module (lwes).
  25
  26 -include_lib ("lwes.hrl").
  27
  28 -ifdef(HAVE_EUNIT).
  29 -include_lib("eunit/include/eunit.hrl").
  30 -endif.
  31
  32 %% API
  33 -export ([ open/3,
  34            emit/2,
  35            listen/4,
  36            close/1 ]).
  37
  38 %%====================================================================
  39 %% API functions
  40 %%====================================================================
  41 open (Type, Ip, Port) ->
  42   try check_args (Type, Ip, Port) of
  43     { T, I, P } -> lwes_channel:open (T, I, P)
  44   catch
  45     _:_ -> {error, cant_open}
  46   end.
  47
  48 emit (Channel, Event) ->
  49   lwes_channel:send_to (Channel, lwes_event:to_binary (Event)).
  50
  51 %
  52 % Callback function - function is called with an event in given format
  53 %                     and the current state, it should return the next
  54 %                     state
  55 %
  56 % Type is one of
  57 %
  58 %   raw    - callback is given raw udp structure, use lwes_event:from_udp to
  59 %            turn into event
  60 %   list   - callback is given an #lwes_event record where the name is a
  61 %            binary, and the attributes is a proplist where keys are binaries,
  62 %            and values are either integers (for lwes int types), binaries
  63 %            (for lwes strings), true|false atoms (for lwes booleans),
  64 %            or 4-tuples (for lwes ip addresses)
  65 %   tagged - callback is given an #lwes_event record where the name is a
  66 %            binary, and the attributes are 3-tuples with the first element
  67 %            the type of data, the second the key as a binary and the
  68 %            third the values as in the list format
  69 %
  70 % Initial State is whatever you want
  71 listen (Channel, CallbackFunction, EventType, CallbackInitialState)
  72   when is_function (CallbackFunction, 2),
  73        EventType =:= raw ; EventType =:= tagged ; EventType =:= list ->
  74   lwes_channel:register_callback (Channel, CallbackFunction,
  75                                   EventType, CallbackInitialState).
  76
  77 close (Channel) ->
  78   lwes_channel:close (Channel).
  79
  80 %%====================================================================
  81 %% Internal functions
  82 %%====================================================================
  83
  84 check_args (Type, Ip, Port) ->
  85   { normalize_type (Type), lwes_util:normalize_ip (Ip), normalize_port (Port) }.
  86
  87 normalize_port (Port) when is_integer (Port), Port >= 0, Port =< 65535 ->
  88   Port;
  89 normalize_port (Port) when is_list (Port) ->
  90   list_to_integer (Port);
  91 normalize_port (_) ->
  92   erlang:error (badarg).
  93
  94 normalize_type (Type) when Type =:= emitter; Type =:= listener ->
  95   Type;
  96 normalize_type (_) ->
  97   erlang:error (badarg).
  98
  99 %%====================================================================
 100 %% Test functions
 101 %%====================================================================
 102 -ifdef(EUNIT).
 103
 104 -endif.