diff --git a/apps/endpoint/include/endpoint.hrl b/apps/endpoint/include/endpoint.hrl
index b02b241..df99a1b 100644
--- a/apps/endpoint/include/endpoint.hrl
+++ b/apps/endpoint/include/endpoint.hrl
@@ -62,12 +62,7 @@
     created_at = 0 :: integer()
 }).
 
--record(north_data, {
-    id :: integer(),
-    location_code,
-    fields,
-    timestamp :: integer()
-}).
+
 
 -record(post_data, {
     id,
diff --git a/apps/endpoint/src/endpoint_buffer.erl b/apps/endpoint/src/endpoint_buffer.erl
index 2a3a1b7..dbf2aee 100644
--- a/apps/endpoint/src/endpoint_buffer.erl
+++ b/apps/endpoint/src/endpoint_buffer.erl
@@ -14,13 +14,14 @@
 %% 消息重发间隔
 -define(RETRY_INTERVAL, 5000).
 
--export([new/1, append/2]).
+-export([new/2, append/2, trigger_next/1, trigger_n/1, cleanup/1, ack/2, stat/1]).
 
 -record(buffer, {
     endpoint,
-    %% ets存储
     next_id = 1 :: integer(),
-    cursor :: integer(),
+    %% 当前数据所在的游标
+    cursor = 0 :: integer(),
+    %% ets存储的引用
     tid :: reference(),
     %% 定时器
     timer_pid :: pid(),
@@ -32,37 +33,42 @@
     acc_num = 0
 }).
 
-new(Endpoint = #endpoint{id = Id}) ->
+-record(north_data, {
+    id :: integer(),
+    location_code,
+    fields,
+    timestamp :: integer()
+}).
+
+-spec new(Endpoint :: #endpoint{}, WindowSize :: integer()) -> Buffer :: #buffer{}.
+new(Endpoint = #endpoint{id = Id}, WindowSize) when is_integer(WindowSize), WindowSize > 0 ->
     %% 初始化存储
-    EtsName = list_to_atom("endpoint_ets:" ++ integer_to_list(Id)),
+    EtsName = list_to_atom("endpoint_buffer_ets:" ++ integer_to_list(Id)),
     Tid = ets:new(EtsName, [ordered_set, private]),
     %% 定义重发器
     TimerPid = endpoint_timer:start_link(?RETRY_INTERVAL),
 
-    #buffer{tid = Tid, timer_pid = TimerPid}.
+    #buffer{cursor = 0, tid = Tid, timer_pid = TimerPid, endpoint = Endpoint, window_size = WindowSize}.
 
+-spec append(tuple(), Buffer :: #buffer{}) -> NBuffer :: #buffer{}.
 append({LocationCode, Fields, Timestamp}, Buffer = #buffer{tid = Tid, next_id = NextId, window_size = WindowSize, flight_num = FlightNum}) ->
     NorthData = #north_data{id = NextId, location_code = LocationCode, fields = Fields, timestamp = Timestamp},
     true = ets:insert(Tid, NorthData),
-
+    NBuffer = Buffer#buffer{next_id = NextId + 1},
     case FlightNum < WindowSize of
         true ->
-            %% Todo
-            [{next_event, info, fetch_next}];
+            trigger_next(NBuffer);
         false ->
-            ok
-    end,
+            NBuffer
+    end.
 
-    Buffer#buffer{next_id = NextId + 1}.
-
-trigger_n(Buffer = #buffer{endpoint = Endpoint = #endpoint{name = Name}, window_size = WindowSize}) ->
-    lager:debug("[iot_endpoint] endpoint: ~p, create postman", [Name]),
+-spec trigger_n(Buffer :: #buffer{}) -> NBuffer :: #buffer{}.
+trigger_n(Buffer = #buffer{window_size = WindowSize}) ->
     %% 最多允许window_size
-    lists:map(fun(_) ->
-        trigger_next(Buffer)
-              end, lists:seq(1, WindowSize)).
+    lists:foldl(fun(_, Buffer0) -> trigger_next(Buffer0) end, Buffer, lists:seq(1, WindowSize)).
 
 %% 触发读取下一条数据
+-spec trigger_next(Buffer :: #buffer{}) -> NBuffer :: #buffer{}.
 trigger_next(Buffer = #buffer{tid = Tid, cursor = Cursor, timer_pid = TimerPid, flight_num = FlightNum, endpoint = #endpoint{name = Name, mapper_fun = MapperFun}}) ->
     case ets:next(Tid, Cursor) of
         '$end_of_table' ->
@@ -70,7 +76,6 @@ trigger_next(Buffer = #buffer{tid = Tid, cursor = Cursor, timer_pid = TimerPid,
         NKey ->
             [NorthData = #north_data{id = Id, location_code = LocationCode}] = ets:lookup(Tid, NKey),
             %lager:debug("[iot_endpoint] endpoint: ~p, fetch_next success, north data is: ~p", [Name, NorthData]),
-
             %% 重发机制, 在发送的过程中mapper可能会改变
             case safe_invoke_mapper(MapperFun, NorthData) of
                 {ok, Body} ->
@@ -90,18 +95,21 @@ trigger_next(Buffer = #buffer{tid = Tid, cursor = Cursor, timer_pid = TimerPid,
             end
     end.
 
-ack(Id, Buffer = #buffer{tid = Tid, timer_pid =  TimerPid, acc_num = AccNum, flight_num = FlightNum}) ->
+-spec ack(Id :: integer(), Buffer :: #buffer{}) -> NBuffer :: #buffer{}.
+ack(Id, Buffer = #buffer{tid = Tid, timer_pid =  TimerPid, acc_num = AccNum, flight_num = FlightNum}) when is_integer(Id) ->
     true = ets:delete(Tid, Id),
     endpoint_timer:ack(TimerPid, Id),
     trigger_next(Buffer#buffer{acc_num = AccNum + 1, flight_num = FlightNum - 1}).
 
 %% 获取当前统计信息
+-spec stat(Buffer :: #buffer{}) -> map().
 stat(#buffer{acc_num = AccNum, tid = Tid}) ->
     #{
         <<"acc_num">> => AccNum,
         <<"queue_num">> => ets:info(Tid, size)
     }.
 
+-spec cleanup(Buffer :: #buffer{}) -> ok.
 cleanup(#buffer{timer_pid = TimerPid}) ->
     endpoint_timer:cleanup(TimerPid),
     ok.