diff --git a/agentx.cabal b/agentx.cabal
--- a/agentx.cabal
+++ b/agentx.cabal
@@ -2,8 +2,8 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                agentx
-version:             0.1.0.2
-synopsis:            AgentX protocol for snmp subagents
+version:             0.1.0.3
+synopsis:            AgentX protocol for write SNMP subagents
 description:         Native implementation agentx protocol (rfc2741)       
 license:             BSD3
 license-file:        LICENSE
@@ -15,20 +15,29 @@
 -- extra-source-files:  
 cabal-version:       >=1.10
 
+flag example
+  description: Install a "agentx_example" executable.
+  default: False
+
 library
-  exposed-modules:     Network.Protocol.Snmp.AgentX, 
-                       Network.Protocol.Snmp.AgentX.MIBTree, 
-                       Network.Protocol.Snmp.AgentX.Packet, 
-                       Network.Protocol.Snmp.AgentX.Handlers,
-                       Network.Protocol.Snmp.AgentX.Service,
-                       Network.Protocol.Snmp.AgentX.Types
-  other-modules: Network.Protocol.Snmp.AgentX.MIBTree.Tree, Network.Protocol.Snmp.AgentX.MIBTree.MIBTree, Network.Protocol.Snmp.AgentX.MIBTree.Types,
-                 Network.Protocol.Snmp.AgentX.Packet.Binary, Network.Protocol.Snmp.AgentX.Packet.Get, Network.Protocol.Snmp.AgentX.Packet.Put, 
-                 Network.Protocol.Snmp.AgentX.Packet.Types      
+  exposed-modules: Network.Protocol.Snmp.AgentX 
+                 , Network.Protocol.Snmp.AgentX.MIBTree 
+                 , Network.Protocol.Snmp.AgentX.Packet 
+                 , Network.Protocol.Snmp.AgentX.Handlers
+                 , Network.Protocol.Snmp.AgentX.Service
+                 , Network.Protocol.Snmp.AgentX.Types
+  other-modules: Network.Protocol.Snmp.AgentX.MIBTree.Tree
+               , Network.Protocol.Snmp.AgentX.MIBTree.MIBTree
+               , Network.Protocol.Snmp.AgentX.MIBTree.Types
+               , Network.Protocol.Snmp.AgentX.Packet.Binary
+               , Network.Protocol.Snmp.AgentX.Packet.Get
+               , Network.Protocol.Snmp.AgentX.Packet.Put
+               , Network.Protocol.Snmp.AgentX.Packet.Types      
   -- other-extensions:    
-  build-depends:       base >=4.6 && <4.8
+  build-depends:       base >=4.6 && <4.9
                      , snmp
                      , binary
+                     , unix
                      , bytestring
                      , bitwise
                      , network
@@ -46,6 +55,33 @@
   hs-source-dirs:      src
   ghc-options: -Wall
   default-language:    Haskell2010
+
+executable agentx_example
+  if !flag(example)
+    buildable: False
+  main-is: Main.hs
+  build-depends:       base >=4.6 && <4.9
+                     , snmp
+                     , binary
+                     , unix
+                     , bytestring
+                     , bitwise
+                     , network
+                     , fclabels
+                     , Diff
+                     , mtl
+                     , transformers
+                     , time
+                     , data-default
+                     , containers
+                     , safe
+                     , pipes-network
+                     , pipes
+                     , pipes-concurrency
+  hs-source-dirs:      src
+  ghc-options: -Wall -O2 -threaded
+  default-language:    Haskell2010
+
 
 source-repository head
   type:              git
diff --git a/src/Main.hs b/src/Main.hs
new file mode 100644
--- /dev/null
+++ b/src/Main.hs
@@ -0,0 +1,82 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE RankNTypes #-}
+module Main where
+
+import Network.Protocol.Snmp.AgentX 
+import qualified Data.ByteString as BS
+import Data.ByteString (ByteString)
+import Data.Fixed (div')
+import Data.Time.Clock.POSIX (getPOSIXTime)
+import Control.Applicative ((<$>))
+import Control.Monad.State
+import Data.IORef
+
+
+
+str :: ByteString -> PVal
+str x = rsValue (String x)
+
+now :: PVal
+now = rdValue $  TimeTicks . flip div' 1 <$> liftIO getPOSIXTime
+
+rws :: IORef Value -> PVal
+rws io = rwValue readV commit test undo
+  where
+    test (String x) 
+      | BS.length x < 10 = return NoTestError
+      | otherwise = return TooBig
+    test _ = return WrongType
+    commit v = do
+        writeIORef io v
+        return NoCommitError
+    undo _ = return NoUndoError
+    readV = readIORef io
+
+rwi :: IORef Value -> PVal
+rwi io = rwValue readV commit test undo
+  where
+    test (Integer x) 
+      | x < 5 = return NoTestError
+      | otherwise = return TooBig
+    test _ = return WrongType
+    commit v = do
+        writeIORef io v
+        return NoCommitError
+    undo _ = return NoUndoError
+    readV = readIORef io
+
+dynTree :: IORef Value -> Update
+dynTree i = Update $ do
+    Integer count <- liftIO $ readIORef i
+    return $ concatMap fun [0 .. count]
+    where
+    fun x = [ mkObject (fromIntegral x) "trees" ("tree" ++ show x) Nothing
+            , mkObjectType 0 ("tree" ++ show x) "abr" Nothing (str "abr")
+            , mkObjectType 1 ("tree" ++ show x) "abrvalg" Nothing (str "abrvalg")
+            ]
+
+ver :: Maybe Context
+ver = Just "version"
+
+simpleTree :: IORef Value -> IORef Value -> [MIB]
+simpleTree m i = 
+      [ mkObject 0 "Fixmon" "about" Nothing
+      , mkObjectType 0 "about" "name" Nothing $ rsValue (String "Fixmon agent")
+      , mkObjectType 1 "about" "version" Nothing $ rsValue (String "0.0.1")
+      , mkObjectType 1 "about" "version" ver $ rsValue (String "Alpha")
+      , mkObjectType 2 "about" "comment" Nothing (rws m) 
+      , mkObject 1 "Fixmon" "dyn" Nothing
+      , mkObjectType 0 "dyn" "counter" Nothing (rwi i)
+      , mkObject 1 "dyn" "trees" (Just $ dynTree i)
+      ]
+
+tree :: IO [MIB]
+tree = do
+    m <- newIORef (String "init")
+    i <- newIORef (Integer 0)
+    return $ simpleTree m i
+    
+main :: IO ()
+main = agent "/var/agentx/master" [1,3,6,1,4,1,44729] Nothing =<< tree
+
diff --git a/src/Network/Protocol/Snmp/AgentX.hs b/src/Network/Protocol/Snmp/AgentX.hs
--- a/src/Network/Protocol/Snmp/AgentX.hs
+++ b/src/Network/Protocol/Snmp/AgentX.hs
@@ -15,6 +15,7 @@
 , UndoError(..)
 , Context
 , agent
+, runAgent
 , Client
 -- * Usage
 -- ** Imports
@@ -163,18 +164,12 @@
 > > defPrivType DES
 > > defContext ""
 > 
-> Build and start example
-> > cabal install example
-> > .cabal-sandbox/bin/example
-> > .cabal-sandbox/bin/agentx
-> > "set sid SessionID 15"
-> > "R ([1,3,6,1,4,1,44729,1,1,0,1],Nothing)"
-> > "R ([1,3,6,1,4,1,44729,1,1,0,0],Nothing)"
-> > "R ([1,3,6,1,4,1,44729,1,0],Nothing)"
-> > "R ([1,3,6,1,4,1,44729,0,2],Nothing)"
-> > "R ([1,3,6,1,4,1,44729,0,1],Just (Context \"version\"))"
-> > "R ([1,3,6,1,4,1,44729,0,1],Nothing)"
-> > "R ([1,3,6,1,4,1,44729,0,0],Nothing)"
+> Build example
+> > cabal install -f example
+> Start SNMP server
+> > sudo snmpd
+> Start SNMP agent
+> > .cabal-sandbox/bin/agentx_example
 > 
 > Get MIB tree
 >  > snmpwalk -r 1 -On localhost 1.3.6.1.4.1.44729
diff --git a/src/Network/Protocol/Snmp/AgentX/Service.hs b/src/Network/Protocol/Snmp/AgentX/Service.hs
--- a/src/Network/Protocol/Snmp/AgentX/Service.hs
+++ b/src/Network/Protocol/Snmp/AgentX/Service.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE BangPatterns #-}
 module Network.Protocol.Snmp.AgentX.Service 
 ( agent 
+, runAgent
 , Client(..) 
 , request
 , requestWithResponse
@@ -11,7 +12,7 @@
 
 import Network.Socket (close, Socket, socket, Family(AF_UNIX), SocketType(Stream), connect, SockAddr(SockAddrUnix))
 import Network.Socket.ByteString.Lazy (recv, send)
-import Control.Concurrent (killThread, threadDelay, ThreadId)
+import Control.Concurrent (killThread, threadDelay, ThreadId, myThreadId)
 import Data.Binary (encode, decode)
 import Data.Monoid ((<>))
 import Control.Applicative hiding (empty)
@@ -29,6 +30,8 @@
 import Data.Default
 import qualified Data.Map.Strict as Map 
 import qualified Data.Label as DL
+import System.Exit
+import System.Posix.Signals
 
 import Network.Protocol.Snmp (OID)
 import Network.Protocol.Snmp.AgentX.Packet 
@@ -50,6 +53,9 @@
 openSocket :: String -> IO Socket
 openSocket path = socket AF_UNIX Stream 0 >>= \x -> connect x (SockAddrUnix path) >> return x
 
+-- | start agent with socket
+-- exit when catch sigQUIT, sigTERM, keyboardSignal
+-- show MIB tree when catch sigUSR1
 runAgent :: OID -> [MIB] -> Maybe Client -> Socket -> IO ()
 runAgent modOid tree mclient socket' = do
     hSetBuffering stdout LineBuffering
@@ -69,18 +75,25 @@
     run st $ resp >-> openSession >-> output
     -- start register, unregister fiber
     regPid <- fiber st $ resp >-> registrator >->  output
-    -- start server fiber
+    -- start server fibers
     serverPid <-  fiber st $ req >-> server
     serverPid1 <-  fiber st $ req >-> server
     serverPid2 <-  fiber st $ req >-> server
     -- start agent fiber
     agentPid <- fiber st $ resp >-> runClient (maybe def id mclient) >-> output
     regPidTimer <- registerTimer st
-    _ <-  getLine :: IO String
-    liftIO $ putStrLn "unregister all MIB"
-    evalStateT unregisterFullTree =<< readIORef (mibs st)
-    liftIO $ threadDelay 1000000
-    void $ mapM (liftIO . killThread) [serverPid, serverPid1, serverPid2, sortPid, agentPid, regPid, timer, regPidTimer] -- p2,p3,p4,p5, 
+    mainPid <- myThreadId
+    let stopAgent = do
+            liftIO $ putStrLn "unregister all MIB"
+            evalStateT unregisterFullTree =<< readIORef (mibs st)
+            liftIO $ threadDelay 1000000
+            void $ mapM (liftIO . killThread) [serverPid, serverPid1, serverPid2, sortPid, agentPid, regPid, timer, regPidTimer] 
+            throwTo mainPid ExitSuccess
+    void $ installHandler keyboardSignal (Catch stopAgent) Nothing
+    void $ installHandler sigTERM (Catch stopAgent) Nothing
+    void $ installHandler sigQUIT (Catch stopAgent) Nothing
+    void $ installHandler sigUSR1 (Catch (print =<< readIORef (mibs st))) Nothing
+    forever $ threadDelay 10000000
 
 initAgent :: OID -> [MIB] -> Socket -> IO SubAgentState
 initAgent modOid tree socket' = do
@@ -192,8 +205,8 @@
     s <- mibs <$> ask
     m  <- liftIO $ readIORef s
     (toReg, toUnReg) <- liftIO $ takeMVar (DL.get MIBTree.register m)
-    liftIO $ mapM_ (\x -> print ("R " ++ show x)) toReg
-    liftIO $ mapM_ (\x -> print ("UR " ++ show x)) toUnReg
+--    liftIO $ mapM_ (\x -> print ("R " ++ show x)) toReg
+--    liftIO $ mapM_ (\x -> print ("UR " ++ show x)) toUnReg
     return $ map toRegPacket toReg <> map toUnRegPacket toUnReg
         where
         toRegPacket :: (OID, Maybe Context) -> Packet
@@ -226,16 +239,10 @@
     sesRef <- sessions <$> ask
     s <- liftIO $ readIORef sesRef
     case s of
-         Nothing -> do
-             liftIO $ atomicModifyIORef' sesRef (const $ (Just sid', ()))
-             msg
+         Nothing -> liftIO $ atomicModifyIORef' sesRef (const $ (Just sid', ()))
          Just x 
            | x == sid' -> return ()
-           | otherwise -> do
-               liftIO $ atomicModifyIORef' sesRef (const $ (Just sid', ()))
-               msg
-    where
-    msg = liftIO $ print $ "set sid " ++ show sid'
+           | otherwise -> liftIO $ atomicModifyIORef' sesRef (const $ (Just sid', ()))
     
 
 getPid :: SubAgent PacketID