diff --git a/src/Data/Opentracing/Tracer.hs b/src/Data/Opentracing/Tracer.hs
--- a/src/Data/Opentracing/Tracer.hs
+++ b/src/Data/Opentracing/Tracer.hs
@@ -17,7 +17,7 @@
 import           Control.Monad.IO.Class
 import qualified Data.HashMap.Lazy      as HM
 import           Data.Opentracing.Types
-import           Data.Time.Clock.POSIX
+-- import           Data.Time.Clock.POSIX
 import           Yam.Types.Prelude
 
 type SpanName = Text
@@ -35,7 +35,8 @@
 
 
 getNow :: MonadIO m => m Int
-getNow = liftIO $ round . (* 1000) <$> getPOSIXTime
+-- getNow = liftIO $ round . (* 1000) <$> getPOSIXTime
+getNow = return 0
 
 newSpan' :: MonadTracer m => SpanName -> SpanContext -> [SpanReference] -> m Span
 newSpan' name context references = do
diff --git a/src/Yam.hs b/src/Yam.hs
--- a/src/Yam.hs
+++ b/src/Yam.hs
@@ -5,6 +5,7 @@
   , module Yam.Swagger
   , module Yam.Middleware
   , module Yam.Middleware.Auth
+  , module Yam.Middleware.Client
   , module Yam.Middleware.Trace
   ) where
 
@@ -12,6 +13,7 @@
 import           Yam.Logger
 import           Yam.Middleware
 import           Yam.Middleware.Auth
+import           Yam.Middleware.Client
 import           Yam.Middleware.Trace
 import           Yam.Swagger
 import           Yam.Types
diff --git a/src/Yam/Internal.hs b/src/Yam/Internal.hs
--- a/src/Yam/Internal.hs
+++ b/src/Yam/Internal.hs
@@ -6,37 +6,32 @@
   , start
   ) where
 
-import qualified Data.ByteString.Lazy.Char8         as B
-import qualified Data.Vault.Lazy                    as L
+import qualified Data.Vault.Lazy          as L
 import           Network.Wai.Handler.Warp
 import           Servant
-import           Servant.Server.Internal.ServantErr
 import           Servant.Swagger
 import           Yam.Logger
 import           Yam.Middleware
-import           Yam.Middleware.Trace
+import           Yam.Middleware.Default
 import           Yam.Swagger
 import           Yam.Types
 
-whenException :: SomeException -> Response
-whenException e = responseServantErr $ fromMaybe err400 { errBody = B.pack $ show e } (fromException e :: Maybe ServantErr)
-
 startYam
   :: forall api. (HasSwagger api, HasServer api '[Env])
   => AppConfig
   -> SwaggerConfig
   -> LogConfig
-  -> TraceConfig
+  -> Bool
   -> Version
   -> [AppMiddleware]
   -> Proxy api
   -> ServerT api App
   -> IO ()
-startYam ac@AppConfig{..} sw@SwaggerConfig{..} logConfig traceConfig vs middlewares proxy server
+startYam ac@AppConfig{..} sw@SwaggerConfig{..} logConfig enableDefaultMiddleware vs middlewares proxy server
   = withLogger name logConfig $ do
       logInfo $ "Start Service [" <> name <> "] ..."
       logger <- askLoggerIO
-      let act = runAM $ foldr1 (<>) (traceMiddleware traceConfig : middlewares)
+      let act = runAM $ foldr1 (<>) ((if enableDefaultMiddleware then defaultMiddleware else []) <> middlewares)
       act (putLogger logger $ Env L.empty Nothing ac) $ \(env, middleware) -> do
         let cxt                  = env :. EmptyContext
             pCxt                 = Proxy :: Proxy '[Env]
@@ -47,6 +42,7 @@
                                  & setPort port
                                  & setOnException (\_ _ -> return ())
                                  & setOnExceptionResponse whenException
+                                 & setSlowlorisSize slowlorisSize
         when enabled $
           logInfo $ "Swagger enabled: http://localhost:" <> portText <> "/" <> pack urlDir
         logInfo $ "Servant started on port(s): " <> portText
@@ -77,4 +73,4 @@
   (p .>> "yam.application")
   (p .>> "yam.swagger"    )
   (p .>> "yam.logging"    )
-  (p .>> "yam.trace"      )
+  (p .?> "yam.middleware.default.enabled" .|= True)
diff --git a/src/Yam/Logger.hs b/src/Yam/Logger.hs
--- a/src/Yam/Logger.hs
+++ b/src/Yam/Logger.hs
@@ -11,8 +11,6 @@
   ) where
 
 import qualified Data.Text             as T
-import           GHC.Stack
-import           Servant
 import           System.IO.Unsafe      (unsafePerformIO)
 import           System.Log.FastLogger
 import           Yam.Types.Env
@@ -22,8 +20,8 @@
   fromProperties = fromProperties >=> go
     where
       go :: Property -> Return LogLevel
-      go (PStr t) = OK (gt $ T.toLower t)
-      go _        = Fail "loglevel shoudbe string"
+      go (PStr t) = return (gt $ T.toLower t)
+      go _        = error "loglevel shoudbe string"
       gt "debug" = LevelDebug
       gt "info"  = LevelInfo
       gt "warn"  = LevelWarn
@@ -63,18 +61,19 @@
   let ft = if file == ""
             then LogStdout $ fromIntegral bufferSize
             else LogFile (FileLogSpec file (toInteger maxSize) (fromIntegral rotateHistory)) $ fromIntegral bufferSize
+      ln = " [" <> toLogStr name <> "] "
   (l,close) <- newTimedFastLogger tc ft
-  return (toLogger l, close)
+  return (toLogger ln l, close)
   where
-    toLogger f Loc{..} _ ll s = when (level <= ll) $ f $ \t ->
+    toLogger xn f Loc{..} _ ll s = when (level <= ll) $ f $ \t ->
       let locate = if ll /= LevelError then "" else " @" <> toLogStr loc_filename <> toLogStr (show loc_start)
-      in toLogStr t <> " " <> toStr ll <> " [" <> toLogStr name <> "] " <> toLogStr loc_module <> locate <> " - " <> s <> "\n"
+      in toLogStr t <> " " <> toStr ll <> xn <> toLogStr loc_module <> locate <> " - " <> s <> "\n"
 
 withLogger :: Text -> LogConfig -> LoggingT IO a -> IO a
 withLogger n lc action = bracket (newLogger n lc) snd $ \(f,_) -> runLoggingT action f
 
 addTrace :: LogFunc -> Text -> LogFunc
-addTrace f tid a b c d = f a b c ("[" <> toLogStr tid <> "] " <> d)
+addTrace f tid a b c d = let p = "[" <> toLogStr tid <> "] " in f a b c (p <> d)
 
 {-# NOINLINE loggerKey #-}
 loggerKey :: Key LogFunc
@@ -98,8 +97,3 @@
       nlf x (Just t) = addTrace x t
       nlf x _        = x
   in maybe (\_ _ _ _ -> return ()) (`nlf` trace) logger
-
-throwS :: (HasCallStack, MonadIO m, MonadLogger m) => ServantErr -> Text -> m a
-throwS e msg = do
-  logErrorCS ?callStack msg
-  liftIO $ throw e
diff --git a/src/Yam/Middleware.hs b/src/Yam/Middleware.hs
--- a/src/Yam/Middleware.hs
+++ b/src/Yam/Middleware.hs
@@ -3,10 +3,11 @@
     AppMiddleware(..)
   , simpleAppMiddleware
   , simpleWebMiddleware
+  , runMiddleware
   ) where
 
-import           Yam.Types.Env
-import           Yam.Types.Prelude
+import           Yam.Logger
+import           Yam.Types
 
 -- | Application Middleware
 newtype AppMiddleware = AppMiddleware {runAM :: Env -> ((Env, Middleware)-> LoggingT IO ()) -> LoggingT IO ()}
@@ -20,7 +21,7 @@
 -- | Simple AppMiddleware
 simpleAppMiddleware :: HasCallStack => (Bool, Text) -> Key a -> a -> AppMiddleware
 simpleAppMiddleware (enabled,amname) k v =
-  if enabled
+  v `seq` if enabled
     then AppMiddleware $ \e f -> do
       logInfoCS ?callStack $ amname <> " enabled"
       f (setAttr k v e, id)
@@ -33,3 +34,8 @@
       logInfoCS ?callStack $ amname <> " enabled"
       f (e,m)
     else mempty
+
+runMiddleware :: MonadIO m => AppMiddleware -> App a -> m ()
+runMiddleware (AppMiddleware f) a = liftIO $ withLogger "test" def $ do
+  lf <- askLoggerIO
+  f (putLogger lf def) $ \(e,_) -> liftIO $ void $ runApp e a
diff --git a/src/Yam/Middleware/Client.hs b/src/Yam/Middleware/Client.hs
new file mode 100644
--- /dev/null
+++ b/src/Yam/Middleware/Client.hs
@@ -0,0 +1,45 @@
+module Yam.Middleware.Client(
+    ClientConfig(..)
+  , runClient
+  , clientMiddleware
+  , parseBaseUrl
+  , BaseUrl
+  ) where
+
+import           Network.HTTP.Client
+import           Servant.Client
+import           System.IO.Unsafe    (unsafePerformIO)
+import           Yam.Middleware
+import           Yam.Types
+
+data ClientConfig = ClientConfig
+  { enabled :: Bool
+  } deriving (Eq, Show)
+
+instance Default ClientConfig where
+  def = ClientConfig True
+
+instance FromProperties ClientConfig where
+  fromProperties p = ClientConfig
+    <$> p .?> "enabled" .?= enabled def
+
+{-# NOINLINE managerKey #-}
+managerKey :: Key Manager
+managerKey = unsafePerformIO newKey
+
+clientMiddleware :: ClientConfig -> AppMiddleware
+clientMiddleware ClientConfig{..} = AppMiddleware $ \e f -> do
+  mg <- liftIO $ newManager defaultManagerSettings { managerModifyRequest = go e}
+  f (setAttr managerKey mg e, id)
+  where
+    go env req = do
+      runApp env $ logDebug $ showText req
+      return req
+
+runClient :: ClientM a -> BaseUrl -> App a
+runClient action url = do
+  mg <- requireAttr managerKey
+  c  <- liftIO $ runClientM action $ mkClientEnv mg url
+  case c of
+    Left  e -> throw e
+    Right a -> return a
diff --git a/src/Yam/Middleware/Default.hs b/src/Yam/Middleware/Default.hs
new file mode 100644
--- /dev/null
+++ b/src/Yam/Middleware/Default.hs
@@ -0,0 +1,12 @@
+module Yam.Middleware.Default where
+
+import           Yam.Middleware
+import           Yam.Middleware.Client
+import           Yam.Middleware.Trace
+import           Yam.Types.Prelude
+
+defaultMiddleware :: [AppMiddleware]
+defaultMiddleware =
+  [ traceMiddleware  def
+  , clientMiddleware def
+  ]
diff --git a/src/Yam/Middleware/Trace.hs b/src/Yam/Middleware/Trace.hs
--- a/src/Yam/Middleware/Trace.hs
+++ b/src/Yam/Middleware/Trace.hs
@@ -31,7 +31,7 @@
   fromProperties = fromProperties >=> go
     where
       go :: Property -> Return TraceNotifyType
-      go _ = OK NoTracer
+      go _ = return NoTracer
 
 instance FromProperties TraceConfig where
   fromProperties p = TraceConfig
@@ -108,8 +108,11 @@
           tid = decodeUtf8 $ traceId <> "," <> spanId
           v   = L.insert extensionLogKey tid (vault req)
           v'  = L.insert spanKey s v
-      liftIO $ app req {vault = v'}
-        $ resH . mapResponseHeaders (\hs -> (hTraceId, traceId):(hSpanId, spanId):hs)
+          rh' = resH . mapResponseHeaders (\hs -> (hTraceId, traceId):(hSpanId, spanId):hs)
+          c e = do
+            runApp env (logError $ showText e)
+            rh' $ whenException e
+      liftIO (app req {vault = v'} rh' `catch` c)
 
 traceMiddleware :: TraceConfig -> AppMiddleware
 traceMiddleware TraceConfig{..}
diff --git a/src/Yam/Types.hs b/src/Yam/Types.hs
--- a/src/Yam/Types.hs
+++ b/src/Yam/Types.hs
@@ -2,6 +2,7 @@
   -- * AppM Monad
     App
   , runApp
+  , runTestApp
   , askApp
   , askAttr
   , withAttr
@@ -21,8 +22,11 @@
     , MonadIO
     , MonadReader Env)
 
-runApp :: Env -> App a -> IO a
-runApp e a = runReaderT (runApp' a) e
+runApp :: MonadIO m => Env -> App a -> m a
+runApp e a = liftIO $ runReaderT (runApp' a) e
+
+runTestApp :: Key a -> a -> App b -> IO b
+runTestApp k v a = runApp def $ withAttr k v a
 
 instance MonadUnliftIO App where
   withRunInIO f = do
diff --git a/src/Yam/Types/Env.hs b/src/Yam/Types/Env.hs
--- a/src/Yam/Types/Env.hs
+++ b/src/Yam/Types/Env.hs
@@ -10,17 +10,19 @@
 import           Yam.Types.Prelude
 
 data AppConfig = AppConfig
-  { name :: Text
-  , port :: Int
+  { name          :: Text
+  , port          :: Int
+  , slowlorisSize :: Int -- Bytes
   } deriving (Eq, Show)
 
 instance FromProperties AppConfig where
   fromProperties p = AppConfig
-    <$> p .?> "name" .?= name def
-    <*> p .?> "port" .?= port def
+    <$> p .?> "name"           .?= name def
+    <*> p .?> "port"           .?= port def
+    <*> p .?> "slowloris-size" .?= slowlorisSize def
 
 instance Default AppConfig where
-  def = AppConfig "application" 8888
+  def = AppConfig "application" 8888 2048
 
 data Env = Env
   { attributes    :: Vault
diff --git a/src/Yam/Types/Prelude.hs b/src/Yam/Types/Prelude.hs
--- a/src/Yam/Types/Prelude.hs
+++ b/src/Yam/Types/Prelude.hs
@@ -1,10 +1,18 @@
+{-# LANGUAGE CPP                  #-}
+{-# LANGUAGE ImplicitParams       #-}
+{-# LANGUAGE UndecidableInstances #-}
 module Yam.Types.Prelude(
     randomString
   , showText
+  , throwS
+  , whenException
+#if MIN_VERSION_salak(0,2,1)
+#else
   , (.>>)
   , (.?>)
   , (.?=)
   , (.|=)
+#endif
   , LogFunc
   , Default(..)
   , Text
@@ -17,6 +25,7 @@
   , bracket
   , throw
   , try
+  , catch
   , module Data.Proxy
   , module Data.Vault.Lazy
   , module Data.Maybe
@@ -34,16 +43,16 @@
   ) where
 
 import           Control.Applicative
-import           Control.Exception              hiding (Handler)
+import           Control.Exception                  hiding (Handler)
 import           Control.Monad
 import           Control.Monad.Except
 import           Control.Monad.IO.Unlift
 import           Control.Monad.Logger.CallStack
 import           Control.Monad.Reader
-import qualified Data.Binary                    as B
-import           Data.ByteString                (ByteString)
-import qualified Data.ByteString.Base16.Lazy    as B16
-import qualified Data.ByteString.Lazy           as L
+import qualified Data.Binary                        as B
+import           Data.ByteString                    (ByteString)
+import qualified Data.ByteString.Base16.Lazy        as B16
+import qualified Data.ByteString.Lazy               as L
 import           Data.Default
 import           Data.Function
 import           Data.Maybe
@@ -52,50 +61,63 @@
     ( FromProperties (..)
     , Properties
     , Property (..)
-    , Return (..)
+    , Return
     , defaultPropertiesWithFile
+#if MIN_VERSION_salak(0,2,1)
+    , (.>>)
+    , (.?=)
+    , (.?>)
+    , (.|=)
+#endif
     )
-import qualified Data.Salak                     as S
-import           Data.Text                      (Text, pack, unpack)
-import           Data.Text.Encoding             (decodeUtf8, encodeUtf8)
-import           Data.Vault.Lazy                (Key, Vault, newKey)
+import           Data.Text                          (Text, pack)
+import           Data.Text.Encoding                 (decodeUtf8, encodeUtf8)
+import           Data.Vault.Lazy                    (Key, Vault, newKey)
 import           Data.Version
 import           Data.Word
 import           GHC.Stack
 import           Network.HTTP.Types
 import           Network.Wai
-import           System.IO.Unsafe               (unsafePerformIO)
+import           Servant
+import           Servant.Server.Internal.ServantErr
+import           System.IO.Unsafe                   (unsafePerformIO)
 import           System.Random.MWC
 
+#if MIN_VERSION_salak(0,2,1)
+#else
+import qualified Data.Salak                         as S
+import           Data.Text                          (unpack)
+
 infixl 5 .?>
 (.?>) :: FromProperties a => Properties -> Text -> Return a
 (.?>) = flip S.lookup'
 
 infixl 5 .|=
 (.|=) :: Return a -> a -> a
-(.|=) (OK   a) _ = a
-(.|=) (Fail e) _ = error e
-(.|=) _        d = d
+(.|=) (S.OK   a) _ = a
+(.|=) (S.Fail e) _ = error e
+(.|=) _        d   = d
 
 infixl 5 .?=
 (.?=) :: Return a -> a -> Return a
-(.?=) a b = OK (a .|= b)
+(.?=) a b = S.OK (a .|= b)
 
 infixl 5 .>>
 (.>>) :: FromProperties a => Properties -> Text -> a
 (.>>) p k = case p .?> k of
-  OK v   -> v
-  Empty  -> case fromProperties S.empty of
-    (OK   a) -> a
-    (Fail e) -> error e
-    _        -> error $ "Config " <> unpack k <> " not found"
-  Fail e -> error e
+  S.OK v   -> v
+  S.Empty  -> case fromProperties S.empty of
+    (S.OK   a) -> a
+    (S.Fail e) -> error e
+    _          -> error $ "Config " <> unpack k <> " not found"
+  S.Fail e -> error e
+#endif
 
 type LogFunc = Loc -> LogSource -> LogLevel -> LogStr -> IO ()
 
 {-# NOINLINE randomGen #-}
 randomGen :: GenIO
-randomGen = unsafePerformIO create
+randomGen = unsafePerformIO createSystemRandom
 
 -- | Utility
 randomString :: IO ByteString
@@ -105,3 +127,11 @@
 showText :: Show a => a -> Text
 showText = pack . show
 
+throwS :: (HasCallStack, MonadIO m, MonadLogger m) => ServantErr -> Text -> m a
+throwS e msg = do
+  logErrorCS ?callStack msg
+  liftIO $ throw e
+
+
+whenException :: SomeException -> Response
+whenException e = responseServantErr $ fromMaybe err400 (fromException e :: Maybe ServantErr)
diff --git a/yam.cabal b/yam.cabal
--- a/yam.cabal
+++ b/yam.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.12
 name: yam
-version: 0.5.6
+version: 0.5.7
 license: BSD3
 license-file: LICENSE
 copyright: (c) 2018 Daniel YU
@@ -19,8 +19,10 @@
         Yam
         Yam.Internal
         Yam.Middleware
+        Yam.Middleware.Default
         Yam.Middleware.Auth
         Yam.Middleware.Trace
+        Yam.Middleware.Client
         Yam.Swagger
         Yam.Types
         Yam.Types.Prelude
@@ -55,6 +57,7 @@
         bytestring >=0.10.8.2 && <0.11,
         data-default >=0.7.1.1 && <0.8,
         fast-logger >=2.4.13 && <2.5,
+        http-client >=0.5.14 && <0.6,
         http-types >=0.12.2 && <0.13,
         lens ==4.17.*,
         monad-logger >=0.3.30 && <0.4,
@@ -63,16 +66,17 @@
         reflection >=2.1.4 && <2.2,
         salak >=0.1.4 && <0.3,
         scientific >=0.3.6.2 && <0.4,
+        servant-client ==0.15.*,
         servant-server ==0.15.*,
         servant-swagger >=1.1.7 && <1.2,
         servant-swagger-ui >=0.3.2.3.19.3 && <0.4,
         swagger2 >=2.3.1 && <2.4,
         text >=1.2.3.1 && <1.3,
-        time >=1.8.0.2 && <1.9,
         unliftio-core >=0.1.2.0 && <0.2,
         unordered-containers >=0.2.9.0 && <0.3,
         vault >=0.3.1.2 && <0.4,
         wai >=3.2.1.2 && <3.3,
+        wai-extra >=3.0.24.3 && <3.1,
         warp >=3.2.25 && <3.3
 
 test-suite spec
@@ -89,6 +93,8 @@
         Yam.Logger
         Yam.Middleware
         Yam.Middleware.Auth
+        Yam.Middleware.Client
+        Yam.Middleware.Default
         Yam.Middleware.Trace
         Yam.Swagger
         Yam.Types
@@ -120,6 +126,7 @@
         data-default >=0.7.1.1 && <0.8,
         fast-logger >=2.4.13 && <2.5,
         hspec ==2.*,
+        http-client >=0.5.14 && <0.6,
         http-types >=0.12.2 && <0.13,
         lens ==4.17.*,
         monad-logger >=0.3.30 && <0.4,
@@ -128,14 +135,15 @@
         reflection >=2.1.4 && <2.2,
         salak >=0.1.4 && <0.3,
         scientific >=0.3.6.2 && <0.4,
+        servant-client ==0.15.*,
         servant-server ==0.15.*,
         servant-swagger >=1.1.7 && <1.2,
         servant-swagger-ui >=0.3.2.3.19.3 && <0.4,
         swagger2 >=2.3.1 && <2.4,
         text >=1.2.3.1 && <1.3,
-        time >=1.8.0.2 && <1.9,
         unliftio-core >=0.1.2.0 && <0.2,
         unordered-containers >=0.2.9.0 && <0.3,
         vault >=0.3.1.2 && <0.4,
         wai >=3.2.1.2 && <3.3,
+        wai-extra >=3.0.24.3 && <3.1,
         warp >=3.2.25 && <3.3