diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -42,9 +42,6 @@
   * Test legacy data types
 
 
-* Transaction support
-
-
 * Implement data types
   * AltMetaData
   * AltRow
@@ -71,8 +68,6 @@
   * Login7: client program version
   * Login7: timezone
   * Login7: language
-  * Login7: collation
-  * RpcReqBatchProcId: ProcID
   * TSEnvChange: Type
   * TSLoginAck: Interface
   * TSReturnValue: Status
@@ -80,7 +75,7 @@
 
 * Implement Flag interfaces
   * Header status
-  * PLOEncription
+  * PLOEncryption
   * PLOMars
   * Login7 flag1
   * Login7 flag2
@@ -102,7 +97,6 @@
   * Mars support
   * SSPI support
   * FedAuth support
-  * Variable PacketSize support
   * TDS protocol versions other than 7.1
 
   * Attention  
diff --git a/ms-tds.cabal b/ms-tds.cabal
--- a/ms-tds.cabal
+++ b/ms-tds.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 49394a8278191a141ae8a27d9e19f2c2d1bbab3d689aa2454d6b9b44ae2312e9
+-- hash: efad0660f5cf0042c8ade6a168534cd8a14bd8d00708563ceeb560d6e059d864
 
 name:           ms-tds
-version:        0.2.0.0
+version:        0.3.0.0
 synopsis:       TDS Protocol implemented in Haskell
 description:    Please see the README on GitHub at <https://github.com/mitsuji/ms-tds#readme>
 category:       Database
diff --git a/src/Database/Tds/Message.hs b/src/Database/Tds/Message.hs
--- a/src/Database/Tds/Message.hs
+++ b/src/Database/Tds/Message.hs
@@ -1,9 +1,14 @@
 module Database.Tds.Message ( -- * Client Message
                               ClientMessage (..)
+                            , getClientMessage
+                            , putClientMessage
                               
                             -- ** Login
                             , Login7
+                            , tdsVersion
                             , defaultLogin7
+                            , l7PacketSize
+                            , l7ClientProgVer
                             , l7ConnectionID
                             , l7OptionFlags1
                             , l7OptionFlags2
@@ -11,6 +16,7 @@
                             , l7TypeFlags
                             , l7TimeZone
                             , l7Collation
+                            , l7CltIntName
                             , l7Language
                             , l7ClientPID
                             , l7ClientMacAddr
@@ -20,7 +26,6 @@
                             , l7UserName
                             , l7Password
                             , l7Database
-                            , tdsVersion
                             
                             -- ** SQL Batch
                             , SqlBatch (..)
@@ -39,7 +44,8 @@
                             
                             -- * Server Message
                             , ServerMessage (..)
-                            , ServerMessageInstance (..)
+                            , getServerMessage
+                            , putServerMessage
                             
                             , TokenStreams (..)
                             , TokenStream (..)
@@ -152,6 +158,9 @@
 
 import Control.Applicative((<$>))
 
+import qualified Data.ByteString.Lazy as LB
+import qualified Data.ByteString.Builder as BB
+
 import Data.Word (Word8(..),Word16(..),Word32(..),Word64(..))
 import Data.Int (Int8(..),Int16(..),Int32(..),Int64(..))
 
@@ -159,6 +168,9 @@
 import qualified Data.Binary.Put as Put
 import qualified Data.Binary.Get as Get
 
+import Control.Monad.Writer (WriterT(..),runWriterT,tell)
+import Control.Monad.Trans (lift)
+
 import Database.Tds.Primitives.Null
 import Database.Tds.Primitives.Decimal
 import Database.Tds.Primitives.Money
@@ -174,7 +186,41 @@
 
 
 
+putMessage :: Word32 -> Word8 -> LB.ByteString -> Put
+putMessage ps pt bs = mapM_ f $ split (ps -headerLength) bs
+  where
+    f :: (Bool,LB.ByteString) -> Put
+    f (isLast,bs) = do
+      let
+        len = (fromIntegral $ LB.length bs) + headerLength
+        flg = if isLast then 0x01 else 0x00 -- last flag
+      put $ Header pt flg len 0 0 0
+      Put.putLazyByteString bs
 
+  
+    split :: Word32 -> LB.ByteString -> [(Bool,LB.ByteString)]
+    split len lbs =
+      let
+        (lbs',rem) = LB.splitAt (fromIntegral len) lbs
+      in if LB.null rem
+         then [(True,lbs')]
+         else (False,lbs'): split len rem
+
+
+getMessage :: Get (Word8,LB.ByteString)
+getMessage = (\(pt,bs) -> (pt,BB.toLazyByteString bs)) <$> runWriterT f
+  where
+    f :: WriterT BB.Builder Get Word8
+    f = do
+      (Header pt flg len _ _ _) <- lift get
+      tell =<< BB.byteString <$> (lift $ Get.getByteString (fromIntegral $ len -8))
+      if flg == 0x01
+        then return pt
+        else f
+
+
+
+
 -- | [\[MS-TDS\] 2.2.1 Client Messages](https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-tds/7ea9ee1a-b461-41f2-9004-141c0e712935)
 data ClientMessage = CMPrelogin !Prelogin
                    | CMLogin7 !Login7
@@ -182,14 +228,14 @@
                    | CMRpcRequest !RpcRequest
                    deriving (Show)
 
-putClientMessage :: ClientMessage -> Put
-putClientMessage x =
+putClientMessage :: Word32 -> ClientMessage -> Put
+putClientMessage ps x =
   let (pt,bs) = case x of
         CMPrelogin   pr -> (0x12,encode pr)
         CMLogin7     l7 -> (0x10,encode l7)
         CMSqlBatch   b  -> (0x01,encode b)
         CMRpcRequest r  -> (0x03,encode r)
-  in putMessage pt bs
+  in putMessage ps pt bs
 
 getClientMessage :: Get ClientMessage
 getClientMessage = do
@@ -201,34 +247,23 @@
     0x03 -> return $ CMRpcRequest $ decode bs
     _ -> fail "getClientMessage: invalid packet type"
 
-instance Binary ClientMessage where
-  put = putClientMessage
-  get = getClientMessage
 
 
 
-class Binary a => ServerMessageInstance a
-instance ServerMessageInstance Prelogin
-instance ServerMessageInstance TokenStreams
+-- | [\[MS-TDS\] 2.2.2 Server Messages](https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-tds/342f4cbb-2b4b-489c-8b63-f99b12021a94)
+class Binary a => ServerMessage a
+instance ServerMessage Prelogin
+instance ServerMessage TokenStreams
 
-putServerMessageInstance :: ServerMessageInstance a => a -> Put
-putServerMessageInstance x =
-  putMessage 0x04 $ encode x
+putServerMessage :: ServerMessage a => Word32 -> a -> Put
+putServerMessage ps x =
+  putMessage ps 0x04 $ encode x
 
-getServerMessageInstance :: ServerMessageInstance a => Get a
-getServerMessageInstance = do
+getServerMessage :: ServerMessage a => Get a
+getServerMessage = do
   (pt,bs) <- getMessage
   case pt of
     0x04 -> return $ decode bs
     _ -> fail "getServerMessageInstance: invalid packet type"
-
-
--- | [\[MS-TDS\] 2.2.2 Server Messages](https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-tds/342f4cbb-2b4b-489c-8b63-f99b12021a94)
-newtype ServerMessage a = ServerMessage a
-                        deriving (Show)
-
-instance (ServerMessageInstance a) => Binary (ServerMessage a) where
-  put (ServerMessage x) = putServerMessageInstance x
-  get = ServerMessage <$> getServerMessageInstance
 
 
diff --git a/src/Database/Tds/Message/Client.hs b/src/Database/Tds/Message/Client.hs
--- a/src/Database/Tds/Message/Client.hs
+++ b/src/Database/Tds/Message/Client.hs
@@ -6,7 +6,10 @@
 
 
 module Database.Tds.Message.Client ( Login7
+                                   , tdsVersion
                                    , defaultLogin7
+                                   , l7PacketSize
+                                   , l7ClientProgVer
                                    , l7ConnectionID
                                    , l7OptionFlags1
                                    , l7OptionFlags2
@@ -14,6 +17,7 @@
                                    , l7TypeFlags
                                    , l7TimeZone
                                    , l7Collation
+                                   , l7CltIntName
                                    , l7Language
                                    , l7ClientPID
                                    , l7ClientMacAddr
@@ -58,7 +62,6 @@
 
 import Control.Monad (foldM,foldM_)
 
-import Database.Tds.Message.Header
 import Database.Tds.Message.Prelogin
 import Database.Tds.Message.DataStream
 import Database.Tds.Primitives.Collation
@@ -90,20 +93,29 @@
                      }
             deriving (Show)
 
+
+tdsVersion :: Word32
+tdsVersion = 0x71000001
+-- [MEMO]
+-- tds70Version = 0x70000000
+-- tds71Version = 0x71000001
+-- tds72Version = 0x72090002
+-- tds73Version = 0x730B0003
+-- tds74Version = 0x74000004
+
+
 defaultLogin7 :: Login7
 defaultLogin7 = Login7 { l7TdsVersion = tdsVersion
-                         , l7PacketSize = packetSize
-                         , l7ClientProgVer = 0x0683f2f8  -- [MEMO] 0x00000007
+                         , l7PacketSize = 4096
+                         , l7ClientProgVer = 0 -- [MEMO] 0x0683f2f8, 0x00000007
                          , l7ConnectionID = 0
                          , l7OptionFlags1 = 0x80 + 0x40 + 0x20
                          , l7OptionFlags2 = 0  -- [MEMO] 0x02 + 0x01
-
-
                          , l7OptionFlags3 = 0
                          , l7TypeFlags = 0
                          , l7TimeZone = 0  -- [MEMO] -120
                          , l7Collation = 0x00000000  -- [MEMO] 0x36040000, 0x1104d000, 0x09040000
-                         , l7CltIntName = T.pack "DB-Library" -- [MDMO] "OLEDB", "ODBC"
+                         , l7CltIntName = mempty -- [MDMO] "DB-Library", "OLEDB", "ODBC"
                          , l7Language = mempty -- [MEMO] "us_english"
                          , l7ClientPID = 0
                          , l7ClientMacAddr = mempty
diff --git a/src/Database/Tds/Message/DataStream.hs b/src/Database/Tds/Message/DataStream.hs
--- a/src/Database/Tds/Message/DataStream.hs
+++ b/src/Database/Tds/Message/DataStream.hs
@@ -499,7 +499,7 @@
 
 
 withValidIntegral :: String -> TypeInfo -> (TypeInfo -> a) -> a
-withValidIntegral ht = f
+withValidIntegral tn = f
   where
     f :: TypeInfo -> (TypeInfo -> a) -> a
     f ti@TIBit g = g ti
@@ -512,7 +512,7 @@
     f ti@TIIntN2 g = g ti 
     f ti@TIIntN4 g = g ti
     f ti@TIIntN8 g = g ti
-    f ti _ = error $ "withValidIntegral: " <> (show ti) <> " is not convertible from/to " <> ht
+    f ti _ = error $ "withValidIntegral: " <> (show ti) <> " is not convertible from/to " <> tn
 
 withValidBool = withValidIntegral "Bool"
 withValidInt = withValidIntegral "Int"
@@ -522,16 +522,12 @@
 isIntegralN = f
   where
     f :: TypeInfo -> Bool
-    f TIBit = False
-    f TIInt1 = False
-    f TIInt2 = False
-    f TIInt4 = False
-    f TIInt8 = False
     f TIBitN = True
     f TIIntN1 = True
     f TIIntN2 = True
     f TIIntN4 = True
     f TIIntN8 = True
+    f _ = False
 
 
 getIntegral :: Integral a => TypeInfo -> Get a
@@ -576,10 +572,9 @@
 isMoneyN = f
   where
     f :: TypeInfo -> Bool
-    f TIMoney4 = False
-    f TIMoney8 = False
     f TIMoneyN4 = True
     f TIMoneyN8 = True
+    f _ = False
     
 getMoney :: TypeInfo -> Get Money
 getMoney TIMoney4 = bytesToMoney4 <$> Get.getInt32le
@@ -613,10 +608,9 @@
 isUTCTimeN = f
   where
     f :: TypeInfo -> Bool
-    f TIDateTime4 = False
-    f TIDateTime8 = False
     f TIDateTimeN4 = True
     f TIDateTimeN8 = True
+    f _ = False
     
 getUTCTime :: TypeInfo -> Get UTCTime
 getUTCTime TIDateTime4 = bytesToUtc4 <$> Get.getWord16le <*> Get.getWord16le
@@ -640,14 +634,14 @@
 
 
 withValidFloat' :: String -> TypeInfo -> (TypeInfo -> a) -> a
-withValidFloat' hn = f
+withValidFloat' tn = f
   where
     f :: TypeInfo -> (TypeInfo -> a) -> a
     f ti@TIFlt4 g = g ti
     f ti@TIFlt8 g = g ti
     f ti@TIFltN4 g = g ti
     f ti@TIFltN8 g = g ti
-    f ti _ = error $ "withValidFloat': " <> (show ti) <> " is not convertible from/to " <> hn
+    f ti _ = error $ "withValidFloat': " <> (show ti) <> " is not convertible from/to " <> tn
 
 withValidFloat = withValidFloat' "Float"
 withValidDouble = withValidFloat' "Double"
@@ -656,10 +650,9 @@
 isFloatN = f
   where
     f :: TypeInfo -> Bool
-    f TIFlt4 = False
-    f TIFlt8 = False
     f TIFltN4 = True
     f TIFltN8 = True
+    f _ = False
     
 getFloat :: Fractional a => TypeInfo -> Get a
 getFloat TIFlt4 = realToFrac . wordToFloat <$> Get.getWord32le
@@ -729,18 +722,20 @@
 
 
 
-withValidText :: TypeInfo -> (TypeInfo -> a) -> a
-withValidText  = f
+withValidText' :: String -> TypeInfo -> (TypeInfo -> a) -> a
+withValidText' tn = f
   where
     f :: TypeInfo -> (TypeInfo -> a) -> a
     f ti@(TINChar _ _) g = g ti
     f ti@(TINVarChar _ _) g = g ti
     f ti@(TINText _ _) g = g ti
-    f ti _ = error $ "withValidText: " <> (show ti) <> " is not convertible from/to Text"
-    
+    f ti _ = error $ "withValidText: " <> (show ti) <> " is not convertible from/to " <> tn
 
+withValidText = withValidText' "Text"
+withValidString = withValidText' "String"
 
 
+
 runGet :: Get a -> LB.ByteString -> a
 runGet f bs = Get.runGet f bs
 
@@ -843,8 +838,13 @@
   fromRawBytes ti Nothing = withValidText ti $ \_ -> error "Text.fromRawBytes: Null value is not convertible to Text"
   toRawBytes ti t = withValidText ti $ \_ -> Just $ LT.encodeUtf16LE t
 
+instance Data String where
+  fromRawBytes ti (Just bs) = withValidString ti $ \_ -> LT.unpack $ LT.decodeUtf16LE bs
+  fromRawBytes ti Nothing = withValidString ti $ \_ -> error "String.fromRawBytes: Null value is not convertible to String"
+  toRawBytes ti s = withValidString ti $ \_ -> Just $ LT.encodeUtf16LE $ LT.pack s
 
 
+
 instance Data (Maybe Bool) where
   fromRawBytes ti rb = withValidBool ti $ \vt -> runGetBool vt <$> rb
   toRawBytes ti b = withValidBool ti $ \vt ->
@@ -927,5 +927,9 @@
 instance Data (Maybe LT.Text) where
   fromRawBytes ti rb = withValidText ti $ \_ -> LT.decodeUtf16LE <$> rb 
   toRawBytes ti t = withValidText ti $ \_ -> LT.encodeUtf16LE <$> t
+
+instance Data (Maybe String) where
+  fromRawBytes ti rb = withValidString ti $ \_ -> LT.unpack . LT.decodeUtf16LE <$> rb 
+  toRawBytes ti s = withValidString ti $ \_ -> LT.encodeUtf16LE . LT.pack <$> s
 
 
diff --git a/src/Database/Tds/Message/Header.hs b/src/Database/Tds/Message/Header.hs
--- a/src/Database/Tds/Message/Header.hs
+++ b/src/Database/Tds/Message/Header.hs
@@ -1,18 +1,10 @@
 {-# OPTIONS_HADDOCK hide #-}
 -- Packet Header:   https://msdn.microsoft.com/en-us/library/dd340948.aspx
 
-module Database.Tds.Message.Header ( packetSize
-                                   , tdsVersion
-                                   , Header (..)
-                                   , putMessage
-                                   , getMessage
+module Database.Tds.Message.Header ( Header (..)
+                                   , headerLength
                                    ) where
 
-import Control.Applicative((<$>))
-
-import qualified Data.ByteString.Lazy as LB
-import qualified Data.ByteString.Builder as BB
-
 import Data.Word (Word8(..),Word16(..),Word32(..),Word64(..))
 import Data.Int (Int8(..),Int16(..),Int32(..),Int64(..))
 
@@ -20,10 +12,7 @@
 import qualified Data.Binary.Put as Put
 import qualified Data.Binary.Get as Get
 
-import Control.Monad.Writer (WriterT(..),runWriterT,tell)
-import Control.Monad.Trans (lift)
 
-
 type Type = Word8
 type Status = Word8
 type Length = Word16
@@ -37,21 +26,7 @@
 headerLength :: Integral a => a
 headerLength = fromIntegral 8
 
-packetSize :: Integral a => a
-packetSize = fromIntegral 4096
 
-tdsVersion :: Word32
-tdsVersion = 0x71000001
-
--- [MEMO]
--- tds70Version = 0x70000000
--- tds71Version = 0x71000001
--- tds72Version = 0x72090002
--- tds73Version = 0x730B0003
--- tds74Version = 0x74000004
-
-
-
 -- https://msdn.microsoft.com/en-us/library/dd340948.aspx
 putHeader :: Header -> Put
 putHeader (Header pt st len spid pcid win) = do
@@ -78,40 +53,5 @@
   put = putHeader
   get = getHeader
 
-
-
-putMessage :: Word8 -> LB.ByteString -> Put
-putMessage pt bs = mapM_ f $ split (packetSize -headerLength) bs
-  where
-    f :: (Bool,LB.ByteString) -> Put
-    f (isLast,bs) = do
-      let
-        len = (fromIntegral $ LB.length bs) + headerLength
-        flg = if isLast then 0x01 else 0x00 -- last flag
-      put $ Header pt flg len 0 0 0
-      Put.putLazyByteString bs
-
-
-    split :: Int64 -> LB.ByteString -> [(Bool,LB.ByteString)]
-    split len lbs =
-      let
-        (lbs',rem) = LB.splitAt len lbs
-      in if LB.null rem
-         then [(True,lbs')]
-         else (False,lbs'): split len rem
-
-
-
-
-getMessage :: Get (Word8,LB.ByteString)
-getMessage = (\(pt,bs) -> (pt,BB.toLazyByteString bs)) <$> runWriterT f
-  where
-    f :: WriterT BB.Builder Get Word8
-    f = do
-      (Header pt flg len _ _ _) <- lift get
-      tell =<< BB.byteString <$> (lift $ Get.getByteString (fromIntegral $ len -8))
-      if flg == 0x01
-        then return pt
-        else f