diff --git a/rdpy/protocol/network/error.py b/rdpy/protocol/network/error.py
index 6371486..a6ad224 100644
--- a/rdpy/protocol/network/error.py
+++ b/rdpy/protocol/network/error.py
@@ -46,3 +46,13 @@ class InvalidType(Exception):
         '''
         Exception.__init__(self, message)
         
+class InvalidSize(Exception):
+    '''
+    raise when invalid size is present in packet type occured
+    '''
+    def __init__(self, message = ""):
+        '''
+        constructor with message
+        @param message: message show when exception is raised
+        '''
+        Exception.__init__(self, message)  
diff --git a/rdpy/protocol/network/type.py b/rdpy/protocol/network/type.py
index 4c59691..a2ea388 100644
--- a/rdpy/protocol/network/type.py
+++ b/rdpy/protocol/network/type.py
@@ -3,6 +3,7 @@
 '''
 
 import struct
+from copy import deepcopy
 from StringIO import StringIO
 from error import InvalidValue, InvalidType
 
@@ -240,6 +241,28 @@ class CompositeType(Type):
             size += sizeof(self.__dict__[name])
         return size
 
+    def __eq__(self, other):
+        '''
+        compare each properties which are Type inheritance
+        if one is different then not equal
+        @param other: CompositeType
+        @return: True if each subtype are equals
+        '''
+        if self._typeName != other._typeName:
+            return False
+        for name in self._typeName:
+            if self.__dict__[name] != other.__dict__[name]:
+                return False
+        return True
+    
+    def __ne__(self, other):
+        '''
+        return not equal result operator
+        @param other: CompositeType
+        @return: False if each subtype are equals
+        '''
+        return not self.__eq__(other)
+
 class UInt8(SimpleType):
     '''
     unsigned byte
@@ -460,15 +483,29 @@ class Stream(StringIO):
                 self.writeType(element)
             return
         value.write(self)
-        
-    def write_unistr(self, value):
-        for c in value:
-            self.write_uint8(ord(c))
-            self.write_uint8(0)
-        self.write_uint8(0)
-        self.write_uint8(0)
+
+def CheckValueOnRead(cls):
+    '''
+    wrap read method of class
+    to check value on read
+    if new value is different from old value
+    raise InvalidValue
+    @param cls: class that inherit from Type
+    '''
+    oldRead = cls.read
+    def read(self, s):
+        old = deepcopy(self)
+        oldRead(self, s)
+        if self != old:
+            raise InvalidValue("CheckValueOnRead %s != %s"%(self, old))
+    cls.read = read
+    return cls
 
 def hexDump(src, length=16):
+    '''
+    print hex representation of sr
+    @param src: string
+    '''
     FILTER = ''.join([(len(repr(chr(x))) == 3) and chr(x) or '.' for x in range(256)])
     for c in xrange(0, len(src), length):
         chars = src[c:c+length]
diff --git a/rdpy/protocol/rdp/ber.py b/rdpy/protocol/rdp/ber.py
index d0f4791..bf1d016 100644
--- a/rdpy/protocol/rdp/ber.py
+++ b/rdpy/protocol/rdp/ber.py
@@ -3,7 +3,8 @@
 '''
 from rdpy.protocol.network.type import UInt8, UInt16Be, UInt32Be, String
 from rdpy.utils.const import ConstAttributes
-from rdpy.protocol.network.error import InvalidExpectedDataException
+from rdpy.protocol.network.error import InvalidExpectedDataException,\
+    InvalidSize
 
 @ConstAttributes
 class BerPc(object):
@@ -228,9 +229,8 @@ def readEnumerated(s):
     '''
     if not readUniversalTag(s, Tag.BER_TAG_ENUMERATED, False):
         raise InvalidExpectedDataException("invalid ber tag")
-    size = readLength(s)
-    if size != UInt32Be(1):
-        raise InvalidExpectedDataException("enumerate size is wrong")
+    if readLength(s) != 1:
+        raise InvalidSize("enumerate size is wrong")
     enumer = UInt8()
     s.readType(enumer)
     return enumer.value
diff --git a/rdpy/protocol/rdp/mcs.py b/rdpy/protocol/rdp/mcs.py
index a259ea2..ba57e47 100644
--- a/rdpy/protocol/rdp/mcs.py
+++ b/rdpy/protocol/rdp/mcs.py
@@ -2,28 +2,30 @@
 @author: sylvain
 '''
 
-from rdpy.utils.const import ConstAttributes
+from rdpy.utils.const import ConstAttributes, TypeAttributes
 from rdpy.protocol.network.layer import LayerAutomata
 from rdpy.protocol.network.type import sizeof, Stream, UInt8
 from rdpy.protocol.rdp.ber import writeLength
+from rdpy.protocol.network.error import InvalidExpectedDataException, InvalidValue, InvalidSize
 
 import ber, gcc
 
 @ConstAttributes
+@TypeAttributes(UInt8)
 class Message(object):
     '''
     message type
     '''
-    MCS_TYPE_CONNECT_INITIAL = UInt8(0x65)
-    MCS_TYPE_CONNECT_RESPONSE = UInt8(0x66)
-    MCS_EDRQ =  UInt8(1)
-    MCS_DPUM = UInt8(8)
-    MCS_AURQ = UInt8(10)
-    MCS_AUCF = UInt8(11)
-    MCS_CJRQ = UInt8(14)
-    MCS_CJCF = UInt8(15)
-    MCS_SDRQ = UInt8(25)
-    MCS_SDIN = UInt8(26)
+    MCS_TYPE_CONNECT_INITIAL = 0x65
+    MCS_TYPE_CONNECT_RESPONSE = 0x66
+    MCS_EDRQ = 1
+    MCS_DPUM = 8
+    MCS_AURQ = 10
+    MCS_AUCF = 11
+    MCS_CJRQ = 14
+    MCS_CJCF = 15
+    MCS_SDRQ = 25
+    MCS_SDIN = 26
     
 class Channel:
     MCS_GLOBAL_CHANNEL = 1003
@@ -66,6 +68,8 @@ class MCS(LayerAutomata):
                self.writeDomainParams(0xffff, 0xfc17, 0xffff, 0xffff),
                ber.writeOctetstring(ccReqStream.getvalue()))
         self._transport.send((ber.writeApplicationTag(Message.MCS_TYPE_CONNECT_INITIAL, sizeof(tmp)), tmp))
+        #we must receive a connect response
+        self.setNextState(self.recvConnectResponse)
     
     def writeDomainParams(self, maxChannels, maxUsers, maxTokens, maxPduSize):
         '''
@@ -81,5 +85,34 @@ class MCS(LayerAutomata):
                        ber.writeInteger(1), ber.writeInteger(0), ber.writeInteger(1),
                        ber.writeInteger(maxPduSize), ber.writeInteger(2))
         return (ber.writeUniversalTag(ber.Tag.BER_TAG_SEQUENCE, True), writeLength(sizeof(domainParam)), domainParam)
+    
+    def readDomainParams(self, s):
+        '''
+        read domain params structure
+        '''
+        if not ber.readUniversalTag(s, ber.Tag.BER_TAG_SEQUENCE, True):
+            raise InvalidValue("bad BER tags")
+        length = ber.readLength(s)
+        max_channels = ber.readInteger(s)
+        max_users = ber.readInteger(s)
+        max_tokens = ber.readInteger(s)
+        ber.readInteger(s)
+        ber.readInteger(s)
+        ber.readInteger(s)
+        max_pdu_size = ber.readInteger(s)
+        ber.readInteger(s)
+        
+    def recvConnectResponse(self, data):
+        ber.readApplicationTag(data, Message.MCS_TYPE_CONNECT_RESPONSE)
+        ber.readEnumerated(data)
+        ber.readInteger(data)
+        self.readDomainParams(data)
+        if not ber.readUniversalTag(data, ber.Tag.BER_TAG_OCTET_STRING, False):
+            raise InvalidExpectedDataException("invalid expected tag")
+        gccRequestLength = ber.readLength(data)
+        if data.dataLen() != gccRequestLength:
+            raise InvalidSize("gcc request have ")
+        from rdpy.protocol.network.type import hexDump
+        hexDump(data.getvalue())
         
         
\ No newline at end of file
diff --git a/rdpy/protocol/rdp/per.py b/rdpy/protocol/rdp/per.py
index b142b20..e140497 100644
--- a/rdpy/protocol/rdp/per.py
+++ b/rdpy/protocol/rdp/per.py
@@ -2,7 +2,7 @@
 @author: sylvain
 '''
 
-from rdpy.protocol.network.type import UInt8, UInt16Be, UInt32Be, String, Stream
+from rdpy.protocol.network.type import UInt8, UInt16Be, UInt32Be, String
 from rdpy.protocol.network.error import InvalidValue, InvalidExpectedDataException
 
 def readLength(s):
diff --git a/rdpy/protocol/rdp/tpdu.py b/rdpy/protocol/rdp/tpdu.py
index cae6673..9fe03f1 100644
--- a/rdpy/protocol/rdp/tpdu.py
+++ b/rdpy/protocol/rdp/tpdu.py
@@ -4,37 +4,40 @@
 from rdpy.protocol.network.layer import LayerAutomata
 from rdpy.protocol.network.type import UInt8, UInt16Le, UInt16Be, UInt32Le, CompositeType, sizeof
 from rdpy.protocol.network.error import InvalidExpectedDataException, NegotiationFailure
-from rdpy.utils.const import ConstAttributes
+from rdpy.utils.const import ConstAttributes, TypeAttributes
 
 @ConstAttributes
+@TypeAttributes(UInt8)
 class MessageType(object):
     '''
     message type
     '''
-    X224_TPDU_CONNECTION_REQUEST = UInt8(0xE0)
-    X224_TPDU_CONNECTION_CONFIRM = UInt8(0xD0)
-    X224_TPDU_DISCONNECT_REQUEST = UInt8(0x80)
-    X224_TPDU_DATA = UInt8(0xF0)
-    X224_TPDU_ERROR = UInt8(0x70)
+    X224_TPDU_CONNECTION_REQUEST = 0xE0
+    X224_TPDU_CONNECTION_CONFIRM = 0xD0
+    X224_TPDU_DISCONNECT_REQUEST = 0x80
+    X224_TPDU_DATA = 0xF0
+    X224_TPDU_ERROR = 0x70
 
 @ConstAttributes
+@TypeAttributes(UInt8)
 class NegociationType(object):
     '''
     negotiation header
     '''
-    TYPE_RDP_NEG_REQ = UInt8(0x01)
-    TYPE_RDP_NEG_RSP = UInt8(0x02)
-    TYPE_RDP_NEG_FAILURE = UInt8(0x03)
+    TYPE_RDP_NEG_REQ = 0x01
+    TYPE_RDP_NEG_RSP = 0x02
+    TYPE_RDP_NEG_FAILURE = 0x03
 
 @ConstAttributes
+@TypeAttributes(UInt32Le)
 class Protocols(object):
     '''
     protocols available for TPDU layer
     '''
-    PROTOCOL_RDP = UInt32Le(0x00000000)
-    PROTOCOL_SSL = UInt32Le(0x00000001)
-    PROTOCOL_HYBRID = UInt32Le(0x00000002)
-    PROTOCOL_HYBRID_EX = UInt32Le(0x00000008)
+    PROTOCOL_RDP = 0x00000000
+    PROTOCOL_SSL = 0x00000001
+    PROTOCOL_HYBRID = 0x00000002
+    PROTOCOL_HYBRID_EX = 0x00000008
     
 class TPDUConnectHeader(CompositeType):
     '''
@@ -46,6 +49,15 @@ class TPDUConnectHeader(CompositeType):
         self.code = code
         self.padding = (UInt16Be(), UInt16Be(), UInt8())
         
+class TPDUDataHeader(CompositeType):
+    '''
+    header send when tpdu exchange application data
+    '''
+    def __init__(self):
+        CompositeType.__init__(self)
+        self.header = UInt8(2)
+        self.messageType = MessageType.X224_TPDU_DATA
+        self.separator = UInt8(0x80)
     
 class Negotiation(CompositeType):
     '''
@@ -69,7 +81,6 @@ class TPDU(LayerAutomata):
         @param presentation: MCS layer
         '''
         LayerAutomata.__init__(self, presentation)
-        
         #default protocol is SSl because is the only supported
         #in this version of RDPY
         self._protocol = Protocols.PROTOCOL_SSL
@@ -103,9 +114,19 @@ class TPDU(LayerAutomata):
         LayerAutomata.connect(self)
     
     def recvData(self, data):
-        print "TPDU data"
-        from rdpy.protocol.network.type import hexDump
-        hexDump(data.getvalue())
+        '''
+        read data header from packet
+        and pass to presentation layer
+        @param data: stream
+        '''
+        header = TPDUDataHeader()
+        data.readType(header)
+        if header.messageType == MessageType.X224_TPDU_DATA:
+            LayerAutomata.recv(self, data)
+        elif header.messageType == MessageType.X224_TPDU_ERROR:
+            raise Exception("receive error from tpdu layer")
+        else:
+            raise InvalidExpectedDataException("unknow tpdu code %s"%header.messageType)
         
     def sendConnectionRequest(self):
         '''
@@ -121,7 +142,7 @@ class TPDU(LayerAutomata):
         write message packet for TPDU layer
         add TPDU header
         '''
-        self._transport.send((UInt8(2), MessageType.X224_TPDU_DATA, UInt8(0x80), message))
+        self._transport.send((TPDUDataHeader(), message))
 
     def readNeg(self, data):
         '''
diff --git a/rdpy/protocol/rfb/message.py b/rdpy/protocol/rfb/message.py
index 3a3df65..5b01072 100644
--- a/rdpy/protocol/rfb/message.py
+++ b/rdpy/protocol/rfb/message.py
@@ -3,58 +3,63 @@
 '''
 
 from rdpy.protocol.network.type import UInt8, UInt16Be, UInt32Be, SInt32Be, String, CompositeType
-from rdpy.utils.const import ConstAttributes
+from rdpy.utils.const import ConstAttributes, TypeAttributes
 
 @ConstAttributes
+@TypeAttributes(String)
 class ProtocolVersion(object):
     '''
     different ptotocol version
     '''
-    UNKNOWN = String()
-    RFB003003 = String("RFB 003.003\n")
-    RFB003007 = String("RFB 003.007\n")
-    RFB003008 = String("RFB 003.008\n")
+    UNKNOWN = ""
+    RFB003003 = "RFB 003.003\n"
+    RFB003007 = "RFB 003.007\n"
+    RFB003008 = "RFB 003.008\n"
 
 @ConstAttributes 
+@TypeAttributes(UInt8)
 class SecurityType(object):
     '''
     security type supported 
     (or will be supported)
     by rdpy
     '''
-    INVALID = UInt8(0)
-    NONE = UInt8(1)
-    VNC = UInt8(2)
+    INVALID = 0
+    NONE = 1
+    VNC = 2
 
 @ConstAttributes
+@TypeAttributes(UInt32Be)
 class Pointer(object):
     '''
     mouse event code (which button)
     actually in RFB specification only$
     three buttons are supported
     '''
-    BUTTON1 = UInt32Be(0x1)
-    BUTTON2 = UInt32Be(0x2)
-    BUTTON3 = UInt32Be(0x4)
+    BUTTON1 = 0x1
+    BUTTON2 = 0x2
+    BUTTON3 = 0x4
 
-@ConstAttributes  
+@ConstAttributes
+@TypeAttributes(SInt32Be)  
 class Encoding(object):
     '''
     encoding types
     '''
-    RAW = SInt32Be(0)
+    RAW = 0
 
 @ConstAttributes
+@TypeAttributes(UInt8)
 class ClientToServerMessages(object):
     '''
     messages types
     '''
-    PIXEL_FORMAT = UInt8(0)
-    ENCODING = UInt8(2)
-    FRAME_BUFFER_UPDATE_REQUEST = UInt8(3)
-    KEY_EVENT = UInt8(4)
-    POINTER_EVENT = UInt8(5)
-    CUT_TEXT = UInt8(6)
+    PIXEL_FORMAT = 0
+    ENCODING = 2
+    FRAME_BUFFER_UPDATE_REQUEST = 3
+    KEY_EVENT = 4
+    POINTER_EVENT = 5
+    CUT_TEXT = 6
     
 class PixelFormat(CompositeType):
     '''
diff --git a/rdpy/utils/const.py b/rdpy/utils/const.py
index 6c1b012..fbd3dd8 100644
--- a/rdpy/utils/const.py
+++ b/rdpy/utils/const.py
@@ -33,16 +33,27 @@ class Constant(object):
         delete is forbidden on constant
         '''
         raise Exception("can't delete constant")
-    
+
+def TypeAttributes(typeClass):
+    '''
+    call typeClass ctor on each attributes
+    to uniform atributes type on class
+    @param typeClass: class use to construct each class attributes
+    @return: class decorator
+    '''
+    def wrapper(cls):
+        for c_name, c_value in cls.__dict__.iteritems():
+            if c_name[0] != '_' and not callable(c_value):
+                setattr(cls, c_name, typeClass(c_value))
+        return cls
+    return wrapper
 
 def ConstAttributes(cls):
     '''
+    copy on read attributes
     transform all attributes of class 
     in constant attribute
     only attributes which are not begining with '_' char
     and are not callable
     '''
-    for c_name, c_value in cls.__dict__.iteritems():
-        if c_name[0] != '_' and not callable(c_value):
-            setattr(cls, c_name, Constant(c_value))
-    return cls
+    return TypeAttributes(Constant)(cls)
\ No newline at end of file