diff --git a/rdpy/display/rle.py b/rdpy/display/rle.py
index e9295b8..a321513 100644
--- a/rdpy/display/rle.py
+++ b/rdpy/display/rle.py
@@ -45,7 +45,9 @@ def decode(src, width, height, colorType):
     insertMix = False
     fom_mask = 0
     mask = 0
-    dst = Stream("\x00" * (width * height * sizeof(colorType())))
+    line = 0
+    typeSize = sizeof(colorType())
+    dst = Stream("\x00" * (width * height * typeSize))
     
     while src.dataLen() > 0:
         #compute orders
@@ -107,7 +109,10 @@ def decode(src, width, height, colorType):
                     raise InvalidExpectedDataException("In RLE decompression height must be greater than 0")
                 x = 0
                 height -= 1
-                #prevline = line
+                prevline = line
+                line = width * height * typeSize
+            
+            
     return dst
             
                 
\ No newline at end of file
diff --git a/rdpy/network/error.py b/rdpy/network/error.py
index 69eacea..46b0080 100644
--- a/rdpy/network/error.py
+++ b/rdpy/network/error.py
@@ -21,6 +21,16 @@
 All exceptions error use in RDPY
 """
 
+class CallPureVirtualFuntion(Exception):
+    """
+    Raise when a virtual function is called and not implemented
+    """
+    def __init__(self, message = ""):
+        """
+        @param message: message show when exception is raised
+        """
+        Exception.__init__(self, message)
+
 class InvalidValue(Exception):
     """
     Raise when invalid value type occurred
diff --git a/rdpy/network/layer.py b/rdpy/network/layer.py
index 5c2d514..dc011dd 100644
--- a/rdpy/network/layer.py
+++ b/rdpy/network/layer.py
@@ -23,88 +23,94 @@ Join RDPY design with twisted design
 RDPY use Layer Protocol design (like twisted)
 """
 
+from rdpy.network.error import CallPureVirtualFuntion
+
 class LayerMode(object):
     NONE = 0
     SERVER = 1
     CLIENT = 2
-
+    
+    
+class StreamListener(object):
+    """
+    Interface use to inform that we can handle receive stream
+    """
+    def recv(self, s):
+        """
+        Signal that data is available for this layer
+        call by transport layer
+        default is to pass data to presentation layer
+        @param s: raw Stream receive from transport layer
+        """
+        raise CallPureVirtualFuntion("%s:%s defined by interface %s"%(self.__class__, "recv", "StreamListener"))
+    
+class StreamSender(object):
+    """
+    Interface use to show stream sender capability 
+    """
+    def send(self, data):
+        '''
+        Send Stream on layer
+        @param data: Type or tuple element handle by transport layer
+        '''
+        raise CallPureVirtualFuntion("%s:%s defined by interface %s"%(self.__class__, "send", "StreamSender"))
+    
 class Layer(object):
-    '''
-    Network abstraction for protocol
-    Try as possible to divide user protocol in layer
-    default implementation is a transparent layer
-    '''
-    def __init__(self, mode = LayerMode.NONE, presentation = None):
-        '''
-        Constructor
-        @param presentation: Layer which handled connect and recv messages
-        '''
+    """
+    A simple double linked list with presentation and transport layer
+    and a subset of event (connect and close)
+    """
+    def __init__(self, mode, presentation = None):
+        """
+        @param mode: LayerMode use
+        @param presentation: presentation layer
+        """
         #presentation layer higher layer in model
         self._presentation = presentation
         #transport layer under layer in model
         self._transport = None
-        #register layer mode
+        #network layer mode
         self._mode = mode
         #auto set transport layer of own presentation layer
         if not self._presentation is None:
             self._presentation._transport = self
     
     def connect(self):
-        '''
-        call when transport layer is connected
+        """
+        Call when transport layer is connected
         default is send connect event to presentation layer
-        '''
+        """
         if not self._presentation is None:
             self._presentation.connect()
     
-    def recv(self, s):
-        '''
-        signal that data is available for this layer
-        call by transport layer
-        default is to pass data to presentation layer
-        @param s: raw Stream receive from transport layer
-        '''
-        if not self._presentation is None:
-            self._presentation.recv(s)
-      
-    def send(self, data):
-        '''
-        classical use by presentation layer
-        write data for this layer
-        default pass data to transport layer
-        @param data: Type or tuple element handle by transport layer
-        '''
-        if not self._transport is None:
-            self._transport.send(data)
-    
     def close(self):
-        '''
-        close layer and send close signal 
-        to transport layer
-        '''
+        """
+        Close layer event
+        default is sent to transport layer
+        """
         if not self._transport is None:
             self._transport.close()
             
-class LayerAutomata(Layer):
-    '''
-    layer with automata state
-    we can set next recv function used
-    '''
+class LayerAutomata(Layer, StreamListener):
+    """
+    Layer with automata state
+    we can set next recv function used for Stream packet
+    """
     def __init__(self, mode, presentation = None):
-        '''
-        Constructor
+        """
+        @param mode: LayerMode use
         @param presentation: presentation Layer
-        '''
+        """
         #call parent constructor
         Layer.__init__(self, mode, presentation)
         
     def setNextState(self, callback = None):
-        '''
-        set recv function to next callback or
+        """
+        Set receive function to next callback or
         current self.recv function if it's None
         @param callback: a callable object that can 
         receive Layer, Stream parameters
-        '''
+        """
         if callback is None:
             callback = self.__class__.recv
         
@@ -115,16 +121,17 @@ from twisted.internet import protocol
 #first that handle stream     
 from type import Stream
 
-class RawLayer(protocol.Protocol, LayerAutomata):
-    '''
+class RawLayer(protocol.Protocol, LayerAutomata, StreamSender):
+    """
     Inherit from protocol twisted class
     allow this protocol to wait until expected size of packet
     and use Layer automata to call next automata state
-    '''
+    """
     def __init__(self, mode, presentation = None):
-        '''
-        Constructor
-        '''
+        """
+        @param mode: LayerMode use
+        @param presentation: presentation layer in layer list
+        """
         #call parent automata
         LayerAutomata.__init__(self, mode, presentation)
         #data buffer received from twisted network layer
@@ -133,11 +140,11 @@ class RawLayer(protocol.Protocol, LayerAutomata):
         self._expectedLen = 0
         
     def dataReceived(self, data):
-        '''
-        inherit from protocol class
+        """
+        Inherit from protocol class
         main event of received data
         @param data: string data receive from twisted
-        '''
+        """
         #add in buffer
         self._buffer += data
         #while buffer have expected size call local callback
@@ -150,29 +157,29 @@ class RawLayer(protocol.Protocol, LayerAutomata):
             self.recv(expectedData)
             
     def connectionMade(self):
-        '''
+        """
         inherit from twisted protocol
-        '''
+        """
         #join two scheme
         self.connect()
             
     def expect(self, expectedLen, callback = None):
-        '''
-        configure layer to change next state with callback only
+        """
+        Configure layer to change next state with callback only
         when expectLen bytes is received from transport layer
-        @param expectedLen: in bytes len use to call nextstate
-        @param callback: callback call when expectedlen bytes is received
-        '''
+        @param expectedLen: in bytes length use to call next state
+        @param callback: callback call when expected length bytes is received
+        """
         self._expectedLen = expectedLen
         #default callback is recv from LayerAutomata
         self.setNextState(callback)
         
     def send(self, message):
-        '''
-        send stream on tcp layer
+        """
+        Send Stream on TCP layer
         format message into raw stream understood by transport layer
         @param message: (tuple | Type)
-        '''
+        """
         s = Stream()
         s.writeType(message)
         self.transport.write(s.getvalue())
\ No newline at end of file
diff --git a/rdpy/protocol/rdp/ber.py b/rdpy/protocol/rdp/ber.py
index 1300cec..5e6eabc 100644
--- a/rdpy/protocol/rdp/ber.py
+++ b/rdpy/protocol/rdp/ber.py
@@ -1,6 +1,27 @@
-'''
-@author: sylvain
-'''
+#
+# Copyright (c) 2014 Sylvain Peyrefitte
+#
+# This file is part of rdpy.
+#
+# rdpy is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+"""
+Basic Encoding Rules use in RDP.
+ASN.1 standard
+"""
+
 from rdpy.network.type import UInt8, UInt16Be, UInt32Be, String
 from rdpy.network.const import ConstAttributes, TypeAttributes
 from rdpy.network.error import InvalidExpectedDataException, InvalidSize
@@ -35,24 +56,24 @@ class Tag(object):
     BER_TAG_SEQUENCE_OF = 0x10
 
 def berPC(pc):
-    '''
-    return BER_CONSTRUCT if true
+    """
+    Return BER_CONSTRUCT if true
     BER_PRIMITIVE if false
     @param pc: boolean
     @return: BerPc value
-    '''
+    """
     if pc:
         return BerPc.BER_CONSTRUCT
     else:
         return BerPc.BER_PRIMITIVE
     
 def readLength(s):
-    '''
-    read length of ber structure
+    """
+    Read length of BER structure
     length be on 1 2 or 3 bytes
     @param s: stream
-    @return: int or python long
-    '''
+    @return: int or Python long
+    """
     size = None
     length = UInt8()
     s.readType(length)
@@ -64,50 +85,50 @@ def readLength(s):
         elif byte == 2:
             size = UInt16Be()
         else:
-            raise InvalidExpectedDataException("ber length may be 1 or 2")
+            raise InvalidExpectedDataException("BER length may be 1 or 2")
         s.readType(size)
     else:
         size = length
     return size.value
 
 def writeLength(size):
-    '''
-    return strcture length as expected in Ber specification
+    """
+    Return structure length as expected in BER specification
     @param size: int or python long
     @return: UInt8 or (UInt8(0x82), UInt16Be)
-    '''
+    """
     if size > 0x7f:
         return (UInt8(0x82), UInt16Be(size))
     else:
         return UInt8(size)
     
 def readUniversalTag(s, tag, pc):
-    '''
-    read tag of ber packet
+    """
+    Read tag of BER packet
     @param tag: Tag class attributes
     @param pc: boolean
     @return: true if tag is correctly read
-    '''
+    """
     byte = UInt8()
     s.readType(byte)
     return byte == ((Class.BER_CLASS_UNIV | berPC(pc)) | (Tag.BER_TAG_MASK & tag))
 
 def writeUniversalTag(tag, pc):
-    '''
-    return universal tag byte
+    """
+    Return universal tag byte
     @param tag: tag class attributes
     @param pc: boolean
     @return: UInt8 
-    '''
+    """
     return ((Class.BER_CLASS_UNIV | berPC(pc)) | (Tag.BER_TAG_MASK & tag))
 
 def readApplicationTag(s, tag):
-    '''
-    read application tag
+    """
+    Read application tag
     @param s: stream
     @param tag: tag class attributes
     @return: length of application packet
-    '''
+    """
     byte = UInt8()
     s.readType(byte)
     if tag > UInt8(30):
@@ -123,22 +144,22 @@ def readApplicationTag(s, tag):
     return readLength(s)
 
 def writeApplicationTag(tag, size):
-    '''
-    return struct that represent ber application tag
+    """
+    Return structure that represent BER application tag
     @param tag: UINt8
     @param size: size to rest of packet  
-    '''
+    """
     if tag > UInt8(30):
         return (((Class.BER_CLASS_APPL | BerPc.BER_CONSTRUCT) | Tag.BER_TAG_MASK), tag, writeLength(size))
     else:
         return (((Class.BER_CLASS_APPL | BerPc.BER_CONSTRUCT) | (Tag.BER_TAG_MASK & tag)), writeLength(size))
     
 def readBoolean(s):
-    '''
-    return boolean
+    """
+    Return boolean
     @param s: stream
     @return: boolean
-    '''
+    """
     if not readUniversalTag(s, Tag.BER_TAG_BOOLEAN, False):
         raise InvalidExpectedDataException("bad boolean tag")
     size = readLength(s)
@@ -149,24 +170,24 @@ def readBoolean(s):
     return bool(b.value)
 
 def writeBoolean(b):
-    '''
-    return structure that represent boolean in ber specification
+    """
+    Return structure that represent boolean in BER specification
     @param b: boolean
-    @return: ber boolean structure
-    '''
+    @return: BER boolean structure
+    """
     boolean = UInt8(0)
     if b:
         boolean = UInt8(0xff)
     return (writeUniversalTag(Tag.BER_TAG_BOOLEAN, False), writeLength(1), boolean)
 
 def readInteger(s):
-    '''
-    read integer structure from stream
+    """
+    Read integer structure from stream
     @param s: stream
     @return: int or long python
-    '''
+    """
     if not readUniversalTag(s, Tag.BER_TAG_INTEGER, False):
-        raise InvalidExpectedDataException("bad integer tag")
+        raise InvalidExpectedDataException("Bad integer tag")
     
     size = readLength(s)
     
@@ -189,14 +210,14 @@ def readInteger(s):
         s.readType(integer)
         return integer.value
     else:
-        raise InvalidExpectedDataException("wrong integer size")
+        raise InvalidExpectedDataException("Wrong integer size")
     
 def writeInteger(value):
-    '''
-    write integer value
+    """
+    Write integer value
     @param param: int or python long
-    @return ber interger structure 
-    '''
+    @return: BER integer structure 
+    """
     if value <= 0xff:
         return (writeUniversalTag(Tag.BER_TAG_INTEGER, False), writeLength(1), UInt8(value))
     elif value <= 0xffff:
@@ -205,30 +226,30 @@ def writeInteger(value):
         return (writeUniversalTag(Tag.BER_TAG_INTEGER, False), writeLength(4), UInt32Be(value))
 
 def readOctetString(s):
-    '''
-    read ber string structure
+    """
+    Read BER string structure
     @param s: stream
     @return: String
-    '''
+    """
     if not readUniversalTag(s, Tag.BER_TAG_OCTET_STRING, False):
-        raise InvalidExpectedDataException("unexpected ber tag")
+        raise InvalidExpectedDataException("Unexpected BER tag")
     size = readLength(s)
     return String(s.read(size.value))
 
 def writeOctetstring(value):
-    '''
-    write string in ber representation
+    """
+    Write string in ber representation
     @param value: string
     @return: string ber structure 
-    '''
+    """
     return (writeUniversalTag(Tag.BER_TAG_OCTET_STRING, False), writeLength(len(value)), String(value))
 
 def readEnumerated(s):
-    '''
-    read enumerated structure
+    """
+    Read enumerated structure
     @param s: Stream
     @return: int or long
-    '''
+    """
     if not readUniversalTag(s, Tag.BER_TAG_ENUMERATED, False):
         raise InvalidExpectedDataException("invalid ber tag")
     if readLength(s) != 1:
diff --git a/rdpy/protocol/rdp/mcs.py b/rdpy/protocol/rdp/mcs.py
index b0f2a46..37d1afe 100644
--- a/rdpy/protocol/rdp/mcs.py
+++ b/rdpy/protocol/rdp/mcs.py
@@ -1,9 +1,32 @@
-'''
-@author: citronneur
-'''
+#
+# Copyright (c) 2014 Sylvain Peyrefitte
+#
+# This file is part of rdpy.
+#
+# rdpy is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+"""
+Implement Multi Channel Service
+
+Each channel have a particular role.
+The main channel is the graphical channel.
+It exist channel for file system order, audio channel, clipboard etc...
+"""
 
 from rdpy.network.const import ConstAttributes, TypeAttributes
-from rdpy.network.layer import LayerAutomata, Layer, LayerMode
+from rdpy.network.layer import LayerAutomata, LayerMode, StreamSender
 from rdpy.network.type import sizeof, Stream, UInt8, UInt16Be
 from rdpy.network.error import InvalidExpectedDataException, InvalidValue, InvalidSize
 from rdpy.protocol.rdp.ber import writeLength
@@ -13,18 +36,18 @@ import ber, gcc, per
 @ConstAttributes
 @TypeAttributes(UInt8)
 class Message(object):
-    '''
-    message type
-    '''
+    """
+    Message type
+    """
     MCS_TYPE_CONNECT_INITIAL = 0x65
     MCS_TYPE_CONNECT_RESPONSE = 0x66
 
 @ConstAttributes
 @TypeAttributes(UInt8)
 class DomainMCSPDU:
-    '''
-    domain mcs pdu header
-    '''
+    """
+    Domain MCS PDU header
+    """
     ERECT_DOMAIN_REQUEST = 1
     DISCONNECT_PROVIDER_ULTIMATUM = 8
     ATTACH_USER_REQUEST = 10
@@ -37,27 +60,28 @@ class DomainMCSPDU:
 @ConstAttributes
 @TypeAttributes(UInt16Be)
 class Channel:
+    """
+    Channel id of main channels use in RDP
+    """
     MCS_GLOBAL_CHANNEL = 1003
     MCS_USERCHANNEL_BASE = 1001
 
 class MCS(LayerAutomata):
-    '''
+    """
     Multi Channel Service layer
     the main layer of RDP protocol
     is why he can do everything and more!
-    '''
-    
-    class MCSProxySender(Layer):
-        '''
-        Proxy use to set as trnsport layer for upper channel
+    """
+    class MCSProxySender(StreamSender):
+        """
+        Proxy use to set as transport layer for upper channel
         use to abstract channel id for presentation layer
-        '''
+        """
         def __init__(self, mcs, channelId):
-            '''
-            ctor
-            @param mcs: mcs layer use as proxy
+            """
+            @param mcs: MCS layer use as proxy
             @param channelId: channel id for presentation layer 
-            '''
+            """
             self._mcs = mcs
             self._channelId = channelId
             
@@ -94,11 +118,10 @@ class MCS(LayerAutomata):
         
     
     def __init__(self, mode, presentation):
-        '''
-        ctor call base class ctor
-        @param mode: mode of mcs layer
+        """
+        @param mode: mode of MCS layer
         @param presentation: presentation layer
-        '''
+        """
         LayerAutomata.__init__(self, mode, presentation)
         self._clientSettings = gcc.ClientSettings()
         self._serverSettings = gcc.ServerSettings()
@@ -110,17 +133,17 @@ class MCS(LayerAutomata):
         self._channelIdsRequest = {}
     
     def connect(self):
-        '''
-        connection send for client mode
+        """
+        Connection send for client mode
         a write connect initial packet
-        '''
+        """
         self._clientSettings.core.serverSelectedProtocol = self._transport._selectedProtocol
         self.sendConnectInitial()
         
     def connectNextChannel(self):
-        '''
-        send sendChannelJoinRequest message on next unconnect channel
-        '''
+        """
+        Send sendChannelJoinRequest message on next unconnect channel
+        """
         for (channelId, layer) in self._channelIds.iteritems():
             #for each unconnect channel send a request
             if not self._channelIdsRequest.has_key(channelId):
@@ -138,9 +161,9 @@ class MCS(LayerAutomata):
                 layer.connect()
                 
     def sendConnectInitial(self):
-        '''
-        send connect initial packet
-        '''
+        """
+        Send connect initial packet
+        """
         ccReq = gcc.writeConferenceCreateRequest(self._clientSettings)
         ccReqStream = Stream()
         ccReqStream.writeType(ccReq)
@@ -155,28 +178,28 @@ class MCS(LayerAutomata):
         self.setNextState(self.recvConnectResponse)
         
     def sendErectDomainRequest(self):
-        '''
-        send a formated erect domain request for RDP connection
-        '''
+        """
+        Send a formated erect domain request for RDP connection
+        """
         self._transport.send((self.writeMCSPDUHeader(DomainMCSPDU.ERECT_DOMAIN_REQUEST), per.writeInteger(0), per.writeInteger(0)))
         
     def sendAttachUserRequest(self):
-        '''
-        send a formated attach user request for RDP connection
-        '''
+        """
+        Send a formated attach user request for RDP connection
+        """
         self._transport.send(self.writeMCSPDUHeader(DomainMCSPDU.ATTACH_USER_REQUEST))
         
     def sendChannelJoinRequest(self, channelId):
-        '''
-        send a formated Channel join request from client to server
-        '''
+        """
+        Send a formated Channel join request from client to server
+        """
         self._transport.send((self.writeMCSPDUHeader(DomainMCSPDU.CHANNEL_JOIN_REQUEST), self._userId, channelId))
         
     def recvConnectResponse(self, data):
-        '''
-        receive mcs connect response from server
+        """
+        receive MCS connect response from server
         @param data: Stream
-        '''
+        """
         ber.readApplicationTag(data, Message.MCS_TYPE_CONNECT_RESPONSE)
         ber.readEnumerated(data)
         ber.readInteger(data)
@@ -196,10 +219,10 @@ class MCS(LayerAutomata):
         self.setNextState(self.recvAttachUserConfirm)
         
     def recvAttachUserConfirm(self, data):
-        '''
-        receive an attach user confirm
+        """
+        Receive an attach user confirm
         @param data: Stream
-        '''
+        """
         opcode = UInt8()
         confirm = UInt8()
         data.readType((opcode, confirm))
@@ -217,10 +240,10 @@ class MCS(LayerAutomata):
         self.connectNextChannel()
     
     def recvChannelJoinConfirm(self, data):
-        '''
-        receive a channel join confirm from server
+        """
+        Receive a channel join confirm from server
         @param data: Stream
-        '''
+        """
         opcode = UInt8()
         confirm = UInt8()
         data.readType((opcode, confirm))
@@ -239,10 +262,10 @@ class MCS(LayerAutomata):
         self.connectNextChannel()
         
     def recvData(self, data):
-        '''
-        main receive method
+        """
+        Main receive method
         @param data: Stream 
-        '''
+        """
         opcode = UInt8()
         data.readType(opcode)
         
@@ -278,51 +301,52 @@ class MCS(LayerAutomata):
         self._channelIds[channelId].recv(data)
         
     def send(self, channelId, data):
-        '''
-        specific send function for channelId
+        """
+        Specific send function for channelId
+        @param channelId: Channel use to send
         @param data: message to send
-        '''
+        """
         self._transport.send((self.writeMCSPDUHeader(DomainMCSPDU.SEND_DATA_REQUEST), self._userId, channelId, UInt8(0x70), UInt16Be(sizeof(data)) | UInt16Be(0x8000), data))
         
     
     def writeDomainParams(self, maxChannels, maxUsers, maxTokens, maxPduSize):
-        '''
-        write a special domain param structure
+        """
+        Write a special domain parameter structure
         use in connection sequence
-        @param maxChannels: number of mcs channel use
-        @param maxUsers: number of mcs user used (1)
+        @param maxChannels: number of MCS channel use
+        @param maxUsers: number of MCS user used (1)
         @param maxTokens: unknown
         @param maxPduSize: unknown
-        @return: domain param structure
-        '''
+        @return: domain parameter structure
+        """
         domainParam = (ber.writeInteger(maxChannels), ber.writeInteger(maxUsers), ber.writeInteger(maxTokens),
                        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 writeMCSPDUHeader(self, mcsPdu, options = 0):
-        '''
-        write mcs pdu header
-        @param mcsPdu: pdu code
+        """
+        Write MCS PDU header
+        @param mcsPdu: PDU code
         @param options: option contains in header
         @return: UInt8
-        '''
+        """
         return (mcsPdu << 2) | options
     
     def readMCSPDUHeader(self, opcode, mcsPdu):
-        '''
-        read mcsPdu header and return options parameter
+        """
+        Read mcsPdu header and return options parameter
         @param opcode: UInt8 opcode
         @param mcsPdu: mcsPdu will be checked
         @return: true if opcode is correct
-        '''
+        """
         return (opcode >> 2) == mcsPdu
     
     def readDomainParams(self, s):
-        '''
-        read domain params structure
+        """
+        Read domain parameters structure
         @return: (max_channels, max_users, max_tokens, max_pdu_size)
-        '''
+        """
         if not ber.readUniversalTag(s, ber.Tag.BER_TAG_SEQUENCE, True):
             raise InvalidValue("bad BER tags")
         ber.readLength(s)#length
diff --git a/rdpy/protocol/rdp/pdu.py b/rdpy/protocol/rdp/pdu.py
index f5a0a8a..60323df 100644
--- a/rdpy/protocol/rdp/pdu.py
+++ b/rdpy/protocol/rdp/pdu.py
@@ -2,16 +2,12 @@
 @author: citronneur
 '''
 
-from rdpy.network.layer import LayerAutomata, LayerMode
-from rdpy.network.type import CompositeType, UniString, String, UInt8, UInt16Le, UInt32Le, sizeof, ArrayType,\
-    FactoryType
+from rdpy.network.layer import LayerAutomata
+from rdpy.network.type import CompositeType, UniString, String, UInt8, UInt16Le, UInt32Le, sizeof, ArrayType, FactoryType
 from rdpy.network.const import ConstAttributes, TypeAttributes
 from rdpy.network.error import InvalidExpectedDataException, ErrorReportedFromPeer
 
-import gcc
-import lic
-import caps
-import rdp
+import gcc, lic, caps
 
 @ConstAttributes
 @TypeAttributes(UInt16Le)
diff --git a/rdpy/protocol/rdp/rdp.py b/rdpy/protocol/rdp/rdp.py
index 7d21a2e..4735a26 100644
--- a/rdpy/protocol/rdp/rdp.py
+++ b/rdpy/protocol/rdp/rdp.py
@@ -2,8 +2,8 @@
 @author: sylvain
 '''
 from twisted.internet import protocol
-import tpkt, tpdu, mcs, pdu
 from rdpy.network.layer import LayerMode
+import tpkt, tpdu, mcs, pdu
 
 class RDPController(object):
     """
diff --git a/rdpy/protocol/rdp/tpdu.py b/rdpy/protocol/rdp/tpdu.py
index f124fcd..31a3658 100644
--- a/rdpy/protocol/rdp/tpdu.py
+++ b/rdpy/protocol/rdp/tpdu.py
@@ -24,7 +24,7 @@ This layer have main goal to negociate ssl transport
 RDP basic security is not supported by RDPY (because is not a true security layer...)
 """
 
-from rdpy.network.layer import LayerAutomata, LayerMode
+from rdpy.network.layer import LayerAutomata, LayerMode, StreamSender
 from rdpy.network.type import UInt8, UInt16Le, UInt16Be, UInt32Le, CompositeType, sizeof
 from rdpy.network.error import InvalidExpectedDataException
 from rdpy.network.const import ConstAttributes, TypeAttributes
@@ -116,7 +116,7 @@ class Negotiation(CompositeType):
         self.selectedProtocol = UInt32Le(conditional = lambda: self.code == NegociationType.TYPE_RDP_NEG_RSP)
         self.failureCode = UInt32Le(conditional = lambda: self.code == NegociationType.TYPE_RDP_NEG_FAILURE)
 
-class TPDU(LayerAutomata):
+class TPDU(LayerAutomata, StreamSender):
     """
     TPDU layer management
     there is an connection automata
@@ -223,7 +223,7 @@ class TPDU(LayerAutomata):
         """
         header = TPDUDataHeader()
         data.readType(header)
-        LayerAutomata.recv(self, data)
+        self._presentation.recv(data)
         
     def sendConnectionRequest(self):
         """