diff --git a/Esiur/Data/Codec.cs b/Esiur/Data/Codec.cs
index 247c82b..6b4e17d 100644
--- a/Esiur/Data/Codec.cs
+++ b/Esiur/Data/Codec.cs
@@ -338,11 +338,11 @@ public static class Codec
     };
 
 
-    internal static (TransmissionDataUnitIdentifier identifier, byte[])
+    internal static (TransmissionDataUnitIdentifier identifier, byte[] data, byte[] metadata)
         ComposeInternal(object valueOrSource, Warehouse warehouse, DistributedConnection connection)
     {
         if (valueOrSource == null)
-            return (TransmissionDataUnitIdentifier.Null, null);
+            return (TransmissionDataUnitIdentifier.Null, null, null);
 
         var type = valueOrSource.GetType();
 
@@ -369,7 +369,7 @@ public static class Codec
             valueOrSource = ((IUserType)valueOrSource).Get();
 
         if (valueOrSource == null)
-            return (TransmissionDataUnitIdentifier.Null, null);
+            return (TransmissionDataUnitIdentifier.Null, null, null);
 
 
         type = valueOrSource.GetType();
@@ -377,20 +377,20 @@ public static class Codec
 
         if (Composers.ContainsKey(type))
         {
-            var (hdr, data) = Composers[type](valueOrSource, warehouse, connection);
-            return (hdr, data);
+            var (hdr, data, metadata) = Composers[type](valueOrSource, warehouse, connection);
+            return (hdr, data, metadata);
         }
         else
         {
             if (Codec.ImplementsInterface(type, typeof(IResource)))
             {
-                var (hdr, data) = DataSerializer.ResourceComposer(valueOrSource, warehouse, connection);
-                return (hdr, data);
+                var (hdr, data, metadata) = DataSerializer.ResourceComposer(valueOrSource, warehouse, connection);
+                return (hdr, data, metadata);
             }
             else if (Codec.ImplementsInterface(type, typeof(IRecord)))
             {
-                var (hdr, data) = DataSerializer.RecordComposer(valueOrSource, warehouse, connection);
-                return (hdr, data);
+                var (hdr, data, metadata) = DataSerializer.RecordComposer(valueOrSource, warehouse, connection);
+                return (hdr, data, metadata);
             }
             else if (type.IsGenericType)
             {
@@ -402,24 +402,24 @@ public static class Codec
                     var args = type.GetGenericArguments();
                     //if (Composers.ContainsKey(args[0]))
                     //{
-                    var (hdr, data) = DataSerializer.TypedListComposer((IEnumerable)valueOrSource, args[0], warehouse, connection);
-                    return (hdr, data);
+                    var (hdr, data, metadata) = DataSerializer.TypedListComposer((IEnumerable)valueOrSource, args[0], warehouse, connection);
+                    return (hdr, data, metadata);
                     //}
                 }
                 else if (genericType == typeof(Map<,>))
                 {
                     var args = type.GetGenericArguments();
 
-                    var (hdr, data) = DataSerializer.TypedMapComposer(valueOrSource, args[0], args[1], warehouse, connection);
-                    return (hdr, data);
+                    var (hdr, data, metadata) = DataSerializer.TypedMapComposer(valueOrSource, args[0], args[1], warehouse, connection);
+                    return (hdr, data, metadata);
 
                 }
                 else if (genericType == typeof(Dictionary<,>))
                 {
                     var args = type.GetGenericArguments();
 
-                    var (hdr, data) = DataSerializer.TypedDictionaryComposer(valueOrSource, args[0], args[1], warehouse, connection);
-                    return (hdr, data);
+                    var (hdr, data, metadata) = DataSerializer.TypedDictionaryComposer(valueOrSource, args[0], args[1], warehouse, connection);
+                    return (hdr, data, metadata);
 
                 }
 
@@ -431,8 +431,8 @@ public static class Codec
                       || genericType == typeof(ValueTuple<,,,,,,>)
                   )
                 {
-                    var (hdr, data) = DataSerializer.TupleComposer(valueOrSource, warehouse, connection);
-                    return (hdr, data);
+                    var (hdr, data, metadata) = DataSerializer.TupleComposer(valueOrSource, warehouse, connection);
+                    return (hdr, data, metadata);
                 }
             }
             else if (type.IsArray)
diff --git a/Esiur/Data/DataSerializer.cs b/Esiur/Data/DataSerializer.cs
index 7f13186..ba946ec 100644
--- a/Esiur/Data/DataSerializer.cs
+++ b/Esiur/Data/DataSerializer.cs
@@ -483,10 +483,10 @@ public static class DataSerializer
         return rt.ToArray();
     }
 
-    public static (TransmissionDataUnitIdentifier, byte[]) TupleComposer(object value, Warehouse warehouse, DistributedConnection connection)
+    public static TransmissionDataUnitIdentifier TupleComposer(object value, Warehouse warehouse, DistributedConnection connection)
     {
         if (value == null)
-            return (TransmissionDataUnitIdentifier.Null, new byte[0]);
+            return (TransmissionDataUnitIdentifier.Null, new byte[0], new byte[0]);
 
         var rt = new List<byte>();
 
@@ -494,7 +494,6 @@ public static class DataSerializer
         var list = fields.Select(x => x.GetValue(value)).ToArray();
         var types = fields.Select(x => RepresentationType.FromType(x.FieldType).Compose()).ToArray();
 
-        rt.Add((byte)list.Length);
 
         foreach (var t in types)
             rt.AddRange(t);
@@ -502,11 +501,11 @@ public static class DataSerializer
         var composed = ArrayComposer(list, warehouse, connection);
 
         if (composed == null)
-            return (TransmissionDataUnitIdentifier.Null, new byte[0]);
+            return (TransmissionDataUnitIdentifier.Null, new byte[0], new byte[0]);
         else
         {
             rt.AddRange(composed);
-            return (TransmissionDataUnitIdentifier.TypedTuple, rt.ToArray());
+            return (TransmissionDataUnitIdentifier.TypedTuple, rt.ToArray(), composed);
         }
     }
 }
diff --git a/Esiur/Data/TransmissionDataUnit.cs b/Esiur/Data/TransmissionDataUnit.cs
index d72a4f6..d7d0a17 100644
--- a/Esiur/Data/TransmissionDataUnit.cs
+++ b/Esiur/Data/TransmissionDataUnit.cs
@@ -39,7 +39,7 @@ public struct TransmissionDataUnit
 
     }
 
-    public static byte[] Compose(TransmissionDataUnitIdentifier identifier, byte[] data, byte[] typeMetadata = null)
+    public static byte[] Compose(TransmissionDataUnitIdentifier identifier, byte[] data, byte[] typeMetadata)
     {
 
         if (data == null || data.Length == 0)
@@ -50,7 +50,8 @@ public struct TransmissionDataUnit
         {
             return DC.Combine(new byte[] { (byte)identifier }, 0, 1, data, 0, (uint)data.Length);
         }
-        else if (cls == TransmissionDataUnitClass.Dynamic)
+        else if (cls == TransmissionDataUnitClass.Dynamic
+            || cls == TransmissionDataUnitClass.Extension)
         {
             var len = (ulong)data.LongLength;
 
@@ -151,8 +152,8 @@ public struct TransmissionDataUnit
                 rt[0] = (byte)((byte)identifier | 0x8);
                 rt[1] = (byte)len;
 
-
-                Buffer.BlockCopy(data, 0, rt, 2, (int)len);
+                Buffer.BlockCopy(typeMetadata, 0, rt, 2, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 2 + typeMetadata.Length, data.Length);
                 return rt;
             }
             else if (len <= 0xFF_FF)
@@ -161,7 +162,9 @@ public struct TransmissionDataUnit
                 rt[0] = (byte)((byte)identifier | 0x10);
                 rt[1] = (byte)((len >> 8) & 0xFF);
                 rt[2] = (byte)(len & 0xFF);
-                Buffer.BlockCopy(data, 0, rt, 3, (int)len);
+
+                Buffer.BlockCopy(typeMetadata, 0, rt, 3, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 3 + typeMetadata.Length, data.Length);
                 return rt;
             }
             else if (len <= 0xFF_FF_FF)
@@ -171,7 +174,10 @@ public struct TransmissionDataUnit
                 rt[1] = (byte)((len >> 16) & 0xFF);
                 rt[2] = (byte)((len >> 8) & 0xFF);
                 rt[3] = (byte)(len & 0xFF);
-                Buffer.BlockCopy(data, 0, rt, 4, (int)len);
+
+                Buffer.BlockCopy(typeMetadata, 0, rt, 4, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 4 + typeMetadata.Length, data.Length);
+
                 return rt;
             }
             else if (len <= 0xFF_FF_FF_FF)
@@ -182,7 +188,10 @@ public struct TransmissionDataUnit
                 rt[2] = (byte)((len >> 16) & 0xFF);
                 rt[3] = (byte)((len >> 8) & 0xFF);
                 rt[4] = (byte)(len & 0xFF);
-                Buffer.BlockCopy(data, 0, rt, 5, (int)len);
+
+                Buffer.BlockCopy(typeMetadata, 0, rt, 5, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 5 + typeMetadata.Length, data.Length);
+
                 return rt;
             }
             else if (len <= 0xFF_FF_FF_FF_FF)
@@ -194,7 +203,10 @@ public struct TransmissionDataUnit
                 rt[3] = (byte)((len >> 16) & 0xFF);
                 rt[4] = (byte)((len >> 8) & 0xFF);
                 rt[5] = (byte)(len & 0xFF);
-                Buffer.BlockCopy(data, 0, rt, 6, (int)len);
+
+                Buffer.BlockCopy(typeMetadata, 0, rt, 6, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 6 + typeMetadata.Length, data.Length);
+
                 return rt;
             }
             else if (len <= 0xFF_FF_FF_FF_FF_FF)
@@ -207,7 +219,10 @@ public struct TransmissionDataUnit
                 rt[4] = (byte)((len >> 16) & 0xFF);
                 rt[5] = (byte)((len >> 8) & 0xFF);
                 rt[6] = (byte)(len & 0xFF);
-                Buffer.BlockCopy(data, 0, rt, 7, (int)len);
+
+                Buffer.BlockCopy(typeMetadata, 0, rt, 7, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 7 + typeMetadata.Length, data.Length);
+
                 return rt;
             }
             else //if (len <= 0xFF_FF_FF_FF_FF_FF_FF)
@@ -221,10 +236,15 @@ public struct TransmissionDataUnit
                 rt[5] = (byte)((len >> 16) & 0xFF);
                 rt[6] = (byte)((len >> 8) & 0xFF);
                 rt[7] = (byte)(len & 0xFF);
-                Buffer.BlockCopy(data, 0, rt, 8, (int)len);
+
+                Buffer.BlockCopy(typeMetadata, 0, rt, 8, typeMetadata.Length);
+                Buffer.BlockCopy(data, 0, rt, 8 + typeMetadata.Length, data.Length);
+
                 return rt;
             }
         }
+
+        throw new Exception("Not supported class type.");
     }
 
     public static (ulong, TransmissionDataUnit?) Parse(byte[] data, uint offset, uint ends)