--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/Common/EntityBase.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,131 @@
+using System;
+using System.Collections;
+using System.ComponentModel;
+using System.Runtime.InteropServices;
+
+using BLToolkit.ComponentModel;
+using BLToolkit.Mapping;
+using BLToolkit.Validation;
+
+namespace BLToolkit.Common
+{
+	[Serializable, Trimmable, ComVisible(true), JetBrains.Annotations.UsedImplicitly]
+	public abstract class EntityBase : ICustomTypeDescriptor
+	{
+		#region Protected members
+
+		protected virtual ICustomTypeDescriptor CreateTypeDescriptor()
+		{
+			return new CustomTypeDescriptorImpl(GetType());
+		}
+
+		#endregion
+
+		#region ICustomTypeDescriptor Members
+
+		private static readonly Hashtable _hashDescriptors = new Hashtable();
+
+		[NonSerialized]
+		private ICustomTypeDescriptor _typeDescriptor;
+		private ICustomTypeDescriptor  TypeDescriptor
+		{
+			get
+			{
+				if (_typeDescriptor == null)
+				{
+					Type key = GetType();
+
+					_typeDescriptor = (ICustomTypeDescriptor)_hashDescriptors[key];
+
+					if (_typeDescriptor == null)
+						_hashDescriptors[key] = _typeDescriptor = CreateTypeDescriptor();
+				}
+
+				return _typeDescriptor;
+			}
+		}
+
+		AttributeCollection ICustomTypeDescriptor.GetAttributes()
+		{
+			return TypeDescriptor.GetAttributes();
+		}
+
+		string ICustomTypeDescriptor.GetClassName()
+		{
+			return TypeDescriptor.GetClassName();
+		}
+
+		string ICustomTypeDescriptor.GetComponentName()
+		{
+			return TypeDescriptor.GetComponentName();
+		}
+
+		TypeConverter ICustomTypeDescriptor.GetConverter()
+		{
+			return TypeDescriptor.GetConverter();
+		}
+
+		EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
+		{
+			return TypeDescriptor.GetDefaultEvent();
+		}
+
+		PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
+		{
+			return TypeDescriptor.GetDefaultProperty();
+		}
+
+		object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
+		{
+			return TypeDescriptor.GetEditor(editorBaseType);
+		}
+
+		EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
+		{
+			return TypeDescriptor.GetEvents(attributes);
+		}
+
+		EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
+		{
+			return TypeDescriptor.GetEvents();
+		}
+
+		PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
+		{
+			return TypeDescriptor.GetProperties(attributes);
+		}
+
+		PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
+		{
+			return TypeDescriptor.GetProperties();
+		}
+
+		object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
+		{
+			// Do not relay this call to TypeDescriptor. We are the owner.
+			//
+			return this;
+		}
+
+		#endregion
+
+		#region Validation
+
+		public virtual void Validate()
+		{
+			Validator.Validate(this);
+		}
+
+		public virtual bool IsValid(string fieldName)
+		{
+			return Validator.IsValid(this, fieldName);
+		}
+
+		public virtual string[] GetErrorMessages(string fieldName)
+		{
+			return Validator.GetErrorMessages(this, fieldName);
+		}
+
+		#endregion
+	}
+}