I want to add more property for every shape
So I tried to create a cusom class that inherited from Nshape
but I failed because the Nshape has no new construction and is created by factory
How could I implement this functionality

Hi, the serializable attribute affects only the binary serialization. So the sample class is meant to be serialized binary. If you want to use the XML serialization with a custom class it should implement the IXmlSerializable interface.

Best Regards,
Nevron Support Team