DataContractSerializer and Internal types

Under Silverlight only public types may be serialized with the DataContractSerializer. If you want to make your data classes internal to your assembly and serialise them for use in a WCF service you will find that the service call will fail at runtime with a SecurityException inside a misleading exception about inability to communicate with the service. There is a workaround however which involves exposing your internal types to the Silverlight base class libraries with the InternalsVisibleTo attribute. Simply add the following code to your AssemblyInfo.cs file:-

If you use the DataContractJsonSerializer you must also add the System.Servicemodel.Web assembly (the public key is the same).