RE: WCF 3.5 and Problem with KnownTypeAttribute

Hi coconet,

Regarding on the "Type not serializable" exception you encountered, it is a
typical error in WCF service when you use base class/interface with derived
classes actually send in WCF service method.

For your case, the problem here is that you only declare the Interface type
in your WCF method( the IPrincipal type which is not a DataContract).
However, WCF service will only expose metadata for types that is decorated
with "DataContract" attribute or any type that is declared as "KnowType".
I saw the you've add "KnowTypeAttribute" in the "TestPrincipal" class, this
is not the correct means of using "KnownTypeAttribute".
"KnownTypeAttribute" should be apply on the base type(base class or
interface) or on a DataContract type which has member of the base
type/interface. See the following reference:

#Data Contract Known Types
http://msdn2.microsoft.com/en-us/library/ms730167.aspx

To address the problem in your case, since you haven't use a base class,
you can add the known type declaration at service contract level. e.g.

=========
[ServiceContract]
[ServiceKnownType(typeof(TestPrincipal ))]
public interface IYourServiceInterface
.....
==============

the following article include all the three means that can be used for
apply "KnownType" info for WCF service's custom data contract:

#Handling Data Contract Object Hierarchies in WCF
http://footheory.com/blogs/bennie/archive/2007/07/28/handling-data-contract-
object-hierarchies-in-wcf.aspx

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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--------------------
NNTP-Posting-Date: Fri, 29 Feb 2008 10:34:26 -0600
From: coconet <coconet@xxxxxxxxxxxxxxxx>
Newsgroups: microsoft.public.dotnet.framework.aspnet.webservices
Subject: WCF 3.5 and Problem with KnownTypeAttribute
Date: Fri, 29 Feb 2008 11:34:26 -0500



I have an Interface and an implementing class (receiver) and calling
class (sender) in a single DLL. The DLL is referenced in a web site
that received WCF calls and also in a seperate web site that makes
calls to the WCF site .svc. Why would I get an Exception about
KnownTypeAttribute?


InnerException thrown is:

System.Runtime.Serialization.SerializationException: Type
'nstestSecurity.TestPrincipal' with data contract name
'TestPrincipal:http://schemas.datacontract.org/2004/07/nstest.Security'
is not expected. Add any types not known statically to the list of
known types - for example, by using the KnownTypeAttribute attribute
or by adding them to the list of known types passed to
DataContractSerializer..

But my stuff looks like this:

[KnownType(typeof(IPrincipal))]
[DataContract(Name="DashboardPrincipal")]
public class TestPrincipal : IPrincipal
{
....
}

An instance of TestPrincipal is one of two parameters for a class that
uses this interface:

[ServiceContract(Name="IWcfReceiver",Namespace="http://nstest/200804/IWcfRe
ceiver")]
public interface IWcfReceiver
{
[OperationContract]
List<ITestStuff> Do( IPrincipal inputPrincipal , List<ITestStuff>
testList );
}



.

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