System.RuntimeType with data contract name is not expected!!

Question

Hi guys,

 

I'm invoking WCF service method with following signature

 

Code Snippet

[ServiceContract]

[ServiceKnownType(typeof(DataScenario))]

[ServiceKnownType(typeof(PropertyDataCollection))]

[ServiceKnownType(typeof(IPDUnitDataTables))]

[ServiceKnownType(typeof(IPDDataItem))]

[ServiceKnownType(typeof(IPDDataEnumeration))]

public interface IService

{

[OperationContract]

void InvokePLC(string PlcAssemblyName, string Plc, string PlcMethod, object[] Params, out object ReturnValue);

}

 

 

I call the method as below

 

Code Snippet

proxy.InvokePLC("IPD.ProcessLogic.PLC.ExpressionEngine",

"PLCValidation",

"EvaluateExpressionSingle",

new object[] { _dataScenario, _propertyData, _expression, tp.FocusedDataRowView });

 

 

I have added _dataScenario, _propertyData, _expression classes as knowntype shown in the code above. But when I invoke this method I get following exception

 

System.ServiceModel.CommunicationException: There was an error while trying to serialize parameter http://tempuri.org/Params. The InnerException message was 'Type 'System.RuntimeType' with data contract name 'RuntimeType:http://schemas.datacontract.org/2004/07/System' is not expected.

 

I just stuck and don't know what to do. Does any have the solution? Am I missing something?

Answer 1

I suspect this as to do with the out parameter.  Since this operation returns void anyway, why not just have it return the ReturnValue instead of using an out parameter?

 

Answer 2

I get the same exception even if I return value rather using out param. However I get no error if I just send null as param value.

 

But still not clear why it gives me exception if I pass param values.

Answer 3

 

When passing a collection as a DataContract it needs to be decorated with the CollectionDataContract attribute

More here: http://msdn.microsoft.com/en-us/library/aa347850.aspx