Hi guys,

I'm invoking WCF service method with following signature

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?

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

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?

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.

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