WCF DataContract and derived classes

Hello. I've a qouestion about DataContracts and it's implementation.

In my contract library i've define data contract class like this one:
[DataContract]
public class SyncData
{
private int _amount;

[DataMember]
public int Amount { get { return _amount; } set { _amount =
value; } }
}

After that i created method at my ServiceContract class that accept
argument of SyncData type. Like this:

[ServiceContract]
public class IMyService
{
void UpdateData(SyncData data);
}

This interface and SyncData class hosted at assembly that called
Contract.dll.

In ,y Client project i've made reference to the Contract.dll and
define derived class of SyncData:

public class SyncDataEx : SyncData
{
public void IncrementAmount()
{
this.Amount++;
}
}

And made a remote call:
SyncDataEx data = new SyncDataEx();

data.Amount = 1;
data.IncrementAmount();

ClientProxy.UpdateData(data); //sic!

I have an exception InvalidDataContractException:Type 'SyncDataEx'
cannot be serialized. Consider marking it with the
DataContractAttribute attribute, and marking all of its members you
want serialized with the DataMemberAttribute attribute.

Why object can't be serialized like SyncData type?

In case you haven't already tried it. This should work, if you decorate
SyncDataEx with the DataContract attribute.

Alternatively you can get this to work by using the KnownType decoration.
http://msdn2.microsoft.com/en-us/library/ms730167.aspx

Cheers,
--
Naraendirakumar R.R
Senior Software Architect

"Gomolyako Eduard" <eduard.gomolyako@gmail.com> wrote in message
news:1182256843.993598.269790@q69g2000hsb.googlegroups.com...
> Hello. I've a qouestion about DataContracts and it's implementation.
>
> In my contract library i've define data contract class like this one:
> [DataContract]
> public class SyncData
> {
> private int _amount;
>
> [DataMember]
> public int Amount { get { return _amount; } set { _amount =
> value; } }
> }
>
> After that i created method at my ServiceContract class that accept
> argument of SyncData type. Like this:
>
> [ServiceContract]
> public class IMyService
> {
> void UpdateData(SyncData data);
> }
>
> This interface and SyncData class hosted at assembly that called
> Contract.dll.
>
> In ,y Client project i've made reference to the Contract.dll and
> define derived class of SyncData:
>
> public class SyncDataEx : SyncData
> {
> public void IncrementAmount()
> {
> this.Amount++;
> }
> }
>
> And made a remote call:
> SyncDataEx data = new SyncDataEx();
>
> data.Amount = 1;
> data.IncrementAmount();
>
> ClientProxy.UpdateData(data); //sic!
>
> I have an exception InvalidDataContractException:Type 'SyncDataEx'
> cannot be serialized. Consider marking it with the
> DataContractAttribute attribute, and marking all of its members you
> want serialized with the DataMemberAttribute attribute.
>
> Why object can't be serialized like SyncData type?
>