Example service contract for http://stackoverflow.com/q/29132014/19818

gistfile1.cs

[ServiceContract]
public interface IService2
{
    [OperationContract]
    void setSalesItems(setSalesItems obj);
    [OperationContract]
    void setSalesItemsV3(setSalesItemsV3 obj);
}

[DataContract(Namespace = "")]
public class setSalesItems
{
    [DataMember]
    public DateTime start { get; set; }
}

[DataContract(Namespace = "")]
public class setSalesItemsV3
{
    [DataMember]
    public SimpleDate start { get; set; }
}

[DataContract(Namespace = "")]
public class SimpleDate
{
    [DataMember]
    public int Month { get; set; }
    [DataMember]
    public int Year { get; set; }
    [DataMember]
    public int Day { get; set; }
}