C#

• I have 2 data contracts (classes Foo and Bar) defined thusly:

  [DataContract]
  [Serializable]
  public class Foo
  {
    [DataMember]
    public string FooData;
   
    [DataMember]
    public Bar TheBar;
  }
   
  [DataContract]
  [Serializable]
  public class Bar
  {
    [DataMember]
    public string BarStringData;
   
    [DataMember]
    public int BarIntData;
  }

• My service consists of a single operation:

  [ServiceContract()]
  public interface IMyService
  {
    [OperationContract]
    Foo GetFoo();
  }

• GetFoo() is implemented as:

  public Foo GetFoo()
  {
    Foo f = new Foo();
    f.FooData = "foo";
    f.TheBar = new Bar();
    f.TheBar.BarStringData = "bar";
    f.TheBar.BarIntData = 42;
  }

• When the service is invoked, it returns a Foo object that contains a Bar object.  However, the properties of the Bar instance aren't returned - its BarStringData is null and its BarIntData is zero.

[DllImport("SomeDll.dll", EntryPoint = "SomeFunction")]<br />
      private static extern bool SomeFunction(<br />
         [MarshalAs(UnmanagedType.LPStr)] string str1,<br />
         [MarshalAs(UnmanagedType.LPStr)] string str2,<br />
         [MarshalAs(UnmanagedType.LPStr)] string str3,<br />
         [MarshalAs(UnmanagedType.LPStr)] string str4,<br />
         long longNum,<br />
         out SomeStruct dataStruct,<br />
         out int int1,<br />
         out int int2);<br />

BOOL SomeFunction(<br />
  const char* str1,<br />
  const char* str2,<br />
  const char* str3,<br />
  const char* str4,<br />
  const long  longNum,           <br />
  SomeStruct* dataStruct,<br />
  int& int1,<br />
  int& int2)<br />

        <br />
[DllImport("kernel32.dll")]<br />
        public static extern bool Beep(int freq, int duration);<br />