serializing.cs

 private unsafe byte[] CreateGatewayRequest()
    {

      var gr = new GatewayRequest();

      var msgHead = new MessageHeaderInComp();
      msgHead.BodyLen = (uint)sizeof(GatewayRequest);
      msgHead.TemplateID = (ushort) ETIMessageType.GatewayRequest;
      gr.MessageHeaderIn = msgHead;

      var reqHead = new RequestHeaderComp();
      reqHead.MsgSeqNum = 1;  
      gr.RequestHeader = reqHead;

      gr.Password = _eurexExecutionFeed.Password;
      gr.DefaultCstmApplVerID = "2.5";
      gr.PartyIDSessionID = (uint) _eurexExecutionFeed.SessionId;
      
      byte[] bytes = new byte[sizeof(GatewayRequest)];
      fixed (byte* p = bytes)
      {
        Mem.Cpy((byte*)&gr, p, sizeof(GatewayRequest));
      }
      return bytes;
    }