How I can use a TClientDataset (of VCL.NET) in a ASP.NET WebService.

Hi Experts,

After days examining different ways to consume a ADO.NET dataset sent
by a webservice method, I found that article of DrBob (http://www.drbob42.com/examines/examin62.htm)
which gave the idea to use the ADONETConnector to take the data to ClientDataset and save it to a
XML string.
The code for the function is below:
 
function ObterXMLDataPacket(
  pADONET_Dataset: DataSet; pNumero_DataTable: Integer): String;
var Conector:TADONETConnector;
    Cds:TclientDataset;
    DSP:TDatasetProvider;
    St: TStringStream;
begin
  If pADONET_Dataset.Tables.Count = 0 then Exit;
  (*Cria os componentes necessários*)
  Cds := TClientDataSet.Create(nil);
  DSP := TDataSetProvider.Create(nil);
  St := TStringStream.Create;
  Conector := TADONETConnector.Create(nil);
  (*Conecta os componentes*)
  DSP.Dataset := Conector;
  Cds.SetProvider(DSP);
  Conector.DataTable := pADONET_Dataset.Tables[pNumero_DataTable];
  (*Obtém os dados*)
  Conector.Open;


  CDS.Open;  // Here the method throws the exception


  (*Transforma os dados em XML Datapacket*)
  Cds.SaveToStream(St,dfXML);
  Result := ST.DataString;
  (*Limpa o ambientes*)
  St.Free;
  Cds.Free;
  Conector.Free;
  DSP.Free;
end;

The function is used in a WebMethod which opens a BDPDataAdapter and calls the function with the Dataset
populated by the Adapter.

Here is the code:

function TCC_DataLayer.RetornaDatasetXMLDPacket: String;
begin
  BdpDataAdapter1.Active := True;
  Result := ObterXMLDataPacket(ds1,0);
end;

With the needed units (ADONetDb, System.Data, etc among a few other ones) - the WebService build without problems. But when the method is called, the execution is aborted with a exception (on the Win32 client, on the browser gave only a internal server error).

Here is the message of the Exception: "Servidor não pôde processar a solicitação. --> Invalid threading model (STAThreadAttribute is required)"

The first part is in Brazilian Portuguese and means: "Server could not process the request"

Here is the code where the WebMethod is called:
 
procedure TForm2.Button2Click(Sender: TObject);
var Comm:THTTPRIO;
begin
  Comm := THTTPRIO.Create(nil);
  WServico := GetTCC_DataLayerSoap(False,'http://localhost/CredCob_DataLayer/uCC_DataLayer.asmx',Comm);
  try
    ClientDataSet1.XMLData := WServico.RetornaDatasetXMLDPacket;
    ClientDataSet1.Open;
  except
  on E: Exception do
    begin
    With TStringList.Create do
      begin
      Add(E.Message);
      SaveToFile('c:\mensagemerro.txt');
      Free;
      end;
    end;
  end;
end;

 
Environment: Delphi 2006 Architect (Borland® Developer Studio for Microsoft® Windows™ Version 10.0.2288.42451 Update 2), IIS + ASP.NET 1.1.4322...
DataBase: MSSQL 2005 (just for the sake of completeness).

Best Regards and thank you very much for the attention,
Fabricio (Delphian)View the Solution FREE for 30 Days