delphi DataSnap 2010 Stream File working Sample - delphi

Question

I am trying to stream an XML File from Server To Client using DataSnap, with the help of ldsandon, i was able to download the sample from embarcadero, but my problem is I cannot follow it.
a pseudo of the program should work this way.
client will request from the server for selected xml file in the combobox.
the server will load the client selected xml file back to client.
i am just am trying to figure it out using delphi DataSnap, if not I will either use synapse or indy for tranferring the file, but I found Datasnap to be interesting.
could anyone help me please, a working if possible?
thanks a lot.
Please Help me, I need your help very badly.. thanks and thanks
I found this link, but I could not figure out how to convert it to TFileStream

Answer 1

// server side
function TServerMethods1.GetCDSXML(SQL: String; var FileSize: Integer): TStream;
begin
QryMisc.Close;
QryMisc.SQL.Text := SQL;
CDSMisc.Open;
Result := TMemoryStream.Create;
try
CDSMisc.SaveToStream(Result, dfXML);
FileSize := Result.Size; // not CDSMisc.DataSize;
Result.Position := 0; // Seek not implemented in abstract class
finally
CDSMisc.Close;
end;
end;
// client side
procedure TClientModule1.PopMiscCDS(SQL: String);
const
BufSize = $8000;
var
RetStream: TStream;
Buffer: PByte;
MemStream: TMemoryStream;
BytesRead: Integer;
FileSize: Integer;
begin
try
MemStream := TMemoryStream.Create;
GetMem(Buffer, BufSize);
try
//---------------------------------------------------------
RetStream := ServerMethods1Client.GetCDSXML(SQL, FileSize);
//---------------------------------------------------------
repeat
BytesRead := RetStream.Read(Pointer(Buffer)^, BufSize);
if BytesRead > 0 then
MemStream.WriteBuffer(Pointer(Buffer)^, BytesRead);
until BytesRead < BufSize;
if FileSize <> MemStream.Size then
raise Exception.Create('Error downloading xml');
MemStream.Seek(0, TSeekOrigin.soBeginning);
CDSMisc.Close;
CDSMisc.LoadFromStream(MemStream);
finally
FreeMem(Buffer, BufSize);
MemStream.Free;
end;
except
on E: Exception do
begin
ShowMessage(E.Message);
end;
end;
end;