Building HTTP Server Application - delphi

Question

I have a project which does financial reports and I want to let user to be able to get this reports through the internet
I tried using TIdHTTPServer which is an Indy component to make my application to work as an HTTP Server and to let it to be able
receive request -> process the request -> send back the result of the request process
using a special port.
now my problem is that I'm getting a lot of Access Violation errors and random exceptions
it looks like about threads problem or I don't know because if I process the same request without using the TIdHTTPServer I don't get any problem
i'm using the OnCommandGet Event to process the request and send the result back to user inside the context stream.
what I need is a demonstration on how to use it with TADODataSet and TADOConnection
for example I need the user to be able to send a request and the TIdHTTPServer takes the request (for example call a stored procedure using to ADODataSet and take the result as XML file and send it back to the user)
please help....thank you.

Answer 1

one possibility how a Server could work ...
unit Unit3;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs,IDContext, IdBaseComponent, IdComponent, IdCustomTCPServer, IdTCPServer, StdCtrls, DB, ADODB;
type
TForm3 = class(TForm)
IdTCPServer1: TIdTCPServer;
Memo1: TMemo;
Button1: TButton;
DummyConnection: TADOConnection;
procedure Button1Click(Sender: TObject);
procedure IdTCPServer1Execute(AContext: TIdContext);
private
{ Private-Deklarationen }
public
{ Public-Deklarationen }
end;
var
Form3: TForm3;
implementation
uses ComObj,AdoInt,ActiveX;
{$R *.dfm}
function SendStream(AContext: TIdContext; AStream: TStream): Boolean;
begin
Result := False;
try
AContext.Connection.IOHandler.Write(AStream.Size); // sending length of Stream first
AContext.Connection.IOHandler.WriteBufferOpen;
AContext.Connection.IOHandler.Write(AStream, AStream.Size);
AContext.Connection.IOHandler.WriteBufferFlush;
finally
AContext.Connection.IOHandler.WriteBufferClose;
end;
Result := True;
end;
procedure TForm3.Button1Click(Sender: TObject);
begin
IdTCPServer1.Active := true;
end;
{ Clientside function
Function RecordsetFromXMLStream(Stream:TStream): _Recordset;
var
RS: Variant;
begin
RS := CreateOleObject('ADODB.Recordset');
RS.Open(TStreamAdapter.Create(Stream) as IUnknown);
Result := IUnknown(RS) as _Recordset;
end;
}
Procedure RecordsetToXMLStream(const Recordset: _Recordset;Stream:TStream);
var
RS: Variant;
begin
if Recordset = nil then Exit;
RS := CreateOleObject('ADODB.Recordset');
RS := Recordset;
RS.Save(TStreamAdapter.Create(stream) as IUnknown, adPersistXML);
Stream.Position := 0;
end;
Procedure GetQueryStream(Const s,ConStr:String;ms:TMemoryStream);
var
AC:TAdoConnection;
ads:TAdodataset;
begin
AC:=TAdoConnection.Create(nil);
try
ads:=TAdodataset.Create(nil);
try
ads.Connection := AC;
AC.ConnectionString := ConStr;
ads.CommandText := s;
ads.Open;
RecordsetToXMLStream(ads.Recordset,ms);
finally
ads.Free
end;
finally
AC.Free
end;
end;
procedure TForm3.IdTCPServer1Execute(AContext: TIdContext);
var
cmd:String;
ms:TMemoryStream;
begin
CoInitialize(nil);
AContext.Connection.IOHandler.Readln(cmd);
ms:=TMemoryStream.Create;
try
GetQueryStream('Select * from Adressen',DummyConnection.ConnectionString,ms);
ms.Position := 0;
SendStream(AContext,ms);
AContext.Connection.Socket.CloseGracefully;
finally
ms.Free;
CoUninitialize;
end;
end;
end.