Hi all, I know its not a real ole matter, but treats also on
exchanging information between Delphi and Excel using sockets.

Im developing one DLL interface for Excel to allow sockets to
transfer data to and from Excel from and to other apps.

Im stuck at the point that my DLL is getting worksheets changes and
sending to other app correcly, but on oposite side, the DLL is getting
the messages from other app and buffering OK, but Excel is getting the
messages from the dll by poling only.

Im working with Delphi and copy parts of the code bellow where Im
trying to pass the VBA callback routine address to DLL and execute it.

When I try the code bellow, occurs one exception when the dll tries to
call the callback routine.

Do you have any suggestion on whats  wrong ?
Copy of code and files  at
www.geocities.com/CapeCanaveral/3505/sock.zip

Thanks in advance.
Ricardo Dunna

**************
At DLL:

Type
  Tproc=procedure;stdcall;  
Var
  Proc:^Tproc;   {callback routine pointer}

Function setcallback(p:longint):longint;stdcall;  {exported function}
begin
  proc:=pointer(p);                   {points proc to VBA callback
routine}
  setcallback:=1;
end;

procedure Tmyobj.OnSockRead(Sender: TObject; Socket:
TCustomWinSocket);
var
 sBuf      : string;
 pData     : pointer;
 Size      : integer;
begin
  SockRead( socket, pData, Size );
  if Size > 0 then
  begin
   showmessage("message received");    {just for debug pourposes}
   SetLength( sBuf, Size );
   move(pdata^,sbuf[1],size);
   list.add(sbuf);                     {adds string message to list
buffer}
   if proc<>nil then
      proc^; {*** I get error here, trying to execute the callback
routine}
   FreeMem(pData);
  end;
end;

function getxfer: Pchar;stdcall;  {exported to Excel VBA}
begin
  if list.count=0 then result:=pchar(sNIL) else
    Result := pchar(list.strings[0]);  {returns first TCP message from
VBA}
end;
*****************
At VBA :  (open/close sockets routines not shown)
Public Declare Function getxfer Lib "testedll" () As String
Public Declare Function setcallback Lib "testedll" (l As Long) As Long

Sub Gets()          ' this should be the callback routine
Dim s As String    
  s = getxfer()     ' here it gets the string from list in DLL
  cells(1,1)= s      ' tranfer s to Excel cells

End Sub

Public Sub Setacb()  {runs once at worksheet and socket open only}
Dim ret As Long
 ret = setcallback(AddressOf Gets)
End Sub