asked on

Delphi 7, DDE Client problem

I have a Delphi7 DDE client that talks do a 16 bit DDE server application.
This ran beautifully until recently. The 16 bit server is not mine so I have no

control over it.

When I try the openlink ( with the 16 bit server not running ( or modally busy ),

the D7 client freezes and I get an "application not responding" type message in

the Windows task manager.
(a timer running in the client application don't trigger ontimer events when this

happens)

If the 16 bit server IS running, everything works as expected.

Tried the code below but 16 bit server not seen with DDE.WaitStat (understandably)

procedure TForm1.mIRCDDE(Service, Topic, Cmd: string);
var
DDE: TDDEClientConv;
begin
try
DDE := TDDEClientConv.Create(nil);
DDE.ConnectMode := ddeManual;
DDE.SetLink(Service, Topic);
Timer1.Enabled := true; // for freeze test to see if ontimer event

works
If DDE.WaitStat then // If DDE server available //won't work with 16

bit server
begin
DDE.OpenLink
DDE.PokeData(Topic, PChar(Cmd));
end;
finally
DDE.Free;
end;
end;

I changed the code to

if DDE.OpenLink then
DDE.PokeData(Topic, PChar(Cmd));
finally
DDE.Free;
end;

Basically the application freezes on the openlink and stays frozen until terminated

with a three fingered salute. I tried wrapping the Openlink in a Try/except but it

stayed frozen. Eureka doesn't work either.

I need a timeout on the DDEOpenlink I guess. Any help greatly appreciated.
Thanks

ASKER CERTIFIED SOLUTION

Lukasz Zielinski

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SarusSystems

ASKER

Thanks. The server is 16 bit aplication so I guess I'll have a big job finding the window handle of the 16 bit application.

It sounds very possible and a logical way forward. I'll look into it. Thanks

SarusSystems

ASKER

Thanks.

Lukasz Zielinski

>>I guess I'll have a big job finding the window handle of the 16 bit application

not sure about 16bit but:

procedure TForm1.Button1Click(Sender: TObject);
var tmpHWND: THandle;
pid: Cardinal;
wndtxt: array[0..MAX_PATH] of Char;
begin
pid := GetCurrentProcessId;
tmpHWND := FindWindow(nil, nil);
while tmpHWND <> 0 do begin
if GetParent(tmpHWND) = 0 then begin
if pid = GetHandlesPID(tmpHWND) then begin
GetWindowText(tmpHWND, wndtxt, MAX_PATH);
ShowMessage('found: ' + Trim(wndtxt));
end;
end;
tmpHWND := GetWindow(tmpHWND, GW_HWNDNEXT);
end;
end;

function TForm1.GetHandlesPID(AHandle: THandle): Cardinal;
begin
GetWindowThreadProcessId(AHandle, Result);
end;

just change pid := GetCurrentProcessId; to PID obtained by OpenProcess() on DDE server

ziolko.