Hello all,
I'm trying to create application that would run on multiple machines.
This application has to know IP addresses of all other machines running
same software.
I'm trying to do something like discovery on network. Protocol I decided
to use for discovery is UDP. On mailing list I already saw, that only
one TWSocket component
can be used for receiving and sending data. So, I wrote following code
for listening:
UDPSocket.Proto :='udp';
UDPSocket.Addr :='0.0.0.0';
UDPSocket.Port :='1234';
UDPSocket.Listen;
Timer1.Enabled :=True;
and on timer event there is code for sending broadcast data to notofy
others about existence:
procedure TForm1.Timer1Timer(Sender: TObject);
var
SendTo:TSockAddrIn;
LenSendTo:integer;
Data:string;
begin
LenSendTo:=SizeOf(SendTo);
Data:='Test'+#0;
SendTo.sin_port :=htons(1234);
SendTo.sin_addr :=StrToInAddr('255.255.255.255');
SendTo.sin_family :=AF_INET;
UDPSocket.SendTo(SendTo,LenSendTo,@Data[1],Length(Data));
end;
StrToInAddr is function that I found in mailing list.
On receive even I have code from udplistener sample:
var
Buffer : array [0..1023] of char;
Len : Integer;
Src : TSockAddrIn;
SrcLen : Integer;
begin
SrcLen := SizeOf(Src);
Len := WSocket.ReceiveFrom(@Buffer, SizeOf(Buffer), Src, SrcLen);
if Len >= 0 then begin
Buffer[Len] := #0;
listbox1.Items.Add(StrPas(Buffer));
end;
end;
Problem is that sending is ok (no error), but ondataavaliable event
never gets fired, so I'm assuming that nothing is sent.
What am I doing wrong.
P.S. I have been using ICS for awhile now and I think that this is most
stable component suite for networking. Keep the good work.
Regards,
Skok Tone
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