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Juan Rosell · Guest

Hi,

I´m new to Delphi and I was trying to implement a kind of distributed
application. The idea is having 3 different computers in a network running
the same application, this 3 instances of the application do share some
configuration issues which I´d like to be shared on the network. The idea
was, by using UDPSockets, to broadcast the configuration all over the
network whenever it was changed in any of the nodes. I was trying to use
TUDPSocket, but I cannot receive anything (even when I try to connect to
only one machine.)

I´ve build a couple of test applications; one of them acts as a UDP server
, binds to a port and waits for the client to send a string and then, shows
it. But the string never arrives. Here you are the code I use, maybe I´m
missing something? Any hint will be appreciated.

application one (server).
------------------------

type
TForm1 = class(TForm)
UdpSocket1: TUdpSocket;
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
procedure OnReceive(Sender: TObject; Buf: pchar; var DataLen: Integer);
procedure OnConnect(Sender: TObject);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.OnConnect(Sender:Tobject);
begin
ShowMessage('Conectado!');
end;

procedure TForm1.OnReceive(Sender: TObject; Buf: pchar; var DataLen:
Integer);
begin
ShowMessage(buf);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
UdpSocket1.LocalHost:='juan';
UdpSocket1.LocalPort:='3000';
UdpSocket1.OnReceive:= OnReceive;
UdpSocket1.OnConnect:=OnConnect;
UdpSocket1.Open;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
UdpSocket1.Close;
end;

end.

application two (client).
----------------------

type
TForm1 = class(TForm)
UdpSocket1: TUdpSocket;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
str:string;
begin
UdpSocket1.RemoteHost:='juan';
UdpSocket1.RemotePort:='3000';
str:='hola';
if UdpSocket1.Connect then
begin
{
just to see where it´s connected.
}
ShowMessage('Remote host='+UdpSocket1.RemoteHost + ' remote
port='+UdpSocket1.RemotePort);
UdpSocket1.Sendln(str);
end;
end;

end.

I read also in the news that someone was missing the "bind" method in
TUDPSockets, well I´m missing it to, maybe the local port is bound as soon
as it´s associated?

Regards,

Juan

CheshireCat · Guest

Is this borlands udp sockets? If so then don't use them - they were buggy
and didn't work when I last used them. Use Indys UDP server sockets instead.
Also, you don't connect sockets with UDP. It's a discrete datagram protocol.

Look at the broadcast method too

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