How to make TCP/IP connection between Client and Server in Delphi?
This article demonstrates a code snippet showing you how to make TCP/IP connection between Clent and Server in Delphi? We will use Indy Component to make TCP/IP connection between Clent and Server. We are going to use two TidTCPClient Class of Indy Components.
Server Side coding:
Setup TidTCPClient:
IdTCPServer1.Bindings.Clear;
IdTCPServer1.Bindings.Add.SetBinding('127.0.0.1', 8080);
IdTCPServer1.Active := True;
IdTCPServer1.Bindings.Add.SetBinding('127.0.0.1', 8080);
IdTCPServer1.Active := True;
This tells the server to listen on the loopback address only, at port 8080. This prevents anyone outside of your computer from connecting to it.
Put following code in your TIdTCPServer component's OnExecute event:
var
sResponse: string;
begin
//Send "Hello" message to client immediately after connection
AContext.Connection.Socket.WriteLn('Hello');
//Receive "Hi" response from client
sResponse:= AContext.Connection.Socket.ReadLn;
//Disconnect
AContext.Connection.Disconnect;
end;
sResponse: string;
begin
//Send "Hello" message to client immediately after connection
AContext.Connection.Socket.WriteLn('Hello');
//Receive "Hi" response from client
sResponse:= AContext.Connection.Socket.ReadLn;
//Disconnect
AContext.Connection.Disconnect;
end;
Client Side coding
Suppose you have a delphi form and a button on it. By pressing the button, you make tcp/ip connection to the server.
procedure TForm1.Button1Click(Sender: TObject);
var
sMsg : string;
begin
try
IdTCPClient1.Port := xxxx; //Set port to connect to
IdTCPClient1.Host := 'xxx.xxx.xxx.xxx'; //Set host to connect to
IdTCPClient1.Connect; //Make tcp ip connection
sMsg := IdTCPClient1.Socket.ReadLn; //Read the Hello message from the server
ShowMessage(sMsg); //Show the message
IdTCPClient1.Socket.WriteLn('Hi'); //Ping server with Hi message
except
on E : Exception do
begin
ShowMessage('Connection Error: ' + E.Message);
exit;
end;
end;
end;
var
sMsg : string;
begin
try
IdTCPClient1.Port := xxxx; //Set port to connect to
IdTCPClient1.Host := 'xxx.xxx.xxx.xxx'; //Set host to connect to
IdTCPClient1.Connect; //Make tcp ip connection
sMsg := IdTCPClient1.Socket.ReadLn; //Read the Hello message from the server
ShowMessage(sMsg); //Show the message
IdTCPClient1.Socket.WriteLn('Hi'); //Ping server with Hi message
except
on E : Exception do
begin
ShowMessage('Connection Error: ' + E.Message);
exit;
end;
end;
end;
Explanation: You have to set port number and host IP address first. Then just connect to it. A TCP/IP connection will be established between Client and Sever. If you get connected successfully, you will get 'Hello' from server. Then you will send "Hi" to the server.
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