Demos | Server Chat

This demo shows how build a Server Chat using TsgcWebSocketHTTPServer and WebSockets as communication protocol.

Every time a new peer sends a message, the server reads the message and broadcast the message to all connected clients.

 

Start Server

Before start the server, you must configure it to set the listening port, if use a secure connection or not...

 

• First I create a new instance of TsgcWebSocketHTTPServer.
• If Server will use secure connections, it needs a PEM certificate, just set where is located this certificate and the listening port for SSL You can configure the TLS version and the OpenSSL API (if needed)

 

  WSServer.HTTP2Options.Enabled := chkHTTP2.Checked;
  if WSServer.HTTP2Options.Enabled then
  begin
    WSServer.SSLOptions.OpenSSL_Options.APIVersion := oslAPI_1_1;
    WSServer.SSLOptions.Version := tls1_3;
  end
  else
  begin
    case cboOpenSSLAPI.ItemIndex of
      0: WSServer.SSLOptions.OpenSSL_Options.APIVersion := oslAPI_1_0;
      1: WSServer.SSLOptions.OpenSSL_Options.APIVersion := oslAPI_1_1;
    end;
    case cboTLSVersion.ItemIndex of
      0: WSServer.SSLOptions.Version := tlsUndefined;
      1: WSServer.SSLOptions.Version := tls1_0;
      2: WSServer.SSLOptions.Version := tls1_1;
      3: WSServer.SSLOptions.Version := tls1_2;
      4: WSServer.SSLOptions.Version := tls1_3;
    end;
  end;

• By default, if you start the server, it will listening on ALL IPs of listening port, so it's recommended use the binding property to only listen on 1 specific IP.

 

With WSServer.Bindings.Add do
begin
  Port := StrToInt(txtDefaultPort.Text);
  IP := txtHost.Text;
end;

 

• Once configured all options, call Server.Active = true to start the server.

 

Events Configuration

• Use OnConnect and OnDisconnect events to know when a client connects to server.
• Messages sent from client to server are received OnMessage event, so use this event handler to broadcast the message received to all clients

 

procedure TfrmServerChat.WSServerMessage(Connection: TsgcWSConnection; const Text: string);
begin
  WSServer.Broadcast(Text);
end;

 

Dispatch HTTP Requests

WebSocket HTTP Server allows to handle WebSocket and HTTP Protocols on the same listening port, so a web-browser can request a web page to access your server. OnCommandGet is the event used to read the HTTP Request and send the HTTP Responses.

 

Use ARequestInfo parameter to read the HTTP Request and AResponseInfo to write the HTTP Response.

 

Basically, use the ARequestInfo.Document to read which document is requesting the client and send a response using the following properties: ResponseNo, ContentType and ContentText.

 

Example: a client request document '/jquery.js'

procedure TfrmServerChat.WSServerCommandGet(AContext: TIdContext; ARequestInfo:
    TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
begin
  if ARequestInfo.Document = '/jquery.js' then
  begin
    AResponseInfo.ContentText := pageJQuery.Content;
    AResponseInfo.ContentType := 'text/javascript';
    AResponseInfo.ResponseNo := 200;
  end;
end;