(Delphi ActiveX) WebSocket Connect

Demonstrates how to establish a WebSocket connection. Once the connection is established, messages may be sent back-and-forth. Messages are sent in frames, where the last frame in the message is indicated by a "final" bit. A frame constitutes the entire message if the first frame sent has the "final" bit sent. (In most cases, you'll probably be sending single-frame messages.)

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
rest: TChilkatRest;
success: Integer;
ws: TChilkatWebSocket;
responseBody: WideString;
statusCode: Integer;

begin
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// --------------------------------------------------
// A WebSocket connection begins life as an HTTP GET request containing a few special header fields,
// such as "Upgrade: websocket".   

// Your application will use the Chilkat Rest class to send the initial HTTP GET.  This allows you
// to use the full capability of the Chilkat Rest class to customize the GET for any particular situation.
// For example:
// 
//   - If custom HTTP request header fields must be added.
//   - If authentication is required, such as OAuth2, OAuth1, Basic HTTP Auth, etc.
//   - If HTTPS, SSH Tunneling, Proxies (HTTP or SOCKS), or other advanced connection or TLS features are required.
// 

rest := TChilkatRest.Create(Self);
success := rest.Connect('someserver.com',80,0,0);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

ws := TChilkatWebSocket.Create(Self);

// Tell the WebSocket to use this connection.
success := ws.UseConnection(rest.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(ws.LastErrorText);
    Exit;
  end;

// Add the standard WebSocket open handshake headers that will be needed.
// (This adds the required HTTP request headers to the rest object.)
ws.AddClientHeaders();

// Add any additional headers that might be desired.
// Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
rest.AddHeader('Sec-WebSocket-Protocol','x-something');
rest.AddHeader('Origin','http://someserver.com');

// Do the open handshake.
responseBody := rest.FullRequestNoBody('GET','/something');
if (rest.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// If successful, the HTTP response status code should be 101,
// and the response body will be empty. (If it failed, we'll have a look
// at the response body..)
statusCode := rest.ResponseStatusCode;
Memo1.Lines.Add('Response status code: ' + IntToStr(statusCode));

if (statusCode <> 101) then
  begin
    Memo1.Lines.Add(responseBody);
    Memo1.Lines.Add('-- Failed because of unexpected response status code.');
    Exit;
  end;

// We have the expected 101 response, so let's now validate the 
// contents of the response, such as the value sent by the server in the
// Sec-WebSocket-Accept header. 
success := ws.ValidateServerHandshake();
if (success <> 1) then
  begin
    Memo1.Lines.Add(ws.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('WebSocket connection successful.');

// The application may now begin sending and receiving frames on the WebSocket connection.
// (At this point, we're done with the rest object...)
end;