Delphi ActiveX

WebSocket Connect through HTTP Proxy

See more WebSocket Examples

This example shows how to establish a WebSocket connection through an HTTP proxy server. Delphi ActiveX

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
success: Integer;
rest: TChilkatRest;
socket: TChilkatSocket;
bTls: Integer;
port: Integer;
maxWaitMs: Integer;
ws: TChilkatWebSocket;
responseBody: WideString;
statusCode: Integer;

begin
success := 0;

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

// --------------------------------------------------
// This example borrows the code from the REST using HTTP Proxy example.
// We first use the Chilkat Socket object to establish a connection to the WebSocket server through an HTTP proxy.
// Next, the Rest object uses the Socket object for its connection.
// Finally, the WebSocket object uses the Rest object for its connection.  
// 

rest := TChilkatRest.Create(Self);
socket := TChilkatSocket.Create(Self);

// Set the HTTP proxy domain or IP address, and port.
socket.HttpProxyHostname := '192.168.1.79';
socket.HttpProxyPort := 808;

// Provide authentication to the HTTP proxy, if needed.
socket.HttpProxyUsername := 'HTTP_PROXY_LOGIN';
socket.HttpProxyPassword := 'HTTP_PROXY_PASSWORD';
socket.HttpProxyAuthMethod := 'Basic';

// Indicate that HTTP requests (i.e. the WebSocket opening handshake) will be sent over the socket.
// This is important for how the HTTP proxy connection is established.
socket.HttpProxyForHttp := 1;

// Connect to the websocket server through the HTTP proxy.
bTls := 0;
port := 80;
maxWaitMs := 5000;
success := socket.Connect('some-websocket-server.com',port,bTls,maxWaitMs);
if (success <> 1) then
  begin
    Memo1.Lines.Add('Connect Failure Error Code: ' + IntToStr(socket.ConnectFailReason));
    Memo1.Lines.Add(socket.LastErrorText);
    Exit;
  end;

// Tell the Rest object to use the connected socket.
success := rest.UseConnection(socket.ControlInterface,1);
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-some-websocket-subprotocol');
rest.AddHeader('Origin','http://some-websocket-server.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 and socket objects...)

Memo1.Lines.Add('Success.');
end;