Delphi DLL

WebSocket Connect through HTTP Proxy

See more WebSocket Examples

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
rest: HCkRest;
socket: HCkSocket;
bTls: Boolean;
port: Integer;
maxWaitMs: Integer;
ws: HCkWebSocket;
responseBody: PWideChar;
statusCode: Integer;

begin
success := False;

// 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 := CkRest_Create();
socket := CkSocket_Create();

// Set the HTTP proxy domain or IP address, and port.
CkSocket_putHttpProxyHostname(socket,'192.168.1.79');
CkSocket_putHttpProxyPort(socket,808);

// Provide authentication to the HTTP proxy, if needed.
CkSocket_putHttpProxyUsername(socket,'HTTP_PROXY_LOGIN');
CkSocket_putHttpProxyPassword(socket,'HTTP_PROXY_PASSWORD');
CkSocket_putHttpProxyAuthMethod(socket,'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.
CkSocket_putHttpProxyForHttp(socket,True);

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

// Tell the Rest object to use the connected socket.
success := CkRest_UseConnection(rest,socket,True);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

ws := CkWebSocket_Create();

// Tell the WebSocket to use this connection.
success := CkWebSocket_UseConnection(ws,rest);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkWebSocket__lastErrorText(ws));
    Exit;
  end;

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

// Add any additional headers that might be desired.
// Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
CkRest_AddHeader(rest,'Sec-WebSocket-Protocol','x-some-websocket-subprotocol');
CkRest_AddHeader(rest,'Origin','http://some-websocket-server.com');

// Do the open handshake.
responseBody := CkRest__fullRequestNoBody(rest,'GET','/something');
if (CkRest_getLastMethodSuccess(rest) <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    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 := CkRest_getResponseStatusCode(rest);
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 := CkWebSocket_ValidateServerHandshake(ws);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkWebSocket__lastErrorText(ws));
    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.');

CkRest_Dispose(rest);
CkSocket_Dispose(socket);
CkWebSocket_Dispose(ws);

end;