Dart

WebSocket Connect

See more WebSocket Examples

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.) Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // 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.
  // 

  final rest = CkRest();
  try {
    rest.connect('someserver.com', 80, false, false);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final ws = CkWebSocket();

  // Tell the WebSocket to use this connection.
  try {
    ws.useConnection(rest);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // 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.
  final String responseBody;
  try {
    responseBody = rest.fullRequestNoBody('GET', '/something');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // 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..)
  final statusCode = rest.responseStatusCode;
  print('Response status code: $statusCode');

  if (statusCode != 101) {
    print(responseBody);
    print('-- Failed because of unexpected response status code.');
    return;
  }

  // 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. 
  try {
    ws.validateServerHandshake();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('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...)
}