web_socket_channel_manager 1.1.0+2

web_socket_channel_manager: ^1.1.0+2 copied to clipboard

example/lib/main.dart

import 'package:flutter/material.dart';
import 'dart:async';

import 'package:web_socket_channel_manager/web_socket_manager.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('WebSocket Manager Example'),
        ),
        body: const Center(
          child: StartSocketButton(),
        ),
      ),
    );
  }
}

class StartSocketButton extends StatelessWidget {
  const StartSocketButton({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: () {
        initSocket();
      },
      child: const Text('Start socket'),
    );
  }

  void initSocket() async {
    // =============================
    // 1. Define WebSocket endpoint
    // =============================
    // This is the URL of the WebSocket server you want to connect to.
    // For demonstration, we use a public echo server that simply sends back any message you send.
    final wsUrl = 'wss://echo.websocket.events';

    // =====================================
    // 2. Create WebSocketManager instance
    // =====================================
    // WebSocketManager is implemented as a singleton, so you always get the same instance.
    final wsManager = WebSocketManager();

    // =====================================
    // 3. Define subscription and message
    // =====================================
    // sentRequest: a unique name for this subscription. You can use any string.
    // consent: the message you want to send to the WebSocket server.
    const sentRequest = 'echo_subscription';
    const consent = 'Hello WebSocket!';

    // =====================================================
    // 4. Initialize the WebSocket connection (connect once)
    // =====================================================
    // The first parameter is the WebSocket server URL.
    // The second parameter is for cookies (if your server requires authentication via cookies).
    // For most public servers, you can pass null for cookies.
    await wsManager.initWebSocket(wsUrl, null);

    try {
      // =====================================================
      // 5. Send a message to the WebSocket server
      // =====================================================
      // This sends the 'consent' string to the server. For an echo server, you'll get the same message back.
      wsManager.sendRequestData(consent);

      // =====================================================
      // 6. Subscribe to the WebSocket stream
      // =====================================================
      // This sets up listeners for messages, errors, completion, and timeouts.
      // Each callback is explained in detail below.
      try {
        wsManager.subscribe(
          sentRequest, // Unique name for this subscription. Used for managing multiple subscriptions.
          10, // Timeout in seconds. If no message is received in this time, onTimeOut is called.
          // =============================
          // Called when a message is received from the server.
          // 'response' contains the message data.
          // For an echo server, this will be the same as what you sent.
          // =============================
          onMessage: (response) async {
            print('Received: $response');
            // It's good practice to unsubscribe after receiving the expected message to avoid memory leaks.
            wsManager.unsubscribe(sentRequest);
          },
          // =============================
          // Called if an error occurs in the WebSocket stream.
          // 'error' contains error details.
          // =============================
          onError: (error) async {
            print('Error: $error');
            wsManager.unsubscribe(sentRequest);
          },
          // =============================
          // Called when the WebSocket stream is closed by the server or client.
          // =============================
          onDone: () async {
            print('WebSocket closed');
            wsManager.unsubscribe(sentRequest);
          },
          // =============================
          // Called if the subscription times out (no message received within the timeout period).
          // =============================
          onTimeOut: () {
            print('Subscription timed out');
            wsManager.unsubscribe(sentRequest);
          },
          // =============================
          // Called if the WebSocket session itself times out (e.g., server closes the connection).
          // =============================
          onSessionTimeOut: () {
            print('Session timed out');
            wsManager.unsubscribe(sentRequest);
          },
        );
      } catch (e) {
        // Handles errors that occur during subscription setup.
        print('Inner error: $e');
        wsManager.unsubscribe(sentRequest);
      }
    } catch (e) {
      // Handles errors that occur during sending or outer logic.
      print('Outer error: $e');
      wsManager.unsubscribe(sentRequest);
    }

    // =====================================================
    // 7. Wait for a short period to allow message exchange
    // =====================================================
    // This gives the server time to respond before closing the connection.
    await Future.delayed(Duration(seconds: 5));

    // =====================================================
    // 8. Close the WebSocket connection and clean up
    // =====================================================
    wsManager.closeWebSocket();
    print('WebSocket connection closed.');
  }
}