Building a Real-Time Chat App with WebSocket Flutter Example

Flutter is an open-source mobile application development SDK created by Google. It allows developers to build beautiful, fast, and responsive apps for both Android and iOS platforms using a single codebase. Flutter also supports real-time communication via WebSocket, which is an advanced technology for creating real-time, bidirectional, and event-driven communication between clients and servers.

What is a WebSocket?

A WebSocket is a communication protocol that provides full-duplex communication channels over a single TCP connection. Unlike HTTP, which is a request-response protocol, WebSocket allows bi-directional communication between clients and servers. This means that once a WebSocket connection is established, either the client or server can send data to the other party at any time.

WebSocket is an advanced technology that enables real-time communication between clients and servers. It is ideal for building real-time applications such as chat apps, stock trading apps, and gaming apps.

What is Flutter?

Flutter is an open-source mobile application development SDK created by Google. It allows developers to build beautiful, fast, and responsive apps for both Android and iOS platforms using a single codebase. Flutter uses the Dart programming language and provides a rich set of pre-built widgets and tools that make it easy to build high-quality mobile apps.

How to use WebSocket in Flutter?

To use WebSocket in Flutter, you need to add the web_socket_channel package to your project. This package provides a WebSocketChannel class that you can use to create a WebSocket connection between your Flutter app and a server.

Here’s an example of how to use WebSocket in Flutter:

  1. Add the web_socket_channel package to your pubspec.yaml file:
  2. dependencies:

  • web_socket_channel: ^1.1.0
  • Import the web_socket_channel package:
  • import ‘package:web_socket_channel/web_socket_channel.dart’;

  • Create a WebSocket connection:
  • final channel = WebSocketChannel.connect(Uri.parse(‘ws://localhost:8080’));

  • Send and receive data:
  • // Send datachannel.sink.add(‘Hello, Server!’);// Receive datachannel.stream.listen((data) {print(‘Received: $data’);});

    With these simple steps, you can create a WebSocket connection and start sending and receiving data between your Flutter app and a server.

    Building a Real-Time Chat App with WebSocket Flutter Example

    Now that you know how to use WebSocket in Flutter, let’s build a real-time chat app using WebSocket. In this example, we’ll use the Flutter web_socket_channel package to create a WebSocket connection between a Flutter app and a server.

    Step 1: Set up the Server

    The first step is to set up the server that will handle the WebSocket connection. For this example, we’ll use Node.js and the ws package to create a WebSocket server.

    1. Create a new Node.js project:
    2. mkdir websocket-servercd websocket-servernpm init -y

    3. Install the ws package:
    4. npm install ws

    5. Create a new file called server.js:
    6. touch server.js

    7. Add the following code to the server.js file:
    8. const WebSocket = require(‘ws’);

      const wss = new WebSocket.Server({ port: 8080 });

      wss.on(‘connection’, function connection(ws) {console.log(‘Client connected’);

      ws.on(‘message’, function incoming(message) {console.log(‘Received: %s’, message);ws.send(‘Server received: ‘ + message);});

      ws.on(‘close’, function close() {console.log(‘Client disconnected’);});});

    This code creates a WebSocket server that listens on port 8080. When a client connects, the server logs a message to the console. When a message is received from the client, the server logs the message and sends a response back to the client. When the client disconnects, the server logs a message to the console.

    Step 2: Set up the Flutter App

    The next step is to set up the Flutter app that will connect to the WebSocket server. For this example, we’ll use the Flutter web_socket_channel package to create a WebSocket connection.

    1. Create a new Flutter project:
    2. flutter create websocket-flutter-example

    3. Open the main.dart file:
    4. cd websocket-flutter-exampleopen -a “Visual Studio Code” lib/main.dart

    5. Add the following code to the main.dart file:
    6. import ‘package:flutter/material.dart’;import ‘package:web_socket_channel/io.dart’;

      void main() => runApp(MyApp());

      class MyApp extends StatelessWidget {@overrideWidget build(BuildContext context) {final channel = IOWebSocketChannel.connect(‘ws://localhost:8080’);

      return MaterialApp(title: ‘WebSocket Flutter Example’,home: Scaffold(appBar: AppBar(title: Text(‘WebSocket Flutter Example’),),body: Center(child: StreamBuilder(stream: channel.stream,builder: (context, snapshot) {if (snapshot.hasData) {return Text(snapshot.data);} else {return Text(‘Connecting…’);}},),),),);}}

    This code creates a Flutter app that connects to the WebSocket server at ws://localhost:8080. The app displays a text widget that shows the data received from the server. If no data is received yet, the text widget shows “Connecting…”.

    Step 3: Test the App

    The final step is to test the app by running both the server and the Flutter app.

    1. Start the server:
    2. node server.js

    3. Run the Flutter app:
    4. flutter run

    Once the app is running, you should see the text widget showing “Connecting…”. When you send a message from the client, the text widget should update to show the message received from the server.

    FAQ

    What are some other use cases for WebSocket?

    WebSocket is ideal for building real-time applications such as chat apps, stock trading apps, and gaming apps. It can also be used for real-time collaboration tools, live streaming apps, and IoT applications.

    What are the benefits of using Flutter for mobile app development?

    Flutter provides many benefits for mobile app development, including:

    • Fast development cycle
    • Hot reload feature for quick iteration
    • Cross-platform development with a single codebase
    • High-quality and customizable pre-built widgets
    • High-performance rendering and animations

    What is the difference between WebSocket and HTTP?

    WebSocket is a communication protocol that provides full-duplex communication channels over a single TCP connection. Unlike HTTP, which is a request-response protocol, WebSocket allows bi-directional communication between clients and servers. This means that once a WebSocket connection is established, either the client or server can send data to the other party at any time.

    What is Dart?

    Dart is a programming language developed by Google. It is used for building web, mobile, and desktop applications. Dart is the language used by Flutter for building mobile apps.