Socket Communication in Flutter: Building Real-time Apps

Welcome to the world of Socket communication in Flutter! This blog will go on a journey of discovery to discover the intricate details of developing real-time applications using Flutter’s powerful socket-based programming abilities. Learn the secrets of smooth data transfer between the clients and learn to design fluid, responsive apps which thrive on live updates and synchronized experience.

No matter if you’re a veteran Flutter developer or you’re just beginning, this guide will provide you with the necessary know-how and abilities to unlock the full potential of socket communications and take the development of your app to new levels.

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What are sockets?

Sockets serve as communication endpoints to connect two computers or devices via a network. They allow bidirectional data exchange between processes running on different machines. Sockets are a standard communication mechanism that allows processes to run on different devices, regardless of their underlying hardware or operating system.

There are two types of sockets

Server Socket: A server socket is waiting for connections to arrive from clients. It listens to a port on which a client tries to connect.

Client Socket: A client socket initiates the connection with a server socket. It specifies the IP address and port number of the server to which it wants to connect. Once the connection has been established, both the client and the server can begin exchanging data.

Many network applications use sockets, such as web browsing, email, file transfer, and real time applications like live chat and online gaming

The web_socket_channel is the package most commonly used by developers to establish socket connections in Flutter. Flutter’s web_socket_channel is a great tool to integrate WebSocket connections in applications. This package provides StreamChannel Wrappers to ensure compatibility across all platforms. It offers a unified WebSocketChannel, a versatile implementation that communicates over a foundational StreamChannel. It also includes wrappers that support both dart :html WebSocket and dart :io WebSocket classes, which allows seamless integration of both client-side and server-side WebSocket communications.

Installation

                    
                        Add the `web_socket_channel` package to your `pubspec'. yaml` file:
 
                        dependencies:
                        web_socket_channel: ^2.4.1
                        Run `flutter pub get` to install the package.
                        
                    
                    

Code implementation

                    
                        Below is the main.dart file of the project:
                        void main() => runApp(const MyApp());
                        class MyApp extends StatelessWidget {
                        const MyApp({Key? key});
                         
                        @override
                        Widget build(BuildContext context) {
                        return MaterialApp(
                        debugShowCheckedModeBanner: false,
                        home: MyHomePage(
                        channel: IOWebSocketChannel.connect("ws://echo.websocket.org"),
                        ),
                        );
                        }
                        }
                         
                    
                    

Observed, we begin by initializing the WebSocket Channel. A convenient endpoint server is available to test WebSocket clients and Server-Sent Events.

This server was designed to test HTTP proxy servers and clients. It will send back information about HTTP request bodies and headers. This server supports both WebSockets as well as server-sent events to simplify the process of using these technologies.

Here is the code snippet where we are actively streaming real-time data through the channel

                    
                        StreamBuilder(
                            stream: widget.channel.stream,
                            builder: (context, snapshot) {
                            return Padding(
                            padding: const EdgeInsets.all(20.0),
                            child: Center(
                            child: Stack(
                            children: [
                            BubbleWidget(
                            key: _bubbleKey,
                            text: snapshot.data ?? '',
                            ),
                            ],
                            ),
                            ));
                            },
                            )
                            
                    
                    

WebSocket channels allow for real-time data transfer, which is ideal for applications that require instant updates. This includes chat applications, notifications in real time, and collaborative editing. Web_socket_channel allows developers to easily implement WebSocket communications in Flutter. This ensures efficient and responsive data transfers between the client-server in their application. What we will see in this project.

Let’s delve deeper. Here, we’ve got a function responsible for dispatching our messages to the WebSocket channel’s server

We utilize a TextEditingController to capture user messages from the text field. These messages are then sent to our server through the WebSocket channel.

                    
                        void _sendMessage() {
                            if (textController.text.isNotEmpty) {
                            try {
                            widget.channel.sink.add(textController.text);
                            } catch (e) {
                            print("Error: $e");
                            }
                            setState(() {});
                            textController.clear();
                            }
                            }