Websocket Manager

A Flutter plugin for Android and iOS supports websockets. This plugin is based on two different native libraries Starscream for iOS and okHttp for Android.

This plugin was created due to our necessity to maintain a WebSocket connection active in background while Flutter's WebSocket from cookbook doesn't keep alive while screen is locked or the application was in background.

Introduction

Websocket Manager doesn't manipulate websockets in Dart codes directly, instead, the plugin uses Platform Channel to expose Dart APIs that Flutter application can use to communicate with two very powerful websocket native libraries. Because of that, all credits belong to these libraries.

How to install

Android

You only need this configuration if your server doesn't have SSL/TLS

Since Android P http is blocked by default and there are many ways to configure. One way to configure is explicitly saying that you accept clear text for some host.

• Create res/xml/network_security_config.xml with content:

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">your_domain</domain>
    </domain-config>
</network-security-config>

• Point to this file from your manifest (for bonus points add it only for the test manifest):

<application
    android:networkSecurityConfig="@xml/network_security_config"
    android:label="@string/app_name"
    android:theme="@style/AppTheme">
    <activity android:name=" (...)
</application>

iOS

Doesn't require any configuration

Example

int messageNum = 0;
// Configure WebSocket url
final socket = WebsocketManager('wss://echo.websocket.org');
// Listen to close message
socket.onClose((dynamic message) {
    print('close');
});
// Listen to server messages
socket.onMessage((dynamic message) {
    print('recv: $message');
    if messageNum == 10 {
        socket.close();
    } else {
        messageNum += 1;
        final String msg = '$messageNum: ${DateTime.now()}';
        print('send: $msg');
        socket.send(msg);
    }
});
// Connect to server
socket.connect();

Credits

• Android: okHttp created by Square
• iOS: Starscream created by daltoniam