WebSocket for Android is a Cordova plugin that makes WebSocket (RFC 6455) available on Android.
This is based on Jetty 8 under the terms of the Apache License v2.0.
- Android 2.3 or later (recommended 4.1 or later)
cordova-android@3.0.0or later or compatible frameworkcordova-plugin-whitelistorcordova-plugin-legacy-whitelistif usingcordova-android@4.0.0and later
The plugin for Cordova 2.x can be found here.
| version | WS protocol | WSS protocol | text message | binary message |
|---|---|---|---|---|
| 2.3.3 (API 10) | ✓ | ✓ | ✓ | |
| 4.0 (API 14) | ✓ | ✓ | ✓ | ✓ |
| 4.0.3 (API 15) | ✓ | ✓ | ✓ | ✓ |
| 4.1.2 (API 16) | ✓ | ✓ | ✓ | ✓ |
| 4.2.2 (API 17) | ✓ | ✓ | ✓ | ✓ |
| 4.3.1 (API 18) | ✓ | ✓ | ✓ | ✓ |
| 4.4.2 (API 19) | - | - | - | - |
| 5.0.1 (API 21) | - | - | - | - |
| 5.1.1 (API 22) | - | - | - | - |
- WSS protocol is only supported TLS. SSLv3 is not.
- Android 3.x (Honeycomb) are not supported (might work but is not tested).
- A new WebView based on Chromium supports WebSocket. Specifically Android 4.4 (KitKat) and later support them, so this plugin is NOT used on them by default.
- In
cordova-android@4.0.0and later, this plugin can be used together with Crosswalk. In this case also it is not used by default because Crosswalk supports WebSocket. - To support Android 5.x (Lollipop), would be better to build with
cordova-android@3.7.1or later.
Use Cordova Command-Line Interface (CLI). At first, check Cordova version:
$ cordova --versionIf using 5.0.0 or later, you can install it via npm:
$ cordova plugin add cordova-plugin-websocketIf using other old versions, you can install it via GitHub:
$ cordova plugin add https://github.com/knowledgecode/WebSocket-for-Android.gitCordova core plugins have been moved to npm from Cordova plugins registry (CPR). This plugin has been moved as well. It will be no longer updated in CPR. Not recommended even if you can still install it from there:
$ cordova plugin add com.knowledgecode.cordova.websocketcordova-android@4.0.0 supports SCP. In order to permit WebSocket access using cordova-plugin-whitelist, append connect-src directive in index.html:
connect-src ws://example.com wss://example.comFor example:
<head>
<meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *; connect-src ws://example.com wss://example.com">Check the plugin id:
$ cordova pluginRemove and reinstall:
$ cordova plugin rm <PLUGIN ID>
$ cordova plugin add cordova-plugin-websocketAlso will need to install cordova-plugin-whitelist or cordova-plugin-legacy-whitelist if using cordova-android@4.0.0 and later.
When install this plugin, it adds INTERNET permission to platforms/android/AndroidManifest.xml. If remove this plugin, the permission is also removed at the same time even if it is required for other plugins.
The WebSocket(url, protocols) constructor takes one or two arguments. The first argument, url, specifies the URL to which to connect. The second, protocols, is either a string or an array of strings.
A simple code is as follows:
document.addEventListener('deviceready', function () {
var ws = new WebSocket('ws://echo.websocket.org');
ws.onopen = function () {
console.log('open');
this.send('hello'); // transmit "hello" after connecting
};
ws.onmessage = function (event) {
console.log(event.data); // will be "hello"
this.close();
};
ws.onerror = function () {
console.log('error occurred!');
};
ws.onclose = function (event) {
console.log('close code=' + event.code);
};
}, false);This plugin has the following options. All these parameters are optional. Of course these don't affect built-in WebSocket.
| key | type | default value | supported version |
|---|---|---|---|
| origin | String | file:// (usually) | v0.3.0 ~ |
| maxConnectTime | Number | 75000 | v0.4.0 ~ |
| maxTextMessageSize | Number | -1 | v0.4.0 ~ (except v0.8.x) |
| maxBinaryMessageSize | Number | -1 | v0.4.0 ~ (except v0.8.x) |
| override | Boolean | false | v0.8.0 ~ |
| agent | String | (depends on device) | v0.9.0 ~ |
| perMessageDeflate | Boolean | true | v0.10.0 ~ |
origin is a value to set the request header field. Default value is usually file://. This is the same value as when using built-in WebSocket.
maxConnectTime is time to wait for connection. A unit is millisecond.
maxTextMessageSize and maxBinaryMessageSize are receivable maximum size from the server. Default value is -1 (unlimited. depends on heap size of devices). A unit is byte.
override is a flag to force WebView to use this plugin even if it supports WebSocket. However in most cases it will be slower than built-in WebSocket.
agent is user-agent to set the request header field. Default value depends on devices. This is the same value as when using built-in WebSocket.
perMessageDeflate is a flag whether to use permessage-deflate extension or not. Default value is true (but as of v0.10 was false). Sends data with compression if the server also supports permessage-deflate. However if mainly sending compressed binary like JPEG images, recommended to set to false.
If change these parameters, need to do before creating a instance:
WebSocket.pluginOptions = {
origin: 'http://example.com',
maxConnectTime: 5000,
override: true
};
var ws = new WebSocket('ws://echo.websocket.org');Transmits data to the server over the WebSocket connection. The data takes a string, a blob, or an arraybuffer.
An upper limit of the message size depends on heap size of devices. It would be better to consider a way to split the message if it is quite large.
Closes the WebSocket connection or connection attempt, if any.
See CHANGELOG.md.
This plugin is available under the terms of the Apache License Version 2.0.