sockjs
Advanced tools
Package description
SockJS is a JavaScript library that provides a WebSocket-like object in environments where true WebSockets are not available or not fully supported. It is designed to work both on the client-side and server-side to enable seamless communication between the two. SockJS provides a consistent API and attempts to provide a low-latency, full duplex, cross-domain communication channel that can work even behind restrictive corporate proxies.
Server-side WebSocket emulation
This code sample demonstrates how to create a SockJS server that emulates a WebSocket. It listens for connections on the '/echo' path and simply echoes back any messages it receives.
const http = require('http');
const sockjs = require('sockjs');
const echo = sockjs.createServer({ prefix: '/echo' });
echo.on('connection', function(conn) {
conn.on('data', function(message) {
conn.write(message);
});
});
const server = http.createServer();
echo.installHandlers(server, { prefix: '/echo' });
server.listen(9999, '0.0.0.0');Client-side WebSocket emulation
This code sample shows how to create a SockJS client that connects to a SockJS server. It sends a message when the connection is opened and logs any messages it receives before closing the connection.
const SockJS = require('sockjs-client');
let sock = new SockJS('http://localhost:9999/echo');
sock.onopen = function() {
console.log('open');
sock.send('test');
};
sock.onmessage = function(e) {
console.log('message', e.data);
sock.close();
};
sock.onclose = function() {
console.log('close');
};The 'websocket' package provides both client and server-side components for working with WebSockets. It is a more direct implementation of the WebSocket protocol and does not include the fallback mechanisms that SockJS offers for environments where WebSockets are not supported.
Socket.IO is a popular real-time communication library that abstracts WebSockets and other methods to provide a consistent API across different browser and server environments. It offers features like auto-reconnection, broadcasting, and rooms, which can be more feature-rich compared to SockJS, but it also requires using the Socket.IO client to communicate with a Socket.IO server.
Engine.IO is the lower-level component of Socket.IO that provides the core real-time transport functionality. It is designed to be as minimal and flexible as possible, focusing on the essentials of real-time communication. Engine.IO is similar to SockJS in that it provides WebSocket-like functionality with fallbacks, but it is part of the broader Socket.IO ecosystem.
Faye is a set of tools for simple publish-subscribe messaging between web clients. Its 'faye-websocket' package is a WebSocket client and server implementation that allows for easy WebSocket communication. Unlike SockJS, it does not provide fallback options for non-WebSocket environments.
Readme
SockJS family:
SockJS-node is a Node.js server side counterpart of SockJS-client browser library written in CoffeeScript.
To install sockjs-node run:
npm install sockjs
An simplified echo SockJS server could look more or less like:
var http = require('http');
var sockjs = require('sockjs');
var echo = sockjs.createServer(sockjs_opts);
echo.on('connection', function(conn) {
conn.on('data', function(message) {
conn.write(message);
});
conn.on('close', function() {});
});
var server = http.createServer();
echo.installHandlers(server, {prefix:'[/]echo'});
server.listen(9999, '0.0.0.0');
(Take look at examples directory for a complete version.)
Subscribe to SockJS mailing list for discussions and support.
SockJS-client comes with some QUnit tests and a few smoke tests that are using SockJS-node. At the moment they are deployed in few places:
The API design is based on the common Node API's like Streams API or Http.Server API.
SockJS module is generating a Server class, similar to
Node.js http.createServer
module.
var sockjs_server = sockjs.createServer(options);
Where options is a hash which can contain:
Once you have create Server instance you can hook it to the
http.Server instance.
var http_server = http.createServer();
sockjs_server.installHandlers(http_server, options);
http_server.listen(...);
Where options can overshadow options given when creating Server
instance.
Server instance is an
EventEmitter,
and emits following event:
All http requests that don't go under the path selected by prefix
will remain unanswered and will be passed to previously registered
handlers. You must install your custom http handlers before calling
installHandlers.
A Connection instance supports
Node Stream API and
has following methods and properties:
A Connection instance emits the following events:
For example:
sockjs_server.on('connection', function(conn) {
console.log('connection' + conn);
conn.on('close', function() {
console.log('close ' + conn);
});
conn.on('data', function(message) {
console.log('message ' + conn,
message);
});
});
A fully working echo server does need a bit more boilerplate (to
handle requests unanswered by SockJS), see the
echo example
for a complete code.
If you want to see samples of running code, take a look at:
There are two issues that needs to be considered when planning a non-trivial SockJS-node deployment: WebSocket-compatible load balancer and sticky sessions (aka session affinity).
Often WebSockets don't play nicely with proxies and loadbalancers. Deploying a SockJS server behind Nginx or Apache could be painful.
Fortunetely recent versions of an excellent loadbalancer HAProxy are able to proxy WebSocket connections. We propose to put HAProxy as a front line load balancer and use it to split SockJS traffic from normal HTTP data. Take a look at the sample SockJS HAProxy configuration.
The config also shows how to use HAproxy balancing to split traffic between multiple Node.js servers. You can also do balancing using dns names.
If you plan depling more than one SockJS server, you must make sure that all HTTP requests for a single session will hit the same server. SockJS has two mechanisms that can be usefull to achieve that:
/resource/<server_number>/<session_id>/transport. This is
usefull for load balancers that support prefix-based affinity
(HAProxy does).JSESSIONID cookie is being set by SockJS-node. Many load
balancers turn on sticky sessions if that cookie is set. This
technique is derived from Java applications, where sticky sessions
are often neccesary. HAProxy does support this method, as well as
some hosting providers, for example CloudFoundry. In order to
enable this method on the client side, please supply a
cookie:true option to SockJS constructor.If you want to update SockJS-node source code, clone git repo and follow this steps. First you need to install dependencies:
cd sockjs-node
npm install --dev
You're ready to compile CoffeeScript to js:
make
If you want to automatically recompile when the source files are
modified, take a look at make serve. Make sure your changes to
SockJS-node don't break test code in SockJS-client and don't break the
SockJS-protocol test suite.
FAQs
SockJS-node is a server counterpart of SockJS-client a JavaScript library that provides a WebSocket-like object in the browser. SockJS gives you a coherent, cross-browser, Javascript API which creates a low latency, full duplex, cross-domain communication
The npm package sockjs receives a total of 8,647,152 weekly downloads. As such, sockjs popularity was classified as popular.
We found that sockjs demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 5 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
CISA launched a new project called Vulnrichment to enrich CVEs with details that help prioritize patching and mitigation efforts, as the NVD backlog of unenriched CVEs awaiting analysis surpasses 10,000.
Security News
Socket is joining forces with CISA and other industry leaders at the RSA Conference to sign the Secure by Design pledge, committing to uphold the highest security standards in our products.
Research
The Socket research team breaks down a sampling of malicious packages that download and execute files, among other suspicious behaviors, targeting the popular Discord platform.