A browser websocket client library for NATS
npm install --save ws-nats<!DOCTYPE html>
<html lang="en">
<head></head>
<body>
<script src="ws-nats.umd.js"></script>
<script>
var nats = NATS.connect({ url: 'ws://0.0.0.0:8080', json: true });
nats.publish('foo', { message: 'Hello World!' });
</script>
</body>
</html>// var NATS = window.NATS;
var NATS = require('ws-nats');
var nats = NATS.connect({ url: 'ws://0.0.0.0:8080', json: true });
// Simple Publisher
nats.publish('foo', { message: 'Hello World!' });
// Simple Subscriber
nats.subscribe('foo', function(msg) {
console.log('Received a message: ' + msg);
});
// "*" matches any token, at any level of the subject.
nats.subscribe('foo.*.baz', function(msg, reply, subject) {
console.log('Msg received on [' + subject + '] : ' + msg);
});
nats.subscribe('foo.bar.*', function(msg, reply, subject) {
console.log('Msg received on [' + subject + '] : ' + msg);
});
// Using Wildcard Subscriptions
// ">" matches any length of the tail of a subject, and can only be
// the last token E.g. 'foo.>' will match 'foo.bar', 'foo.bar.baz',
// 'foo.foo.bar.bax.22'
nats.subscribe('foo.>', function(msg, reply, subject) {
console.log('Msg received on [' + subject + '] : ' + msg);
});
// Unsubscribing
var sid = nats.subscribe('foo', function(msg) {});
nats.unsubscribe(sid);
// Request Streams
var sid = nats.request('request', function(response) {
console.log('Got a response in msg stream: ' + response);
});
// Request with Auto-Unsubscribe. Will unsubscribe after
// the first response is received via {'max':1}
nats.request('help', {}, {'max':1}, function(response) {
console.log('Got a response for help: ' + response);
});
// Request for single response with timeout.
nats.requestOne('help', {}, {}, 1000, function(response) {
// `NATS` is the library.
if(response instanceof NATS.NatsError && response.code === NATS.REQ_TIMEOUT) {
console.log('Request for help timed out.');
return;
}
console.log('Got a response for help: ' + response);
});
// Replies
nats.subscribe('help', function(request, replyTo) {
nats.publish(replyTo, 'I can help!');
});This library is compatible with all the API methods in node-nats
To test ws-nats, you need to connect to a NATS server using a Websocket-to-TCP relay such as nats-relay or ws-tcp-relay.
You can use Docker to run the gnatsd server and the Websockets to TCP relay:
# launch the gnatsd server
docker run -it --name=nats --rm -d -p 4222:4222 -p 8222:8222 nats -D -m 8222
# launch the relay (assumes we are using Linux!)
docker run -it --name=relay --rm -d -p 8080:8080 aaguilar/nats-relay -p 8080 $(hostname -i):4222
# then configure ws-nats to connect to the relay
var nats = NATS.connect({ url: 'ws://0.0.0.0:8080', json: true });
Tested in the following browsers versions:
- Google Chrome 53+
- Firefox 37+
- Internet Explorer 11
- Microsoft Edge 12+
- Safari 9+
- Mobile Safari 11+
- Opera 46+
- TLS connections to NATS server are not supported because we are using Websocket as transport
- The
nkeyspublic-key signature system has been disabled from the codebase to reduce bundle size (we plan to port this at a later stage) - The size of the library bundle has increased because we are using sockjs-client, we will remove this dependency in future releases.
This library is heavily inspired by websocket-nats and re-uses the sames API methods from the original node-nats library.