qpubs

Simple, light-weight pub-sub engine modeled on Nodejs event emitters.

wildcard topic prefix and suffic matching
support for message receipt confirmation

Summary

var QPubs = require('qpubs');
var pubs = new QPubs({ separator: '.' });
pubs.listen('my.event', function(message) {
    console.log('message == %s', message);
    // => message == 42,
    //    message == 451
})
pubs.listen('your.*', function(msg) {
    console.log('msg == %s', msg);
    // => msg == 77
})
pubs.listen('*.event', function(ev, ack) {
    console.log('ev == %s', ev);
    ack();
    // => ev == 42
    //    ev == 77
    //    ev == 451
})
pubs.emit('my.event', 42);
pubs.emit('your.event', 77);
pubs.emit('my.event', 451);

Api

new QPubs( [options] )

Construct and configure the pubsub engine.

Options:

separator - string that separates topic components. Default is a . dot.

listen( topic, listener(message [,cb]) )

Listen for messages published to the named topic. Each received message is passed to all interested listener()-s. The wildcard * matches leading or trailing topic components (one or the other, not both). Route components are separated by the separator string passed to the constructor. If the listener function takes a callback cb, it must be called to acknowledge receipt of the message; the emit() callback waits for all listeners to confirm.

emit( topic, message [,callback(err, errors)] )

Send the message to all the listeners listening to the topic. If a callback is given, it will be invoked once all recipients have acknowledged the message. The callback will return all errors encountered while notifying the listeners, the first error as err and the all errors in the errors array.

unlisten( topic, listener )

Make the listener stop receiving messages from the given topic. If listen() was called multiple times for this topic with this listener, each ignore() undoes one listen.

Todo

think about incremental checksumming, both front-to-back and back-to-front
time out listener callbacks
stateful, durable message stream subscribe/unsubscribe (with pluggable fifos)
? limit on max payload? (ties up journal, etc)

Changelog

0.4.2 - use newer qfifo for bugfix, remove fifo files after tests
0.4.1 - add a callback to loadSubscriptions, pass deliver to closeSubscription
0.4.0 - refactor qsubs into create/open/close/delete subscription
0.1.2 - allow listeners to take callbacks, faster emit
0.0.5 - faster unwatched subtopic skipping
0.0.4 - wildcard match empty leading/trailing route components
0.0.3 - hash routes by length, callback on emit()
0.0.2 - working version

andrasq/node-qpubs