mubsub

Mubsub is a pub/sub implementation for Node.js and MongoDB. It utilizes Mongo's capped collections and tailable cursors to notify subscribers of inserted documents that match a given query. You should not create lots of channels, because mubsub will poll from the cursor position.

Example

var mubsub = require('mubsub');

var client = mubsub('mongodb://localhost:27017/mubsub_example');
var channel = client.channel('test');

client.on('error', console.error);
channel.on('error', console.error);

channel.subscribe('bar', function(message) {
    console.log(message.foo); // => 'bar'
});

channel.subscribe('baz', function(message) {
    console.log(message); // => 'baz'
});

channel.publish('bar', { foo: 'bar' });
channel.publish('baz', 'baz');

Usage

Create a client

You can pass a Db instance of uri string. For more information about uri format visit http://mongodb.github.io/node-mongodb-native/driver-articles/mongoclient.html

var mubsub = require('mubsub');

// Using uri
var client = mubsub('mongodb://localhost:27017/mubsub_example', [options]);

// Pass mongodb driver `Db` instance directly.
var client = mubsub(new Db(...));

Channels

A channel maps one-to-one with a capped collection (Mubsub will create these if they do not already exist in the database). Optionally specify the byte size of the collection or/and max number of documents in the collection when creating a channel.

var channel = client.channel('foo', { size: 100000, max: 500 });

Subscribe

var subscription = channel.subscribe([event], callback);

Subscriptions register a callback to be called whenever a document matching the specified event is inserted (published) into the collection (channel). You can omit the event to match all inserted documents. To later unsubscribe a particular callback, call unsubscribe on the returned subscription object:

subscription.unsubscribe();

Publish

channel.publish(event, obj, [callback]);

Publishing a document simply inserts the document into the channel's capped collection. Callback is optional.

Listen to events

Following events will be emitted:

    // Subscribe to some specicific event, like channel.subscribe
    channel.on('myevent', console.log);

    // Subscribe to a "message"
    channel.on('message', console.log);

    // Subscribe to "document" event to get the entire mongo document.
    channel.on('document', console.log);

    // Mubsub is ready to receive new documents.
    channel.on('ready', console.log);

    // Connection errors
    client.on('error', console.log);

    // Channel errors
    channel.on('error', console.log);

Close

client.close();

Closes the MongoDB connection.

Install

npm install mubsub

Tests

make test

You can optionally specify the MongoDB URI to be used for tests:

MONGODB_URI=mongodb://localhost:27017/mubsub_tests make test