Redub turns a bunch of objects implementing a simple pub/sub interface
into a redundant pub/sub transport. It works dandy with redis-pubsub, but
there's no hard dependency. 
var pubsub = require('redis-pubsub');
var redub = require('redub');
var transport1 = pubsub.createChannel(...);
var transport2 = pubsub.createChannel(...);
var channel = redub(transport1, transport2);
channel.on('message', function(msg, id) {
console.log(msg);
channel.end();
});
var id = channel.send('Hello world!');
Behind the scenes, messages are wrapped in an envelope with a unique ID:
['2d1222ff-e0cd-4594-a1fb-19335c98e58c','Hello world!']
These IDs are tracked for a short time, and duplicates are dropped. The timeout is configurable:
// Defaults to 10 seconds. 0 means never time out.
// In practice, IDs are tracked anywhere between timeout and 2 × timeout.
channel.timeout = 10000;
The method with which IDs are generated is also configurable:
channel.uid = function(message) {
// generate and return a unique ID string.
};
Redub will accept any object that quacks like an EventEmitter and implements the following:
- method
send(message)- must serialize (e.g.JSON.stringify) the message and publish it. - event
message(message)- must be passed a deserialized message.