sample bus wrapper

bus.js

/*
 * usage:
 * var Bus = require('../utils/bus');
 * var bus = new Bus({ url: 'amqp://guest:guest@localhost:5672' });
 * bus.connect(); // or bus.connectWithRetry();
 *
 * bus.createQueueIfNotExists('queueName', function (err) {
 *    if (err) return console.log('error creating queue', err);
 *    console.log('queue created successfully');
 * });
 *
 * bus.send('queueName', { data: 'something' }, function (err) {
 *    if (err) return console.log(err);
 *    console.log('message sent');
 * });
 *
 * bus.createTopicIfNotExists('topicName', function (err) {
 *     if (err) return console.log('error creating topic', err);
 *     console.log('topic created successfully');
 * });
 *
 * // topic must be created first before creating topic queue
 * bus.createTopicQueueIfNotExists('topicName', 'queueName', 'routingKey', function (err) {
 *     if (err) return console.log('failed to create topic queue', err);
 *     console.log('topic queue created successfully');
 * });
 *
 * bus.publish('topicName', 'routingKey', { data: 'something' }, function (err) {
 *     if (err) return console.log(err);
 *     console.log('message published');
 * });
 *
 * // handles both queue and topic queues
 * bus.on('queueName', function (msg, next) {
 *     console.log(msg);
 *     next(); // call next to ack or next(new Error()) to not ack
 * }, function (err) {
 *     if (err) return console.log('failed to registered handler');
 *     console.log('handler registered successfully');
 * });
 *
 */