node_helper.js

var NodeHelper = require('node_helper');
var request = require('request');

module.exports = NodeHelper.create({
	start: function() {
		console.log('Starting node helper for: ' + this.name);
        this.config = null;
        this.forecastUrl = '';
	},

	socketNotificationReceived: function(notification, payload) {
		var self = this;
        if(notification === 'GET_YR_FORECAST') {
            self.config = payload.config;
            self.forecastUrl = payload.forecastUrl;
            this.getForecast();
        }
	},

	getForecast: function() {
		var self = this;
        var locationData = {};
        var nowcastUrl = this.forecastUrl + '/now';

        request({url: nowcastUrl, method: 'GET'}, function(error, response, message) {
            if (!error && (response.statusCode == 200 || response.statusCode == 304)) {
                locationData.nowcast = JSON.parse(message);
                self.setNextUpdate(response.headers); 

                request({url: self.forecastUrl, method: 'GET'}, function(error, response, message) {
                    if (!error && (response.statusCode == 200 || response.statusCode == 304)) {
                        locationData.forecast = JSON.parse(message);
                        self.sendSocketNotification('YR_FORECAST_DATA', locationData);
                    }
                });
            }
            setTimeout(function() { self.getForecast(); }, self.config.updateInterval);
        });
	},

    setNextUpdate: function(headers) {
        var cacheControlHeader = headers['cache-control'];
        var maxAge = cacheControlHeader.slice(cacheControlHeader.indexOf('=') + 1);
        this.config.updateInterval = maxAge * 1000;
    }
});