This SDK is a PubNub Python based API for MQTT. PubNub is a Push technology intended specifically for high-message-volume applications and games. It is a cloud-based, real-time messaging service for mobile phones, tablets, TVs, HTML5 web browsers and game consoles.
In a world of monolithic web frameworks, Express.js offers an alternative. It is described as a "fast, unopinionated, minimalist server-side web framework for Node.js." and strives to make web application development for Node.js easier. This article breaks down exactly how Express works.