Asynchronous, event-driven "reactive" programming is way too hard in today's world of development tools and frameworks. The huge amount of manual and error-prone plumbing leads to incomprehensible and hard to maintain code. As we reach out to services in the cloud, the desire for asynchronous computation is ever increasing, requiring a fresh look on the problems imposed by reactive programming. Centered around the concept of observable data sources, Rx provides a framework that takes care of the hard parts of reactive programming. Instead of focusing on the hard parts, you now can start dreaming about the endless possibilities of composing queries over asynchronous data sources, piggybacking on convenient LINQ syntax. In this session, we'll cover the design philosophy of Rx, rooted on the deep duality between the interactive IEnumerable interface and the new reactive IObservable interface in .NET 4. From this core understanding, we'll start looking at various combinators and operators defined over observable collections, as provided by Rx, driving concepts home by a bunch of samples. Finally, if time permits, we'll look at the Reactive Extensions for JavaScript which allows us to take the concepts we already know from Rx and apply them to JavaScript and have deep integration with libraries such as jQuery. Democratizing asynchronous programming starts today. Don't miss out on it!