Using RxJava Observable's Completion Semantics for Greater Good Jan 23 rd , 2015 When I first started with RxJava, for me it was all about easy and parametric concurrency. Later I discovered the power of functional composition and real code reuse. But it never ceases to amaze me, so today I want to talk about Observable ’s completion semantics and Subscriber.add(Subscription) method. Unsubscriptio