Reactive Programming with RxJava

Chapter 9. Future Directions

Ben Christensen

Because we took a long time in the 0.x phase before locking down the APIs in RxJava 1.0, it is a fairly mature and stable release. Also, as a result of our decision to support Experimental and Beta markers on APIs, ongoing experimentation can continue before promoting an API to Final. However, the 0.x/1.x phase still ended up with a few decisions that warrant a breaking release; hence, a version 2.0 is being worked on.

Fundamentally, it will be very similar to 1.x, so it won’t require much change in your thinking nor will it be a significant change for usage. Even as 2.0 is released, this book will still apply in most regards. So why a version 2?

Reactive Streams

The first reason is to natively support the Reactive Streams API. Despite the RxJava team being involved in the collaboration that led to Reactive Streams, RxJava v1 APIs were already locked in and couldn’t change to adopt the interfaces in Reactive Streams. Thus, RxJava v1 requires an adaptor, even though it semantically behaves mostly like Reactive Streams. Version 2 will directly implement the Reactive Streams types and comply with the spec so as to better support interoperability across the Java community.

Observable and Flowable

Another reason is to split the Observable type into two types: Observable and Flowable. It was a mistake to make everything require backpressure because not all use cases warrant it. It has a slight performance overhead, but the primary reason ...