The more popular Reactive Programming/Libraries become, the more often we have to deal with those techniques and solutions. Sometimes we have to deal just with smoothies API of Reactive Extensions, sometimes we have to dive into the internals of those libraries, or sometimes we have to build our own implementation. Nevertheless, understanding of the basics patterns, behavior that is hidden inside the most of Reactive Libraries, Tool-Kits / Best Practice might simplify our – life with/debugging of/implementation of Reactive Library. Usually reading a tone of papers and blogs about the internals of Reactive Libraries, specific rules of Reactive Streams Specification or simply grasping the source code becomes hardcore. Hence, we will summarize all important by implementing own “Reactor” in Java.

What will we do to learn? We will: * Remind the sense and importance of Reactive Streams Specification; * Naively implement essential part of the reactive library – Publisher; * Find toolkit which will help in verification of the implementation; * Iteratively follow all the rules of Reactive Streams and implement the correct solution; * Build a couple of operators like Map, PublishOn