Non-Blocking/Asynchronous API(s) using Java 8 and above

A Good Style of explaining the evolution of Java API(s) to achieve Concurrency.

https://www.callicoder.com/java-concurrency-multithreading-basics/


Analogy/Use Scenario Visualization:
(*) If you are core busniess layer, who need to integrate with legacy Java components ( which are the actual workhorses ) and you are being called from upstream busniess layers, there is always a need for Asynchronous invocation.
This is where following article

https://www.callicoder.com/java-8-completablefuture-tutorial/
best explains concepts

Prerequistie : Java Lamba familarity, Supplier , Consumer , functional interfaces in Java 

Other Analogies:
1) SwingWorker in old AWT/applet kind of application 
2) Promise in JavaScript 
3) Work delegation and collating back (Typical Manager)