Transactional saga in Java

Part IV : Intermezzo

.. in which we try and fail exceptionally to have Futures more complete

Having developed the third Scala version I got curious about doing the same in Java.  I more or less expected the CompletableFuture to be a more verbose flavor of the Scala Future. It had also been a year since I stopped writing Java and I wanted to check how I felt about it. If you remember the last Scala iteration the following should look familiar:

At first glance "thenCompose" is like "flatMap" and "exceptionally" resembles "recoverWith". Close but no cigar. You cannot return a CompletableFuture from a function taken by CF::exceptionally. It does not cancel the rest of saga execution either. Not even in JDK10. So I had to throw an exception and to manually roll back transactions the way it worked in the second Scala version. It's tolerable but not exactly elegant.

One lesson here is that Scala Futures are at least a little more powerful than the Java ones. Once you get used to monadic composition two dozen Java signatures do not look all that readable anymore. While typing Java code I also noticed how tedious it is in comparison with Scala. All trivial bits such as constructors, semicolons, and no variable type inference result in constant friction. I am afraid I don't feel like writing Java anymore.