piątek, 3 listopada 2017

Spring framework 5 - new & noteworthy

Spring platform

Seems that nowadays everybody at least know (and most use) Spring framework. Well, no wonder. Years ago Spring pioneered lightweight DI container for masses. Later on provided nice (and also lightweight) MVC implementation that could easily play along multiple View (UI) technologies (JSP, vanilla JS, Portlets? you name it). With each and every modern (sometimes only trendy) solution / approach they were ready (REST, polyglot persistence etc.). Apart from the main Spring Framework, there are also additional Spring projects - for example fantastic microservice-enabling Spring Boot.

Spring framework 5

Current newest and shiniest version (actually 5.0.1, reference available here) has been the first major release since December 2013. This means 2,5 years of development, quite a lot I'd say in modern fast-changing software development world. So, what are the most interesting parts of the release?

Reactive Programming

Biggest star of the show - Spring-native reactive programming (go ahead and read Reactive Manifesto if you're not familiar with whole "reactive" hype). Based upon industry-agreed specification which is called Reactive Streams (specification here). Current Java 9 implements Reactive Streams natively, but as Spring 5 is coupled with Java 8, it uses an external implementation of the API - Project Reactor (click here for more info).
The reactive module is called WebFlux. Nevertheless, Spring MVC (REST-style) is still of course supported. Nice comparison in 5 use cases of "new fancy" versus "old proven" can be found here: https://www.infoq.com/presentations/servlet-reactive-stack
In order to make an application fully reactive, it has to use non-blocking model thru all layers, down to persistence. This means that currently it will work only with Mongo, Redis etc. Unfortunately, JPA / JBDC are still inherently blocking :( This can be worked around by separating persistence layer with a queue / working thread, reading / publishing persistence events (Event Sourcing anyone? :-P ).

Core and container changes

Apart from WebFlux, 5.x brings some core enhancements. Among most notable ones is utilisation of Java 8 features. For example, core Spring interfaces have now default method implementations. It means that in many cases you won't need to extends "adapters" implementing the interfaces but simply use them directly. There are also multiple lambdas and streams all around. For example, one can now register beans using a lambda (aka "supplier").  Last but not least, reflection enhancements (for details see here: https://docs.oracle.com/javase/8/docs/technotes/guides/reflection/enhancements.html) are now used for better/faster parameters access.
There is also a nice enhancement for large application start-up. Instead of a time-consuming classpath scanning, applications can now provide an index of candidates in the form of META-INF/spring.components file. Of course the file should be created by a plugin during build (not manually for God sake! :-) ). This should bring noticeable benefits for applications with more than 200 classes. According to the source (JIRA: https://jira.spring.io/browse/SPR-11890), 200 components / 5000 irrelevant classes starts 10% faster. Not that bad at all.


  • Junit 5 fully supported, also on the "integration" side of testing
  • guava (among others) support discontinued :-( 
  • Java 8  / Java EE 7 as a minimum requirement

Further reading


To sum up, Reactive programming seems to be the main theme of the release. Rest of the updates are rather "sugar" like. It's not bad though, as we should remember to always "leave well alone" :-)

Brak komentarzy: