New in Spring 5: Functional Web Framework

Slides from Dutch Spring Meetup

Transcript

1. New in Spring 5: Functional Web Framework Arjen Poutsma Pivotal
2. About Arjen • Twenty years of experience in Enterprise Software Development • Joined SpringSource in 2005 • Development lead of Spring Web Services, Spring MVC, Spring Scala • Working on Spring 5
3. I do like annotations...
4. ...but there are downsides • “Magic” • No clear link between annotation and behavior • Runtime handling • Reflection
5. Design Goals • Functional Style • java.util.function • java.util.stream • More library; less framework • Explicit • Customizable • No reflection
6. Functional Programming (in Java 8)
7. Immutability • No change after construction • Builders • Thread-safety •e.g. String •toUpperCase() •StringBuilder
8. First-class Functions • Functions as first-class citizens • Functions as arguments • Functions as return value • Reusability •e.g. String •indexOf(char) vs indexOf(Predicate<Char>)
9. Pure Functions • Same result given same arguments • No Limit side effects • Application boundaries • Testability • Cacheability • Parallelization
10. Who likes this?
11. Function<ServerRequest, ServerResponse<T>> HandlerFunction h(Req) ! Res
12. ServerRequest • Similar to RequestEntity • Immutable • Headers • Optional<MediaType> contentType() • List<String> header(String) • Body • Mono<T> bodyToMono(Class<T>)
13. ServerResponse • Similar to ResponseEntity • Immutable w/ Builder • Headers • lastModified(ZonedDateTime) • header(String, String...) • Body • body(Publisher<T>, Class<T>)
14. Demo
15. Function<Request, Optional<HandlerFunction<T>> RouterFunction r(Req) ! ⇢ h(Req) ! Res ;
16. RequestPredicate Predicate<Request>
17. RequestPredicates • Common predicates • path • headers (Content-Type, Accept) • Build (compose) your own!
18. Demo
19. BiFunction<Request,HandlerFunction<T>, Response<R>> HandlerFilterFunction f ( Req, h ( x )) ! Res
20. Demo
21. Running a Server • Convert RouterFunction to HttpHandler • HttpHandler runs • Reactor Netty • RxNetty • Servlet 3.1 • Undertow
22. Demo
23. Summary • Handler functions handle request by returning a response • Router functions route to handler functions • Router functions can be filtered by filter functions • Router functions can be run in a reactive web runtime
24. Who likes this?
25. Q & A