What is Spring Fu

What is Spring Fu

• Different flavor

  • Won't replace anything

• Antithesis to Magic

  • Everything is explicit

  • Everything is done in code

Fu is for Functional

Fu is for Functional

• Ja‎­Fu: for Java and Functional

  • JaFu was added later to the Fu family

  • IMO still not great for DSLs

• Ko­Fu: for Kotlin and Functional

  • I'll concentrate on KoFu

Testing

… so that we can stress how easy and intuitive is with KoFu to enable only what you need to test, in contrast of traditional Spring boot, where you have to search for the right annotation that disables what you don’t need for the test.
– KoFu tutorial

What you win: simplicity

What you win: simplicity

• when a project starts growing you may discover yourself spending more time configuring the framework, than building your business
  – KoFu tutorial

• Less magic → less short term productivity 📉

• Less magic → less framework overhead 📈

What you win: startup performance

What you win: startup performance

• 40% faster than regular auto-configuration on a minimal Spring MVC app
  – Spring Fu Readme

• (almost) no reflections → easier native image

What you win: Petclinic example

What you win: Petclinic example

– Spring Boot Revisited with KoFu and JaFu

What you loose: Magic

What you loose: Magic

• AutoConfiguration

  • Spring Fu has (some) adapters: github

• Package scan

• Can work without Proxies

  • no AOP

What you loose: Features – "only"

What you loose: Features – "only"

• Spring MVC / WebFlux / WebClient / Cors / Jackson or kotlin serialization / Thymeleaf and Mustache

• JDBC, R2DBC / Redis / Cassandra / MongoDB

  • no JPA 😶

• Configuration / Logging / Beans / Listeners

What you loose for now: Planned

What you loose for now: Planned

• Scheduling 😭

• WebSockets 😕

• GraphQL 😶

• … plenty more

What remains

What remains

• https://start.spring.io

• Spring Boot infrastructure

• Dependency Management

• Starters

  • but AutoConfiguration won't be automatic

• Acturators

• Standalone JAR / container

It's experimental

It's experimental

• Current focus is on native

• "stalled", last release 05 Apr 2022

• Rest assured that we will work on functional configurations again in the future, be it through Spring Fu, or in another form.
  – Spring Fu Readme

For serverless?

For serverless?

• No/less reflection, package scan

  • → faster startup

• But: still "slow"

  • 1.6s vs 0.08s

• Serverless == native

For native?

For native?

• No reflection/proxies/scan

  • Compile to native is easier to archive

• But the current focus of spring is easy native compilation

For micro services?

For micro services?

• 100 MB memory can be a lot

• 21 MB can also be a lot!

Selling point: no magic?

Selling point: no magic?

• Explicitness

• Discoverability

• Navigable

Maybe a pendulum

Maybe a pendulum

• The pendulum had swung.
  – Type Wars

• Spring Boot was created because

  • someone wanted magic

Magic is not the problem

Magic is not the problem

• Lack of explicitness

• Lack of discoverability

• Lack of knowledge

There is no magic 🤷‍♀️

There is no magic 🤷‍♀️

• It's an excuse

• Magic is the line where you stopped learning

  • chose to

  • were ordered to stop learning

• Avoid simulation of simplicity

  • (term diverted from Security, Moore’s law, and the anomaly of cheap complexity)

Thank's for having me 🙇‍♂️

References