This document discusses serverless computing and Spring Cloud Functions. It provides an overview of serverless platforms like AWS Lambda, Google Cloud Functions, and Azure Functions. Spring Cloud Functions allows developing serverless applications using Spring and exposes functions via these serverless providers. Functions are defined as Spring beans and can work with reactive streams from Project Reactor. This provides benefits of serverless with the familiar Spring programming model while running on any provider.

1. SPRING
SERVERLESS
@smaldini

2. AGENDA
▸ Serverless and functions
▸ Serverless platforms
▸ Spring Cloud Functions
http://github.com/spring-cloud/spring-cloud-function
http://projectreactor.io/

3. SERVERLESS
▸ Event Driven
▸ Dynamic resource utilization, “scale to zero”
▸ Billing per Message
▸ Focus on Business Logic
▸ Easy Integration with Platform Services
CNCF https://github.com/cncf/wg-serverless/tree/master/whitepaper

4. AMAZON LAMBDA

5. GOOGLE CLOUD FUNCTION

6. MICROSOFT AZURE FUNCTIONS

7. SERVERLESS PROVIDERS
▸ (J) Amazon Lambda
▸ Google Cloud Functions
▸ (J) Azure Functions
▸ (J) Riff https://github.com/projectriff
▸ (J) IBM OpenWhisk
▸ (J) Oracle Fn
▸ OpenFaas
▸ Fission
▸ Kubeless
▸ …
(J) = native Java support
Others can run Java, e.g. via custom container or node JRE launcher.

8. JAVA UTIL FUNCTIONS
public interface Function<T, R> {
R apply(T t);
}
public interface Consumer<T> {
void accept(T t);
}
public interface Supplier<T> {
T get();
}

9. SPRING CLOUD FUNCTIONS
@SpringBootApplication
public class Application {
@Bean
public Function<String, String> uppercase() {
return value -> value.toUpperCase();
}
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}

10. PLAIN OLD FUNCTIONS
package functions;
public class Uppercase implements Function<String, String> {
String apply(String input) {
return input.toUpperCase();
}
}

11. AWS COLD START
• Lambda throttles CPU resources when memory is constrained
• … also billing is proportional to memory usage
• … it’s not that simple

12. SPRING CLOUD FUNCTION
All the benefits of serverless, but with full access to Spring (dependency injection, integrations,
autoconfiguration) and build tools (testing, continuous delivery, run locally)
For Spring devs: a smaller, more familiar step than using FaaS APIs and UIs natively
For Functionistas: no need to know anything about Spring
Decouple lifecycle of business logic from runtime platform. Run the same code as a web endpoint,
a stream processor, or a task
Uniform programming model across serverless providers, and also able to run standalone
(locally or in a PaaS)

13. PROJECT REACTOR
public abstract class Flux<T> implements Publisher<T> {
...
}
public abstract class Mono<T> implements Publisher<T> {
...
}

14. SPRING CLOUD FUNCTION
@SpringBootApplication
public class Application {
@Bean
public Function<Flux<String>, Flux<String>> uppercase() {
return flux -> flux
.filter(this::isNotRude)
.map(String::toUpperCase);
}
boolean isNotRude(String word) {
...
}
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}

15. SPRING CLOUD FUNCTION
SERVERLESS PROVIDER
ADAPTER
USER FUNCTION
SPRING BOOT
HTTP MESSAGE

16. SPRING CLOUD FUNCTION
1.Programming model: @Beans of type Function, Consumer and Supplier,
with Flux, Mono, Publisher
2.Component scan for functions (e.g. execute jar with no dependency on Spring at all)
3.Compile strings which are Java function bodies
4.Bind and invoke from an isolated classloader (JVM packing, platform)
5.Adapters for Spring MVC, Spring Cloud Stream, AWS Lambda, Azure, Riff and other
"serverless" service providers

17. LEARNINGS
1.Spring is not slow or "heavy" on its own, classes loaded is important
2.AWS Lambda containers are slow
3.Warm JVM starts app much faster (10x) → class loader isolation
4.Functions are glue code anyway - not latency sensitive
5.Scale to Zero
6.Platform services and integration spaghetti

18. LINKS
• Spring Cloud Function: https://github.com/spring-cloud/spring-cloud-function
• Riff: https://github.com/projectriff/riff
• Spring Boot Thin Launcher: https://github.com/dsyer/spring-boot-thin-launcher
• Spring Initializr: http://start.spring.io
• Spring Cloud: http://cloud.spring.io
• Reactor: http://projectreactor.io

19. THANKS!