The Road to Serverless: Spring Cloud Function

@david_syer, 2017

Agenda

Serverless and functions
Spring Cloud Function
Raising the value line

http://github.com/spring-cloud/spring-cloud-function
http://projectreactor.io/

Serverless and Functions

Event driven
Dynamic resource utilization
Billing per message
Prototypes become production code really quickly
Focus on business logic

Business Logic and the Value Line

Get out of the business of infrastructure and
automation (a.k.a. "undifferentiated heavy lifting")
and integration spaghetti

Amazon Lambda

Google Cloud Function

Microsoft Azure Functions

Riff

Serverless Providers

(J) Amazon Lambda
Google Cloud Functions
(J) Azure Function
(J) IBM OpenWhisk
(J) Oracle Fn
OpenFaaS
Fission
Kubeless
(J) Riff https://github.com/projectriff
…

(J) = native Java support
Others can run Java, e.g. via custom container or node JRE launcher.

Java Util Function

public interface Function<T, R> {
    R apply(T t);
}

public interface Consumer<T> {
    void accept(T t);
}

public interface Supplier<T> {
    T get();
}

Spring Cloud Function

@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);
  }
}

Plain Old Functions

package functions;

public class Uppercase implements Function<String, String> {

  String apply(String input) {
    return input.toUpperCase();
  }

}

Spring Cloud Function Web

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)

Project Reactor

public abstract class Flux<T> implements Publisher<T> {
...
}



public abstract class Mono<T> implements Publisher<T> {
...
}

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);
  }
}

Spring Cloud Function Stream

Spring Cloud Function Adapter

Spring Cloud Function

Programming model: @Beans of type Function, Consumer and Supplier
Component scan for functions (e.g. execute jar with no dependency on Spring at all)
Compile strings which are Java function bodies
Bind and invoke from an isolated classloader (JVM packing, platform)
Adapters for AWS Lambda, Azure, Riff and other "serverless" service providers

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
CNCF WG Whitepaper
Spring Initializr: http://start.spring.io
Spring Cloud: http://cloud.spring.io
Reactor: http://projectreactor.io