Spring Cloud Function


Spring Cloud Function is a project with the following high-level goals:

  • Promote the implementation of business logic via functions.

  • Decouple the development lifecycle of business logic from any specific runtime target so that the same code can run as a web endpoint, a stream processor, or a task.

  • Support a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS).

  • Enable Spring Boot features (auto-configuration, dependency injection, metrics) on serverless providers.

It abstracts away all of the transport details and infrastructure, allowing the developer to keep all the familiar tools and processes, and focus firmly on business logic.


Spring Cloud Function features:

  • Choice of programming styles - reactive, imperative or hybrid.

  • Function composition and adaptation (e.g., composing imperative functions with reactive).

  • Support for reactive function with multiple inputs and outputs allowing merging, joining and other complex streaming operation to be handled by functions.

  • Transparent type conversion of inputs and outputs.

  • Packaging functions for deployments, specific to the target platform (e.g., Project Riff, AWS Lambda and more)

  • Adapters to expose function to the outside world as HTTP endpoints etc.

  • Deploying a JAR file containing such an application context with an isolated classloader, so that you can pack them together in a single JVM.

  • Compiling strings which are Java function bodies into bytecode, and then turning them into @Beans that can be wrapped as above.

  • Adapters for AWS Lambda, Microsoft Azure, Apache OpenWhisk and possibly other "serverless" service providers.

Here’s a complete, executable, testable Spring Boot application (implementing a simple string manipulation):

public class Application {
  public static void main(String[] args) {, args);

  public Function<Flux<String>, Flux<String>> uppercase() {
    return flux -> -> value.toUpperCase());

Spring Boot Config

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