50 lines
2.7 KiB
Plaintext
50 lines
2.7 KiB
Plaintext
= Introduction
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Spring Cloud Function is a project with the following high-level goals:
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* Promote the implementation of business logic via functions.
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* 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.
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* Support a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS).
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* Enable Spring Boot features (auto-configuration, dependency injection, metrics) on serverless providers.
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It abstracts away all of the transport details and
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infrastructure, allowing the developer to keep all the familiar tools
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and processes, and focus firmly on business logic.
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Here's a complete, executable, testable Spring Boot application
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(implementing a simple string manipulation):
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[source,java]
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----
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@SpringBootApplication
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public class Application {
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@Bean
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public Function<String, String> uppercase() {
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return value -> value.toUpperCase();
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}
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public static void main(String[] args) {
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SpringApplication.run(Application.class, args);
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}
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}
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----
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It's just a Spring Boot application, so it can be built, run and
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tested, locally and in a CI build, the same way as any other Spring
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Boot application. The `Function` is from `java.util` and `Flux` is a
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https://www.reactive-streams.org/[Reactive Streams] `Publisher` from
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https://projectreactor.io/[Project Reactor]. The function can be
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accessed over HTTP or messaging.
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Spring Cloud Function has the following features:
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* _Choice of programming styles - reactive, imperative or hybrid._
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* _Function composition and adaptation (e.g., composing imperative functions with reactive)._
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* _Support for reactive function with multiple inputs and outputs allowing merging, joining and other complex streaming operation to be handled by functions._
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* _Transparent type conversion of inputs and outputs._
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* _Packaging functions for deployments, specific to the target platform (e.g., Project Riff, AWS Lambda and more)_
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* _Adapters to expose function to the outside world as HTTP endpoints etc._
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* _Deploying a JAR file containing such an application context with an isolated classloader, so that you can pack them together in a single JVM._
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* _Adapters for https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-aws[AWS Lambda], https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-azure[Azure], https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-gcp[Google Cloud Functions], and possibly other "serverless" service providers._
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