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Add Spring Cloud Function sample (#356)
* Add Spring Cloud Function sample Signed-off-by: Dave Syer <[email protected]> * Fix example curl command with structured event Signed-off-by: Dave Syer <[email protected]>
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‎docs/spring.md

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@@ -188,3 +188,6 @@ Check out the integration tests and samples:
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- [spring-rsocket](https://github.com/cloudevents/sdk-java/tree/master/examples/spring-rsocket)
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shows how to receive and send CloudEvents through RSocket using Spring Boot.
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- [spring-cloud-function](https://github.com/cloudevents/sdk-java/tree/master/examples/spring-function)
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shows how to consume and process CloudEvents via Spring Cloud Function.

‎examples/pom.xml

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<module>amqp-proton</module>
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<module>spring-reactive</module>
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<module>spring-rsocket</module>
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<module>spring-function</module>
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</modules>
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</project>

‎examples/spring-function/README.md

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# Spring Reactive + CloudEvents sample
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## Build
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```shell
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mvn package
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```
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## Start HTTP Server
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```shell
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mvn spring-boot:run
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```
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You can try sending a request using curl, and it echos back a cloud event the same body and with new `ce-*` headers:
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```shell
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curl -v -d '{"value": "Foo"}' \
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-H'Content-type: application/json' \
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-H'ce-id: 1' \
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-H'ce-source: cloud-event-example' \
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-H'ce-type: my.application.Foo' \
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-H'ce-specversion: 1.0' \
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http://localhost:8080/event
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```
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It also accepts data in "structured" format:
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```shell
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curl -v -H'Content-type: application/cloudevents+json' \
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-d '{"data": {"value": "Foo"},
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"id: 1,
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"source": "cloud-event-example"
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"type": "my.application.Foo"
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"specversion": "1.0"}' \
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http://localhost:8080/event
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```
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The `/event endpoint is implemented like this (the request and response are modelled directly as a `CloudEvent`):
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```java
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@PostMapping("/event")
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public Mono<CloudEvent> event(@RequestBody Mono<CloudEvent> body) {
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return ...;
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}
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```
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and to make that work we need to install the codecs:
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```java
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@Configuration
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public static class CloudEventHandlerConfiguration implements CodecCustomizer {
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@Override
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public void customize(CodecConfigurer configurer) {
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configurer.customCodecs().register(new CloudEventHttpMessageReader());
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configurer.customCodecs().register(new CloudEventHttpMessageWriter());
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}
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}
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```
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The same feature in Spring MVC is provided by the `CloudEventHttpMessageConverter`.
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The `/foos` endpoint does the same thing. It doesn't use the `CloudEvent` data type directly, but instead models the request and response body as a `Foo` (POJO type):
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```java
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@PostMapping("/foos")
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public ResponseEntity<Foo> echo(@RequestBody Foo foo, @RequestHeader HttpHeaders headers) {
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...
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}
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```
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Note that this endpoint only accepts "binary" format cloud events (context in HTTP headers like in the first example above). It translates the `HttpHeaders` to `CloudEventContext` using a utility class provided by `cloudevents-spring`.

‎examples/spring-function/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<parent>
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<artifactId>cloudevents-examples</artifactId>
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<groupId>io.cloudevents</groupId>
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<version>2.1.0-SNAPSHOT</version>
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</parent>
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<modelVersion>4.0.0</modelVersion>
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<artifactId>cloudevents-spring-function-example</artifactId>
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<properties>
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<spring-boot.version>2.4.3</spring-boot.version>
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</properties>
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<dependencyManagement>
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-dependencies</artifactId>
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<version>${spring-boot.version}</version>
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<type>pom</type>
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<scope>import</scope>
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</dependency>
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</dependencies>
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</dependencyManagement>
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<dependencies>
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<dependency>
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<groupId>org.springframework.cloud</groupId>
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<artifactId>spring-cloud-function-web</artifactId>
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<version>3.1.1</version>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-webflux</artifactId>
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</dependency>
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<dependency>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-spring</artifactId>
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<version>${project.version}</version>
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</dependency>
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<dependency>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-http-basic</artifactId>
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<version>${project.version}</version>
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</dependency>
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<dependency>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-json-jackson</artifactId>
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<version>${project.version}</version>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-test</artifactId>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>
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<plugins>
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<plugin>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-maven-plugin</artifactId>
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<version>${spring-boot.version}</version>
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</plugin>
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</plugins>
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</build>
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</project>

‎examples/spring-function/src/main/java/io/cloudevents/examples/spring/DemoApplication.java

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package io.cloudevents.examples.spring;
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import java.net.URI;
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import java.util.UUID;
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import java.util.function.Function;
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import io.cloudevents.CloudEvent;
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import io.cloudevents.core.builder.CloudEventBuilder;
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import io.cloudevents.spring.messaging.CloudEventMessageConverter;
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import io.cloudevents.spring.webflux.CloudEventHttpMessageReader;
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import io.cloudevents.spring.webflux.CloudEventHttpMessageWriter;
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import org.springframework.boot.SpringApplication;
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import org.springframework.boot.autoconfigure.SpringBootApplication;
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import org.springframework.boot.web.codec.CodecCustomizer;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.http.codec.CodecConfigurer;
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import org.springframework.web.bind.annotation.RestController;
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@SpringBootApplication
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@RestController
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public class DemoApplication {
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public static void main(String[] args) throws Exception {
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SpringApplication.run(DemoApplication.class, args);
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}
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@Bean
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public Function<CloudEvent, CloudEvent> events() {
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return event -> CloudEventBuilder.from(event)
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.withId(UUID.randomUUID().toString())
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.withSource(URI.create("https://spring.io/foos"))
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.withType("io.spring.event.Foo")
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.withData(event.getData().toBytes())
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.build();
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}
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/**
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* Configure a MessageConverter for Spring Cloud Function to pick up and use to
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* convert to and from CloudEvent and Message.
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*/
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@Configuration
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public static class CloudEventMessageConverterConfiguration {
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@Bean
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public CloudEventMessageConverter cloudEventMessageConverter() {
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return new CloudEventMessageConverter();
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}
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}
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/**
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* Configure an HTTP reader and writer so that we can process CloudEvents over
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* HTTP via Spring Webflux.
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*/
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@Configuration
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public static class CloudEventHandlerConfiguration implements CodecCustomizer {
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@Override
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public void customize(CodecConfigurer configurer) {
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configurer.customCodecs().register(new CloudEventHttpMessageReader());
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configurer.customCodecs().register(new CloudEventHttpMessageWriter());
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}
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}
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}

‎examples/spring-function/src/main/java/io/cloudevents/examples/spring/Foo.java

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/*
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* Copyright 2019-2019 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package io.cloudevents.examples.spring;
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class Foo {
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private String value;
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public Foo() {
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}
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public Foo(String value) {
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this.value = value;
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}
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public String getValue() {
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return this.value;
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}
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public void setValue(String value) {
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this.value = value;
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}
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@Override
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public String toString() {
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return "Foo [value=" + this.value + "]";
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}
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}

‎examples/spring-function/src/test/java/io/cloudevents/examples/spring/DemoApplicationTests.java

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package io.cloudevents.examples.spring;
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import java.net.URI;
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import org.junit.jupiter.api.Test;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.boot.test.context.SpringBootTest;
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import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
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import org.springframework.boot.test.web.client.TestRestTemplate;
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import org.springframework.boot.web.server.LocalServerPort;
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import org.springframework.http.HttpHeaders;
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import org.springframework.http.HttpStatus;
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import org.springframework.http.MediaType;
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import org.springframework.http.RequestEntity;
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import org.springframework.http.ResponseEntity;
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import static org.assertj.core.api.Assertions.assertThat;
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@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
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public class DemoApplicationTests {
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@Autowired
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private TestRestTemplate rest;
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@LocalServerPort
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private int port;
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@Test
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void echoWithCorrectHeaders() {
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ResponseEntity<String> response = rest
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.exchange(RequestEntity.post(URI.create("http://localhost:" + port + "/foos")) //
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.header("ce-id", "12345") //
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.header("ce-specversion", "1.0") //
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.header("ce-type", "io.spring.event") //
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.header("ce-source", "https://spring.io/events") //
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.contentType(MediaType.APPLICATION_JSON) //
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.body("{\"value\":\"Dave\"}"), String.class);
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assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
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assertThat(response.getBody()).isEqualTo("{\"value\":\"Dave\"}");
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HttpHeaders headers = response.getHeaders();
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assertThat(headers).containsKey("ce-id");
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assertThat(headers).containsKey("ce-source");
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assertThat(headers).containsKey("ce-type");
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assertThat(headers.getFirst("ce-id")).isNotEqualTo("12345");
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assertThat(headers.getFirst("ce-type")).isEqualTo("io.spring.event.Foo");
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assertThat(headers.getFirst("ce-source")).isEqualTo("https://spring.io/foos");
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}
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@Test
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void structuredRequestResponseEvents() {
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ResponseEntity<String> response = rest
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.exchange(RequestEntity.post(URI.create("http://localhost:" + port + "/event")) //
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.contentType(new MediaType("application", "cloudevents+json")) //
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.body("{" //
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+ "\"id\":\"12345\"," //
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+ "\"specversion\":\"1.0\"," //
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+ "\"type\":\"io.spring.event\"," //
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+ "\"source\":\"https://spring.io/events\"," //
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+ "\"data\":{\"value\":\"Dave\"}}"),
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String.class);
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assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
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assertThat(response.getBody()).isEqualTo("{\"value\":\"Dave\"}");
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HttpHeaders headers = response.getHeaders();
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assertThat(headers).containsKey("ce-id");
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assertThat(headers).containsKey("ce-source");
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assertThat(headers).containsKey("ce-type");
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assertThat(headers.getFirst("ce-id")).isNotEqualTo("12345");
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assertThat(headers.getFirst("ce-type")).isEqualTo("io.spring.event.Foo");
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assertThat(headers.getFirst("ce-source")).isEqualTo("https://spring.io/foos");
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}
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@Test
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void requestResponseEvents() {
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ResponseEntity<String> response = rest
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.exchange(RequestEntity.post(URI.create("http://localhost:" + port + "/event")) //
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.header("ce-id", "12345") //
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.header("ce-specversion", "1.0") //
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.header("ce-type", "io.spring.event") //
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.header("ce-source", "https://spring.io/events") //
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.contentType(MediaType.APPLICATION_JSON) //
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.body("{\"value\":\"Dave\"}"), String.class);
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assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
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assertThat(response.getBody()).isEqualTo("{\"value\":\"Dave\"}");
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HttpHeaders headers = response.getHeaders();
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assertThat(headers).containsKey("ce-id");
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assertThat(headers).containsKey("ce-source");
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assertThat(headers).containsKey("ce-type");
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assertThat(headers.getFirst("ce-id")).isNotEqualTo("12345");
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assertThat(headers.getFirst("ce-type")).isEqualTo("io.spring.event.Foo");
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assertThat(headers.getFirst("ce-source")).isEqualTo("https://spring.io/foos");
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}
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}

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