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Dave Syerolegz
Dave Syer
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HTTP converters for CloudEvent in Spring (#312)
Supports MVC and WebFlux (blocking and non-blocking) HTTP. User can work with `CloudEvent` as a `POJO` type and inject it into `@ReqestMapping` methods. Signed-off-by: Dave Syer <[email protected]> Co-authored-by: Oleg Zhurakousky <[email protected]>
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‎pom.xml

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<module>http/vertx</module>
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<module>http/restful-ws</module>
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<module>kafka</module>
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<module>spring</module>
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</modules>
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<properties>

‎spring/README.md

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## Spring Support
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### Introduction
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This module provides classes and interfaces that can be used by [Spring frameworks](https://spring.io/) and integrations to assist with Cloud Event processing.
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Given that Spring defines [Message](https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/messaging/Message.html) abstraction,
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which perfectly maps to the structure defined by Cloud Events specification, one may say Cloud Events are already supported by any Spring framework that
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relies on `Message`. So this modules provides several utilities and strategies to simplify working with Cloud Events in the context of Spring
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frameworks and integrations (see individual component's javadocs for more details).
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Please see individual samples in `examples/spring` directory of this SDK for more details.

‎spring/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<!--
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~ Copyright 2018-Present The CloudEvents Authors
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~ <p>
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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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~ <p>
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~ http://www.apache.org/licenses/LICENSE-2.0
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~ <p>
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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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-->
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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/maven-v4_0_0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-parent</artifactId>
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<version>2.0.0-SNAPSHOT</version>
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</parent>
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<artifactId>cloudevents-spring</artifactId>
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<name>CloudEvents - support for Spring</name>
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<packaging>jar</packaging>
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<properties>
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<module-name>io.cloudevents.spring</module-name>
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<spring-boot.version>2.4.0</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>${spring-boot.version}</version>
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<type>pom</type>
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<scope>import</scope>
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</dependency>
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</dependencies>
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</dependencyManagement>
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<dependencies>
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<dependency>
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<groupId>org.springframework</groupId>
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<artifactId>spring-webmvc</artifactId>
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<optional>true</optional>
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</dependency>
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<dependency>
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<groupId>org.springframework</groupId>
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<artifactId>spring-webflux</artifactId>
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<optional>true</optional>
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</dependency>
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<dependency>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-core</artifactId>
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<version>${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>${project.version}</version>
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<!-- This will be optional too if we want to support messaging -->
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</dependency>
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<dependency>
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<groupId>org.apache.tomcat.embed</groupId>
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<artifactId>tomcat-embed-core</artifactId>
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<optional>true</optional>
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</dependency>
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<!-- Test deps -->
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<dependency>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-json-jackson</artifactId>
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<version>${project.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>io.cloudevents</groupId>
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<artifactId>cloudevents-core</artifactId>
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<classifier>tests</classifier>
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<type>test-jar</type>
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<version>${project.version}</version>
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<scope>test</scope>
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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-web</artifactId>
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<scope>test</scope>
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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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</project>
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‎spring/src/main/java/io/cloudevents/spring/http/CloudEventHttpUtils.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.spring.http;
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import java.util.function.Consumer;
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import java.util.function.Supplier;
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import io.cloudevents.CloudEvent;
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import io.cloudevents.CloudEventContext;
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import io.cloudevents.core.CloudEventUtils;
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import io.cloudevents.core.builder.CloudEventBuilder;
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import io.cloudevents.core.message.MessageReader;
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import io.cloudevents.http.HttpMessageFactory;
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import io.cloudevents.http.impl.HttpMessageWriter;
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import org.springframework.http.HttpHeaders;
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import org.springframework.http.ResponseEntity;
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/**
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* Miscellaneous utility methods to assist with Cloud Events in the context of Spring Web
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* frameworks. Primarily intended for the internal use within Spring-based frameworks or
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* integrations.
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*
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* @author Dave Syer
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* @since 2.0
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*/
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public class CloudEventHttpUtils {
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private CloudEventHttpUtils() {
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}
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/**
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* Create a {@link MessageReader} to assist in conversion of an HTTP request to a
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* {@link CloudEvent}.
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* @param headers the HTTP request headers
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* @param body the HTTP request body as a byte array
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* @return a {@link MessageReader} representing the {@link CloudEvent}
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*/
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public static MessageReader toReader(HttpHeaders headers, Supplier<byte[]> body) {
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return HttpMessageFactory.createReaderFromMultimap(headers, body.get());
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}
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/**
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* Create an {@link HttpMessageWriter} that can hand off a {@link CloudEvent} to an
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* HTTP response. Mainly useful in a blocking (not async) setting because the response
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* body has to be consumed directly.
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* @param headers the response headers (will be mutated)
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* @param sendBody a consumer for the response body that puts the bytes on the wire
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*/
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public static HttpMessageWriter toWriter(HttpHeaders headers, Consumer<byte[]> sendBody) {
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return HttpMessageFactory.createWriter(headers::set, sendBody);
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}
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/**
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* Helper method for extracting {@link HttpHeaders} from a {@link CloudEvent}. Can,
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* for instance, be used in a <code>&#64;RequestMapping</code> to return a
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* {@link ResponseEntity} that has headers copied from a {@link CloudEvent}.
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* @param event the input {@link CloudEvent}
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* @return the response headers represented by the event
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*/
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public static HttpHeaders toHttp(CloudEventContext event) {
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HttpHeaders headers = new HttpHeaders();
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CloudEventUtils.toReader(CloudEventBuilder.fromContext(event).build()).read(toWriter(headers, bytes -> {
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}));
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return headers;
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}
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/**
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* Helper method for converting {@link HttpHeaders} to a {@link CloudEvent}. The input
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* headers must represent a valid event in "binary" form, i.e. it must have headers
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* "ce-id", "ce-specversion" etc.
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* @param headers the input request headers
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* @return a {@link CloudEventBuilder} that can be used to create a new
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* {@link CloudEvent}
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*
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*/
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public static CloudEventBuilder fromHttp(HttpHeaders headers) {
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return CloudEventBuilder
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.fromContext(CloudEventUtils.toEvent(CloudEventHttpUtils.toReader(headers, () -> null)));
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}
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}

‎spring/src/main/java/io/cloudevents/spring/http/CloudEventsHeaders.java

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/*
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* Copyright 2018-Present The CloudEvents Authors
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* <p>
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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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* <p>
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* http://www.apache.org/licenses/LICENSE-2.0
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* <p>
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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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*/
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package io.cloudevents.spring.http;
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import java.util.Map;
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import io.cloudevents.core.message.impl.MessageUtils;
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import org.springframework.http.HttpHeaders;
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public class CloudEventsHeaders {
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public static final String CE_PREFIX = "ce-";
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public static final Map<String, String> ATTRIBUTES_TO_HEADERS = MessageUtils
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.generateAttributesToHeadersMapping(v -> {
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if (v.equals("datacontenttype")) {
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return HttpHeaders.CONTENT_TYPE;
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}
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return CE_PREFIX + v;
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});
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public static final String SPEC_VERSION = ATTRIBUTES_TO_HEADERS.get("specversion");
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}

‎spring/src/main/java/io/cloudevents/spring/http/package-info.java

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/**
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* Provides classes related to working with Cloud Events within the context of Spring and
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* HTTP.
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*/
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package io.cloudevents.spring.http;

‎spring/src/main/java/io/cloudevents/spring/mvc/CloudEventHttpMessageConverter.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.spring.mvc;
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import java.io.IOException;
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import io.cloudevents.CloudEvent;
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import io.cloudevents.core.CloudEventUtils;
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import io.cloudevents.spring.http.CloudEventHttpUtils;
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import org.springframework.http.HttpInputMessage;
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import org.springframework.http.HttpOutputMessage;
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import org.springframework.http.MediaType;
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import org.springframework.http.converter.AbstractHttpMessageConverter;
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import org.springframework.http.converter.HttpMessageConverter;
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import org.springframework.http.converter.HttpMessageNotReadableException;
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import org.springframework.http.converter.HttpMessageNotWritableException;
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import org.springframework.util.StreamUtils;
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/**
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* An {@link HttpMessageConverter} for {@link CloudEvent CloudEvents}. Supports the use of
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* {@link CloudEvent} in a <code>&#64;RequestMapping</code> as either a method parameter
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* or a return value.
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*
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* @author Dave Syer
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*
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*/
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public class CloudEventHttpMessageConverter extends AbstractHttpMessageConverter<CloudEvent> {
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public CloudEventHttpMessageConverter() {
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super(MediaType.APPLICATION_OCTET_STREAM, MediaType.ALL);
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}
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@Override
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protected boolean supports(Class<?> clazz) {
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return CloudEvent.class.isAssignableFrom(clazz);
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}
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@Override
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protected CloudEvent readInternal(Class<? extends CloudEvent> clazz, HttpInputMessage inputMessage)
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throws IOException, HttpMessageNotReadableException {
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byte[] body = StreamUtils.copyToByteArray(inputMessage.getBody());
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return CloudEventHttpUtils.toReader(inputMessage.getHeaders(), () -> body).toEvent();
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}
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@Override
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protected void writeInternal(CloudEvent event, HttpOutputMessage outputMessage)
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throws IOException, HttpMessageNotWritableException {
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CloudEventUtils.toReader(event)
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.read(CloudEventHttpUtils.toWriter(outputMessage.getHeaders(), body -> copy(body, outputMessage)));
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}
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private void copy(byte[] body, HttpOutputMessage outputMessage) {
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try {
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StreamUtils.copy(body, outputMessage.getBody());
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}
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catch (IOException e) {
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throw new IllegalStateException(e);
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}
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}
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}

‎spring/src/main/java/io/cloudevents/spring/mvc/package-info.java

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/**
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* Provides classes related to working with Cloud Events within the context of Spring MVC.
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*/
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package io.cloudevents.spring.mvc;

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