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feat: implement CloudEventMessageConverter for spring-amqp
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‎spring/pom.xml‎

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<artifactId>spring-messaging</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.amqp</groupId>
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<artifactId>spring-rabbit</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>

‎spring/src/main/java/io/cloudevents/spring/amqp/CloudEventMessageConverter.java‎

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/*
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* Copyright 2020-Present The CloudEvents 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.amqp;
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import io.cloudevents.CloudEvent;
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import io.cloudevents.CloudEventContext;
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import io.cloudevents.SpecVersion;
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import io.cloudevents.core.CloudEventUtils;
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import io.cloudevents.core.format.EventFormat;
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import io.cloudevents.core.message.MessageReader;
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import io.cloudevents.core.message.impl.GenericStructuredMessageReader;
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import io.cloudevents.core.message.impl.MessageUtils;
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import org.springframework.amqp.core.Message;
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import org.springframework.amqp.core.MessageProperties;
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import org.springframework.amqp.support.converter.MessageConverter;
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/**
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* A {@link MessageConverter} that can translate to and from a {@link Message} and a {@link CloudEvent}.
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* The {@link CloudEventContext} is canonicalized, with key names given a {@code ce-} prefix in the
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* {@link MessageProperties}.
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*
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* @author Lars Michele
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* @see io.cloudevents.spring.messaging.CloudEventMessageConverter used as stencil for the implementation
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*/
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public class CloudEventMessageConverter implements MessageConverter {
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@Override
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public CloudEvent fromMessage(Message message) {
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return createMessageReader(message).toEvent();
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}
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@Override
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public Message toMessage(Object object, MessageProperties messageProperties) {
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if (object instanceof CloudEvent) {
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CloudEvent event = (CloudEvent) object;
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return CloudEventUtils.toReader(event).read(new MessageBuilderMessageWriter(messageProperties));
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}
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return null;
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}
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private MessageReader createMessageReader(Message message) {
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return MessageUtils.parseStructuredOrBinaryMessage(
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() -> contentType(message.getMessageProperties()),
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format -> structuredMessageReader(message, format),
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() -> version(message.getMessageProperties()),
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version -> binaryMessageReader(message, version)
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);
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}
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private String version(MessageProperties properties) {
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Object header = properties.getHeader(CloudEventsHeaders.SPEC_VERSION);
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return header == null ? null : header.toString();
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}
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private MessageReader binaryMessageReader(Message message, SpecVersion version) {
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return new MessageBinaryMessageReader(version, message.getMessageProperties(), message.getBody());
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}
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private MessageReader structuredMessageReader(Message message, EventFormat format) {
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return new GenericStructuredMessageReader(format, message.getBody());
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}
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private String contentType(MessageProperties properties) {
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String contentType = properties.getContentType();
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if (contentType == null) {
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Object header = properties.getHeader(CloudEventsHeaders.CONTENT_TYPE);
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return header == null ? null : header.toString();
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}
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return contentType;
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}
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}

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

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/*
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* Copyright 2020-Present The CloudEvents 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.amqp;
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public class CloudEventsHeaders {
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/**
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* CloudEvent attributes MUST be prefixed with either "cloudEvents_" or "cloudEvents:" for use in the application-properties section.
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* @see <a href="https://github.com/cloudevents/spec/blob/main/cloudevents/bindings/amqp-protocol-binding.md#3131-amqp-application-property-names">
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* AMQP Protocol Binding for CloudEvents</a>
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* */
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public static final String CE_PREFIX = "cloudEvents_";
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public static final String SPEC_VERSION = CE_PREFIX + "specversion";
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public static final String CONTENT_TYPE = CE_PREFIX + "datacontenttype";
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}

‎spring/src/main/java/io/cloudevents/spring/amqp/MessageBinaryMessageReader.java‎

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/*
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* Copyright 2020-Present The CloudEvents 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.amqp;
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import static io.cloudevents.spring.amqp.CloudEventsHeaders.*;
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import static org.springframework.amqp.support.AmqpHeaders.CONTENT_TYPE;
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import java.util.Map;
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import java.util.function.BiConsumer;
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import io.cloudevents.SpecVersion;
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import io.cloudevents.core.data.BytesCloudEventData;
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import io.cloudevents.core.impl.StringUtils;
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import io.cloudevents.core.message.impl.BaseGenericBinaryMessageReaderImpl;
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import org.springframework.amqp.core.MessageProperties;
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/**
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* Utility for converting {@link MessageProperties} (message headers) to `CloudEvent` contexts.
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*
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* @author Lars Michele
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* @see io.cloudevents.spring.messaging.MessageBinaryMessageReader used as stencil for the implementation
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*/
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class MessageBinaryMessageReader extends BaseGenericBinaryMessageReaderImpl<String, Object> {
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private final Map<String, Object> headers;
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public MessageBinaryMessageReader(SpecVersion version, MessageProperties properties, byte[] payload) {
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super(version, payload == null ? null : BytesCloudEventData.wrap(payload));
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this.headers = properties.getHeaders();
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}
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@Override
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protected boolean isContentTypeHeader(String key) {
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return CONTENT_TYPE.equalsIgnoreCase(key);
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}
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@Override
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protected boolean isCloudEventsHeader(String key) {
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return key != null && key.length() > CE_PREFIX.length() && StringUtils.startsWithIgnoreCase(key, CE_PREFIX);
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}
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@Override
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protected String toCloudEventsKey(String key) {
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return key.substring(CE_PREFIX.length()).toLowerCase();
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}
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@Override
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protected void forEachHeader(BiConsumer<String, Object> fn) {
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headers.forEach(fn);
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}
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@Override
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protected String toCloudEventsValue(Object value) {
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return value.toString();
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}
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}

‎spring/src/main/java/io/cloudevents/spring/amqp/MessageBuilderMessageWriter.java‎

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/*
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* Copyright 2020-Present The CloudEvents 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.amqp;
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import static io.cloudevents.spring.amqp.CloudEventsHeaders.*;
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import java.util.HashMap;
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import java.util.Map;
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import io.cloudevents.CloudEventData;
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import io.cloudevents.SpecVersion;
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import io.cloudevents.core.format.EventFormat;
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import io.cloudevents.core.message.MessageWriter;
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import io.cloudevents.rw.CloudEventContextWriter;
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import io.cloudevents.rw.CloudEventRWException;
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import io.cloudevents.rw.CloudEventWriter;
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import org.springframework.amqp.core.Message;
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import org.springframework.amqp.core.MessageBuilder;
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import org.springframework.amqp.core.MessageProperties;
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/**
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* Internal utility class for copying <code>CloudEvent</code> context to {@link MessageProperties} (message
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* headers).
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*
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* @author Lars Michele
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* @see io.cloudevents.spring.messaging.MessageBuilderMessageWriter used as stencil for the implementation
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*/
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class MessageBuilderMessageWriter implements CloudEventWriter<Message>, MessageWriter<MessageBuilderMessageWriter, Message> {
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private final Map<String, Object> headers = new HashMap<>();
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public MessageBuilderMessageWriter(MessageProperties properties) {
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this.headers.putAll(properties.getHeaders());
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}
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@Override
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public Message setEvent(EventFormat format, byte[] value) throws CloudEventRWException {
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headers.put(CONTENT_TYPE, format.serializedContentType());
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return MessageBuilder.withBody(value).copyHeaders(headers).build();
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}
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@Override
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public Message end(CloudEventData value) throws CloudEventRWException {
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return MessageBuilder.withBody(value == null ? new byte[0] : value.toBytes()).copyHeaders(headers).build();
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}
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@Override
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public Message end() {
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return MessageBuilder.withBody(new byte[0]).copyHeaders(headers).build();
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}
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@Override
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public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
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headers.put(CE_PREFIX + name, value);
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return this;
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}
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@Override
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public MessageBuilderMessageWriter create(SpecVersion version) {
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headers.put(SPEC_VERSION, version.toString());
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return this;
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}
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}

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

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

‎spring/src/test/java/io/cloudevents/spring/amqp/CloudEventMessageConverterTests.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.amqp;
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import static org.assertj.core.api.Assertions.*;
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import java.net.URI;
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import java.nio.charset.StandardCharsets;
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import java.util.Map;
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import io.cloudevents.CloudEvent;
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import io.cloudevents.SpecVersion;
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import io.cloudevents.core.builder.CloudEventBuilder;
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import io.cloudevents.rw.CloudEventRWException;
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import org.junit.jupiter.api.Test;
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import org.springframework.amqp.core.Message;
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import org.springframework.amqp.core.MessageBuilder;
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import org.springframework.amqp.core.MessageProperties;
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/**
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* @author Lars Michele
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* @see io.cloudevents.spring.messaging.CloudEventMessageConverterTests used as stencil for the implementation
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*/
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class CloudEventMessageConverterTests {
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private static final String JSON = "{\"specversion\":\"1.0\"," //
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+ "\"id\":\"12345\"," //
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+ "\"source\":\"https://spring.io/events\"," //
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+ "\"type\":\"io.spring.event\"," //
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+ "\"datacontenttype\":\"application/json\"," //
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+ "\"data\":{\"value\":\"Dave\"}" //
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+ "}";
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private final CloudEventMessageConverter converter = new CloudEventMessageConverter();
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@Test
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void noSpecVersion() {
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Message message = MessageBuilder.withBody(new byte[0]).build();
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assertThatExceptionOfType(CloudEventRWException.class).isThrownBy(() -> {
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assertThat(converter.fromMessage(message)).isNull();
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});
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}
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@Test
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void notValidCloudEvent() {
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Message message = MessageBuilder.withBody(new byte[0]).setHeader("cloudEvents_specversion", "1.0").build();
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assertThatExceptionOfType(IllegalStateException.class).isThrownBy(() -> {
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assertThat(converter.fromMessage(message)).isNull();
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});
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}
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@Test
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void validCloudEvent() {
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Message message = MessageBuilder.withBody(new byte[0]).setHeader("cloudEvents_specversion", "1.0")
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.setHeader("cloudEvents_id", "12345").setHeader("cloudEvents_source", "https://spring.io/events")
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.setHeader("cloudEvents_type", "io.spring.event").build();
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CloudEvent event = converter.fromMessage(message);
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assertThat(event).isNotNull();
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assertThat(event.getSpecVersion()).isEqualTo(SpecVersion.V1);
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assertThat(event.getId()).isEqualTo("12345");
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assertThat(event.getSource()).isEqualTo(URI.create("https://spring.io/events"));
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assertThat(event.getType()).isEqualTo("io.spring.event");
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}
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@Test
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void structuredCloudEvent() {
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byte[] payload = JSON.getBytes(StandardCharsets.UTF_8);
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Message message = MessageBuilder.withBody(payload)
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.setContentType("application/cloudevents+json").build();
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CloudEvent event = converter.fromMessage(message);
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assertThat(event).isNotNull();
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assertThat(event.getSpecVersion()).isEqualTo(SpecVersion.V1);
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assertThat(event.getId()).isEqualTo("12345");
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assertThat(event.getSource()).isEqualTo(URI.create("https://spring.io/events"));
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assertThat(event.getType()).isEqualTo("io.spring.event");
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}
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@Test
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void fromCloudEvent() {
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CloudEvent attributes = CloudEventBuilder.v1().withId("A234-1234-1234")
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.withSource(URI.create("https://spring.io/")).withType("org.springframework")
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.withData("hello".getBytes(StandardCharsets.UTF_8)).build();
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Message message = converter.toMessage(attributes, new MessageProperties());
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Map<String, ?> headers = message.getMessageProperties().getHeaders();
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assertThat(headers.get("cloudEvents_id")).isEqualTo("A234-1234-1234");
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assertThat(headers.get("cloudEvents_specversion")).isEqualTo("1.0");
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assertThat(headers.get("cloudEvents_source")).isEqualTo("https://spring.io/");
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assertThat(headers.get("cloudEvents_type")).isEqualTo("org.springframework");
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assertThat("hello".getBytes(StandardCharsets.UTF_8)).isEqualTo(message.getBody());
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}
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@Test
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void fromNonCloudEvent() {
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assertThat(converter.toMessage(new byte[0], new MessageProperties())).isNull();
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}
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}

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