Add Cloud Events support to Spring Integration

build.gradle

@@ -53,6 +53,7 @@ ext {
     avroVersion = '1.12.1'
     awaitilityVersion = '4.3.0'
     camelVersion = '4.15.0'
+    cloudEventsVersion = '4.0.1'
     commonsDbcp2Version = '2.13.0'
     commonsIoVersion = '2.20.0'
     commonsNetVersion = '3.12.0'
@@ -486,6 +487,21 @@ project('spring-integration-cassandra') {
     }
 }
 
+project('spring-integration-cloudevents') {
+    description = 'Spring Integration CloudEvents Support'
+
+    dependencies {
+        api "io.cloudevents:cloudevents-core:$cloudEventsVersion"
+        testImplementation "io.cloudevents:cloudevents-json-jackson:$cloudEventsVersion"
+
+        testImplementation("io.cloudevents:cloudevents-avro-compact:$cloudEventsVersion") {
+            exclude group: 'org.apache.avro', module: 'avro'
+        }
+        testImplementation "org.apache.avro:avro:$avroVersion"
+        testImplementation "io.cloudevents:cloudevents-xml:$cloudEventsVersion"
+    }
+}
+
 project('spring-integration-core') {
     description = 'Spring Integration Core'
 

spring-integration-cloudevents/src/main/java/org/springframework/integration/cloudevents/package-info.java

@@ -0,0 +1,3 @@
+
+@org.jspecify.annotations.NullMarked
+package org.springframework.integration.cloudevents;

spring-integration-cloudevents/src/main/java/org/springframework/integration/cloudevents/transformer/CloudEventMessageConverter.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2025-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.cloudevents.transformer;
+
+import java.util.Objects;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.CloudEventUtils;
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.integration.transformer.MessageTransformationException;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.converter.MessageConverter;
+
+/**
+ * Convert Spring Integration {@link Message}s to CloudEvents.
+ *
+ * @author Glenn Renfro
+ *
+ * @since 7.0
+ */
+class CloudEventMessageConverter implements MessageConverter {
+
+	private final String cloudEventPrefix;
+
+	private final String specVersionKey;
+
+	private final String dataContentTypeKey;
+
+	/**
+	 * Construct a CloudEventMessageConverter with the specified configuration.
+	 * @param cloudEventPrefix the prefix for CloudEvent headers in binary content mode
+	 * @param specVersionKey the header name for the specification version
+	 * @param dataContentTypeKey the header name for the data content type
+	 */
+	CloudEventMessageConverter(String cloudEventPrefix, String specVersionKey, String dataContentTypeKey) {
+		this.cloudEventPrefix = cloudEventPrefix;
+		this.specVersionKey = specVersionKey;
+		this.dataContentTypeKey = dataContentTypeKey;
+	}
+
+	/**
+	 * This converter only supports CloudEvent to Message conversion.
+	 * @throws UnsupportedOperationException always, as this operation is not supported
+	 */
+	@Override
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
+		throw new UnsupportedOperationException("CloudEventMessageConverter does not support fromMessage method");
+	}
+
+	@Override
+	public Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
+		if (payload instanceof CloudEvent event) {
+			return CloudEventUtils.toReader(event).read(new MessageBuilderMessageWriter(this.cloudEventPrefix,
+					this.specVersionKey, this.dataContentTypeKey, Objects.requireNonNull(headers)));
+		}
+		throw new MessageTransformationException("Unsupported payload type.  Should be CloudEvent but was: " +
+				payload.getClass());
+	}
+
+}

spring-integration-cloudevents/src/main/java/org/springframework/integration/cloudevents/transformer/MessageBuilderMessageWriter.java

@@ -0,0 +1,137 @@
+/*
+ * Copyright 2025-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.cloudevents.transformer;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import io.cloudevents.CloudEventData;
+import io.cloudevents.SpecVersion;
+import io.cloudevents.core.format.EventFormat;
+import io.cloudevents.core.message.MessageWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
+import io.cloudevents.rw.CloudEventRWException;
+import io.cloudevents.rw.CloudEventWriter;
+
+import org.springframework.integration.support.MessageBuilder;
+import org.springframework.messaging.Message;
+
+/**
+ * Adapt CloudEvents to Spring Integration {@link Message}s using the CloudEvents SDK
+ * {@link MessageWriter} abstraction.
+ * Write CloudEvent attributes as message headers with a configurable prefix for
+ * binary content mode serialization. Used internally by {@link CloudEventMessageConverter}
+ * to convert CloudEvent objects into Spring Integration messages.
+ *
+ * @author Glenn Renfro
+ *
+ * @since 7.0
+ *
+ * @see CloudEventMessageConverter
+ */
+class MessageBuilderMessageWriter
+		implements CloudEventWriter<Message<byte[]>>, MessageWriter<MessageBuilderMessageWriter, Message<byte[]>> {
+
+	private final String cloudEventPrefix;
+
+	private final String specVersionKey;
+
+	private final String dataContentTypeKey;
+
+	private final Map<String, Object> headers = new HashMap<>();
+
+	/**
+	 * Construct a MessageBuilderMessageWriter with the specified configuration.
+	 * @param cloudEventPrefix the prefix to prepend to CloudEvent attribute names in message headers
+	 * @param specVersionKey the header name for the CloudEvent specification version
+	 * @param dataContentTypeKey the header name for the data content type
+	 * @param headers the base message headers to include in the output message
+	 */
+	MessageBuilderMessageWriter(String cloudEventPrefix, String specVersionKey, String dataContentTypeKey, Map<String, Object> headers) {
+		this.headers.putAll(headers);
+		this.cloudEventPrefix = cloudEventPrefix;
+		this.specVersionKey = specVersionKey;
+		this.dataContentTypeKey = dataContentTypeKey;
+	}
+
+	/**
+	 * Set the event in structured content mode.
+	 * Create a message with the serialized CloudEvent as the payload and set the
+	 * data content type header to the format's serialized content type.
+	 * @param format the event format used to serialize the CloudEvent
+	 * @param value the serialized CloudEvent bytes
+	 * @return the Spring Integration message containing the serialized CloudEvent
+	 * @throws CloudEventRWException if an error occurs during message creation
+	 */
+	@Override
+	public Message<byte[]> setEvent(EventFormat format, byte[] value) throws CloudEventRWException {
+		this.headers.put(this.dataContentTypeKey, format.serializedContentType());
+		return MessageBuilder.withPayload(value).copyHeaders(this.headers).build();
+	}
+
+	/**
+	 * Complete the message creation with CloudEvent data.
+	 * Create a message with the CloudEvent data as the payload. CloudEvent attributes
+	 * are already set as headers via {@link #withContextAttribute(String, String)}.
+	 * @param value the CloudEvent data to use as the message payload
+	 * @return the Spring Integration message with CloudEvent data and attributes
+	 * @throws CloudEventRWException if an error occurs during message creation
+	 */
+	@Override
+	public Message<byte[]> end(CloudEventData value) throws CloudEventRWException {
+		return MessageBuilder.withPayload(value.toBytes()).copyHeaders(this.headers).build();
+	}
+
+	/**
+	 * Complete the message creation without CloudEvent data.
+	 * Create a message with an empty payload when the CloudEvent contains no data.
+	 * CloudEvent attributes are set as headers via {@link #withContextAttribute(String, String)}.
+	 * @return the Spring Integration message with an empty payload and CloudEvent attributes as headers
+	 */
+	@Override
+	public Message<byte[]> end() {
+		return MessageBuilder.withPayload(new byte[0]).copyHeaders(this.headers).build();
+	}
+
+	/**
+	 * Add a CloudEvent context attribute to the message headers.
+	 * Map the CloudEvent attribute to a message header by prepending the configured prefix
+	 * to the attribute name (e.g., "id" becomes "ce-id" with default prefix).
+	 * @param name the CloudEvent attribute name
+	 * @param value the CloudEvent attribute value
+	 * @return this writer for method chaining
+	 * @throws CloudEventRWException if an error occurs while setting the attribute
+	 */
+	@Override
+	public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
+		this.headers.put(this.cloudEventPrefix + name, value);
+		return this;
+	}
+
+	/**
+	 * Initialize the writer with the CloudEvent specification version.
+	 * Set the specification version as a message header using the configured version key.
+	 * @param version the CloudEvent specification version
+	 * @return this writer for method chaining
+	 */
+	@Override
+	public MessageBuilderMessageWriter create(SpecVersion version) {
+		this.headers.put(this.specVersionKey, version.toString());
+		return this;
+	}
+
+}