GH-??? - Initial prototype to automatically externalize events.

We now provide an SPI to plug custom implementations to externalize events that match an EventExternalizationConfiguration (EEC) into messaging technology. The first implementation of that API is based on Spring Kafka to consume a KafkaTemplate and translate events into Kafka messages.

spring-modulith-api/src/main/java/org/springframework/modulith/Externalized.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2023 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.modulith;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.core.annotation.AliasFor;
+
+/**
+ * Marks domain events as to be externalized.
+ *
+ * @author Oliver Drotbohm
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE })
+public @interface Externalized {
+
+	/**
+	 * The logical target name. Will default to a strategy defined by configuration if empty.
+	 *
+	 * @return
+	 * @see #target()
+	 */
+	@AliasFor("target")
+	String value() default "";
+
+	/**
+	 * The logical target name. Will default to a strategy defined by configuration if empty.
+	 *
+	 * @return
+	 * @see #value()
+	 */
+	@AliasFor("value")
+	String target() default "";
+}

spring-modulith-events/pom.xml

@@ -14,11 +14,13 @@
 	<name>Spring Modulith - Events</name>
 
 	<modules>
+		<module>spring-modulith-events-api</module>
 		<module>spring-modulith-events-core</module>
 		<module>spring-modulith-events-jpa</module>
 		<module>spring-modulith-events-jdbc</module>
 		<module>spring-modulith-events-mongodb</module>
 		<module>spring-modulith-events-jackson</module>
+		<module>spring-modulith-events-kafka</module>
 	</modules>
 
 	<profiles>

spring-modulith-events/spring-modulith-events-api/pom.xml

@@ -0,0 +1,35 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>org.springframework.modulith</groupId>
+		<artifactId>spring-modulith-events</artifactId>
+		<version>1.1.0-SNAPSHOT</version>
+	</parent>
+
+	<name>Spring Modulith - Events - API</name>
+	<artifactId>spring-modulith-events-api</artifactId>
+
+	<properties>
+		<module.name>org.springframework.modulith.events.api</module.name>
+	</properties>
+
+	<dependencies>
+
+		<dependency>
+			<groupId>org.springframework.modulith</groupId>
+			<artifactId>spring-modulith-api</artifactId>
+			<version>${project.version}</version>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-core</artifactId>
+		</dependency>
+
+	</dependencies>
+
+</project>