Event4J

Event4J is a library designed to simplify message publishing to Kafka and REST endpoints with built-in support for error handling and retries. This library uses custom annotations to mark methods for Kafka and REST publishing and provides an annotation processor to handle the message publishing logic.

Getting Started

Prerequisites

• Java 17
• Maven 3.6+
• A running Kafka instance (for Kafka publishing)
• A PostgreSQL database (for error logging with REST publishing)

Installation

Add the following dependency to your Maven pom.xml file:

<dependency>
    <groupId>org.event4j</groupId>
    <artifactId>event4j</artifactId>
    <version>1.0.0</version>
</dependency>

Configuration

Add the following properties to your application.properties file:

# Kafka Configuration
event4j.kafka.enable=false
event4j.kafka.topic=topic
event4j.kafka.retry-topic=retry-topic
event4j.kafka.error-topic=error-topic
event4j.kafka.retry-count=4
event4j.kafka.hosts=localhost:9092
event4j.kafka.retry-group-id=my-consumer-group

# REST Configuration
event4j.rest.enable=true
event4j.rest.url=http://localhost:8081/3
event4j.rest.error-table=error_table
event4j.rest.retry-count=4
event4j.rest.connection-url=jdbc:postgresql://localhost:5432/mydb
event4j.rest.connection-user=myuser
event4j.rest.connection-password=mypassword

Usage

Create a Spring Boot application and import the Event4JAnnotationProcessor class:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Import;

@SpringBootApplication
@Import(Event4JAnnotationProcessor.class)
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

Create a REST controller and use the @KafkaPublisher and @RestPublisher annotations to mark methods for message publishing:

package com.example.demo;

import org.event4j.kafka.KafkaPublisher;
import org.event4j.rest.RestPublisher;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ConfigController {

    @PostMapping("1")
    @KafkaPublisher
    public Person postConf1(@RequestBody Person person) {
        return person;
    }

    @PostMapping("2")
    @RestPublisher
    public Person postConf2(@RequestBody Person person) {
        return person;
    }
}

License

This project is licensed under the MIT License - see the LICENSE file for details.