# event-processing-sample

**Repository Path**: mirrors_codecentric/event-processing-sample

## Basic Information

- **Project Name**: event-processing-sample
- **Description**: Examples for the article: Event-driven Microservices & Event Processing
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-08
- **Last Updated**: 2025-09-27

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Event Processing in a lightweight context

## Purpose & Scope

The project outlines the usage of event processing within an event-driven architecture (EDA) in a lightweight way. 

**Note:**

This project contains the examples of the article: [Event-driven Microservices & Event Processing](https://blog.codecentric.de/2016/08/event-driven-microservices-event-processing/).
The code is just for demonstration purposes – it is not production ready. The nomenclature does not distinguish between the terms complex event processing (CEP) and event stream processing (ESP). ESP is rather treated as a subset of CEP.

## Application

The event channel of the EDA is realized by the message-broker [Apache Kafka](http://kafka.apache.org). The CEP part is based on the event processing engine and event processing language from [Esper](http://www.espertech.com/esper/about_esper_java.php). The Esper component of the EIP framework [Apache Camel](http://camel.apache.org/esper.html) connects the event channel to the event processing engine. Additionally the [Elastic stack](https://www.elastic.co) is used to visualize some results/statistics of events that occurred.

The example can be started as a [spring boot application](http://projects.spring.io/spring-boot/).
The class `CepExampleApplication.java` is the boot-class of the application.

**Packages**
* `de.codecentric.channel` – contains the event-channel integration
* `de.codecentric.events` – contains a few example events and a simplified event-structure to keep events standardized in the system. However Esper has it's own event-structure internally
* `de.codecentric.processing` – contains routes to create faked shopping-cart events and CEP examples which do complex event processing on the cart events

## Build
mvn install

## Deploy
A few hints to setup a testable environment and how to test the application are summarized in the [environment-notes](environment-notes.md).
	
## Test the application
Start the application in your IDE or via command-line as an Spring Boot application. The application produces faked shopping carts [CreateCartsRoute](src/main/java/de/codecentric/processing/CreateCartsRoute.java) which are published to the event-channel. Furthermore the application reads from the event-channel, evaluates the incomming events and occasionally produces derived events. Consult the source code of [CepExamplesRoute](src/main/java/de/codecentric/processing/CepExampleRoutes.java) for details.