SDA Commons Server CloudEvents

Provides some glue code to work with CloudEvents on top of Apache Kafka.

⚠️ Experimental ⚠

The bundle is still in an early state. APIs are open for change.

Introduction

CloudEvents is a general standard that can be used in combination with your favourite eventing tool like ActiveMQ or Kafka. The CloudEvents specification defines concrete bindings to define how the general specification should be applied to a specific tool. This module brings you the Kafka protocol binding .

The following code examples will show you how you can use this bundle in combination with our Kafka bundle.

Producing CloudEvents

CloudEvents gives you two possibilities to encode your CloudEvents:

• BINARY content mode The binary content mode seperated event metadata and data; data will be put into the value of your Kafka record; metadata will be put into the headers
• STRUCTURED content mode The structured content mode keeps event metadata and data together in the payload, allowing simple forwarding of the same event across multiple routing hops, and across multiple protocols.

We suggest using the structured content mode. It is very explicit and easy to use because you get the whole event as a simple POJO class.

For simplicity, we recommend extending our base class:

import org.sdase.commons.server.cloudevents.CloudEventV1;

public class PartnerCreatedEvent extends CloudEventV1<PartnerCreatedEvent.PartnerCreated> {

  public static class PartnerCreated {
    private String id;

    public String getId() {
      return id;
    }

    public PartnerCreated setId(String id) {
      this.id = id;
      return this;
    }
  }
}

You can simply use a standard KafkaJsonSerializer to publish the event.

Take a look at the source code of the examples in directory src/test/java/.../app of the module sda-commons-server-cloud-events to get some ideas how you can work with CloudEvents.

Consuming CloudEvents

You can easily consume the CloudEvent using a standard KafkaJsonDeserializer.