Discovering Kyma Eventing

In Kyma, you can send and receive events with the help of the Eventing module's processing back end. The module aims to make the process of subscribing and publishing events easier. It eliminates the need for users to carry out protocols or back-end operations themselves.

The Eventing module's process involves the following technologies:

• NATS (an open-source messaging system)
• NATS JetStream (provides the back end)
• HTTP post requests (delivered via POST-requests in terms of sending and receiving the events)
• Subscription custom resources (CRs) (abstracts the creation of different Kubernetes primitives)

Now, the question is, how does the actual process of Kyma Eventing look like? First of all, it is important to mention that the Eventing module is based on the Pub/Sub messaging pattern. This means that messages which are triggered in the Eventing module, are not sent to subscribers on a direct path but instead are published to a messaging back end, where they are processed, filtered, and then sent to subscribers.

Understanding this process is important when using SAP BTP, Kyma runtime to run extensions, which should be executed when a certain event is emitted. For example, the SAP SuccessFactors systems might publish an event that a new hire joined the company. You can configure your extension to subscribe to the event and carry out further actions with this data. For example, to enroll the new hire to an onboarding session.

While having the delivery and processing flow of Kyma in mind, you can use the Eventing module within SAP BTP for two scenarios:

1. When connected SAP & Non-SAP Solutions consume business events:
   Note

   Only CX solutions support the Eventing module, for example: SAP Commerce Cloud, SAP Sales Cloud, FSM. Other solutions like SAP S/4HANA currently do not send events using the Eventing module, as they send them directly to event mesh from where you need to set up a webhook. For more information, see Use SAP BTP, Kyma runtime to extend SAP Marketing Cloud.
   
2. When event-driven microservices use in-cluster events:

In Kyma dashboard, you can view and update the Subscriptions for a specific workload, or you can do it at the namespace level under Configuration→ Subscriptions.