Mendix Business Events

Last modified: February 4, 2026

Introduction

Business events are like a mailing list to share event notifications between apps. The key difference between business events and traditional communication between apps, like REST or web services, is that there is no direct communication between the different apps.

With Mendix Business Events, applications can signal when something important happens and can independently subscribe to these events if they want to be informed.

To deliver these events reliably between your applications, an event broker is required. For apps running Mendix Cloud on licensed nodes, you will need to purchase a license for the Mendix Event Broker.

Business events are supported in Studio Pro 9.18 and above and currently can only be deployed to the Mendix Cloud.

Typical Use Cases

Business events help you automate the resulting actions when something happens in your organization. They can be useful in a variety of situations, such as:

Uploading a payment receipt in one app, while another app processes the outgoing payment in the company's ledger
Making an appointment with a service provider in an appointment app, then needing it to be added to the scheduling app of the service provider
Customers placing an order in a web shop, and other apps need to take follow-up actions like scheduling shipments, sending an invoice, and reordering inventory stock

Prerequisites

To use Mendix Business Events, you will need the following:

The Mendix Business Events service from the Mendix Marketplace
Studio Pro 9.24 and above
An event broker; this can be a licensed Mendix Event Broker for apps running in Mendix Cloud or the local testing broker (see Deployment)
Docker for local deployment

Licensing

The Mendix Business Events service itself does not require a license, but it depends on an event broker to deploy to production environments. You can purchase a Mendix Event Broker License for a broker to be set up for you. See the Mendix Event Broker platform service page for more details. You can also run business events on your own Kafka cluster.

Frequently Asked Questions

Can I undo a Publish Event action in case my microflow fails?
Yes. If you do a rollback in an error handler, the business event will not be sent to other applications.
Can I publish my own events from other software directly to a Kafka topic?
No, that is currently not supported when using Mendix Cloud Event Broker. This can be achieved on your own Kafka cluster.
Can I send related or associated objects as a single business event?
No, only a flat object. For complex data structures, provide an API where the consuming app can retrieve the complex structure upon retrieval of a business event. Alternatively, you can use a string attribute in the business event to store JSON or XML using mappings.
I want to replicate data between my Mendix apps. Should I use business events?
Business events can help you replicate data more efficiently by ensuring you do not have to poll continuously. To share data, it is still preferable to use OData or REST.
Are business events guaranteed to be delivered only once?
The Outbox will publish each business event only once. This does not prevent business logic from sending duplicate messages to the Outbox.
Are business events guaranteed to be delivered in the original sequence?
Events are delivered in the sequence they are produced. The Mendix Business Events service, however, persists the event to the Entity table in this order. Once the entity is persisted, it triggers the microflow for the persisted entity. A failure in the microflow can cause data to become out of sequence. Event ordering is not currently a feature of the Mendix Business Event service.
How do I detect and correct failed processing of received events?
The Mendix Business Events service uses Task Queue to publish and consume events, so all the capabilities of observability of task queue can be used here as well.
How do I configure which Kafka cluster to use?
During modeling, you can use the Constants described in the Configuring Local Deployments section to configure to a local or other Kafka. This does not transfer through to runtime.
How do I delete or clean up events and tasks?
This will be implemented in a forthcoming release. In the meantime, you could use scheduled event to clean up the events yourself (make sure the consumer doesn’t need them anymore). For the task queue, the Task Queue Helpers, a service linked in Task Queue, can be used.
How do I know the event was successfully published?
Messages are first queued within the Outbox for successful delivery as a business event, after which they are deleted. You can match the unique Event Id to your business event. Monitoring the Outbox entity will allow the developer to determine if there are unpublished business event entities. See the Business Event Entities for more information on the Outbox.
How do I know events are consumed successfully?
The flow of events are controlled by the persistence of the event to the Consumed Business Event entity (see Business Event Entities). The flow will not continue in the case of such a failure. They only cause for such failure would be database-related and is unlikely to occur.
On the microflow, a log message action can be added after the start action in order to track the movement. Refer to the Dead Letter Queue for Failed Messages section for more information.

Read more to learn how to configure and deploy business events in the following documents: