Backoffice UI
Jmix Backoffice UI allows you to develop the rich web UI using Java and XML. It is based on the Vaadin web framework.
In Backoffice UI, your UI components work in the same JVM as your backend, which greatly simplifies working with data and invoking business logic. Also, you don’t have to be familiar with the modern JavaScript/HTML/CSS stack.
The Backoffice UI technology has a limited scalability: the backend side of the UI is stateful and consumes the amount of resources proportional to the number of concurrent user sessions. So Backoffice UI is suitable when you have a predictable and not very high (up to tens of thousands) number of users working with the system at the same time.
For a web-scale project and full freedom of UI customization, consider creating a frontend application using a traditional frontend technology. It can work with the Jmix backend through the REST API.