> Markdown version of [Session & UI Listeners](https://vaadin.com/docs/next/flow/advanced/session-and-ui-init-listener). Section index: [llms.txt](https://vaadin.com/docs/next/flow/llms.txt)

# Session & UI Listeners

A `SessionInitListener` can be used to receive an event each time a new `VaadinSession` is initialized. Similarly, a `UIInitListener` can be used to receive an event each time a new `UI` is instantiated.

The ideal place to add both `SessionInitListener` and `UIInitListener` is inside a [VaadinServiceInitListener](https://vaadin.com/docs/next/flow/advanced/service-init-listener.md).

```java
public class ServiceListener implements VaadinServiceInitListener {

    @Override
    public void serviceInit(ServiceInitEvent event) {

        event.getSource().addSessionInitListener(
                initEvent -> LoggerFactory.getLogger(getClass())
                        .info("A new Session has been initialized!"));

        event.getSource().addUIInitListener(
                initEvent -> LoggerFactory.getLogger(getClass())
                        .info("A new UI has been initialized!"));
    }
}
```

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