[Home](./index.md) > [@empathyco/x-components](./x-components.md) > [XPriorityBus](./x-components.xprioritybus.md) ## XPriorityBus class A default [XBus](./x-components.xbus.md) implementation using a [priority queue](./x-components.xpriorityqueue.md) as its data structure to prioritise the emission of events. The priorities are preconfigured based on event naming. **Signature:** ```typescript export declare class XPriorityBus implements XBus ``` **Implements:** [XBus](./x-components.xbus.md)<SomeEvents, SomeEventMetadata> ## Constructors | Constructor | Modifiers | Description | | --- | --- | --- | | [(constructor)(config)](./x-components.xprioritybus._constructor_.md) | | Creates a new instance of a [XPriorityBus](./x-components.xprioritybus.md). | ## Methods | Method | Modifiers | Description | | --- | --- | --- | | [emit(event, payload, metadata)](./x-components.xprioritybus.emit.md) | | Emits an event. See [XBus.emit](./x-components.xbus.emit.md). | | [on(event, withMetadata)](./x-components.xprioritybus.on.md) | | Retrieves an observable for the event. See [XBus.on](./x-components.xbus.on.md). |