# OpenSCD Core should make use of a central event-bus
Date: 2023-06-05
## Status
Open
...
Context
Since menu
type plugins are siblings in the DOMTree, it is not possible for menu
type plugins to communicate with each other. Next to the menu
type plugin, it is not possible to communicate from an editor
type plugin to another editor
type plugin or a menu
type plugin.
Info |
---|
Example use-case An end-user selects 2 IED's in 1 plug-in. In order to make a connection between IED's, the user want to open the selection in an another plug. |
Also, since Addons are not extending from a HTMLElement, Addons cannot subscribe to events on themselves.
HTML Events are only going up in the DOMTree, not down and/or to siblings.
Decision
If we want plugins for OpenSCD to be asynchronous accessible to each other, OpenSCD Core should make use of a central event-bus.
Instead of dispatching an event on the plugin itself, the plugin can dispatch an event on the central event-bus. HTML Events are only going up in the domtree, not down and/or to siblings.
We can solve this by creating a central event-bus that will be passed down to each plugin.This will take care of the current problems we're facing:
Addons
```ts
export class EventBus implements EventTarget {
...
removeEventListener(type: string, callback: EventListenerOrEventListenerObject): void {
if (this._eventListeners.has(type)) {
this._eventListeners.set(type, this._eventListeners.get(type)!.filter((cb) => cb !== callback));
}
}
}
```
## Decision
T.B.D.
...
Alternatives
Find a (seperate solution) for all problems mentioned.
Pro's:
Con's
Consequences
Implementing a central event-bus means that current OSCD plugins need some refactoring to dispatch events to the event-bus instead of dispatching events on itself.