import { JsonObject } from '@backstage/types';
/** @public */
export declare const signalApiRef: import("@backstage/core-plugin-api").ApiRef<SignalApi>;
/** @public */
export interface SignalSubscriber {
    unsubscribe(): void;
}
/** @public */
export interface SignalApi {
    subscribe<TMessage extends JsonObject = JsonObject>(channel: string, onMessage: (message: TMessage) => void): SignalSubscriber;
}