import type { IAction, IActorArgs, IActorOutput, IActorTest, Mediate } from '@comunica/core';
import { Actor } from '@comunica/core';
import type * as RDF from '@rdfjs/types';
/**
 * A comunica actor for rdf-metadata-extract events.
 *
 * Actor types:
 * * Input:  IActionRdfMetadataExtract:      A metadata quad stream
 * * Test:   <none>
 * * Output: IActorRdfMetadataExtractOutput: A metadata hash.
 *
 * @see IActionDereferenceRdf
 * @see IActorDereferenceRdfOutput
 */
export declare abstract class ActorRdfMetadataExtract<TS = undefined> extends Actor<IActionRdfMetadataExtract, IActorTest, IActorRdfMetadataExtractOutput, TS> {
    /**
     * @param args -
     *   \ @defaultNested {<default_bus> a <cc:components/Bus.jsonld#Bus>} bus
     *   \ @defaultNested {Metadata extraction failed: none of the configured actors were able to extract metadata from ${action.url}} busFailMessage
     */
    constructor(args: IActorRdfMetadataExtractArgs<TS>);
}
export interface IActionRdfMetadataExtract extends IAction {
    /**
     * The page URL from which the quads were retrieved.
     */
    url: string;
    /**
     * The resulting quad data stream.
     */
    metadata: RDF.Stream;
    /**
     * The time it took to request the page in milliseconds.
     * This is the time until the first byte arrives.
     */
    requestTime: number;
    /**
     * The headers of the page.
     */
    headers?: Headers;
}
export interface IActorRdfMetadataExtractOutput extends IActorOutput {
    /**
     * A metadata key-value mapping.
     */
    metadata: Record<string, any>;
}
export type IActorRdfMetadataExtractArgs<TS = undefined> = IActorArgs<IActionRdfMetadataExtract, IActorTest, IActorRdfMetadataExtractOutput, TS>;
export type MediatorRdfMetadataExtract = Mediate<IActionRdfMetadataExtract, IActorRdfMetadataExtractOutput>;