import { IProxyIncomingMessageEnvelope, IProxyMessagingProvider, IProxyOutgoingMessageEnvelope } from '../contracts.js';
/**
 * A getAgent standards compliant proxy messaging provider.
 * Publishes messages on and subscribes to messages from the MessagePort provided in the constructor
 */
export declare class DefaultProxyMessagingProvider implements IProxyMessagingProvider {
    private messagePort;
    private callbacks;
    constructor(messagePort: MessagePort);
    sendMessage(message: IProxyOutgoingMessageEnvelope): void;
    addResponseHandler(callback: (message: IProxyIncomingMessageEnvelope) => void): void;
}