import IOBuffer from './iobuffer';
/**
 * The WebSocket connection is the main class that holds a connection between the client and the server
 */
declare class WebSocketConnection {
    private _open;
    private _wsOpen;
    private _closingPromise;
    private readonly _onMessage;
    private readonly _onError;
    private readonly _pendingRequests;
    private readonly _ws;
    /**
     * This constructor should not be called directly
     *
     * @param url the URL of the remote MillenniumDB server
     * @param onMessage the callback that will handle the received data
     */
    constructor(url: URL, onMessage: (iobuffer: IOBuffer) => void, onError: (error: string) => void);
    /**
     * Write a request. If the connection is not established yet, it will be enqueued
     * @param iobuffer a buffer containing the request
     */
    write(iobuffer: IOBuffer): void;
    /**
     * Close the connection
     * @returns Promise that will be resolved when the connection is closed
     */
    close(): Promise<void>;
    private _safeCloseWebSocket;
    private _ensureOpen;
    /**
     * Create the WebSocket instance for the connection
     * @returns the WebSocket instance
     */
    private _createWebSocket;
}
export default WebSocketConnection;