import { ITracingOptions } from '../interface/ITracingOptions';
import { Request, Response, NextFunction } from 'express';
/**
 * Creates a middleware that traces incoming requests. The span will finish itself whenever the request is finished.
 *
 * @param {*} [options={}] Takes in an optional tracer, uses global tracer if none is defined
 * @returns Function fulfilling an express middleware (req, res, next)
 */
export declare function tracingMiddleware(options?: ITracingOptions): (req: Request, res: Response, next: NextFunction) => void;