import { Client } from "../client/client.ts";
import type { ConnNext } from "../client/mod.ts";
/**
 * Fetches data from a file and returns it as a string
 *
 * @param filename
 * @returns Promise
 *
 * Fetches data from a file and returns it as a string
 * @example
 * const data = await getFileData("data.txt");
 */
export declare function getFileData(filename: string | undefined): Promise<string | undefined>;
/**
 * TcpClient extends the Client class to provide TCP based clients
 * it is used by the MQTTclient to connect to the broker
 * see mqtt.ts in the /bin folder as an example
 */
export declare class TcpClient extends Client {
    /** Connect using MQTT over TCP
     * @param hostname the name of the host to connect to
     * @param port the port number
     */
    protected connectMQTT(hostname: string, port?: number): Promise<ConnNext>;
    /**
     * Connect using MQTT over TLS
     * @param hostname the name of the host to connect to
     * @param port the port number
     * @param caCerts the CA certificates to trust
     * @param cert the clients certificate
     * @param key the clients private key
     * @returns a ConnNext object
     */
    protected connectMQTTS(hostname: string, port?: number, ca?: string[], cert?: string, key?: string): Promise<ConnNext>;
}
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