/**
 * @module node-opcua-transport
 *
 * Transport-agnostic base class for client-side OPC UA transports.
 *
 * Owns the UACP HEL/ACK handshake, the negotiated transport settings, and the
 * post-connect connection-break detector. Concrete subclasses (`ClientTCP_transport`,
 * `ClientWS_transport`, ...) implement only the socket-creation step in `connect()`.
 *
 * Browser-safe: does not import `node:net`, `node:os`, `node:util`, or any other
 * Node-only built-in beyond what `TCP_transport` already inherits from `node:events`.
 */
import type { ErrorCallback } from "node-opcua-status-code";
import { AcknowledgeMessage } from "./AcknowledgeMessage";
import type { TransportSettingsOptions } from "./i_client_transport";
import { TCP_transport } from "./tcp_transport";
export interface ClientTransportBase {
    on(eventName: "chunk", eventHandler: (messageChunk: Buffer) => void): this;
    on(eventName: "close", eventHandler: (err: Error | null) => void): this;
    on(eventName: "connection_break", eventHandler: (err: Error | null) => void): this;
    on(eventName: "connect", eventHandler: () => void): this;
    once(eventName: "chunk", eventHandler: (messageChunk: Buffer) => void): this;
    once(eventName: "close", eventHandler: (err: Error | null) => void): this;
    once(eventName: "connection_break", eventHandler: (err: Error | null) => void): this;
    once(eventName: "connect", eventHandler: () => void): this;
    emit(eventName: "chunk", messageChunk: Buffer): boolean;
    emit(eventName: "close", err?: Error | null): boolean;
    emit(eventName: "connection_break", err?: Error | null): boolean;
    emit(eventName: "connect"): boolean;
}
export declare abstract class ClientTransportBase extends TCP_transport {
    static defaultMaxChunk: number;
    static defaultMaxMessageSize: number;
    static defaultReceiveBufferSize: number;
    static defaultSendBufferSize: number;
    endpointUrl: string;
    serverUri: string;
    numberOfRetry: number;
    parameters?: AcknowledgeMessage;
    private _counter;
    private _helloSettings;
    constructor(transportSettings?: TransportSettingsOptions);
    getTransportSettings(): TransportSettingsOptions;
    dispose(): void;
    /**
     * Connect to `endpointUrl` and perform the UACP HEL/ACK handshake.
     * Concrete subclasses are responsible for opening the underlying socket
     * (TCP, WebSocket, ...) and then driving the inherited HEL/ACK machinery.
     */
    abstract connect(endpointUrl: string, callback: ErrorCallback): void;
    /**
     * Install the post-connect "connection break" detector. Subclasses call this
     * once the underlying socket is open and the HEL/ACK transaction has succeeded.
     *
     * Detects ECONNRESET / EPIPE / premature socket termination on the live socket
     * and re-emits them as `connection_break` so reconnection logic upstream can
     * react.
     */
    protected _install_post_connect_error_handler(endpointUrl: string): void;
    protected _perform_HEL_ACK_transaction(callback: ErrorCallback): void;
    private _send_HELLO_request;
    private _on_ACK_response;
    private _handle_ACK_response;
}