/**
 * @hidden
 * @beta
 *
 * Fetches a MessagePort to allow access to the host's data layer worker.
 * The port is cached once received, so subsequent calls return the same port.
 * @returns MessagePort.
 *
 * @throws Error if {@linkcode app.initialize} has not successfully completed,
 * if the host does not support the feature, or if the port request is rejected.
 *
 * @internal
 * Limited to Microsoft-internal use
 */
export declare function getDataLayerPort(): Promise<MessagePort>;
/**
 * @hidden
 *
 * @beta
 *
 * Checks if the messageChannels.dataLayer capability is supported by the host
 * @returns boolean to represent whether the messageChannels.dataLayer capability is supported
 *
 * @throws Error if {@linkcode app.initialize} has not successfully completed
 *
 * @internal
 * Limited to Microsoft-internal use
 */
export declare function isSupported(): boolean;
/**
 * @hidden
 * Undocumented function used to clear state between unit tests
 *
 * @beta
 *
 * @internal
 * Limited to Microsoft-internal use
 */
export declare function _clearDataLayerPort(): void;