@MessageMapping("/upload")
 fun upload(@Payload fileData: ByteArray?): Mono<String> {
 println("========= OK")
 println("========= OK "+ fileData!!.size)
 val uploadFile = File("/Users/Downloads/uploaded_file.png")
// return Mono.just("ok")
 return Mono.just("ok").doOnSuccess {
 
 try {
 FileOutputStream(uploadFile).use { fos ->
 fos.write(fileData!!)
 }
 } catch (e: IOException) {
 e.printStackTrace()
 }
 }
 }

 upload(file) {
 let route = encodeRoute("/upload");
 let compositeMetaData = encodeCompositeMetadata([
 [WellKnownMimeType.MESSAGE_RSOCKET_ROUTING, route]
 ]);
 const reader = new FileReader();
 reader.onload = (event) => {
 let result = event.target.result as ArrayBuffer;
 console.log(result)
 this.socket.requestResponse({data: Buffer.from(result), metadata: compositeMetaData}, {
 onComplete(): void {
 }, onError(error: Error): void {
 console.error("Error", error);
 }, onExtension(extendedType: number, content: Buffer | null | undefined, canBeIgnored: boolean): void {
 }, onNext(payload: Payload, isComplete: boolean): void {
 console.log("OK", isComplete);
 console.log("payload", payload.data);
 }
 })
 }
 reader.readAsArrayBuffer(file);
 }