Serverless Sagas with Fn Flow

book-1.java

    public void book1(TripReq input) {
        Flow f = Flows.currentFlow();

        FlowFuture<BookingRes> flightFuture =
            f.invokeFunction("./flight/book", input.flight, BookingRes.class);

        FlowFuture<BookingRes> hotelFuture =
            f.invokeFunction("./hotel/book", input.hotel, BookingRes.class);

        FlowFuture<BookingRes> carFuture =
            f.invokeFunction("./car/book", input.carRental, BookingRes.class);

        flightFuture.thenCompose(
            (flightRes) -> hotelFuture.thenCompose(
                (hotelRes) -> carFuture.whenComplete(
                    (carRes, e) -> EmailReq.sendSuccessMail(flightRes, hotelRes, carRes)
                )
            )
        );
    }