public class Booking {
	String uniqueId;
	User guest;
	User host;
	Date bookingTime;
	Date confirmationTime;
	Date cancellationTime;
	Status status; //PENDING, CONFIRMED, CANCELLED_BY_GUEST, CANCELLED_BY_HOST
	User lastUpdatedBy;
}

// In Booking Service
public void cancelBookingByGuest(String bookingId, Date cancellationTime) {
	Booking originalBooking = readFromDB(bookingId);
	originalBooking.lastUpdatedBy = originalBooking.guest;
	originalBooking.cancellationTime = cancelltaionTime;
	originalBooking.status = CANCELLED_BY_GUEST;
	// Trigger notification to host
	// Trigger refund if payment was taken
	updateInDB(originalBooking);
}
public void cancelBookingByHost(String bookingId, Date cancellationTime) {
	Booking originalBooking = readFromDB(bookingId);
	originalBooking.lastUpdatedBy = originalBooking.host;
	originalBooking.cancellationTime = cancellationTime;
	originalBooking.status = CANCELLED_BY_HOST;
	// Trigger notification to guest
	// Trigger refund if payment was taken
	updateInDB(originalBooking);
}
// Other APIs to handle combinations of new/old variables...