If the proposed username is already taken, you will need to send a message back to the XForms form.
如果提交的用户名已被占用,那么需要向Xforms表单发回一个消息。
When the shipping process completes, it needs to send a message back to the OrderProcessing component to notify it that the order is complete.
配送流程结束时,需要向OrderProcessing组件发送消息,以通知后者订单已完成。
When the worker finishes its work, it will send a message back to the main thread.
当此worker完成其作业后,它会向主线程发送回一个消息。