The service provider, the user can not be separated from each other. If separated, the service will not occur, such as in the store. If there are no employees, the service is unable to pay the cashier.
The service users can not be separated from each other. If separated, the service will not occur. In such a store If the cashier Users can not pay the item.
Service providers and users cannot be separated. If separate services will not occur, such as in the store. If there is a cashier. Users can't pay the goods.