Người dùng có thể không thể tưởng tượng một hệ thống mới hoặc làm thế nào họ sẽ sử dụng nó, nhưng họ Chương 3: Thu thập yêu cầu từ các bên liên quan Viết Yêu cầu tốt hơn 3,1 có thể kỹ thuậttrong khi product2 chỉ đơn giản là sẽ giúp làm rõ mã. Ví dụ 4-12. Một bối cảnh nhạy cảm biến | Writing Better Requirement 59 on the channel. The constraint should therefore be applied to the whole scenario all steps in that scenario have together to comply. Budgeting to meet end-to-end system constraints In the corresponding system specification the constraint will be translated into a single performance budget shared out among the system functions. The need to budget logically traces back to a single constraint on the channel s performance. The way the budget is shared depends on the system engineer s understanding of the system design specification and design influence each other. Trade-offs usually have to be made between them and also with the user requirements as the development team works out what can be done realistically within the schedule and cost constraints on the project. The users may be asked to decide whether to accept a system that delivers slightly less performance than anticipated but which can be delivered on time and to cost. Performance constraints often apply across whole systems If the transmission has to be 15 more efficient . to deliver 15 more of the input power to the wheels than the old model which component has to be improved Very probably all of them so the constraint is system-wide. You need to make sure your readers see at once that the end-to-end performance constraints apply to the whole system. Other kinds of constraint which are often like this include cost reliability maintainability and environmental as well as physical considerations such as size weight and non-toxicity. Not reliability but dependability Requirements of any of these kinds usually make sense only for a system as a whole. The driver of a car is not necessarily interested in the reliability of individual engine components the key requirement is the ability of the car to make the next journey successfully. This user-level constraint is sometimes known as dependability to distinguish it from component qualities such as reliability or availability. Users
