tailieunhanh - addison wesley writing effective use cases phần 3

Tham khảo tài liệu 'addison wesley writing effective use cases phần 3', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 3. Scope Design scope - Page 48 A small true story To help with constructing a fixed-time fixed-cost bid of a large system we were walking through some sample designs. I picked up the printer and spoke its function. The IS expert laughed You personal computer people crack me up You think we just use a little laser printer to print our invoices We have a huge printing system with chain printer batch I O and everything. We produce invoices by the boxfull I was shocked You mean the printer is not in the scope of the system Of course not We ll use the printing system we already have. Indeed we found that there was a complicated interface to the printing system. Our system was to prepare a magnetic tape with things to be printed. Overnight the printing system read the tape and printed what it could. It prepared a reply tape describing the results of the printing job with error records for anything it couldn t print. The following day our system would read back the results and note what had not been printed correctly. The design job for interfacing to that tape was significant and completely different from what we had been expecting. The printing system was not for us to design it was for us to use. It was out of our design scope. It was as described in the next section a supporting actor. Had we not detected this mistake we would have written the use case to include it in scope and turned in a bid to build more system than was needed. Figure 10. Design scope can be any size. Typically the writer considers it obvious what the design scope of the system is. It is so obvious that they don t mention it. However once there are multiple writers and multiple readers then the design scope of a use case is not at all obvious. One writer is thinking of the entire corporation as the design scope see Figure 10. one is thinking of all of the company s software systems one is Chapter 3. Scope Page 49 - Design scope thinking of the new client-server system and one is thinking