Structured Systems Analysis and Design Methodology

1. Structured Systems Analysis and Design Methodology Northern College Diploma Philip Bird

2. Why Bother? • Need to plan and organise – link to life cycle. • Help communicate ideas. • Get processes (functions) right – Data flow modelling. • Get data right – Entity modelling. • Cross reference the two – checks built-in. • Can be automated.

3. Data Flow Modelling • Describe the current physical system. • Show processes together with data flows between them. • Show data stores. • Use these to discuss problems with users and help identify requirements for new system.

4. Check stock availability Copy order Product Customer Order Stock level Order Order Order

5. I have a problem Patient GP X-Ray Request What’s the result? Meet Appt Appt Request Appt Report X-Ray/History Report Consultant X-Ray Dept System Boundary X-Ray Example

6. Patient Take X-Ray Produce Report X-Ray Dept 1 2 Consultant GP X-Ray L1 DFD Appointment Appt Card Appt Request X-Ray/History Report Report

7. Scenario RecordsClerk – Chaka Khan Takes the X-Ray Request and uses this to find old, historical X-Rays and Reports for that Patient. Appends new X-Rays to the historical records and sends them, together with the copy of the X-Ray Request, to the Consultant. Files away the historical records and the new Report from the Consultant. Receptionist – Mae Pang Completes an Appointment Card for the patient at the Radiology clinic and makes an appointment in the Diary. (16th December). Passes the X-Ray Request to the OfficeAssistant. When the Patient attends the appointment the Appointment Card is taken and checked in the Diary. The Patient is sent to the waiting room while the Appointment Card is passed to the OfficeAssistant. Patient – Mark Twain Visits the GP with a pain in the middle finger, left hand. (Lives at 14 Sheffield Road, Deepvale) Makes a hospital appointment, (16th December) and attends the hospital appointment. Revisits the GP to gets the results. OfficeAssistant – Bart Simpson Takes the X-Ray Request, finds the patient number from the Patients Record Card file and adds it to the X-Ray Request then files the X-Ray Request away. Takes the Appointment Card, finds the patient number and uses this to retrieve the X-Ray Request. Makes a copy of the X-Ray Request and passes one copy to the Radiographer and the other to the RecordsClerk. Consultant– Don Waters Examines the new X-Rays, checks the X-Ray history and dictates the new Report diagnosing the findings. One copy of the Report goes back to the X-Ray Department with the historical records and one copy goes to the GP. GP – Stig McNasty Fills in an X-Ray Request form for the Patient. (Area to investigate is “Index finger, left hand”) On receipt of the Report from the hospital they request the Patient to make a follow up visit to get the results. Radiographer – Gaynor Glow Collects the next X-Ray Request from the pending file, calls the Patient from the waiting room and takes the X-Ray. Passes the X-Ray to the Records Clerk.

8. X-Ray Dept Send to X-Ray Dept Put in In Tray Write Report Send to GP View & Dictate Diagnosis Copy Report Out Tray In Tray GP X-Ray L2 DFD Consultant X-Ray/History History Report History Report Report Report

9. Entity Modelling • Things the system needs to store data about • Physical – cars, products • People – customers, employees • Abstractions – order, invoice, booking • Each entity has a unique identifier – key attribute/field. • Entities linked via relationships.

10. One to One 1:1 Woman Is the husband of Is married to Man

11. One to Many 1:N Tutor Has Is allocated to Student

12. Actor Has Role Appears in Film Many to Many M:N Actor Film

13. Entity Attributes ° Employee number Name Address Tax code NI number Pay to date Tax to date Employee °Key field

14. Booking Car Service Mechanic An Example – Hire Car Booking Customer Customer#, Name, Address, Tel Customer#, Date, Car reg, Duration Car reg, Make, Model, Type, Seats, Cost Date, Mileage, Description, Mechanic Name, Qualifications

15. Entity Life Histories • Describes the entity over time. • Check to see there are no missing processes. Are there processes to create, update and delete the entity? • Produce diagram that serves as an initial program design.

16. ELH For Appointment Entity Appt Make Appt Change Appt * Visit New Year Where in the DFD is there a process to change an appointment? º º º = Alternative Has Appt No Appt * = Repetition