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

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Presentation on theme: "Structured Systems Analysis and Design Methodology Northern College Diploma Philip Bird."— Presentation transcript:

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

2 Information Systems Philip Bird 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 Information Systems Philip Bird 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 Information Systems Philip Bird Check stock availability Order Product Customer Copy order Order Stock level

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

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

7 Information Systems Philip Bird Scenario 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. 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. 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 Office Assistant. 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 Office Assistant. Office Assistant – 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 Records Clerk. 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. Records Clerk – 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. 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.

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

9 Information Systems Philip Bird 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 Information Systems Philip Bird One to One 1:1 Woman Man Is the husband of Is married to

11 Information Systems Philip Bird One to Many 1:N Tutor Student Has Is allocated to

12 Information Systems Philip Bird Many to Many M:N Actor Film Has Appears in Actor Film Role

13 Information Systems Philip Bird Entity Attributes Employee ° Employee number Name Address Tax code NI number Pay to date Tax to date ° Key field

14 Information Systems Philip Bird An Example – Hire Car Booking Customer BookingCarServiceMechanic Customer#, Name, Address, Tel Customer#, Date, Car reg, Duration Car reg, Make, Model, Type, Seats, Cost Date, Mileage, Description, Mechanic Name, Qualifications

15 Information Systems Philip Bird 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 Information Systems Philip Bird ELH For Appointment Entity Appt Make Appt Change Appt VisitNew Year Has Appt No Appt * ºº º = Alternative * = Repetition Where in the DFD is there a process to change an appointment?


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