1. Learning Objectives Today we will Learn: How to identify the data requirements of a IT system using a Data Flow Diagram

2. Data Flow Diagram A data flow diagram looks at how data flows through a system. It concerns things like where the data will come from and go to as well as where it will be stored.

3. Components Customer External Entity: An external entity can represent a human, system or subsystem. It is where certain data comes from or goes to. It is external to the system we study, in terms of the business process. For this reason, people used to draw external entities on the edge of a diagram.

4. Components Calculate total order, apply P&P. Authorise payment 2Payment Processing Process: A process is a business activity or function where the manipulation and transformation of data takes place.

5. Components D1 Orders Data Store: A data store represents the storage of data required and/or produced by the process. Here are some examples of data stores: membership forms, database table, etc.

6. Components Data Flow: A data flow represents the flow of information, with its direction represented by an arrow head that shows at the end(s) of flow connector.

7. Context Diagram A context diagram, a simple representation of the whole system.

8. Context Diagram Draw a context diagram for Westford Stationary

9. Data Flow Diagram A data flow diagram shows additional information about the major functions of the system.

10. Data Flow Diagram Draw a Level 1 DFD for Westford Stationary

13. Results of the analysis stage

19. Components of a DFD Terminators, processes, flow arrows and stores

20. System Flowcharts Show the input/process/output like a data flow diagram but also display the hardware required for inputting data, processing data, outputting data and storing data. Examples: Input – Bar Code reader Output – Screen/Colour Printer Storage – Hard Disk Drive

21. Learning Objectives Today we will Learn: What a systems flow chart is The symbols of a systems flowchart The difference between a DFD and a Flow Chart

22. The Differnces The DFD helps identify the information requirements, as well as the inputs, processing, storage and output A systems flowcharts helps identify the hardware/software needed in the new system

23. Output of the analysis stage How can we identify the hardware/software requirements from all the tasks completed in the analysis stage: Investigation – Interviews, observation, documents, questionnaires DFD diagrams, systems flow chart

24. Learning Objectives Today we will Learn: Why we need to design the data structures How to design the data structures

26. Learning Objectives Today we will Learn: Design techniques for designing screen layouts

27. Learning Objectives Today we will Learn: Design techniques for designing screen layouts

28. Learning Objectives Make it obvious where data needs to be entered, use boxes or different colours Vary the size of the boxes to indicate how much data needs to be entered Use drop down menus, radio buttons and checkboxes for limited choices Think about the order in which you want the user to enter data (tab key) – it must match the data collection form

29. Learning Objectives Build in data validation techniques to reduce errors Ask users to enter passwords and e-mail addresses twice for verification. What colours will be used? Think about house style and colours that are clear for the user The number of mouse clicks and key presses should be kept minimal

32. Volume of data will be determined from the Systems flow Chart/existing documentation This will come from the user’s requirement identified from the Interviews, questionnaires etc This will come from the user’s requirement which can be identified from the investigation stage This will be identified from the Data Flow Diagram - based on the data stores and processes