DATA FLOW DIAGRAMS

1. DATA FLOW DIAGRAMS Budi Arifitama

2. Key Definitions • Process model • A formal way of representing how a business operates • Illustrates the activities that are performed and how data moves among them • Data flow diagramming • A popular technique for creating process models

3. Key Definitions • Logicalprocess models describe processes without suggesting how they are conducted • Physical process models include process implementation information

4. DFD Elements • Process • An activity or function performed for a specific business reason • Manual or computerized • Data flow • A single piece of data or a logical collection of data • Always starts or ends at a process

5. DFD Elements • Data Store • A collection of data that is stored in some way • Data flowing out is retrieved from the data store • Data flowing in updates or is added to the data store • External entity • A person, organization, or system that is external to the system but interacts with it.

6. Process Data flow Data store External entity Naming and Drawing DFD Elements

7. Balancing involves insuring that information presented at one level of a DFD is accurately represented in the next level DFD. Key Definition

8. First DFD in every business process Shows the context into which the business process fits Shows the overall business process as just one process (process 0) Shows all the external entities that receive information from or contribute information to the system Context Diagram

9. Context Diagram Lemonade System Context Level DFD Sales Forecast CUSTOMER 0.0 Lemonade System EMPLOYEE Order Production Schedule Product Served Pay Payment Time Worked Received Goods Payment Purchase Order VENDOR

10. Shows all the major processes that comprise the overall system – the internal components of process 0 Shows how the major processes are interrelated by data flows Shows external entities and the major processes with which they interact Adds data stores Level 0 Diagram

11. DFD Level 0 Level 0 DFD 1.0 Sale Sales Forecast Customer Order Product Ordered Payment CUSTOMER 2.0 Production EMPLOYEE Production Schedule Product Served Inventory Received Goods VENDOR 3.0 Procure-ment Purchase Order Order Decisions Payment Pay Time Worked 4.0 Payroll

12. Generally, one level 1 diagram is created for every major process on the level 0 diagram Shows all the internal processes that comprise a single process on the level 0 diagram Shows how information moves from and to each of these processes If a parent process is decomposed into, for example, three child processes, these three child processes wholly and completely make up the parent process Level 1 Diagrams

13. DFD Level 1 Order Decision PURCHASE ORDER 3.1 Produce Purchase Order Quantity On-Hand RAW MATERIALS Quantity Received Received Goods 3.2 Receive Items RECEIVED ITEMS Payment Approval 3.3 Pay Vendor VENDOR Payment

14. Basic Symbols Four basic symbols are: • A double square for an external entity--a source or destination of data. • An arrow for movement of data from one point to another. • A rectangle with rounded corners for the occurrence of transforming process. • An open-ended rectangle for a data store.

15. Basic Symbols

16. DFD Examples

17. Creating Data Flow Diagrams Steps: • Create a list of activities • Construct Context Level DFD(identifies external entities and processes) • Construct Level 0 DFD (identifies manageable sub process ) • Construct Level 1- n DFD (identifies actual data flows and data stores ) • Check against rules of DFD

18. DFD Naming Guidelines • External Entity  Noun • Data Flow  Names of data • Process  verb phrase • a system name • a subsystem name • Data Store  Noun

19. Creating Data Flow Diagrams Lemonade Stand Example

20. Creating Data Flow Diagrams Example Steps: The operations of a simple lemonade stand will be used to demonstrate the creation of dataflow diagrams. • Create a list of activities • Old way: no Use-Case Diagram • New way: use Use-Case Diagram • Construct Context Level DFD(identifies sources and sink) • Construct Level 0 DFD (identifies manageable sub processes ) • Construct Level 1- n DFD (identifies actual data flows and data stores )

21. Creating Data Flow Diagrams Example • Create a list of activities Think through the activities that take place at a lemonade stand. Customer Order Serve Product Collect Payment Produce Product Store Product

22. Creating Data Flow Diagrams Example • Create a list of activities Also think of the additional activities needed to support the basic activities. Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor

23. Creating Data Flow Diagrams Example • Create a list of activities Group these activities in some logical fashion, possibly functional areas. Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor

24. Creating Data Flow Diagrams Example • Construct Context Level DFD(identifies sources and sink) Create a context level diagram identifying the sources and sinks (users). Context Level DFD Sales Forecast CUSTOMER 0.0 Lemonade System EMPLOYEE Order Production Schedule Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor Product Served Pay Payment Time Worked Received Goods Payment Purchase Order VENDOR

25. Creating Data Flow Diagrams Example • Construct Level 0 DFD (identifies manageable sub processes ) Create a level 0 diagram identifying the logical subsystems that may exist. Level 0 DFD 1.0 Sale Sales Forecast Customer Order Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor Product Ordered Payment CUSTOMER 2.0 Production EMPLOYEE Production Schedule Product Served Inventory Received Goods VENDOR 3.0 Procure-ment Purchase Order Order Decisions Payment Pay Time Worked 4.0 Payroll

26. Creating Data Flow Diagrams Example • Construct Level 1- n DFD (identifies actual data flows and data stores ) Create a level 1 decomposing the processes in level 0 and identifying data stores. Level 1 DFD CUSTOMER Customer Order Request for Forecast Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor ORDER 1.1 Record Order 1.3 Produce Sales Forecast Severed Order Payment Sales Forecast 1.2 Receive Payment PAYMENT

27. Creating Data Flow Diagrams Example • Construct Level 1 (continued) Create a level 1 decomposing the processes in level 0 and identifying data stores. Level 1 DFD Product Order ORDER 2.1 Serve Product Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor Quantity Severed RAW MATERIALS Production Schedule 2.2 Produce Product Quantity Used INVENTORTY Production Data 2.3 Store Product Quantity Produced & Location Stored

28. Creating Data Flow Diagrams Example • Construct Level 1 (continued) Create a level 1 decomposing the processes in level 0 and identifying data stores. Level 1 DFD Order Decision PURCHASE ORDER 3.1 Produce Purchase Order Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor Quantity On-Hand RAW MATERIALS Quantity Received Received Goods 3.2 Receive Items RECEIVED ITEMS Payment Approval 3.3 Pay Vendor VENDOR Payment

29. Creating Data Flow Diagrams Example • Construct Level 1 (continued) Create a level 1 decomposing the processes in level 0 and identifying data stores. Level 1 DFD Time Worked TIME CARDS 4.1 Record Time Worked Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor Employee ID EMPLOYEE Payroll Request 4.2 Calculate Payroll Unpaid time cards PAYROLL Payment Approval 4.3 Pay Employee PAYMENTS Payment

30. Process Decomposition 1.0 Sale 1.1 Record Order 1.2 Receive Payment 2.0 Production 2.1 Serve Product 2.2 Produce Product 2.3 Store Product 0.0 Lemonade System 3.0 Procure-ment 3.1 Produce Purchase Order 3.2 Receive Items 3.3 Pay Vendor 4.0 Payroll 4.1 Record Time Worked 4.2 Calculate Payroll 4.3 Pay Employee Context Level Level 0 Level 1

31. Latihan • Bagi Menjadi 10 kelompok • Buatlah sebuah Data Flow Diagram lengkap dengan DFD context diagram, Level0, dan level 1 dari sebuah sistem informasi akademik di trilogi.

32. DFD Example: Bus Garage Repairs • Buses come to a garage for repairs. • A mechanic and helper perform the repair, record the reason for the repair and record the total cost of all parts used on a Shop Repair Order. • Information on labor, parts and repair outcome is used for billing by the Accounting Department, parts monitoring by the inventory management computer system and a performance review by the supervisor.