Structured Analysis

1. Structured Analysis

2. Component of Structure Analysis • Graphic symbols. • Data dictionary. • Procedure and process description. • Rules.

3. Data Flow Analysis • Data drive business activity. They can trigger events. • Following the flow of data through the business process tells a great deals about how the organizational objective are accomplish. • It documents the finding in data flow diagram.

4. Tools for data flow strategy • Data flow strategy shows the use of data in the system pictorially. • Data flow tools helps in understanding business process by illustrating essential component of the system and their interconnection.

5. Tools for data flow strategy • Data flow analysis make use of the following tools: • Data flow Diagram (DFD). • Data Dictionary. • Data structure diagram. • Structure chart.

6. DFD's Notation

7. Data flows • Data flows represent the data being passed into or out of a process, source, sink or store. It is represented as a labeled arrow: Taxable Income

8. process • process are denoted by circles with one or more incoming and outgoing information flows: Taxable Income Tax owed Calculate Tax Tax Tables

9. External Entities • Entities (Information sources and sinks) are information that come into the system, or leave the system, and are represented by squares: Pay Hours Payroll System Pay Check Rate

10. Information stores • Information Stores represent locations where information can be store for the duration of the system activity: Total Payroll Expense

11. Types of DFD • Physical DFD: It shows what task are carried out and how they are performed. • Logical DFD: Focus on the flow of data between process without regards for the specific device, storage location, people etc.

12. Data Flow Diagrams Levels DeMarco & Yourdon Context Level DFD Source/ Sink Source/ Sink 0.0 Process Source/ Sink Data Flow Data Flow Data Flow Level 0 DFD 0.0 Process 1.0 Process Data Flow Data Flow Data Flow Source/ Sink 2.0 Process Source/ Sink DATA STORE Data Flow Data Flow Data Flow Data Flow Lines 3.0 Process Data Flow

13. Data Flow Diagrams Levels Source Source Sink DeMarco & Yourdon Level 1 DFD (and on) Source/ Sink Data Flow 1.1 Process DATA STORE 0.0 Process 1.2 Process Data Flow DATA STORE Data Flow Data Flow Lines

14. Data Flow Diagrams Levels

15. Creating Data Flow Diagrams Steps: • Create a list of activities • Construct Context Level DFD(identifies sources and sink) • Construct Level 0 DFD (identifies manageable sub process ) • Construct Level 1- n DFD (identifies actual data flows and data stores )

16. Creating Data Flow Diagrams Lemonade Stand Example

17. 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 • 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 )

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. Developing DFD • The analyst must first study current system. • The physical system is translated into logical description focusing on data and process. • Data flow diagram are of two types: • Physical DFD: It shows what task are carried out and how they are perform. • Logical DFD: Focusing on flow of data between process without regards for specific device, storage location or people in the system.

29. Data Dictionary • A data dictionary is a catalog, a repository of element in a system. • The major elements are dataflow, data store and process.

30. Uses of Data Dictionary • To manage the detail in large systems. • To communicate a common meaning for all system elements. • To document the feature of the system. • To facilitate analysis of the details in order to evaluate characteristic and determine where system changes should be made. • To locate errors and omissions in the system.

31. Contains of Data Dictionary • Data Elements: The most fundamental data level is data element. • Data Name. • Data description. • Aliases. • Length. • Data Value(Prefix).

32. Contains of Data Dictionary • Data Structure: A data structure is a set of data item that are related to one another and that collectively describe a component in the system. • Sequence Relationship. • Selection Relationship. • Iteration Relationship. • Optional Relationship.

33. Notation in Data Dictionary • Symbols: • + and • [] Either/or • {} iteration of • () optional