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Structured Analysis

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Structured Analysis Component of Structure Analysis Graphic symbols. Data dictionary. Procedure and process description. Rules. Data Flow Analysis Data drive business ... – PowerPoint PPT presentation

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Title: Structured Analysis


1
Structured Analysis
2
Component of Structure Analysis
  1. Graphic symbols.
  2. Data dictionary.
  3. Procedure and process description.
  4. 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
0.0 Process
Source/ Sink
Source/ Sink
Data Flow
Data Flow
Data Flow
Level 0 DFD
0.0 Process
1.0 Process
Data Flow
Data Flow
Data Flow
2.0 Process
Source/ Sink
Source/ Sink
DATA STORE
Data Flow
Data Flow
Data Flow
Data Flow Lines
3.0 Process
Data Flow
13
Data Flow Diagrams Levels
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
  1. Create a list of activities
  2. Construct Context Level DFD (identifies sources
    and sink)
  3. Construct Level 0 DFD (identifies manageable sub
    process )
  4. 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
Steps
Example
  1. Create a list of activities
  2. Construct Context Level DFD (identifies sources
    and sink)
  3. Construct Level 0 DFD (identifies manageable sub
    processes )
  4. Construct Level 1- n DFD (identifies actual data
    flows and data stores )

The operations of a simple lemonade stand will be
used to demonstrate the creation of dataflow
diagrams.
18
Creating Data Flow Diagrams
  1. Create a list of activities

Example
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
  1. 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
  1. 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
  1. Construct Context Level DFD (identifies sources
    and sink)

Create a context level diagram identifying the
sources and sinks (users).
Context Level DFD
Sales Forecast
0.0 Lemonade System
EMPLOYEE
CUSTOMER
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
  1. 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
2.0 Production
EMPLOYEE
CUSTOMER
Production Schedule
Product Served
Inventory
Received Goods
3.0 Procure-ment
VENDOR
Purchase Order
Order Decisions
Payment
Pay
Time Worked
4.0 Payroll
23
Creating Data Flow Diagrams
Example
  1. 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
  1. 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
  1. 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
  1. 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
1.1 Record Order
1.2 Receive Payment
1.0 Sale
2.1 Serve Product
2.2 Produce Product
2.3 Store Product
2.0 Production
0.0 Lemonade System
3.1 Produce Purchase Order
3.2 Receive Items
3.3 Pay Vendor
3.0 Procure-ment
4.1 Record Time Worked
4.2 Calculate Payroll
4.3 Pay Employee
4.0 Payroll
Level 0
Level 1
Context Level
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
  1. To manage the detail in large systems.
  2. To communicate a common meaning for all system
    elements.
  3. To document the feature of the system.
  4. To facilitate analysis of the details in order to
    evaluate characteristic and determine where
    system changes should be made.
  5. 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
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