d. delen msis 5653 – advanced systems development midterm exam statistics

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CHAPTER 7: CHAPTER 7: Determining System Determining System Requirements Requirements 1.1 MSIS 5653 MSIS 5653 Advanced Systems Development Advanced Systems Development Dursun Delen, Ph.D. Dursun Delen, Ph.D. Department of Management Department of Management Oklahoma State University Oklahoma State University

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Page 1: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

CHAPTER 7:CHAPTER 7:

Determining System RequirementsDetermining System Requirements

1.11.1

MSIS 5653MSIS 5653Advanced Systems DevelopmentAdvanced Systems Development

Dursun Delen, Ph.D.Dursun Delen, Ph.D.Department of ManagementDepartment of ManagementOklahoma State UniversityOklahoma State University

Page 2: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Learning ObjectivesLearning Objectives Learn the classical and modern approaches to

Requirements Determination Describe options for designing and conducting

interviews and develop a plan for conducting an interview to determine system requirements

Design, distribute, and analyze questionnaires to determine system requirements

Explain advantages and pitfalls of observing workers and analyzing business documents to determine requirements

7.37.3

Page 3: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Learning ObjectivesLearning Objectives Explain how computing can provide support for

requirements determination (GSS) Learn about Joint Application Design (JAD) Use prototyping during requirements

determination Select the appropriate methods to discover

system requirements Apply requirements determination to Internet

applications

7.47.4

Page 4: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Determining System Determining System Requirements in SDLCRequirements in SDLC

Page 5: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Performing Requirements Performing Requirements DeterminationDetermination

Organizational needs derive the requirements

Gather information on what system should do from many sources

People Reports Forms Procedures

7.67.6

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D. Delen MSIS 5653 – Advanced Systems Development

Performing Requirements Performing Requirements DeterminationDetermination

Characteristics for gathering requirements Impertinence

Question everything Impartiality

Find the best organizational solution Relaxation of constraints Attention to detail Reframing

View the organization in new ways

7.77.7

Page 7: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Deliverables and OutcomesDeliverables and OutcomesTypes of deliverables: Information collected from users Existing documents and files Computer-based information

Understanding of organizational components Business objective Information needs Rules of data processing Key events with respect to changes on the data values

7.87.8

Page 8: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Interviewing and Listening Gather facts, opinions and speculations Observe body language and emotions Guidelines

Plan Checklist Appointment

Be neutral Listen Seek a diverse view

7.97.9

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D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Interviewing (Continued) Interview Questions

Open-Ended No pre-specified answers

Close-Ended Respondent is asked to choose from a set of specified responses T/F, M/C, Rating, and Ranking

Additional Guidelines Do not phrase questions in ways that imply a wrong or right

answer Listen very carefully to what is being said Type up notes within 48 hours Do not set expectations about the new system Seek a variety of perspectives

7.107.10

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D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Administering Questionnaires More cost-effective than interviews Choosing respondents

Should be representative of all users Types of sampling methods

Convenient Random sample Purposeful sample Stratified sample

Design Mostly closed-ended questions Can be administered over the phone or in person

7.117.11

Page 11: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Questionnaires vs. Interviews

7.127.12

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D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Interviewing Groups Advantages

More effective use of time Enables people to hear opinions of others and to agree or

disagree Disadvantages

Difficulty in scheduling

Nominal Group Technique Facilitated process to support idea generation by groups Individuals work alone to generate ideas which are pooled

under guidance of a trained facilitator7.137.13

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D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Directly Observing Users Serves as a good method to supplement interviews Often difficult to obtain unbiased data

People often work differently when being observed

Time and motion study?

7.147.14

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D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Analyzing Procedures and Other Documents Types of information to be discovered:

Problems with existing system Opportunity to meet new need Organizational direction Names of key individuals Values of organization Special information processing circumstances Reasons for current system design Rules for processing data

7.157.15

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D. Delen MSIS 5653 – Advanced Systems Development

Traditional Methods for Traditional Methods for Determining RequirementsDetermining Requirements

Analyzing Procedures and Other Documents Four types of useful documents

Written work procedures Describes how a job is performed Includes data and information used and created in the process

of performing the job or task

Business form Explicitly indicate data flow in or out of a system

Report Enables the analyst to work backwards from the report to the

data that generated it

Description of current information system

7.167.16

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D. Delen MSIS 5653 – Advanced Systems Development

Example:Example:Business Forms and ReportsBusiness Forms and Reports

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D. Delen MSIS 5653 – Advanced Systems Development

Modern Methods for Determining Modern Methods for Determining RequirementsRequirements

Joint Application Design (JAD) Brings together key users, managers and systems analysts Purpose: collect system requirements simultaneously from key

people Conducted off-site

Prototyping Repetitive process Rudimentary version of system is built Replaces or augments SDLC Goal: to develop concrete specifications for ultimate system

4.184.18

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D. Delen MSIS 5653 – Advanced Systems Development

Joint Application Design (JAD)Joint Application Design (JAD)Participants Session Leader Users Managers Sponsor Systems Analysts Scribe IS Staff

4.194.19

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D. Delen MSIS 5653 – Advanced Systems Development

Joint Application Design (JAD)Joint Application Design (JAD)End Result Documentation detailing existing system Features of proposed system

CASE Tools During JAD Upper CASE tools are used Enables analysts to enter system models directly

into CASE during the JAD session Screen designs and prototyping can be done during

JAD and shown to users

4.204.20

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D. Delen MSIS 5653 – Advanced Systems Development

Joint Application Design (JAD)Joint Application Design (JAD)Supporting JAD with GSS

Group support systems (GSS) can be used to enable more participation by group members in JAD

Members type their answers into the computer All members of the group see what other members

have been typing

7.217.21

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D. Delen MSIS 5653 – Advanced Systems Development

PrototypingPrototypingQuickly converts requirements to working version of system

Once the user sees requirements converted to system, will ask for modifications or will generate additional requests

Most useful when: User requests are not clear Few users are involved in the system Designs are complex and require concrete form History of communication problems between analysts and

users Tools are readily available to build prototype

7.227.22

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D. Delen MSIS 5653 – Advanced Systems Development

PrototypingPrototypingDrawbacks

Tendency to avoid formal documentation Difficult to adapt to more general user audience Sharing data with other systems is often not

considered Systems Development Life Cycle (SDLC) checks

are often bypassed

7.237.23

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D. Delen MSIS 5653 – Advanced Systems Development

Business Process Reengineering Business Process Reengineering (BPR)(BPR)

Search for and implementation of radical change in business processes to achieve breakthrough improvements in products and services

Goals Reorganize complete flow of data in major

sections of an organization Eliminate unnecessary steps Combine steps Become more responsive to future change

7.247.24

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D. Delen MSIS 5653 – Advanced Systems Development

Business Process Reengineering Business Process Reengineering (BPR)(BPR)

Identification of processes to reengineer Key business processes

Set of activities designed to produce specific output for a particular customer or market

Focused on customers and outcome Same techniques are used as were used for requirements

determination

Disruptive technologies Technologies that enable the breaking of long-held

business rules that inhibit organizations from making radical business changes >>>

7.257.25

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D. Delen MSIS 5653 – Advanced Systems Development

Business Process Reengineering Business Process Reengineering (BPR)(BPR)

7.267.26

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D. Delen MSIS 5653 – Advanced Systems Development

SummarySummaryInterviews

Open-ended and close-ended questions Preparation is key

Questionnaires Must be carefully designed Can contain close-ended as well as open-ended questions

Other means of gather requirements Observing workers Analyzing business documents

Joint Application Design (JAD)PrototypingBusiness Process Reengineering (BPR)

7.277.27

Page 27: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

CHAPTER 8:CHAPTER 8:

Structuring Systems Requirements: Structuring Systems Requirements: Process ModelingProcess Modeling

2.282.28

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D. Delen MSIS 5653 – Advanced Systems Development

Learning ObjectivesLearning Objectives Understand the logical modeling of processes

through studying data flow diagrams How to draw data flow diagrams using rules

and guidelines How to decompose data flow diagrams into

lower-level diagrams Balancing of data flow diagrams

8.28.2

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D. Delen MSIS 5653 – Advanced Systems Development

Learning ObjectivesLearning Objectives Explain the differences among four types of

DFDs: current physical, current logical, new physical and new logical

Discuss the use of data flow diagrams as analysis tools

Compare and contrast data flow diagrams with Oracle’s process modeling tool and with functional hierarchy diagrams

Discuss process modeling for Internet applications

8.308.30

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D. Delen MSIS 5653 – Advanced Systems Development8.318.31

Requirement Structuring: Requirement Structuring: Process Modeling in SDLCProcess Modeling in SDLC

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D. Delen MSIS 5653 – Advanced Systems Development

Process ModelingProcess ModelingGraphically represent the processes that capture, manipulate, store and distribute data between a system and its environment and among system components

Data flow diagrams (DFD) Graphically illustrate movement of data between

external entities and the processes and data stores within a system

8.328.32

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D. Delen MSIS 5653 – Advanced Systems Development

Process ModelingProcess ModelingModeling a system’s process

Utilize information gathered during requirements determination

Structure of the data is also modeled in addition to the processes

Deliverables and Outcomes Set of coherent, interrelated data flow diagrams

>>>

8.338.33

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D. Delen MSIS 5653 – Advanced Systems Development

Process ModelingProcess ModelingDeliverables and outcomes (Continued…) Context data flow diagram (DFD)

Scope of system DFDs of current system

Enables analysts to understand current system DFDs of new logical system

Technology independent Show data flows, structure and functional requirements of

new system Project dictionary and CASE repository

8.348.34

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming Data Flow Diagramming MechanicsMechanics

Four symbols are used…

8.358.35

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming Data Flow Diagramming MechanicsMechanics

Data Flow Depicts data that are in motion and moving as a unit

from one place to another in the system. Drawn as an arrow Select a meaningful name to represent the data

8.368.36

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming Data Flow Diagramming MechanicsMechanics

Data Store Depicts data at rest May represent data in

File folder Computer-based file Notebook

The name of the store as well as the number are recorded in between lines

8.378.37

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming Data Flow Diagramming MechanicsMechanics

Process Depicts work or action performed on data so that

they are transformed, stored or distributed Number of process as well as name are recorded Name is a verb phrase

8.388.38

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming Data Flow Diagramming MechanicsMechanics

Source/Sink Depicts the origin and/or destination of the data Sometimes referred to as an external entity Drawn as a square symbol Name states what the external agent is Because they are external, many characteristics are

not of interest to us Interactions that occur between sources and sinks What they do with the information internally How to control or redesign them How to provide them with direct access to data stores

8.398.39

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming Data Flow Diagramming DefinitionsDefinitions

Context Diagram A data flow diagram (DFD) of the scope of an

organizational system that shows the system boundaries, external entities that interact with the system and the major information flows between the entities and the system

Level-0 Diagram A data flow diagram (DFD) that represents a

system’s major processes, data flows and data stores at a high level of detail

8.408.40

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D. Delen MSIS 5653 – Advanced Systems Development

Developing DFDs: An ExampleDeveloping DFDs: An ExampleHoosier Burger’s automated food ordering system

Context Diagram (Figure 8-4) contains no data stores

Next step is to expand the context diagram to show the breakdown of processes (Figure 8-5)

8.418.41

Page 41: D. Delen MSIS 5653 – Advanced Systems Development Midterm Exam Statistics

D. Delen MSIS 5653 – Advanced Systems Development

Figure 8-4Figure 8-4Context diagram of Hoosier Burger’s Context diagram of Hoosier Burger’s

food ordering systemfood ordering system

8.428.42

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D. Delen MSIS 5653 – Advanced Systems Development

Figure 8-5Figure 8-5Level-0 DFD of Hoosier Burger’s Level-0 DFD of Hoosier Burger’s

food ordering systemfood ordering system

8.438.43

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming RulesData Flow Diagramming RulesBasic rules that apply to all DFDs

Inputs to a process are always different than outputs

Objects always have a unique name In order to keep the diagram uncluttered, you can repeat

data stores and sources/sinks on a diagram

8.448.44

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming RulesData Flow Diagramming RulesProcess

A. No process can have only outputs (a miracle)

B. No process can have only inputs (black hole)

C. A process has a verb phrase label

Data StoreD. Data cannot be moved

directly from one store to another

E. Data cannot move directly from an outside source to a data store

F. Data cannot move directly from a data store to a data sink

G. Data store has a noun phrase label

8.458.45

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming RulesData Flow Diagramming RulesSource/Sink

H. Data cannot move directly from a source to a sink

I. A source/sink has a noun phrase label

Data FlowJ. A data flow has only one

direction of flow between symbols

K. A fork means that exactly the same data goes from a common location to two or more processes, data stores or sources/sinks

Continues >>>

8.468.46

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D. Delen MSIS 5653 – Advanced Systems Development

Data Flow Diagramming RulesData Flow Diagramming Rules

8.478.47

Data Flow (Continued…)L. A join means that exactly the same data

comes from any two or more different processes, data stores or sources/sinks to a common location

M. A data flow cannot go directly back to the same process it leaves

N. A data flow to a data store means update

O. A data flow from a data store means retrieve or use

P. A data flow has a noun phrase label

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D. Delen MSIS 5653 – Advanced Systems Development

Decomposition of DFDsDecomposition of DFDsFunctional decomposition

Iterative process of breaking the description of a system/process down into finer and finer detail

Repetitive procedure that creates hierarchically related set of diagrams representing the system

Lowest level is called a primitive DFD

Level-N Diagrams A DFD that is the result of n nested decompositions

of a series of sub-processes from a process on a level-0 diagram

8.488.48

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D. Delen MSIS 5653 – Advanced Systems Development

Figure 8-7: Level-1 DFD showing the decomposition Figure 8-7: Level-1 DFD showing the decomposition of Process 1.0 from the Level-0 diagram for Hoosier of Process 1.0 from the Level-0 diagram for Hoosier

Burger’s food ordering systemBurger’s food ordering system

8.498.49

Process Numbering0 1.0, 2.0, … 1.1, 1.2, … 1.1.1, 1.1.2, …

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D. Delen MSIS 5653 – Advanced Systems Development

Balancing DFDsBalancing DFDsWhen decomposing a DFD, you must conserve inputs to and outputs from a process at the next level of decompositionThis is called balancingExample: Hoosier Burgers

In Figure 8-4, notice that there is one input to the system, the customer order

Three outputs: Customer receipt Food order Management reports

8.508.50

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D. Delen MSIS 5653 – Advanced Systems Development

Balancing DFDsBalancing DFDsExample (Continued)

Notice Figure 8-5. We have the same inputs and outputs

No new inputs or outputs have been introduced

We can say that the context diagram and level-0 DFD are balanced

8.518.51

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D. Delen MSIS 5653 – Advanced Systems Development

Figure 8-10Figure 8-10An unbalanced set of data flow diagramsAn unbalanced set of data flow diagrams(a) Context diagram, (b) Level-0 diagram(a) Context diagram, (b) Level-0 diagram

8.538.53

(a)(a)

(b)(b)

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D. Delen MSIS 5653 – Advanced Systems Development

Balancing DFDsBalancing DFDsWe can split a data flow into separate data flows on a lower level diagram

8.548.54

(a)(a)

(b)(b)

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D. Delen MSIS 5653 – Advanced Systems Development

Balancing DFDsBalancing DFDsBalancing leads to four additional advanced rules

8.558.55

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D. Delen MSIS 5653 – Advanced Systems Development

Four Different Types of DFDsFour Different Types of DFDsCurrent Physical

Process label includes an identification of the technology (people or systems) used to process the data

Data flows and data stores are labeled with the actual name of the physical media on which data flow or in which data are stored

Current Logical Physical aspects of system are removed as much

as possible Current system is reduced to data and processes

that transform them8.568.56

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D. Delen MSIS 5653 – Advanced Systems Development

Current Physical DFDCurrent Physical DFDHB Inventory Control SystemHB Inventory Control System

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D. Delen MSIS 5653 – Advanced Systems Development

Current Logical DFDCurrent Logical DFDHB Inventory Control SystemHB Inventory Control System

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D. Delen MSIS 5653 – Advanced Systems Development

Four Different Types of DFDSFour Different Types of DFDSNew Logical

Includes additional functions Obsolete functions are removed Inefficient data flows are reorganized

New Physical Represents the physical implementation of the new

system

8.598.59

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D. Delen MSIS 5653 – Advanced Systems Development

New Logical DFDNew Logical DFDHB Inventory Control SystemHB Inventory Control System

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D. Delen MSIS 5653 – Advanced Systems Development

DFD Development ProcessDFD Development ProcessMain Steps

Determine the processes by making a list of all relevant business activities.

Create the context diagram, including all external entities and the major data flow to or from them.

Create Level-0 Diagram by analyzing the major activities within the context process. Include the external entities and major data stores.

Create a child diagram for each complex process on Level-0 Diagram. Include local data stores and detailed processes.

Detailed data flow diagrams may be developed by Analyzing what happens to an input data flow from an external entity

and what is necessary to create an output data flow to an external entity Examining the data flow to or from a data store

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D. Delen MSIS 5653 – Advanced Systems Development

Guidelines for Drawing DFDsGuidelines for Drawing DFDs

8.628.62

Completeness DFD must include all components necessary for the system Each component must be fully described in the project

dictionary or CASE repository

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D. Delen MSIS 5653 – Advanced Systems Development

Guidelines for Drawing DFDsGuidelines for Drawing DFDsConsistency

The extent to which information contained on one level of a set of nested DFDs is also included on other levels

Missing Level-0 diagram, missing and/or mismatched I/O

Timing Time is not represented well on DFDs Best to draw DFDs as if the system has never started and will

never stop.

Iterative Development Analyst should expect to redraw diagram several times before

reaching the closest approximation to the system being modeled

8.638.63

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D. Delen MSIS 5653 – Advanced Systems Development

Guidelines for Drawing DFDsGuidelines for Drawing DFDsPrimitive DFDs

Lowest logical level of decomposition Decision has to be made when to stop

decomposition Rules for stopping decomposition

When each process has been reduced to a single decision, calculation or database operation

When each data store represents data about a single entity

When the system user does not care to see any more detail

>>>8.648.64

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D. Delen MSIS 5653 – Advanced Systems Development

Guidelines for Drawing DFDsGuidelines for Drawing DFDsRules for stopping decomposition (continued)

When every data flow does not need to be split further to show that data are handled in various ways

When you believe that you have shown each business form or transaction, on-line display and report as a single data flow

When you believe that there is a separate process for each choice on all lowest-level menu options

8.658.65

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D. Delen MSIS 5653 – Advanced Systems Development

Using DFDs as Analysis ToolsUsing DFDs as Analysis ToolsGap Analysis

The process of discovering discrepancies between two or more sets of data flow diagrams or discrepancies within a single DFD

Simulation and/or Activity Based Costing

Inefficiencies in a system can often be identified through DFDs

8.668.66

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D. Delen MSIS 5653 – Advanced Systems Development

Using DFDs in Business Process Using DFDs in Business Process ReengineeringReengineering

Example: IBM Credit

8.678.67

As-IsAs-IsAvg.: 6 DaysAvg.: 6 Days

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D. Delen MSIS 5653 – Advanced Systems Development

Using DFDs in Business Process Using DFDs in Business Process ReengineeringReengineering

Example: IBM Credit (Continued…)

8.688.68

To-BeTo-BeAvg.: 4 HrsAvg.: 4 Hrs

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D. Delen MSIS 5653 – Advanced Systems Development

Oracle’s Process ModelerOracle’s Process Modeler

8.718.71

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D. Delen MSIS 5653 – Advanced Systems Development

Oracle’s Process Modeler and Oracle’s Process Modeler and Functional Hierarchy DiagramsFunctional Hierarchy Diagrams

Functional Hierarchy Diagrams

8.728.72

Picture of various tasks performed in a business and how they are hierarchically related

Similar to IDEF0 Function Diagrams

Does not include data flows

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D. Delen MSIS 5653 – Advanced Systems Development

SummarySummaryData flow diagrams (DFD)

Symbols Rules for creating Decomposition Balancing

Four different kinds of DFDs Current Physical Current Logical New Logical New Physical

DFDs for Analysis and BPROracle’s Process Modeler and Functional Hierarchy Diagrams

8.738.73

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D. Delen MSIS 5653 – Advanced Systems Development

Figure 8.26 – Page 273Figure 8.26 – Page 273

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D. Delen MSIS 5653 – Advanced Systems Development

Figure 8.27 – Page 274Figure 8.27 – Page 274

D1

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D. Delen MSIS 5653 – Advanced Systems Development

Problem and Exercises #1Problem and Exercises #1Scenario: Retail clothing store in a mall

1. List all relevant sources/sinks, processes, data stores and data flows

2. Draw a context diagram

3. Draw a level-0 diagram

0Point-of-Sale

SystemCustomer

StoreManager

Payment

Receipt

PurchaseRequest

ManagementReports

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D. Delen MSIS 5653 – Advanced Systems Development

Scenario: Retail clothing store in a mallScenario: Retail clothing store in a mallLevel-0 DiagramLevel-0 Diagram

ManagementReports

StoreManager

Payment

Customer PurchaseRequest

Receipt

1.0Process

PurchaseRequest

3.0Update

InventoryFile

2.0Update

Goods SoldFile

4.0Update

Total-SalesFile

InventoryData

Sales DataGoods Sold

Data

Goods SoldFile

InventoryFile

Total-SalesFile

FormattedGoods Sold Info

FormattedInventory Info

FormattedTotal-Sales Info

5.0Generate

ManagementReports

InventoryAmounts

Goods SoldAmounts

SalesTotals

D1 D2 D3