Systems Development: Chapter 12

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Management
Information
Systems:
Solving Business
Problems with
Information Technology
Part Four:
Organizing Businesses
and Systems
Chapter Twelve:
Systems Development
Prof. Gerald V. Post
Prof. David L. Anderson
Transaction Processing
System
Input
Process
Systems Development
Communication
Information
Output
Systems Development Life
Cycle Consists Of Six Phases






Systems Planning
Systems Analysis
General Systems Design
Systems Evaluation and Selection
Detailed Systems Design
Systems Implementation
3 Categories of Systems Design
Global-Based Systems
 Group-Based Systems
 Local-Based Systems

Global-Based Systems


Large, Complex Information Systems that Process High
Transaction Volumes
Complete Overhaul or Replacement of Systems Design
Components
– Old output is changed from monthly tabular reports to online
screen displays
– New processes are developed
– Input captured by scanning devices
– Old hierarchical database is converted to new relational
database with standard query language
– Controls are installed
– New technology platform composed of enterprise-wide
network topology supports systems design components
Group-Based Systems

Serve a Single Department or other specific group of users
– smaller than, connected to global-based system
Local-Based Systems

Concentration on Local Environment
Rapid Application Development
Joint Application Development (JAD)
 Specialists with Advanced Tools (SWAT)
 Computer-Aided Systems and Software
Engineering (CASE Tools)
 Prototyping

Design Approaches
Process-Oriented Approach
 Data-Oriented Approach
 Object-Oriented Approach

Design Principles

Modularity
– Maintainability
– Reusability
 Libraries of object class catalogs
– Reliability
– Extendibility
– Standardized
– Independence
– Variety in Use
– Top-Down Design
 Start with Abstract Description of New System
 Refine View in Successive Steps
– Bottom-Up Design
 Start with Objects and Assemble them to completed
product
Process-Oriented Approach
Based upon Stable Set of Input, Process,
and Output
 Transactions-Based Applications

–
–
–
–
Accounts Payable
Accounts Receivable
Payroll
Inventory Control
Data-Oriented Approach
Undefined Systems Processes
 Define All Needed Data Attributes
 Systems Analysts must determine, with
users, how the system will be used

Data-Oriented Approach: Steps

Discuss potential decisions that will be
made from system with users of system
–
Model the purchasing decision support
system through use of flexible modeling
tool



–
–
Product Quality
Past Performance
Product Availability
Divide Each Criterion into Attributes
Develop Data Dictionary


Size, Type, Description, Limits and Exceptions, Ranges, Security
Level, Access Privileges
Changes, Description, Order
Object-Oriented Approach


Catalog objects
– Found by keywords
– In a Library or Database
Objects
– Exhibit certain behaviors
– Attributes and operations are encapsulated or
pulled together
– Operations describes how attributes are
processed
– Behave in certain ways in response to
messages
Object-Oriented Approach



Classes
– Set of Objects that share common structure
and behavior
Inheritance
– Objects receive attributes and operations from
other objects
– Add more attributes and operations of their
own
Polymorphism
– Ability of object to respond to and implement
each object
Object-Oriented Steps
Identify Object Class
 Identify Relationships
 Identify Attributes
 Determine Inheritance Relationships
 Build Class Hierarchy

–
–
–
Order
Transaction Process
Tools Inventory
Joint Application Development

Conceptual Systems Design Model
–
–
–
–
–
Data Flow Diagram
Entity Relationship Diagram
Decision Table
Screen Prototype
Decision Tree
SDLC Strengths
Provide Control over Development Process
 Formality

SDLC Weaknesses
Increased Cost of Development
 Lengthened Development Time
 Difficult when Project is Hard to Define

End-User Development
Users Develop the Prototypes
 Fourth-Generation Languages
 CASE Tools

Steps Toward Integration

Windowing Operating System
–
–
–

OS/2 Presentation Manager
Windows
X-Windows (Sun)
Transaction Processing Systems
–
–
–
–
Payroll Services
Sales Order Processing Systems
Process Control Systems
Corporate Accounting Systems
Steps Toward Integration

Multi-Tasking
–
–
–
–

Allow Users to run different programs at the
same time
Windows
OS/2 (Presentation Manager)
XWindows
Networks
–
Enable Dynamic Integration from Several
Sources
Integration

Vertical
–
–

Different Levels of Production
ex: Oil Company
Horizontal
–
–
Retail Stores
ex:Wal-Mart
Object-Orientation



Different than Transmitting Raw Bits of Data
– Hardware Connections
– Access Controls
– Simple Data Formats
Software Agents
– object-oriented programs written to perform specific tasks in
response to user requests
– agents know how to exchange object attributes
– agents have the ability to activate object functions in other
agents
Multimedia
– Integration of Text, Video, Sound, Pictures, Animation
Integration/Links


Static
– Hard-Coded
– Import
Dynamic
– Linked
– Dynamic Data Exchange (DDE)
– Hot-Linked
– Object-Linking and Embedding (OLE)
 Original Software Package Automatically started
when chosen
Systems Project Proposals


Feasibility Factors
– Technical
– Economic
– Legal
– Operational
– Schedule
Strategic Factors
– Productivity
– Differentiation
– Management
Systems Plan


Business Plan
– Document Company’s Goals and Objectives
– Align Systems Project with Company’s Business
Plan
Enterprise-Wide Model
– Entity Relationship Diagram showing relationship
between organization’s entities and their
relationship to supporting strategies of Business
Plan
– View of Future Organization of Enterprise under a
Business Plan
Two Levels of Planning

Systems Planning
–
–
–

Gives Managers, Users, and Information
Systems Personnel Projects
Establishes what should be done
Sets a budget for the total cost of these projects
Systems Project Planning
–
Setting a plan for the development of each
specific systems project
Systems Professional Skills






Systems Planning
– Form project team after proposed systems project is
cleared for development
Systems Analysis
– Business Systems Analysts knowledgeable in business
General Systems Design
– Business Systems Analysts
Systems Evaluation and Selection
– Business Systems Analysts
Detailed Systems Design
– Wide Range of Systems and Technical Designers
Systems Implementation
– Systems analysts, programmers, and special
technicians
Effective Leadership Style



Autocratic Style
– Crisis-Style Management
– Used to Correct Major Problem, such as Schedule
Slippage
Democratic Style
– Team-oriented Leadership
– Gives each team member the freedom to achieve
goals which he/she helped set
Laissez-Faire Style
– Highly-motivated, Highly-Skilled Team Members
– People who work best alone
Project Management Skills




Planning
– States what should be done
– Estimates how long it will take
– Estimates what it will cost
Leading
– Adapts to dynamics of enterprise and deals with setbacks
– Guides and induces people to perform at maximum
abilities
Controlling
– Monitors Progress Reports and Documented Deliverables
– Compares Plans with Actuals
Organizing
– Staffs a Systems Project Team
– Brings together users, managers, and team members
CASE





Computer-Aided Systems and Software Engineering
Increase Productivity of Systems Professionals
Improve the Quality of Systems Produced
Improve Software Maintenance Issue
Includes:
– workstations
– central repository
– numerous modeling tools
– project management
– Systems Development Life Cycle Support
– Prototyping Applications
– Software Design Features
Central Repository







Models Derived from Modeling Tools
Project Management Elements
Documented Deliverables
Screen Prototypes and Report Designs
Software Code from Automatic Code Generator
Module and Object Libraries of Reusable Code
Reverse Engineering, Reengineering, and
Restructuring Features
Software Maintenance



Reverse Engineering
– Extract original design from spaghetti-like, undocumented
code to make maintenance change request
– Abstract meaningful design specifications that can be used
by maintenance programmers to perform maintenance tasks
Reengineering
– Examination and changing of a system to reconstitute it in
form and functionality
– Reimplementation
Restructuring
– Restructures code into standard control constructs

sequence, selection, repetition
Work Group Technologies
Suite of Products
 GroupWare

Examples of Suite of Products



Microsoft Corporation
– Word
– Excel
– PowerPoint
Lotus Development Corporation
– AmiPro
– Lotus 1-2-3
– Freelance
Novell/Borland
– WordPerfect
– Borland
– dBaseIV
Advantages of Suite of Products
Integrated Document
 Economies of Scale
 Consolidated Training
 Shared Files Across Group

Disadvantages of Suite of Products
Choice Based upon Group Rather than
Advantages of Individual Product
 “Locked In” to Product Company
 Difficulty in Matching Client Requirements

Today’s Organization
Enterprise-Wide Development
 Object-Oriented Definition
 Implementation of Suite Approach

Unsuccessful Systems










Systems were developed which did not support business strategies and
objectives.
Poor systems planning and inadequate project management.
Failure to define or understand user requirements.
Negligence in estimating costs and benefits of the systems project.
Creation of a myriad of design defects and errors.
Acquisition of computers and software that no one needs or knows
how to use.
Installation of incompatible or inadequate technology.
Negligence in implementing adequate controls.
Development of unstructured, unmaintainable software.
Inadequate implementation tasks.
PDM
 Productivity
 Differentiation
 Management
Project Management
Gantt Chart
 Pert Chart

Gantt Chart
Compares Planned Performance against
actual performance to determine whether
the project is ahead of, behind, or on
schedule
 Schedule a complete systems project by
phases

PERT Chart






Estimate, Schedule, and Control a network of interdependent
tasks
Shown by arrows, nodes, or circles
Program, Evaluation and Renew Technique
Determine minimum time needed to complete a project, phase,
or task
Critical Path
– Minimum time needed to complete a project or phase
– Total of the most time-consuming chain of events
Four Steps
– Identify Tasks
– Determine Proper Sequence of Tasks
– Estimate the Time Required to Perform each Task
– Prepare Time-Scaled Chart of Tasks and Events to Determine
the Critical Path
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