Transcript Chapter 5 Instructor Slides

Chapter 5
Data and Process Modeling
Chapter Objectives
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Describe software trends, including the
concept of software as a service
Explain software acquisition alternatives,
including traditional versus Web-based
software development strategies
Describe software outsourcing options,
including the role of service providers
Explain advantages and disadvantages of
developing software in-house versus other
alternatives
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Chapter Objectives
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Explain cost-benefit analysis and financial
analysis tools
Explain the differences between a
request for proposal (RFP) and a request
for quotation (RFQ)
Describe the contents of the system
requirements document
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Chapter Objectives
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Explain the transition from systems
analysis to systems design, and the
difference between logical and physical
design
Explain the transition to systems design
and the importance of prototyping
Discuss guidelines for system design,
and explain the importance of codes
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Introduction
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Chapter 5 describes the remaining
activities in the systems analysis phase
The chapter also describes the
transition to systems design,
prototyping, design guidelines, and
using codes to represent values and
simplify data entry
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Development Strategies
Overview
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Selecting the best development path is
an important decision that requires
companies to consider three key issues
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Web-based software trends
Software outsourcing options
In-house software development
alternatives
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Systems Development
Traditional Development
Legacy issues of compatibility
Web-based development
Web considered the platform
Local and wide area networks
Web issues are considered
enhancements
Scalability issues
Easily scaleable
Can be acquired as a service
(packaged systems)
Requires middleware to talk to legacy
systems
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Web-Based Software Trends
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The Changing Software Marketplace
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In the traditional model, software vendors
develop and sell application packages to
customers
In addition to traditional vendors, the
marketplace now includes many forms of
outsourcing, including application service
providers (ASP) and firms that offer
Internet business services
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Software Outsourcing Options
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Outsourcing is the transfer of
information systems development,
operation, or maintenance to an outside
firm that provides these services, for a
fee, on a temporary or long-term basis
Can refer to relatively minor
programming tasks or the handling of a
company’s entire IT function
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Software Outsourcing Options
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The Growth of Outsourcing
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Traditionally, firms outsourced IT tasks as a
way of controlling costs and dealing with
rapid technological change
Today, outsourcing is a vital business issue
that shapes a company’s overall IT strategy
the most important factor is the potential
saving in operating costs
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Software Outsourcing Options
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The Growth of Outsourcing
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A firm that offers outsourcing solutions is
called a service provider
Application service providers (ASP)
Internet business services (IBS)
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Also called managed hosting
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Software Outsourcing Options
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Outsourcing Fees
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A fixed fee model uses a set fee based on a
specified level of service and user support
A subscription model has a variable fee
based on the number of users or
workstations that have access
A usage model or transaction model
charges a variable fee based on the volume
of transactions or operations
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Software Outsourcing Options
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Outsourcing Issues and Concerns
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Mission-critical IT systems should be outsourced only if the result is a costattractive, reliable, business solution that
fits the company’s long-term business
strategy
out-sourcing can also affect day-to-day
company operations and can raise some
concerns
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Software Outsourcing Options
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Outsourcing Issues and Concerns
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A company must plan outsourcing carefully
to avoid lost revenue, added expenses, and
potential litigation
The solution can be only as good as the
outsourcing firm that provides the service
Outsourcing can be especially attractive to
a company whose volume fluctuates widely
A major disadvantage of outsourcing is
that it raises employee concerns about job
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security
In-House Software
Development Options
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A company can choose to develop its
own systems, or purchase, possibly
customize, and implement a software
package
The most important consideration is total
cost of ownership (TCO)
Companies also develop user
applications designed around commercial
software packages
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In-House Software
Development Options
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Make or Buy Decision
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The choice between developing versus
purchasing software often is called a make
or buy, or build or buy decision
The company’s IT department makes,
builds, and develops in-house software
A software package is obtained from a
vendor or application service provider.
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In-House Software
Development Options
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Make or Buy Decision
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Companies that develop software for sale
are called software vendors
Value-added reseller (VAR)
Vertical application (PkMS)
Horizontal application (MS Money)
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In-House Software
Development Options
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Purchasing a Software Package
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Lower costs
Requires less time to implement
Proven reliability and performance
benchmarks
Requires less technical development staff
Future upgrades provided by the vendor
Input from other companies
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In-House Software
Development Options
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Developing Software In-House
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Satisfy unique business requirements
Minimize changes in business procedures
and policies
Meet constraints of existing systems
Meet constraints of existing technology
Develop internal resources and capabilities
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In-House Software
Development Options
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Customizing a Software Package
1.
2.
3.
You can purchase a basic package that
vendors will customize to suit your needs
You can negotiate directly with the
software vendor to make enhancements
to meet your needs by paying for the
changes
You can purchase the package and make
your own modifications, if this is
permissible under the terms of the
software license
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Considerations in make, buy,
customize decision
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Cost
Time
Skills available
Technology available
Knowledge Base
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A Software Acquisition
Example
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Step 1: Evaluate the Information
System Requirements
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Identify key features
Consider network and web-related issues
Estimate volume and future growth
Specify hardware, software, or personnel
constraints
Prepare a request for proposal or quotation
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Request for proposal (RFP)
Evaluation model
Request for quotation (RFQ)
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A Software Acquisition
Example
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Step 2: Identify Potential Vendors or
Outsourcing Options
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The Internet is a primary marketplace
Another approach is to work with a
consulting firm
Another resource is the Internet bulletin
board systems that contains thousands of
forums, called newsgroups
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A Software Acquisition
Example
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Step 3: Evaluate the Alternatives
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Existing users
Application testing
Benchmarks
Match each package against the RFP
features and rank the choices
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A Software Acquisition
Example
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Step 4: Perform Cost-Benefit Analysis
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Identify and calculate TCO for each option
you are considering
When you purchase software, what you
are buying is a software license
If you purchase a software package,
consider a maintenance agreement
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A Software Acquisition
Example
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Step 5: Prepare a Recommendation
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You should prepare a recommendation that
contains your recommendation and lists
the alternatives, together with the costs,
benefits, advantages, and disadvantages of
each option
At this point, you may be required to
submit a formal system requirements
document and deliver a presentation
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A Software Acquisition
Example
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Step 6: Implement the Solution
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Implementation tasks will depend on the
solution selected
Before the new software becomes
operational, you must complete all
implementation steps, including loading,
configuring, and testing the software;
training users; and converting data files to
the new system’s format
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Completion of Systems
Analysis Tasks
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System Requirements Document
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The system requirements document, or
software requirements specification,
contains the requirements for the new
system, describes the alternatives that
were considered, and makes a specific
recommendation to management
Like a contract
Format and organize it so it is easy to
read and use
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Completion of Systems
Analysis Tasks
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Presentation to Management
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Begin your presentation with a brief
overview of the purpose and primary
objectives of the system project
Summarize the primary viable alternatives.
For each alternative, describe the costs,
advantages, and disadvantages
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Completion of Systems
Analysis Tasks
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Presentation to Management
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Explain why the evaluation and selection
team chose the recommended alternative
Allow time for discussion and for questions
and answers
Obtain a final decision from management
or agree on a timetable for the next step in
the process
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Completion of Systems
Analysis Tasks
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Presentation to Management
Based on their decision, your next task
will be one of the following
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Implement an outsourcing alternative
Develop an in-house system
Purchase or customize a software package
Perform additional systems analysis work
Stop all further work
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The Transition to System
Design
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If management decides to develop the
system in-house, then the transition to
the systems design phase begins
Preparing for Systems Design Tasks
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It is essential to have an accurate and
understandable system requirements
document
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The Transition to System
Design
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The Relationship between Logical and
Physical Design
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The logical design defines the functions
and features of the system and the
relationships among its components
The physical design of an information
system is a plan for the actual
implementation of the system
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Systems Design Guidelines
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The systems analyst must understand
the logical design of the system before
beginning the physical design of any
one component
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Data design
User interface
System design specification
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Systems Design Guidelines
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System Design Objectives
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The goal of systems design is to build a
system that is effective, reliable, and
maintainable
A system is reliable if it adequately handles
errors
A system is maintainable if it is well
designed, flexible, and developed with
future modifications in mind
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Systems Design Guidelines
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System Design Objectives
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User considerations
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Carefully consider any point where users
receive output from, or provide input to, the
system
Anticipate future needs of the users, the
system, and the organization
Provide flexibility
Parameter, default
Data Considerations
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Data should be entered into the system where
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and when it occurs because delays cause errors
Systems Design Guidelines
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System Design Objectives
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Data Considerations
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Automated methods of data entry should be
used whenever possible
Access for data entry should be controlled and
all entries or changes to critical data values
should be reported – audit trails
Every instance of entry and change to data
should be logged
Data should be entered into a system only once
Data duplication should be avoided
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Systems Design Guidelines
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System Design Objectives
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Architecture considerations
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Use a modular design
Design modules that perform a single function
are easier to understand, implement, and
maintain
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Prototyping
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Prototyping produces an early, rapidly
constructed working version of the
proposed information system, called a
prototype
Prototyping allows users to examine a
model that accurately represents
system outputs, inputs, interfaces, and
processes
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Prototyping
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Prototyping Methods
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System prototyping
Design prototyping
Throwaway prototyping
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Prototyping
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Prototyping Methods
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Prototyping offers many benefits
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Users and systems developers can avoid
misunderstandings
Managers can evaluate a working model more
effectively than a paper specification
Also consider potential problems
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The rapid pace of development can create
quality problems
In very complex systems, the prototype
becomes unwieldy and difficult to manage
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Prototyping
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Limitations of Prototypes
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A prototype is a functioning system, but it
is less efficient than a fully developed
system
Systems developers can upgrade the
prototype into the final information system
by adding the necessary capability
Otherwise, the prototype is discarded
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Using Codes During System
Design
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Overview of Codes
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Because codes often are used to represent
data, you encounter them constantly in
your everyday life
They save storage space and costs, reduce
transmission time, and decrease data entry
time
Can reduce data input errors
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Using Codes During System
Design
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Types of Codes
Sequence codes
Block sequence codes
Alphabetic codes
1.
2.
3.
a.
b.
Category codes
Abbreviation codes
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Using Codes During System
Design
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Types of codes
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Significant digit codes
Derivation codes
Cipher codes
Action codes
Self-checking codes
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Using Codes During System
Design
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Developing a Code
1.
2.
3.
4.
5.
6.
Keep codes concise
Allow for expansion
Keep codes stable
Make codes unique
Use sortable codes
Avoid confusing codes
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Using Codes During System
Design
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Developing a Code
7.
8.
9.
Make codes meaningful
Use a code for a single purpose
Keep codes consistent
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Chapter Summary
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This chapter describes system
development strategies, the preparation
and presentation of the system
requirements document, and the
transition to the systems design phase
of the SDLC
An important trend that views software
as a service, rather than a product, has
created new software acquisition
options
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Systems analysts must consider Web-
Chapter Summary
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The systems analyst’s role in the
software development process depends
on the specific development strategy
The most important factor in choosing a
development strategy is total cost of
ownership (TCO)
The process of acquiring software
involves a series of steps
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