Transcript Chapter 10: Systems Development

Chapter 10: Systems
Development
Succeeding with Technology:
Second Edition
Objectives

Describe the systems development life cycle, who
participates in it, and why it is important
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Discuss systems development tools
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Understand how systems development projects are
investigated
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Objectives (continued)
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Describe how an existing system can be evaluated
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Discuss what is involved in planning a new system
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List the steps to implement a new or modified
system
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Describe the importance of updating and monitoring
a system
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An Overview of Systems
Development
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Systems development process
 Typically called a systems development life cycle
(SDLC)
Systems investigation and analysis
 Looks at the existing system and determines if it
can and should be improved
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An Overview of Systems
Development (continued)
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Systems design and implementation
 Modifying an existing system or developing a new
one
Maintenance and review
 Makes sure that the new or modified system is
operating as intended
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Participants in Systems Development
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System stakeholders
 Individuals who will benefit from systems
development project
Users
 Individuals who will be interacting with the system
on a regular basis
Managers
 People most capable of initiating and maintaining
change
Systems analyst
 Specializes in analyzing and designing systems
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Why Start a Systems Development
Project?
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Creative analysis
 Investigating new approaches to existing problems
Critical analysis
 Being skeptical and doubtful
 Questioning whether or not the current computer
system is still effective and efficient
Systems development process
 Begins with gathering information on users’ needs
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End-User Systems Development
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The development of computer systems by
 Individuals outside of the formal computer systems
planning and departmental structure
Systems developed by end users
 Range from the very small to those of significant
organizational value
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Tools and Techniques for Systems
Development
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Systems development tools
 Can greatly simplify the systems development
process
 Include
 Computer-aided software engineering tools
 Flowcharts, decision tables
 Project management tools, prototyping,
 Outsourcing, and object-oriented systems
development
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Computer-Aided Software
Engineering
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Software engineering
 Employs computer-aided software engineering
(CASE) tools
CASE tools
 Automate many systems development tasks
 Allow more than one person to work on the same
system at the same time via a multiuser interface
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Flowcharts
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Reveal the path from a starting point to the final
destination
Can display various amounts of detail
When developing a system
 General flowchart describes the overall purpose and
structure of the system
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Decision Tables
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Can be used as an alternative to or in conjunction
with flowcharts
In general, a decision table displays
 The various conditions that could exist
 The different actions that the computer should take
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Project Management Tools
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Purpose is to plan, monitor, and control necessary
development activities
Program Evaluation and Review Technique (PERT)
 Creates three time estimates for an activity
 The shortest possible time
 The most likely time
 The longest possible time
Gantt charting
 A grid that lists activities and deadlines
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Prototyping
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The creation of a preliminary model or version of a
major subsystem
Iterative approach to systems development
 Each phase of the SDLC is repeated several times
(iterated)
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Outsourcing
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Use of outside company to take over portions of its
workload
Guidelines to make outsourcing a success
 Keep tight controls on the outsourcing project.
 Treat outsourcing companies as partners
 Start with smaller outsourcing job
 Create effective communications channels between
the organization and the outsourcing company
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Object-Oriented Systems
Development
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An extension of object-oriented programming
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Can be used during all phases of systems
development
Organizations
 Have saved time and money using the objectoriented approach to systems development
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Systems Investigation
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Overall purpose
 Determine whether objectives of existing system
satisfy the goals of the organization
Attempts to answer the following questions
 What primary problems might a new or enhanced
system solve?
 What opportunities might a new or enhanced
system provide?
 What are the potential costs?
 What are the associated risks?
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Feasibility Analysis
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Technical feasibility
 Concerned with whether or not hardware/software
can be acquired or developed to solve the problem
Economic feasibility
 Determines if the project makes financial sense
Legal feasibility
 Determines whether laws or regulations may
prevent or limit a systems development project
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Feasibility Analysis (continued)
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Operational feasibility
 Measure of whether or not the project can be put
into action or operation
Schedule feasibility
 Determines if the project can be completed in a
reasonable amount of time
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Systems Analysis
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Attempts to understand how the existing system
helps solve the problem identified in systems
investigation
Overall emphasis
 To gather data on the existing system and the
requirements for the new system
 To consider alternative solutions to the problem and
the feasibility of the solutions
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General Analysis Considerations
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Formalized analysis procedure involves
 Collecting appropriate data
 Analyzing the data
 Determining new system requirements and project
priorities
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Collecting Data
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Purpose
 To seek additional information about problems
identified during systems investigation
Techniques
 Interviews
 Direct observation
 Outputs
 Questionnaires
 Other Data Collection Methods
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Requirements Analysis
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Purpose
 To determine user, stakeholder, and organizational
needs
Tools and techniques
 Asking Directly
 Critical Success Factors
 Joint Application Development
 Rapid Application Development
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Systems Design
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Overall purpose
 To select and plan a system that meets the
requirements needed to deliver the problem solution
Results
 A new or modified system
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Generating Systems Design
Alternatives
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First step of design
 Investigate alternatives for all components
Request for information (RFI)
 Asks a computer systems vendor to provide
information about its products or services
Request for quotes (RFQ)
 Asks a computer systems company to give prices
for its products or services
Request for proposal (RFP)
 Generated during systems development
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Systems Implementation
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Includes
 Hardware acquisition
 Software acquisition or development
 User preparation
 Hiring and training of personnel
 Site and data preparation
 Installation, testing, startup, and user acceptance
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Acquiring Hardware
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Most people and organizations acquire hardware
and computers by
 Purchasing, leasing, or renting computer resources
from a computer systems vendor
“Pay as you go computing”
 Organization pays only for the computer power it
uses
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Selecting and Acquiring Software:
Make, Buy, or Rent
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Program specification
 Description of what the software must accomplish
Algorithm
 Step-by-step sequence of computer instructions
Syntax errors
 Errors in the use of the programming language
syntax
Logic errors
 Errors in the programming logic
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Acquiring Database and
Telecommunications Systems
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A database is one of the most important parts of
system development
 Many projects involve a database
 May require both hardware and software acquisition
Telecommunications is one of the fastest growing
business applications
 May require both hardware and software acquisition
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User Preparation
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Readying users and stakeholders for the new or
modified system
Can include
 Marketing
 Training
 Documentation
 Support
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Site Preparation
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Location of the new system needs to be prepared
For a small system
 May mean rearranging the furniture
Larger systems
 May require special wiring and air conditioning
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Data Preparation
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Converting manual files into computer files
Data conversion
 May be required to transform the existing
computerized files into the proper format
Permanent data
 Must be placed on a permanent storage device
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Installation
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Placing computer equipment on the site and making
it operational
For a small systems development project
 May require making room on top of a desk for a new
PC
 Plugging it into a wall outlet
 Following the manufacturer’s instructions to turn it
on
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Testing
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Unit testing
 Developing test data that will force the computer to
execute every statement in the program
System testing
 Requires the testing of all programs together
Volume testing
 Ensures that entire system can handle a large
amount of data under normal operating conditions
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Testing (continued)
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Integration testing
 Ensures that new programs can interact with other
major applications
Acceptance testing
 Ensures that new or modified system is operating as
intended
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Startup
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Direct conversion
 Stopping the old system and starting the new one
on a given date
Phase-in approach
 New system is slowly phased in, while old one is
slowly phased out
Pilot startup
 Running a pilot or small version of the new system
along with the old
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User Acceptance and
Documentation
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User acceptance document
 Agreement signed by user that a phase of the
complete system is approved
Documentation
 Includes all materials that describe the new or
modified system
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User Acceptance and
Documentation (continued)
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Systems documentation
 Describes the technical aspects of the new or
modified system
User documentation
 Describes how the system can be used by
noncomputer personnel
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Systems Maintenance and Review
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Final steps of systems development
Involves checking, changing, and enhancing the
system
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Reasons for Maintenance
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New requests from stakeholders, users, and
managers
Bugs or errors in the program
Technical and hardware problems
Corporate mergers and acquisitions
Governmental regulations that require changes in
programs
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The Financial Implications of
Maintenance
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For older programs
 Cost of maintenance can be up to five times greater
than cost of development
Average programmer
 Can spend from 50% - over 75% of his/her time
maintaining programs
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Systems Review
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Final phase of the systems development life cycle
Analyzing systems to make sure that they are
operating as intended
Two types of review procedures
 Event-driven review
 Time-driven review
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Summary
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Phases of the SDLC
 Investigation, analysis, design
 Implementation, maintenance, review
Common system development tools and techniques
 CASE tools
 Flowcharts
 Decision tables
Systems investigation
 First step in the development of a new or modified
computer system
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Summary (continued)
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Systems analysis
 The examination of existing systems
Systems design
 Prepares detailed design needs for new system or
modifications to the existing one
Systems implementation
 Includes hardware acquisition, software acquisition
or development, and user preparation
Systems maintenance
 Involves checking, changing, and enhancing the
system
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