Transcript Information Technology Concepts

System Development
ทัศนวรรณ ศูนยกลาง
์
ภาควิชาคอมพิวเตอร ์ คณะ
เนื้อหาบรรยาย
• Overview of
Information
Systems (IS)
• Information
Technology
Concepts
• Business and
Specialized IS
• System
Components of an IS
2
Overview
• Participants
• Information Systems Planning
 Investigation and Analysis
 Design and Implementation
 Maintenance and Review
• Tools
3
Participants
An Overview of Systems
Development
• Today, users of information systems are
involved in their development
• This chapter will:
– Help you avoid systems development failures
or projects that go over budget
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Participants in Systems
Development
• Development team
– Determines objectives of the information
system
– Delivers system that meets objectives
• Project
– Planned collection of activities that achieves a
goal
• Project manager
– Responsible for coordinating all people and
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resources
needed to6 complete a project on
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Participants in Systems
Development (continued)
• Stakeholders
– People who ultimately benefit from project
• Users
– People who will interact with the system
regularly
• Systems development specialists
– Systems analysts
– Programmers
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Participants in Systems Development
(continued)
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Information Systems
Planning
Initiating Systems Development
• Systems development initiatives
– Arise from all levels of an organization
– Can be planned or unplanned
• Number of reasons for initiating systems
development projects
– Mergers, acquisitions, federal regulations, etc.
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Information Systems Planning
and Aligning Corporate and IS
Goals
• Information systems planning
– Translating strategic and organizational goals
into systems development initiatives
• Aligning organizational goals and IS goals
– Critical for successful systems development
effort
• Developing a competitive advantage
– Creative analysis
– Critical analysis
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Information Systems Planning
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Aligning Corporate and IS Goals
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Establishing Objectives for
Systems Development
• Mission-critical systems
– Play pivotal role in organization’s continued
operations and goal attainment
• Critical success factors (CSFs)
– Factors essential to success of a functional
area of an organization
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Establishing Objectives for
Systems Development
(continued)
• Performance objectives
– Output quality or usefulness
– Output accuracy
– Speed at which output is produced
– Scalability of resulting system
– Risk of the system
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Establishing Objectives for
Systems Development
(continued)
• Cost objectives
– Development costs
– Costs of uniqueness of system application
– Fixed investments in hardware and related
equipment
– Ongoing operating costs
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Systems Development Life
Cycles
• The later in the SDLC an error is detected,
the more expensive it is to correct
– Previous phases must be reworked
– More people are affected
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Systems Development Life Cycles
(continued)
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Systems Development Life
Cycles (continued)
• Common systems development life cycles:
– Traditional
– Prototyping
– Rapid application development (RAD)
– End-user development
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The Traditional Systems
Development Life Cycle
• Systems investigation
– Identifies problems and opportunities and
considers them in light of business goals
• Systems analysis
– Studies existing systems and work processes
to identify strengths, weaknesses, and
opportunities for improvement
• Systems design
– Defines how the information system will do
what
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The Traditional Systems
Development Life Cycle
(continued)
• Systems implementation
– Creates or acquires various system
components detailed in systems design,
assembles them, and places new or modified
system into operation
• Systems maintenance and review
– Ensures the system operates as intended
– Modifies the system so that it continues to
meet changing business needs
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The Traditional Systems Development Life
Cycle (continued)
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The Traditional Systems Development Life
Cycle (continued)
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Prototyping
• An iterative approach
• Operational prototype
– Prototype that works
– Accesses real data files, edits input data,
makes necessary computations and
comparisons, and produces real output
• Nonoperational prototype
– A mock-up, or model
– Includes output and input specifications and
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Prototyping (continued)
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Prototyping (continued)
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Prototyping (continued)
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Rapid Application Development,
Agile Development, Joint
Application Development, and
Other Systems Development
Approaches
• Rapid application
development (RAD)
– Employs tools, techniques, and
methodologies designed to speed application
development
– Makes extensive use of the joint application
development (JAD)
• Other approaches to rapid development
– Agile development
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Rapid Application Development, Agile
Development, Joint Application
Development, and Other Systems
Development Approaches (continued)
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The End-User Systems
Development
• End-user systems development
– Systems development project in which
business managers and users assume the
primary effort
– Disadvantages
• Some end users do not have the training to
effectively develop and test a system
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Outsourcing and On-Demand
Computing
• Reduces costs
• Obtains state-of-the-art technology
• Eliminates staffing and personnel
problems
• Increases technological flexibility
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Outsourcing and On-Demand Computing
(continued)
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Factors Affecting Systems
Development Success
• Successful systems development:
– Delivers a system that meets user and
organizational needs on time and within
budget
• Critical for most systems development
projects:
– Getting users and stakeholders involved
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Degree of Change
• Continuous improvement projects
– High degree of success
– Relatively modest benefits
• Managing change
– Ability to recognize and deal with existing or
potential problems
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Degree of Change (continued)
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Quality and Standards
• Quality of project planning
– Bigger the project, the more likely that poor
planning will lead to significant problems
• Capability Maturity Model (CMM)
– One way to measure organizational
experience
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Quality and Standards (continued)
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Use of Project Management
Tools
• Project schedule
– Detailed description of what is to be done
• Project milestone
– Critical date for completion of a major part of
the project
• Project deadline
– Date that the entire project is to be completed
and operational
• Critical path
– Activities that, if delayed, would delay the
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Use of Project Management
Tools (continued)
• Program Evaluation and Review
Technique (PERT)
– Creates three time estimates for an activity
• Shortest possible time
• Most likely time
• Longest possible time
• Gantt chart
– Graphical tool used for planning, monitoring,
and coordinating projects
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Use of Computer-Aided
Software Engineering (CASE)
Tools
• CASE tools
– Automate many tasks required in a systems
development effort
– Encourage adherence to SDLC
• Companies that produce CASE tools:
– Accenture, Microsoft, and Oracle
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Use of Computer-Aided Software
Engineering (CASE) Tools (continued)
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Object-Oriented Systems
Development
• Combines logic of systems development
life cycle with power of object-oriented
modeling and programming
• OOSD tasks:
– Identify potential problems and opportunities
that would be appropriate for OO approach
– Define user requirements
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Object-Oriented Systems
Development (continued)
• OOSD tasks (continued):
– Design system
– Program or modify modules
– User evaluation
– Periodic review and modification
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Systems Investigation
• What primary problems might a new or
enhanced system solve?
• What opportunities might a new or
enhanced system provide?
• What new hardware, software, databases,
telecommunications, personnel, or
procedures will improve an existing
system or are required in a new system?
• What are the potential costs (variable and
fixed)?
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Initiating Systems Investigation
• Systems request form
– Submitted by someone who wants IS
department to initiate systems investigation
– Information included
•
•
•
•
Problems in or opportunities for system
Objectives of systems investigation
Overview of proposed system
Expected costs and benefits of proposed system
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Participants in Systems
Investigation
• Members of development team change
from phase to phase
• Keys to successful investigation teams:
– Cooperation and collaboration
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Participants in Systems Investigation
(continued)
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Feasibility Analysis
•
•
•
•
•
•
Technical feasibility
Economic feasibility
Net present value
Legal feasibility
Operational feasibility
Schedule feasibility
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Feasibility Analysis (continued)
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Object-Oriented Systems
Investigation
• Object-oriented approach
– Can be used during all phases of systems
development
• Use case diagram
– Part of the Unified Modeling Language (UML)
that is used in object-oriented systems
Development
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Object-Oriented Systems Investigation
(continued)
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The Systems Investigation
Report
• Summarizes results of systems
investigation
• Summarizes the process of feasibility
analysis
• Recommends a course of action
– Continue on into systems analysis
– Modify the project in some manner
– Drop the project
• Reviewed by steering committee
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The Systems Investigation Report
(continued)
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Systems Analysis
• Overall emphasis of analysis:
– Gathering data on existing system
– Determining requirements for new system
– Considering alternatives
– Investigating feasibility of solutions
• Primary outcome of systems analysis:
– Prioritized list of systems requirements
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General Considerations
• Steps of a formalized analysis procedure:
– Assembling participants for systems analysis
– Collecting data and requirements
– Analyzing data and requirements
– Preparing a report on existing system, new
system requirements, and project priorities
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Participants in Systems Analysis
• Includes members of the original
investigation team
• Systems analysis team develops:
– List of objectives and activities
– Deadlines
– Statement of resources required
– Major milestones
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Data Collection
• Identifying sources of data
– Internal and external sources
• Collecting data
– Interviews
– Direct observation
– Questionnaires
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Identifying Sources of Data
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Collecting Data
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Data Analysis
•
•
•
•
•
Data modeling
Activity modeling
Application flowcharts
Grid charts
CASE tools
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Data Analysis (continued)
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Requirements Analysis
• Determination of user, stakeholder, and
organizational needs
• Techniques:
– Asking directly
– Critical success factors (CSFs)
– IS plan
– Screen and report layout
– Requirements analysis tools
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Requirements Analysis (continued)
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Object-Oriented Systems
Analysis
• Identify problems or potential opportunities
• Identify key participants and collect data
• With the OO approach a class is used to
describe different types of objects
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Object-Oriented Systems Analysis
(continued)
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The Systems Analysis Report
• Elements:
– Strengths and weaknesses of existing system
from a stakeholder’s perspective
– User/stakeholder requirements for new
system
– Organizational requirements for new system
– Description of what new information system
should do to solve the problem
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The Systems Analysis Report (continued)
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Systems Design
• Answers the question:
– How will the information system solve a
problem?
• Results in a technical design that:
– Details system outputs, inputs, and user
interfaces
– Specifies hardware, software, databases,
telecommunications, personnel, and
procedures
– Shows how these components are related
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Logical and Physical Design
• Logical design
– Describes functional requirements of a
system
• Physical design
– Specifies the characteristics of the system
components necessary to put the logical
design into action
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Object-Oriented Design
• Using the OO approach:
– You can design key objects and classes of
objects in the new or updated system
– Process includes considering the problem
domain, the operating environment, and the
user interface
• During design phase consider the
sequence of events that must happen for
the system to function correctly
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Object-Oriented Design (continued)
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Interface Design and Controls
• System characteristics:
– Sign-on procedure
– Interactive processing
– Help facility
– Lookup tables
– Restart procedure
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Interface Design and Controls (continued)
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Interface Design and Controls (continued)
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Design of System Security and
Controls
• Preventing, detecting, and correcting
errors
• Disaster planning and recovery
– Disaster planning
– Disaster recovery
• Systems controls
– Closed shops
– Open shops
– Deterrence controls
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Environmental Design
Considerations
• Environmental design
– Also called green design
– Involves systems development efforts that
slash power consumption, require less
physical space, and result in systems that can
be disposed in a way that doesn’t negatively
affect the environment
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Generating Systems Design
Alternatives
• Request for proposal (RFP)
– Document that specifies required resources
such as hardware and software in detail
• Financial options:
– Purchase, lease, or rent
• Evaluating and selecting a systems design
– Preliminary evaluation
– Final evaluation
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Generating Systems Design Alternatives
(continued)
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Evaluation Techniques
•
•
•
•
Group consensus
Cost/benefit analysis
Benchmark tests
Point evaluation
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Evaluation Techniques (continued)
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Evaluation Techniques (continued)
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Freezing Design Specifications
• User agrees in writing that the design is
acceptable
• Other organizations:
– Allow or even encourage design changes
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Freezing Design Specifications (continued)
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The Contract
• Vendors provide standard contracts to
protect themselves
• Typically, the request for proposal
becomes part of the contract
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The Design Report
• Primary result of systems design
• Reflects decisions made and prepares the
way for systems implementation
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The Design Report (continued)
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Systems Implementation
• Includes:
– Hardware acquisition
– Programming and software acquisition or
development
– User preparation
– Hiring and training of personnel
– Site and data preparation
– Installation, testing, start-up, and user
acceptance
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Acquiring Software: Make or
Buy?
• Make-or-buy decision
– Whether to obtain software from external or
internal sources
• Externally acquired software and
Software as a Service (SaaS)
– Commercial off-the-shelf (COTS)
development process
• In-house developed software
– CASE and object-oriented approaches
– Cross-platform development
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Integrated
development
environment
Acquiring Database and
Telecommunications Systems
• Databases
– A blend of hardware and software
• Virtual databases and database as a
service (DaaS)
– Popular ways to acquire database capabilities
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User Preparation
• Readying managers, decision makers,
employees, other users, and stakeholders
for new systems
• Important, but often ignored area of
systems implementation
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IS Personnel: Hiring and
Training
• Eventual success of any system depends
on how it is used by the IS personnel
within the organization
• Training programs should be conducted
for the IS personnel who will be using the
computer system
– More detailed than user training in the
technical aspects of the systems
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Site Preparation
• Preparation of the location of a new
system
• Larger systems may require special
equipment
• Developing IS sites that are energy
efficient is important
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Data Preparation
• Also called data conversion
• Ensuring all files and databases are ready
to be used with new computer software
and systems
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Installation
• Process of physically placing computer
equipment on the site and making it
operational
• Normally, manufacturer is responsible for
installing computer equipment
• Someone from the organization (usually IS
manager) should oversee the process
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Testing
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•
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•
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Unit testing
System testing
Volume testing
Integration testing
Acceptance testing
Alpha testing
Beta testing
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Start-Up
• Process of making the final tested
information system fully operational
• Approaches
– Direct conversion (plunge, direct cutover)
– Phase-in approach (piecemeal)
– Pilot start-up
– Parallel start-up
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User Acceptance
• Formal agreement signed by user that
states that a phase of installation or the
complete system is approved
• Legal document that removes or reduces
IS vendor’s liability
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Systems Operation and
Maintenance
• Systems operation
– Use of a new or modified system
• Systems maintenance
– Checking, changing, and enhancing the
system to make it more useful in achieving
user and organizational goals
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Reasons for Maintenance
• Changes in business processes
• New requests from stakeholders, users,
and managers
• Bugs or errors in program
• Technical and hardware problems
• Corporate mergers and acquisitions
• Government regulations
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Types of Maintenance
• Slipstream upgrade
– Usually requires recompiling all the code
• Patch
– Minor change to correct a problem
• Release
– Significant program change
• Version
– Major program change
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The Request for Maintenance
Form
• Form authorizing modification of programs
• Usually signed by a business manager
• IS group:
– Reviews form
– Identifies programs to be changed
– Determines programmer to be assigned to
task
– Estimates expected completion date
– Develops a technical description of change
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Performing Maintenance
• Maintenance team
– Responsible for modifying, fixing, and
updating existing software
• Maintenance function
– Becoming more automated
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The Relationship Between
Maintenance and Design
• Programs are expensive to develop, but
they are even more expensive to maintain
• Determining factor in decision to replace a
system
– The point at which it is costing more to fix than
to replace
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The Relationship Between Maintenance
and Design (continued)
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Systems Review
• Final step of systems development
• Analyzes systems to make sure that they
are operating as intended
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Types of Review Procedures
• Event-driven review
– Triggered by a problem or opportunity
• Time-driven review
– Performed after a specified amount of time
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Types of Review Procedures (continued)
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System Performance
Measurement
• Monitoring the system
– Number of errors encountered
– Amount of memory required
– Amount of processing or CPU time needed
– Other problems
• System performance products
– Software that measures all components of the
computer-based information system
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Summary
• Systems development team
– Stakeholders, users, managers, systems
development specialists, and various support
personnel
• Five phases of the traditional SDLC:
– Investigation, analysis, design,
implementation, and maintenance and
review
• Advantages of the traditional SDLC:
– Provides for maximum
management control
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Summary (continued)
• Rapid application development (RAD)
– Reduces paper-based documentation
– Automates program source code generation
– Facilitates user participation in development
activities
• Factors that affect systems development
success:
– Degree of change introduced by the project
– Continuous improvement and reengineering
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– Ninth
Use
Systems,
Editionof quality programs and standards
Summary (continued)
• Participants in systems investigation:
– Stakeholders, users, managers, employees,
analysts, and programmers
• Data collection methods:
– Observation, interviews, questionnaires, and
statistical sampling
• Requirements analysis
– Determines the needs of users, stakeholders,
and the organization in general
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Summary
• Purpose of systems design:
– To prepare detailed design needs for a new
system
• Logical and physical design
– Can be accomplished using the traditional
systems development life cycle or the object
oriented approach
• Disaster recovery
– Important aspect of systems design
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Summary (continued)
• Purpose of systems implementation:
– To install the system and make everything,
including users, ready for its operation
• Software can be purchased from vendors
or developed in-house
• Cross-platform development and
integrated development environments
(IDEs)
– Make software development easier and more
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Summary (continued)
• Systems operation
– Use of a new or modified system
• Maintenance
– Can be as simple as a program patch to the
more complex upgrading of software with a
new release from a vendor
• Systems review
– Process of analyzing and monitoring systems
to make sure that they are operating as
intended
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