System Development
description
Transcript of System Development
System Development
ทั�ศนวรรณ ศนย์�กลางภาคว�ชาคอมพิ�วเตอร� คณะ
ว�ทัย์าศาสตร�
เน��อหาบรรย์าย์• Overview of
Information Systems (IS)
• Information Technology Concepts
• Business and Specialized IS
• System Development
• IS in Business and Society Components of an IS
2
Overview• Participants• Information Systems
Planning Investigation and Analysis Design and Implementation Maintenance and Review
• Tools
3
Participants
Principles of Information Systems, Ninth Edition
5
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
Principles of Information Systems, Ninth Edition
6
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
resources needed to complete a project on time
Principles of Information Systems, Ninth Edition
7
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
Principles of Information Systems, Ninth Edition 8
Participants in Systems Development (continued)
Information Systems Planning
Principles of Information Systems, Ninth Edition
10
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.
Principles of Information Systems, Ninth Edition
11
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
Principles of Information Systems, Ninth Edition 12
Information Systems Planning
Principles of Information Systems, Ninth Edition 13
Aligning Corporate and IS Goals
Principles of Information Systems, Ninth Edition
14
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
Principles of Information Systems, Ninth Edition
15
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
Principles of Information Systems, Ninth Edition
16
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
Principles of Information Systems, Ninth Edition
17
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
Principles of Information Systems, Ninth Edition 18
Systems Development Life Cycles (continued)
Principles of Information Systems, Ninth Edition
19
Systems Development Life Cycles (continued)
• Common systems development life cycles:– Traditional– Prototyping– Rapid application development (RAD)– End-user development
Principles of Information Systems, Ninth Edition
20
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
it must do to obtain the problem’s solution
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
Principles of Information Systems, Ninth Edition
21
Principles of Information Systems, Ninth Edition 22
The Traditional Systems Development Life Cycle (continued)
Principles of Information Systems, Ninth Edition 23
The Traditional Systems Development Life Cycle (continued)
Principles of Information Systems, Ninth Edition
24
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
formats
Principles of Information Systems, Ninth Edition 25
Prototyping (continued)
Principles of Information Systems, Ninth Edition 26
Prototyping (continued)
Principles of Information Systems, Ninth Edition 27
Prototyping (continued)
Principles of Information Systems, Ninth Edition
28
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– Extreme programming (XP)
Principles of Information Systems, Ninth Edition 29
Rapid Application Development, Agile Development, Joint Application
Development, and Other Systems Development Approaches (continued)
Principles of Information Systems, Ninth Edition
30
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
Principles of Information Systems, Ninth Edition
31
Outsourcing and On-Demand Computing
• Reduces costs• Obtains state-of-the-art technology• Eliminates staffing and personnel
problems• Increases technological flexibility
Principles of Information Systems, Ninth Edition 32
Outsourcing and On-Demand Computing (continued)
Principles of Information Systems, Ninth Edition
33
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
Principles of Information Systems, Ninth Edition
34
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
Principles of Information Systems, Ninth Edition 35
Degree of Change (continued)
Principles of Information Systems, Ninth Edition
36
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
Principles of Information Systems, Ninth Edition 37
Quality and Standards (continued)
Principles of Information Systems, Ninth Edition
38
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
entire project
Principles of Information Systems, Ninth Edition
39
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
Principles of Information Systems, Ninth Edition
40
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
Principles of Information Systems, Ninth Edition 41
Use of Computer-Aided Software Engineering (CASE) Tools (continued)
Principles of Information Systems, Ninth Edition
42
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
Principles of Information Systems, Ninth Edition
43
Object-Oriented Systems Development (continued)
• OOSD tasks (continued):– Design system– Program or modify modules– User evaluation– Periodic review and modification
Principles of Information Systems, Ninth Edition
44
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)?
• What are the associated risks?
Principles of Information Systems, Ninth Edition
45
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
Principles of Information Systems, Ninth Edition
46
Participants in Systems Investigation
• Members of development team change from phase to phase
• Keys to successful investigation teams:– Cooperation and collaboration
Principles of Information Systems, Ninth Edition 47
Participants in Systems Investigation (continued)
Principles of Information Systems, Ninth Edition
48
Feasibility Analysis
• Technical feasibility• Economic feasibility• Net present value• Legal feasibility• Operational feasibility• Schedule feasibility
Principles of Information Systems, Ninth Edition 49
Feasibility Analysis (continued)
Principles of Information Systems, Ninth Edition
50
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
Principles of Information Systems, Ninth Edition 51
Object-Oriented Systems Investigation (continued)
Principles of Information Systems, Ninth Edition
52
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
Principles of Information Systems, Ninth Edition 53
The Systems Investigation Report (continued)
Principles of Information Systems, Ninth Edition
54
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
Principles of Information Systems, Ninth Edition
55
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
Principles of Information Systems, Ninth Edition
56
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
Principles of Information Systems, Ninth Edition
57
Data Collection
• Identifying sources of data– Internal and external sources
• Collecting data– Interviews– Direct observation– Questionnaires
Principles of Information Systems, Ninth Edition 58
Identifying Sources of Data
Principles of Information Systems, Ninth Edition 59
Collecting Data
Principles of Information Systems, Ninth Edition
60
Data Analysis
• Data modeling• Activity modeling• Application flowcharts• Grid charts• CASE tools
Principles of Information Systems, Ninth Edition 61
Data Analysis (continued)
Principles of Information Systems, Ninth Edition
62
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
Principles of Information Systems, Ninth Edition 63
Requirements Analysis (continued)
Principles of Information Systems, Ninth Edition
64
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
Principles of Information Systems, Ninth Edition 65
Object-Oriented Systems Analysis (continued)
Principles of Information Systems, Ninth Edition
66
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
Principles of Information Systems, Ninth Edition 67
The Systems Analysis Report (continued)
Principles of Information Systems, Ninth Edition
68
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
Principles of Information Systems, Ninth Edition
69
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
Principles of Information Systems, Ninth Edition
70
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
Principles of Information Systems, Ninth Edition 71
Object-Oriented Design (continued)
Principles of Information Systems, Ninth Edition
72
Interface Design and Controls
• System characteristics: – Sign-on procedure– Interactive processing– Help facility– Lookup tables– Restart procedure
Principles of Information Systems, Ninth Edition 73
Interface Design and Controls (continued)
Principles of Information Systems, Ninth Edition 74
Interface Design and Controls (continued)
Principles of Information Systems, Ninth Edition
75
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
Principles of Information Systems, Ninth Edition
76
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
Principles of Information Systems, Ninth Edition
77
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
Principles of Information Systems, Ninth Edition 78
Generating Systems Design Alternatives (continued)
Principles of Information Systems, Ninth Edition
79
Evaluation Techniques
• Group consensus• Cost/benefit analysis• Benchmark tests• Point evaluation
Principles of Information Systems, Ninth Edition 80
Evaluation Techniques (continued)
Principles of Information Systems, Ninth Edition 81
Evaluation Techniques (continued)
Principles of Information Systems, Ninth Edition
82
Freezing Design Specifications
• User agrees in writing that the design is acceptable
• Other organizations:– Allow or even encourage design
changes
Principles of Information Systems, Ninth Edition 83
Freezing Design Specifications (continued)
Principles of Information Systems, Ninth Edition
84
The Contract
• Vendors provide standard contracts to protect themselves
• Typically, the request for proposal becomes part of the contract
Principles of Information Systems, Ninth Edition
85
The Design Report
• Primary result of systems design• Reflects decisions made and
prepares the way for systems implementation
Principles of Information Systems, Ninth Edition 86
The Design Report (continued)
Principles of Information Systems, Ninth Edition
87
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
Principles of Information Systems, Ninth Edition
88
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 – Integrated development environment
Principles of Information Systems, Ninth Edition
89
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
Principles of Information Systems, Ninth Edition
90
User Preparation
• Readying managers, decision makers, employees, other users, and stakeholders for new systems
• Important, but often ignored area of systems implementation
Principles of Information Systems, Ninth Edition
91
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
Principles of Information Systems, Ninth Edition
92
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
Principles of Information Systems, Ninth Edition
93
Data Preparation
• Also called data conversion• Ensuring all files and databases are
ready to be used with new computer software and systems
Principles of Information Systems, Ninth Edition
94
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
Testing
• Unit testing• System testing• Volume testing • Integration testing • Acceptance testing• Alpha testing• Beta testing
Principles of Information Systems, Ninth Edition
95
Principles of Information Systems, Ninth Edition
96
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
Principles of Information Systems, Ninth Edition
97
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
Principles of Information Systems, Ninth Edition
98
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
Principles of Information Systems, Ninth Edition
99
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
Principles of Information Systems, Ninth Edition
100
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
Principles of Information Systems, Ninth Edition
101
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
Principles of Information Systems, Ninth Edition
102
Performing Maintenance
• Maintenance team– Responsible for modifying, fixing, and
updating existing software
• Maintenance function– Becoming more automated
Principles of Information Systems, Ninth Edition
103
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
Principles of Information Systems, Ninth Edition 104
The Relationship Between Maintenance and Design (continued)
Principles of Information Systems, Ninth Edition
105
Systems Review
• Final step of systems development• Analyzes systems to make sure that
they are operating as intended
Principles of Information Systems, Ninth Edition
106
Types of Review Procedures
• Event-driven review– Triggered by a problem or opportunity
• Time-driven review – Performed after a specified amount of
time
Principles of Information Systems, Ninth Edition 107
Types of Review Procedures (continued)
Principles of Information Systems, Ninth Edition
108
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
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– Creates considerable system documentation– Produces many intermediate products for review
Principles of Information Systems, Ninth Edition
109
Principles of Information Systems, Ninth Edition
110
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– Use of quality programs and standards
Principles of Information Systems, Ninth Edition
111
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
Principles of Information Systems, Ninth Edition
112
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
Principles of Information Systems, Ninth Edition
113
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
thorough
Principles of Information Systems, Ninth Edition
114
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