Transcript Information Systems 1

IMS9001 - Systems Analysis and Design
INTRODUCTION:
INFORMATION SYSTEMS
DEVELOPMENT,
THE SYSTEMS DEVELOPMENT
LIFECYCLE (SDLC)
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Teaching Staff
 Lecturer:
 Caulfield day:
Dr. Peta Darke
Room S7.13 - Level 7, Chisholm Tower
email - [email protected]
telephone - 9903 2416
Make sure you obtain your tutor’s contact details and the
location and times your tutor is available for student
consultation
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Unit Information
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All unit materials:
lecture notes, tutorials, assignments, notices at
www.sims.monash.edu.au/subjects/IMS9001.nsf
No tutorials this week
Assessment:
 exam - 50%, assignment - 50%
 a pass requires a final mark of 50% or more
 hurdle - you must earn a minimum of 40% for the exam
AND a minimum of 40% for the assignments
 If either hurdle is not met, a result of 44 marks will be
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recorded even if the total mark is > 50
A System
 An assembly of components that interact
in an organised way to accomplish goals
 system elements
 a boundary, a purpose, an environment,
interfaces, inputs, processes, outputs,
feedback, constraints, subsystems
 E.g. natural systems: river systems, mountain
systems, solar system, respiratory system,
nervous system
artificial or man-made systems: computer,
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legal, education, information systems
Information Systems
 An information system is a “formal”
arrangement of people, data and processes
integrated to to manage complexity and
support and improve business operations
and the problem-solving and decisionmaking activities of managers.
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Data vs. Information
 Data - consists of raw or unstructured facts
(text, pictures, sound)
eg. Student number, Course code
 Information - data that is interpreted:
a collection of facts organised so that they
have meaning and use to a particular
recipient in a particular context,
additional value beyond the value of the
facts themselves
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Functions of an
Information System
Any information system performs four main
functions:
 data input - recording information
 data storage/retrieval - keeping information
 data processing - transforming information
 data output - displaying/presenting information
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Business Information System
Problems and Opportunities
 The need to build new information systems or change
existing ones comes about because:
 there are problems in the way in which existing systems
operate
AND/ OR
 changes in circumstances create opportunities to
improve things by doing them differently
AND/ OR
 new functions or activities are to be undertaken
e.g.
changing information needs, business expansion,
cost pressures,competitive pressures,
new business activities, inefficiencies
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Approaches to information
systems development
 early computer information systems development focused
on technology, programming and technical skills
 systems developers were technically trained and skilled,
and used rule-of-thumb and personal experience as the
basis for developing systems
 as computer use became more widespread, a backlog of
computer application requests developed, existing
applications increasingly required changes, and changes
made tended to have unexpected and undesirable effects
 these problems led to awareness of the need for an
overall accepted, standardised approach to system
development
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The Process of
System Development
 There is no 'universal' problem-solving
process which can meet the needs of all
system development situations
 Approaches to developing information
systems to solve business information
processing problems must be tailored to
meet the needs of the situation
 Some elements of the system development
process can be 'standardised' to some
degree
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The Systems Development
Lifecycle (SDLC)
The concept of the systems development life cycle
(SDLC) is an attempt at achieving this
standardisation. It provides:
 a systematic and orderly approach to solving
business information and processing problems
 a means of managing, directing, monitoring and
controlling the process of system building, including:
 a description of the process - steps to be followed
 deliverables - reports/programs/documentation/etc
 milestones - dates of completion of steps or
deliverables
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The Systems Development
Lifecycle (SDLC)
 it has several phases that define the progress
of the development process
 it can be adapted to suit the organisational,
human and technical needs of organisations
and system development projects
 there are many variants of the SDLC:
traditional “waterfall’ or linear model, iterative
model, spiral model etc.
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Benefits of SDLC
 breaks the problem-solving process into
manageable steps
 identifies and defines everything which needs to
be done, and how it should be done
 identifies the resources needed in each step
 identifies who will do each activity and when
they will do it
 provides a basis for project planning
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Guidelines for
System Development
 get the owners and users involved
 use a problem-solving approach
 establish phases and activities
 establish standards for consistent development
and documentation
 justify systems as capital investments
 don’t be afraid to cancel or revise project scope
 divide and conquer
 design systems for growth and change
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Systems Development Phases
Analysts Role
Initiation
Analysis
Design
Implementation
Documentation
Review
Ethics
Project Management
Maintenance
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Initiation (Why?)
 Is this project worth doing?
System
Users
Planned development project
Steering Committee
Survey Project
Feasibility
Feasibility
Report
(scope
defined)
Constraints
Unplanned
development
project
Problem/opportunity
details
ANALYSIS
System Owners
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Initiation
 a preliminary investigation of the problems,
opportunities, constraints and available resources
in order to decide on a course of action
 enhance existing system?
 develop a new information system?
 do nothing .. add it to the backlog?
 define the system scope: the functions/activities
which are to be developed/redeveloped:
poor scope management often results in
unsuccessful systems
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Initiation
 Defining the project scope includes
identifying:
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key stakeholder groups
perceived problems and opportunities
constraints
possible solutions & client expectations
 Key deliverable is a feasibility report:
 Includes overview of proposed solutions with
cost/benefit analyses for each solution
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Analysis (What?)
 Define the client’s requirements (What?)
INITIATION
System
Users
Feasibility Report
Problem/opportunity
details
System
Requirements
Specification Report
Analyse the problem
and define
requirements
System Requirements
Specification Report
DESIGN
System Owners
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Analysis
 “Don’t try to fix it unless you understand it”
 Study the existing system to thoroughly understand
the problems and opportunities
 Review findings with clients and revise scope if
necessary
 Clearly define WHAT the new system must do
 Agree on acceptance criteria for the new system
(signoff on the system specification)
 should the system specification be “frozen”?
 Assess feasibility again
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Design (How?)
 Define how the system will be implemented
ANALYSIS
System
Vendors
System
Requirements
Specification Report
Hardware/Software
deals
Various
Sources
Design
ideas/opinions
Select a design
strategy and specify
details
Technical Design
Report
Design Options
Selected Design
Option
Design in Progress
Report
IMPLEMENTATION
SystemOwners/
Users
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Design
 Generate a number of design options based on
technical, operational, economic, scheduling and
tendering constraints (HOW?)
 The client selects the best option for their needs
(assess feasibility again)
 Acquire the necessary hardware and software
 Design interfaces, databases, networks as
required
 Specify integration requirements and software
requirements (programs)
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Implementation (Build)
System
Users
 Build and deliver the system
DESIGN
User acceptance
testing
Technical
Design Report
User Documentation
System
Vendors
Hardware/
Software
Build, test, install
and deliver the
new system
User Training
Production System
System and
Technical
Documentation
MAINTENANCE
Project Report
System Owners
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Implementation
 Build/modify databases and networks
as required
 Build and test programs
 Prepare users for new system
 acceptance testing, user documentation,
user training, maintenance procedures
 Finalise system and technical
documentation
 Install the system
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Review
System
Users
 What went wrong/right? Why?
System Audit Report
Problems/New ideas
Auditor
Fixes and
enhancements
Review the
system and the
project
MAINTENANCE
Project issues and
system bugs
Project
Review Report
Steering Committee
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Review
 How well were the system and project
objectives met?
 Client’s requirements met, within budget, on
time?
 Can further benefits be realised?
 Are major changes required?
 How successful was the development process
.. what can we learn?
 Review the maintenance effort
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Maintenance
System
Users
 Fix it / Make it better
Fixes and
enhancements
Problems/New ideas
Maintain
the new
system
Additional training and
documentation
Technical problems and
new technology
Project staff
Escalating
maintenance
back to INITIATION
Modifications
PRODUCTION SYSTEM
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Maintenance
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Corrective - fix errors
Adaptive - satisfy changing needs
Perfective - enhance performance
Preventative - fix potential problems
 If the cost of maintenance is too high consider
other options:
 new development, purchase a software
package, re-engineer/modify
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Systems Development:
Cross Life Cycle Activities
Cross Life Cycle Activities are those which overlap many or
all of the life cycle phases. Some of these are:
 Quality - must be embedded in the process of systems
development to achieve a quality outcome
 Project Management - to monitor and control the project
and ensure it stays on track
 Documentation - essential at every stage to help ensure
project and system viability
 Ethics - voluntary compliance with guidelines of IS/IT
professional societies
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Quality
 Quality is defined as fitness for purpose and concerns
both process and product.
 Error detection and correction in analysis and design is
much cheaper than after the system is implemented.
 Achieving quality requires that organisational structures,
responsibilities, procedures, processes and resources for
implementing quality management are in place.
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Project management
 Select systems development methodology
 Plan the project tasks
 Estimate the resources and time required to complete
individual phases of the project
 Staff the project team
 Organise and schedule the project effort(tasks/time/
people/technical resources) and therefore cost
 Control the project development:
direct the team, monitor progress, replan, restaff,
reallocate resources
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Documentation
 Various types of documentation must be
produced throughout the SDLC
 The data dictionary plays an important role
during and after systems development:
 A repository for information about and
definitions of all “objects” identified during
development
 It supports and is maintained throughout the
system lifecycle
 It provides an important source for system
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documentation
Professional ethics
 Australian Computer Society (ACS)
Code of Ethics for IT professionals
 your reputation
 your client's interests
 confidentiality
 the client’s own and their competitors'
 impartiality
 honesty
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Systems Development:
The systems developer’s skills
Systems developers require many different skills
during the SDLC. Some of these are:
 Interpersonal skills - to communicate effectively, facilitate
groups, work in teams, manage expectations and change,
deal with organisational politics
 Analytical skills - to identify problems and determine
solutions
 Business knowledge - understanding of business systems
 Technical skills and knowledge - to use the technology, and
understand its potential and limitations
 Management skills - to manage resources, projects, risk,
and organisational change
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Building Information Systems:
The Role of the Systems Analyst
 To understand the business’s information needs
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what information is needed?
for whom?
in what form?
when?
 To describe the business’s information flows
 To identify problems and opportunities
 To suggest possible system solutions
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Analysis and Design in the SDLC
 Compare with the role of an architect in building a
house
 Analysis - finding out WHAT the client needs
 Design - deciding HOW to meet these needs
 Distinction between the two is not always as clear in
practice as it sounds in theory as they tend to
merge in practice (compare architect’s role)
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The Role of the Systems Analyst
 A systems analyst needs to be able to relate well to
a wide range of different sorts of people:
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business management
system users and owners
technical people (programmers, database programmers,
systems administrators, operations staff, data communications
and network specialists
consultants
vendors
 Critical Systems Thinking (CST), problem solving,
communication, business and IT skills
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Some Approaches to Systems
Development
There are many different approaches to developing
systems depending on the nature of the systems
and the users’ needs. Some of these are:
 Traditional Waterfall SDLC- “formal” approach
which partitions development into distinct phases
 Prototyping - an iterative process of building an
experimental system rapidly
 Application Packages - purchase commercially
available software
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Some Approaches to Systems
Development
 Joint Application Development (JAD) - a
workshop approach in which a facilitator, users,
managers and developers work intensively
together over a short period (days) to specify
requirements and design a system
 Participatory Design (PD) - where the central
focus is the users participating actively in
system development
 RAD - rapid application development using
techniques to build systems quickly where
appropriate
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Who does Systems
Development?
 The organisartion’s information technology
department
(in-house development)
 End-user computing - development of
systems by end-users with minimal assistance
 Outsourcing - contracting development to
external providers
 IT consultants
 Often a combination of the above
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References
 HOFFER, J.A., GEORGE, J.F. and VALACICH (2005) Modern
Systems Analysis and Design, (4th edition), Pearson
Education Inc., Upper Saddle River, New Jersey, USA. Chapter
1, Appendix 1
 WHITTEN, J.L., BENTLEY, L.D. and DITTMAN, K.C. (2001) 5th
ed., Systems Analysis and Design Methods, Irwin/McGraw-HilI,
New York, NY. Chapters 1,3,4
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