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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
An Introduction toObject-Oriented
Systems Analysis and Design with UML and
the Unified Process
McGraw-Hill, 2004
Stephen R. [email protected]
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
CHAPTER 1
INTRODUCTION TO INFORMATION SYSTEMS
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Chapter Overview
Categories of Information Systems Traditional Information System Development
– The Requirements Phase– The Analysis Phase– The Design Phase– The Implementation Phase– The Maintenance Phase– Retirement
Slide 1.4
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Chapter Overview (contd)
Why There Is No Planning Phase Why There Is No Testing Phase Why There Is No Documentation Phase Systems Analysis and Design Maintenance Information Technology Professionals
Slide 1.5
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Jethro’s Boot Emporium
Automated reordering system
Jethro’s formula for predicting future trends
The formula works perfectly …
… at first
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Definitions
Artifact– Component
System– Set of artifacts that achieve some outcome
Information system– System that achieves a business outcome
Computerized information system– COTS (commercial off-the-shelf) package– Custom information system
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Custom Information System
Stakeholders– Client– Users– Developers
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
COTS Software
Shrinkware
Clickware
Stakeholders– Users– Developers
Enterprise Resource Planning (ERP) system– Examples: PeopleSoft, SAP
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Traditional Information System Development
Information system life cycle– The way that software is constructed
Six traditional phases
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Overview of the Traditional Phases
Requirements phase– Find the client’s requirements– Draw up the requirements document
Analysis phase– Draw up the specification document– Draw up the project management plan
Design phase– Determine the modules– Determine algorithms and data structures for each
module
Slide 1.11
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Overview of the Traditional Phases (contd)
Implementation phase– Translate the modules into a programming language– Integrate the modules
Maintenance phase– Modify the system
» Remove any remaining faults » Extend the system in some way
Retirement– The system no longer provides a useful service
Slide 1.12
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Why There Is No Planning Phase
We cannot plan until we have accurate, detailed information
There are three types of planning activities:– There is preliminary planning at the start of the project– The project management plan is drawn up after the
specifications have been approved by the client– Management monitor the plan all through the project
Slide 1.13
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Why There Is No Planning Phase (contd)
Planning activities are carried out all through the life cycle
There is no separate planning phase
Slide 1.14
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Why There is No Testing Phase
Checking the information system just before delivery is much too late
An information system must be checked continually
There is no separate testing phase
Slide 1.15
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Why There Is No Documentation Phase
The documentation must be complete, correct, and up to date at all times– Personnel turnover in the information system industry– Performing a phase requires the documentation from
the previous phase
Testing activities require documentation
Maintenance activities require documentation
There is no separate documentation phase
Slide 1.16
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Systems Analysis and Design
The word analysis is used in two different ways:– Analysis: Phase 2– Systems analysis: Phases 1 and 2
The term systems analyst is also used in two different ways– Responsible for Phases 1 and 2; or– Responsible for Phases 1, 2, and 3
The second usage is more common– That is the way systems analyst is used in this book
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Maintenance
Bad information systems are thrown away
Good information systems are maintained for many years
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
The Financial Implications of Maintenance
For very $1 spent on development, at least $2 is spent on maintenance
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Maintenance Activities
There are three main maintenance activities:
Corrective maintenance– Fixing faults
Perfective maintenance – Adding functionality
Adoptive maintenance– Making changes because the environment changes
– (Enhancement: Corrective + Perfective maintenance)
Slide 1.20
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Software Organizations
Software– Computer program (code) + documentation
Many organizations produce software– They employ systems analysts
Some organizations outsource
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Software Organizations
Organizations like Microsoft and Oracle produce software – As a primary product
Organization like General Motors and General Electric produce software– But not as a primary product
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Typical Information Systems Division
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Information Technology Professionals
Technical positions– Programmer– Programmer/analyst– Systems analyst
Alternative career path– Business analyst– Acquire programming skills Systems analyst
Slide 1.24
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Information Technology Professionals (contd)
Management hierarchy– Manager for information system development– Vice-President for information system development– Chief information officer (CIO)– Chief executive officer (CEO)
Slide 1.25
Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Essential Systems Analyst Skills
Technical skills
Communication skills
Programming knowledge
Sufficient technical knowledge to able to consult– Database administrator– Network administrator – Systems programmers– Software engineers
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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
Ethical Issues
Systems analysts must be ethical in every way
Example: Excerpt from the Code of Ethics of AITP
“I acknowledge:That I have an obligation to my College or University, therefore, I shall uphold its ethical and moral principles.That I have an obligation to my employer whose trust I hold, therefore, I shall endeavor to discharge this obligation to the best of my ability, to guard my employer's interests, and to advise him or her wisely and honestly.I accept these obligations as a personal responsibility and as a member of this Association. I shall actively discharge these obligations and I dedicate myself to that end.”
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