1st & 2nd lecture in the software engineering course

1. INTRODUCTION TO SOFTWARE ENGINEERING
1- INTRODUCTION
Prepared By:
Ahmed Alageed
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2. COURSE DETAILS
This Course will cover the following Topics:
 Introduction.
 Software Process Models.
 Requirements Analysis & Specification
 Design
 Coding
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3. COURSE DETAILS
 Testing
 Maintenance
 Computer Aided Software Engineering
(CASE)
 Software quality assurance
 Managing Software Projects
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4. LEARNING OBJECTIVES
After successfully completing the module
student should be :
 explain the software engineering principles
and techniques that are used in developing
quality software products
 apply software engineering principles and
techniques appropriately to develop
moderately complex software system
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5. ASSESSMENT METHOD
The assessment method will be as following:
 Final Exam: 60%
 Med-Term Exam:20%
 Tutorial & Presentation:20% ( including The
Lab. Remarks & attendance.
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6. COURSE LAB.
 In the practical part of this course you will
learn how to use CASE tools (UML) in
addition to do some tutorial related to the
course subjects.
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7. CONTACT INFO.
 You can contact me at any time by Email:
Aalageed@neelain.edu.sd
 I will be available at my office on Sat. from
12:00 PM to 2:00 PM
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8. COURSE REFERENCES
 Main Reading:
1. Software Engineering by Ian
Sommerville, 8th edition, Addison-
Wesley, 2006.
2. Software Engineering: A practitioner's
approach by Roger S. Pressman, 6th
edition, McGraw-Hill International
edition, 2005.
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9. COURSE REFERENCES
 Supplementary Reading
1. http://portal.acm.org/citation.cfm?id=1159393
2. http://www.vnunet.com/vnunet/news/211731
5/air-traffic-system-already-obsolete
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10. 1. INTRODUCTION
Instructional Objectives
 Describe what software is, different types of
software and software quality attributes
 Describe with the problems associated with
software and software development
 Define what software engineering is and
explain why it is important
 State some professional issues related to
software development
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11. 1.1 SOFTWARE
1.1.1. What is software? [Ref.1: pg. 5-6]
 Computer programs and associated
documentation such as requirements, design
models and user manuals in addition to data
structure.
 Software products may be developed for a
particular customer or may be developed for
a general market.
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12. 1.1.1 WHAT IS SOFTWARE
 Software products may be
 Generic - developed to be sold to a range of
different customers e.g. PC software such as
Excel or Word.
 Custom - developed for a single customer
according to their specification.
 New software can be created by developing
new programs, configuring generic software
systems or reusing existing software.
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13. 1.1 SOFTWARE
1.1.2. Types of software [Ref.2: pg. 40-41]
 System software
 Application Software.
 Engineering and scientific software
 Embedded software
 Product-line software.
 Web-based software
 Artificial intelligence software
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14. 1.1 SOFTWARE
1.1.3. Characteristics of Software [Ref.2: pg. 36-39]
[Ref.4]
 Software is differ form any other thing
that human beings build.
 Software is a logical rather than a
physical system element. Therefore
software has characteristics that are
considerably different than those of
hardware.
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15. 1.1.3. CHARACTERISTICS OF SOFTWARE
 Software is developed or engineered; it is not
manufactured in the classical sense.
 Software doesn’t “wear out”
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16. 1.1.3. CHARACTERISTICS OF SOFTWARE
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17. 1.1.3. CHARACTERISTICS OF SOFTWARE
 Although the industry is moving toward
component-based construction, most
software continues to be custom built
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18. 1.1 SOFTWARE
1.1.4. Attributes of good software [Ref.1: pg. 34-35]
 The software should deliver the required
functionality and performance to the
user and should be maintainable,
dependable and acceptable.
 Maintainability
 Software must evolve to meet changing
needs;
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19. 1.1.4. ATTRIBUTES OF GOOD SOFTWARE
 Dependability
 Software must be trustworthy;
 Efficiency
 Software should not make wasteful use of
system resources;
 Acceptability
 Software must accepted by the users for which it
was designed. This means it must be
understandable, usable and compatible with
other systems.
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20. SUCCESSFUL SOFTWARE SYSTEM
 Software development projects have not
always been successful.
 When do we consider a software application
successful?
 Development completed.
 It’s useful.
 It’s usable.
 And it’s used.
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21. REASONS FOR FAILURE
 Schedule slippage.
 Cost-over run.
 Does not solve user’s problem.
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22. REASONS FOR FAILURE
 Ad hoc software development results in such
problems:
 No planning of development works(e.g no
milestones defined).
 Deliverables to user not identified.
 Poor understanding of user requirements.
 No control or review.
 Technical incompetence of developers.
 Poor understanding of cost and effort by both
developer & user.
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23. ENGINEERING: OTHER DISCIPLINES
 Large projects common and successfully
done:
 Buildings bridges, Dams.
 Power plants
 Aircrafts
Engineering a solution:
 To design, develop( build, fabricates) an artifact
that meets specifications efficiently, cost-
effectively and ensuring quality
 Using scientific principles
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24. ENGINEERING
 Requires well-defined approach:
repeatable, predictable
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25. 1.2. SOFTWARE ENGINEERING
1.2.1. What is software engineering? [Ref.1: pg.
29]
 Software engineering is an engineering
discipline that is concerned with all aspects
of software production.
 Software engineers should adopt a
systematic and organised approach to their
work and use appropriate tools and
techniques depending on the problem to be
solved, the development constraints and the
resources available. 25

26. WHAT IS THE DIFFERENCE BETWEEN SOFTWARE
ENGINEERING AND COMPUTER SCIENCE?
 Computer science is concerned with theory
and fundamentals; software engineering is
concerned with the practicalities of
developing and delivering useful software.
 Computer science theories are still
insufficient to act as a complete underpinning
for software engineering (unlike e.g. physics
and electrical engineering).
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27. WHAT IS THE DIFFERENCE BETWEEN SOFTWARE
ENGINEERING AND SYSTEM ENGINEERING?
 System engineering is concerned with all
aspects of computer-based systems
development including hardware, software
and process engineering. Software
engineering is part of this process concerned
with developing the software infrastructure,
control, applications and databases in the
system.
 System engineers are involved in system
specification, architectural design, integration
and deployment.
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28. WHAT IS A SOFTWARE PROCESS?
 A set of activities whose goal is the
development or evolution of software.
 Generic activities in all software processes
are:
 Specification - what the system should do and its
development constraints
 Development - production of the software system
 Validation - checking that the software is what
the customer wants
 Evolution - changing the software in response to
changing demands.
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29. WHAT IS A SOFTWARE PROCESS MODEL?
 A simplified representation of a software
process, presented from a specific
perspective.
 Examples of process perspectives are
 Workflow perspective - sequence of activities;
 Data-flow perspective - information flow;
 Role/action perspective - who does what.
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30. WHAT IS A SOFTWARE PROCESS MODEL?
 Generic process models
 Waterfall;
 Iterative
development;
 Component-based software engineering.
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31. 1.2. SOFTWARE ENGINEERING
1.2.2. Software engineering costs [Ref.1: pg. 31-33]
 Roughly 60% of costs are development
costs, 40% are testing costs. For custom
software, evolution costs often exceed
development costs.
 Costs vary depending on the type of system
being developed and the requirements of
system attributes such as performance and
system reliability.
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32. 1.2.2. SOFTWARE ENGINEERING COSTS
 Distribution of costs depends on the
development model that is used.
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33. ACTIVITY COST DISTRIBUTION
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34. PRODUCT DEVELOPMENT COSTS
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35. 1.2. SOFTWARE ENGINEERING
1.2.3. What are the key challenges facing
software engineering? [Ref.1: pg. 35-36]
Heterogeneity, delivery and trust.
 Heterogeneity
 Developingtechniques for building software that
can cope with heterogeneous platforms and
execution environments;
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36. 1.2.3. WHAT ARE THE KEY CHALLENGES
FACING SOFTWARE ENGINEERING?
 Delivery
 Developing techniques that lead to faster
delivery of software;
 Trust
 Developing techniques that demonstrate that
software can be trusted by its users.
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37. 1.2. SOFTWARE ENGINEERING
1.2.5. Professional Practice [Ref.1: pg. 36-39; Ref.2: pg.
128-149]
 Confidentiality
 Engineers should normally respect the
confidentiality of their employers or clients
irrespective of whether or not a formal
confidentiality agreement has been signed.
 Competence
 Engineers should not misrepresent their level of
competence. They should not knowingly accept
work which is outwith their competence.
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38. 1.2.5. PROFESSIONAL PRACTICE
 Intellectual property rights
 Engineers should be aware of local laws
governing the use of intellectual property such
as patents, copyright, etc. They should be
careful to ensure that the intellectual property
of employers and clients is protected.
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39. 1.2.5. PROFESSIONAL PRACTICE
 Computer misuse
 Software engineers should not use their
technical skills to misuse other people’s
computers. Computer misuse ranges from
relatively trivial (game playing on an
employer’s machine, say) to extremely
serious (dissemination of viruses).
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