Software Engineering - Introduction and Motivation (Marcello Thiry)

marcello.thiry@gmail.comIntroduction and motivation

marcello.thiry@gmail.com
What are you
doing here?

marcello.thiry@gmail.comhttp://c4.quickcachr.fotos.sapo.pt/i/o51010754/6042055_Jtk8U.jpeg
Should I know
the answer!?

It says here
we will learn
about Software
Engineering!!
http://i0.wp.com/www.nerdglaze.com/wp-
content/uploads/2013/08/nerdy-dude.jpg?resize=450%2C305

marcello.thiry@gmail.com http://ideas.scup.com/pt/files/2013/06/conte%C3%BAdo.jpg
1. Engineering
2. Software Crisis
3. Software relevance
4. Software Engineering
5. Nature of software
6. Quality and Software Quality
7. Software types and domains
Contents.

create, design, construct,
build, devise, invent, ...
Engineer. (verb)
https://awordfromafriend.files.wordpress.com/2014/10/blocktower.jpg?w=500

create, design, construct,
build, devise, invent, ...
Engineer. (verb)

Engineering.
The application of scientific
or empirical methods

The application of scientific or
empirical methods to create,
improve and implement
Engineering.

improve and implement utilities
Engineering.

An utility must
perform an specific
function or goal

How to
develop something
useful?

 Study the problem
 Plan a solution
 Verify economic and
technical feasibility
 Coordinate the construction

But what is
Software
anyway?

John Tukey (1915-2000)
https://en.wikipedia.org/?title=John_Tukey
“In 1958, John Tukey, the
world-renowned statistician,
coined the term software”
(SWEBOK, 2014)

Collection of computer programs,
procedures, and possibly associate
documentation and data pertaining
to the operation of a computer
system
Software.
(IEEE Std 610.12.1990)

Documentation?!
Yeah, documentation!
But we will talk more
about it during our course

Just a
reminder:
The difficult part is
to produce USEFUL
documentation!!!

Thence,
Software
Engineering...

Software Engineering.
improve and implement software

“The term software
engineering was
used in the title of
a NATO conference held in Germany in 1968”
http://homepages.cs.ncl.ac.uk/brian.randell/NATO/

The origins of
Software
Engineering

Back in the day...
Popular Science, Jan 1965, 107
Business Week,
Nov 5, 1966, 127.
http://thecomputerboys.com/?tag=crisis
http://thecomputerboys.com/?tag=crisis

“Software Crisis”
or
“Software Gap”
Late 1960s, early 1970s...

•Many projects were failing or had been
abandoned
• Cost and budget overruns
• Software not reliable and
difficult to maintain
• Difficult to meet the user
requirements
The crisis...
https://kathleenkerridge.files.wordpress.com/2015/02/depre
ssion-week-image-300x300.jpg?w=300

•More powerful computers and
programming languages
• Demand growth
• More complex software
• More people involved
The crisis...
https://pamsblog666.files.wordpress.com/2011/06/computer20studies.jpg

•Improve professionals’ skills
• Methodologies
• Communication with users
• Team work
The crisis...
http://eolocomunicacion.com/wp-content/uploads/2015/05/fusionyadquisiciondempresas-e1431067600969.png

And today?

Software is everywhere...

 The avionics system in the F-22 Raptor
consists of about 1.7 Million LOC
 The Boeing’s 787 Dreamliner contains about 6.5
million LOC
 A premium-class automobile contains close to
100 million LOC
http://spectrum.ieee.org/transportation/systems/this-car-runs-on-code
LOC = lines of software code
http://3.bp.blogspot.com/--
ae42w82PVo/VEU2EOJmQXI/AAAAAAAABoM/x5vv
azR_BQM/s1600/homer-screaming.gif

Ubiquitous or pervasive Computing
Most people don’t even realize
how computing is part of their
lives today
And what is the
impact of this
on software?
http://betanews.com/wp-
content/uploads/2014/09/Internet-of-things.jpg

Do you realize the relevance of
software nowadays?
And what is your role on this?
https://portalbuzzuserfiles.s3.amazonaws.com/ou-
15436/userfiles/images/pointing%20finger.jpg

Let’s define
software
engineering
properly!

(1) The application of a systematic,
disciplined, quantifiable approach to the
development, operation, and maintenance of
software; that is, the application of
engineering to software.
(2) The study of approaches as in (1).
(IEEE Std 610.12.1990)

disciplined, quantifiable approach to
the development, operation, and maintenance
of software; that is, the application of
engineering to software.
(IEEE Std 610.12.1990)

disciplined, quantifiable approach to the
development, operation, and
maintenance of software; that is, the
application of engineering to software.
(IEEE Std 610.12.1990)

http://mrbakersgrade6.weebly.com/uploads/
2/4/7/6/24767728/6979844.jpg?339

Systematic
Principles
Discipline
Knowledge
Maintenance
Operation
Development
Reliable
Application
Technique
Method
Approach
Quality
Software
Procedures
Methodology
Team
Scientific
Practical
Design
Tool
Productivity

And if you have to explain the
nature of software right now?
This was a
question!

I need to
understand the
nature of
software…

Frederick Phillips Brooks, Jr.
(1931-)
https://en.wikipedia.org/wiki/Fred_Brooks
“In 1986, Fred Brooks wrote the
famous paper No Silver Bullet
– Essence and Accident of
Software Engineering”
http://faculty.salisbury.edu/~xswang/Research/Papers/SERelated/no-silver-bullet.pdf
American computer architect, software
engineer, and computer scientist. He is
also the author of the seminal book
“The Mythical Man-Month (1975)”.

http://www.polyvore.com/cgi/img-
thing?.out=jpg&size=l&tid=32131103
“… building software will
always be hard. There is no
silver bullet.”
(Brooks, 1986)
There is no single technique or technology, which
by itself can improve some aspect of software
development 10x in 10 years…

Essence
Difficulties
in Software
Development
Accidents
Inherent in the nature of the software
mapping specification to software and
verifying that the design properly meets
business needs
Related to the production of software
and not inherent
Brooks, 1986
Most methods and techniques
attack the accidents

Just a
reminder:
Accidental occurring by chance
Incidental
Brooks “refired” his paper 10 years
later in the book
The Mythical Man-Month, 20th
Anniversary Edition, 1995
problems which engineers create and can fix
Related to the implementation process

Let’s start with
the Essence…

Simple huh!?
http://www.ideo.com/work/atm-interface

No two parts are alike
If they are, we make them into subroutines
In contrast to elements used in other domains
Huge number of states
Impossible to
enumerate all

There is no way to abstract away
the complexity because it is
essential
Complex domains
Aviation
Telecommunications
Banking
Health sector
…
We still need to
model and implement
their complexity

Technical consequences
Communication difficulties
Product flaws, cost overruns, schedule delays
Difficulty in enumerating, understanding and
anticipating all possible states
Unreliability, security trapdoors
Difficulty in maintaining
Introduction of defects, hard to understand, hard to use

Management consequences
Difficult project
overview
Poor knowledge
management
personnel
turnover
is a huge
problem

Software must conform to
arbitrary limitations
Imposed by human institutions and
systems regulations and rules
Subject to arbitrary
changes
Difficult
to plan
Can occur late in
the development

Software has to conform
to other existing systems
Software has to conform to its
environment
http://www.ktckids.com/images/puzzlePieces.png

Continuous change of
users’ needs
Illusion of
easy malleability
http://pipllp.com/wp-content/uploads/2014/09/evolution-of-cars_CKO.jpg
More pressure
to change the
software

Where is the software?
http://img.gfx.no/806/806035/original.628x353.jpg
Intangibility
No geometric
representation

We need to use different representations
to model different aspects of the software
In UML 2.2
there are 14
types of
diagrams
http://i.stack.imgur.com/8tmN9.jpg

How to attack on
the essence…

Requirements refinement
Incremental development
Grow, not build it
Great Designers
rapid prototyping
Identify, develop and keep them
Reuse
Buy, don’t build

And about
the Accident…

Some breakthroughs helped to
reduce accidental difficulties…
High-level languages
Time-sharing
Programming environments, tools
Object-oriented development
Programming verification
…

http://www.infoq.com/articles/No-Silver-Bullet-Summary
Interesting reading…
No Silver Bullet Reloaded Retrospective OOPSLA Panel Summary
http://cliparts.co/cliparts/dc9/6kL/dc96kLRc7.png

But wait,
there’s more…

Does the software
wear out?
http://chrishowardbooks.com/img/easter-egg-graphics/car.png

Of course not!
But...

It was
working
before...
... installing
the damn
update!
https://www.careeraddict.com/Surprised_Businessman.jpg

Software DETERIORATES
when...
we introduce a new defect when we
change it
there were environmental changes
that could not be foreseen by the
designer

marcello.thiry@gmail.com Pressman, 2015

Of course, we are
considering that the
software first release
has not already been
delivered “rotten”!
http://spc.fotolog.com/photo/44/42/36/deselingue/1200006994_f.jpg

And what is your
role on this?

We should be
concerned about
the quality of
we deliver!
http://www.aw3i.com/images/posts/sid_zen_dressdown.jpg

Quality?
https://pbs.twimg.com/profile_images/434052607297191936/ZRHhp8Fx.jpeg

x
Consider this two products..
http://hobby-armada.com/images/item/tamiya/sportscar/292.jpg
http://cdn.inaxiom.net/web/wp-content/uploads/2011/08/Ford-Ka-2011-06.jpg

Which one
has a better
quality?
http://www.tvmost.com.hk/most/uploads/images/2015/Article/2015.07/2015.07.23/pigteammate/005.jpg

Which are the expected
features for each one?
Quality is the “degree to
which a set of inherent
characteristics fulfils
requirements”
ISO 9000, 2015

Problems
with quality
The sport car has not
reached the required horse
power
The compact car has been
consuming more fuel than
expected

Grade is the “category or rank
given to different quality
requirements for products,
processes or systems having the
same functional use”
Different technical characteristics
High grade brand, first class, ...
low grade brand, second class, ...
ISO 9000, 2015

Got it!?
http://www.clickgratis.com.br/fotos-imagens/saca-
rolha/aHR0cDovL2lzaG9wLnM4LmNvbS5ici9wcm9kdXRvcy8
wMS8wMS9pdGVtLzI4OC82LzI4ODY2N18zR0cuanBn.jpg
http://www.clickgratis.com.br/fotos-imagens/saca-
rolha/aHR0cHM6Ly91cGxvYWQud2lraW1lZGlhLm9yZy93aWtpcGVkaWEvY29tbW9ucy90aHVtYi9lL
2U1L0tvcmtlbnppZWhlcl8wMV9LTUouanBnLzIwMHB4LUtvcmtlbnppZWhlcl8wMV9LTUouanBn.jpg

Difficult to define
Difficult to measure
Different perceptions
http://www.bms.co.in/wp-content/uploads/2014/11/Customer-Decision.jpg
http://businessanalytics.pt/wp-
content/uploads/2013/01/Lupa-
300x268.jpg

And Software
quality?

http://images.clipartpanda.com/happy-computer-user-happy-computeruser.png
http://images.clipartpanda.com/stressor-clipart-computer-stress.jpg

Capability of software product to satisfy
stated and implied needs when used under
specified conditions
(ISO/IEC 25000, 2014)
Software Quality.

Product?
https://pixabay.com/pt/caixa-papel%C3%A3o-
pacote-parcela-brown-158523/

Artifact that is produced, is quantifiable,
and can be either an end item in itself or a
component item.
Additional words for products are material
and goods.
(PMBOK, 2013) also used by (ISO/IEC 25000, 2014)
Product.

PMBOK uses different terms for PRODUCT
(tangible) e SERVICE (intangible)
A product can be:
 a component item
 an improvement of other item
 a final item
PMBOK - Um Guia do Conhecimento em Gerenciamento de Projetos

Software Product
Ready to be released
to users
It needs to be verified
and validated

Software
specification
http://blog.axen.pro/wp-content/uploads/2013/06/Writing-Quality-Software-Requirements.png

But has
everything
been written?
What are
the users
expectations?
http://www.handymanstartup.com/wp-
content/uploads/2013/02/IMG_Customer_rating_buttons.jpg

Does the
USE really
matters?
https://d3ui957tjb5bqd.cloudfront.net/images/screenshots/products/7/79/79359/hammer-o.jpg?1393432661

Ok, I got it!
But all software
are the same?

Can we classify
software products?
http://blog.globalknowledge.com/wp-
content/uploads/2011/08/squarehole95615108.jpg

A software product can be:
Commercial off-the-shelf - COTS
http://tynmedia.com/tynmag/wp-content/uploads/sites/3/2015/07/comercio_electronico.jpg

Defined by a market-driven need,
commercially available, and whose fitness
for use has been demonstrated by a broad
spectrum of commercial users
(ISO/IEC 25030, 2007)
COTS (commercial off-the-shelf).

Fully developed - FD
http://www.spd-haimhausen.de/wp-content/uploads/2010/02/bausteine.jpg

Developed for a specific application
from a user requirements specification
FD (fully developed) or
Custom software development.
(ISO/IEC 25030, 2007)

Fully developed - FD
Modified off-the-
shelf - MOTS
http://www.sundlep.com/wp-content/uploads/2015/02/web12.jpg

Similar to COTS, but it allows some
degree of customization (modification
of its features) from users specific
needs
MOTS (modified off-the-shelf).

Pressman considers 7
broad categories
Challenges!
Pressman, 2015

 System software
 Application software
 Engineering/scientific software
 Embedded software
 Product-line software
 Web/mobile applications
 Artificial intelligence software
(Pressman, 2015)

And more...
http://betanews.com/wp-content/uploads/2014/09/Internet-of-things.jpg
http://1.bp.blogspot.com/-7WLjdMquht4/VAANOVyBZSI/AAAAAAAAEZ8/JDIrrYWeJyc/s1600/Cloud-computing-concept_nobg.png

References.
 (Brooks, 1986). No Silver Bullet: Essence and Accident in Software Engineering. Proceedings of the
IFIP Tenth World Computing Conference: 1069–1076.
 (Brooks, 1995). The Mythical Man-Month. Anniversary Edition. Addison Wesley.
 (IEEE Std 610.12.1990). IEEE Standard Glossary of Software Engineering Terminology.
 (ISO 9000, 2015). Quality management systems — Fundamentals and vocabulary.
 (ISO/IEC 25000, 2014). Systems and software engineering — Systems and software Quality Requirements
and Evaluation (SQuaRE) — Guide to SQuaRE.
 (ISO/IEC 25030, 2007). Software engineering — Software product Quality Requirements and Evaluation
(SQuaRE) — Quality requirements.
 (PMBOK, 2013). A Guide to the Project Management Body of Knowledge (PMBOK® Guide). 5th ed. Project
Management Institute (PMI).
 (Pressman, 2015). Software Engineering: A Practitioner's Approach. 8th ed. McGraw-Hill Education.
 (SWEBOK, 2014). SWEBOK - Guide to the Software Engineering Body of Knowledge. Version 3.0. IEEE.

Software Engineering - Introduction and Motivation (Marcello Thiry)

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