Introduction
Vũ Thị Hồng Nhạn
(vthnhan@vnu.edu.vn)
Dept. of Software Engineering, FIT, UET
Vietnam National Univ., Hanoi
Contents
Professional software development
What does it mean by software engineering
Software engineering ethics
A brief introduction to ethical issues that affect software engineering
Case studies
An introduction to three examples that are used in later lectures
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Professional software development
Answer 10 frequently asked questions about SE
1. What is software?
Software is a computer program and it’s associated with documents
But computer program may be part of a system, so there are several
programs within a system
The documentation is important when we’re doing SE
We’re not just writing a program
We’re also creating the documents and the other information we need to use
over a period of time
Software products can be of 2 kinds, we can have...
Off-the shell products or apps for general markets
Customer software for particular customer, which is build exactly based on the
customer’s specification
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2. What are the attributes of good software?
Software should do what customers wants
& should deliver the functionality they want at a reasonable level of
performance
Should be usable, maintainable, and reliable
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3. What is SE?
SE as an engineering discipline that is concerned with all
aspects of software production
not just coding but everything from understanding what the user
needs to maintaining that software over the lifetime
Engineering means that systematic and disciplined and
managed approaches are used for the production of software
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4. What are the fundamental SE activities?
There are 4 activities that are always part of professional SE
Software specification
Software development
Software validation
Software evolution
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5. What is the difference between
SE & computer science?
SE is part of a more general computer science course
Or fundamentally computer science is the theory of software
Whereas SE is about the practicalities, is about building of
software
and it happens that sometimes the theory and the practice don’t
exactly match
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6. What is the difference between
Software & SE?
We usually talk about Software systems, so what is the difference between
software & SE
SE is concerned with all aspects of computer-based systems
development
including the hardware, the software, and process engineering
Software is a more focused activity
focuse only on the software, but obviously it’s closely associated and
integrated with the SE process
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7. Key Challenges facing in SE?
Firstly, facing with increasing diversity,
Software is in all sorts of devices from smart watches up to space stations
We need to understand the characteristics of the device and the computer
that we’re using to create the most appropriate software for that
Secondly, the challenge of responsiveness or delivering the software
more quickly
Because business & people want things to happen quickly (not wait for
several years)
Finally, delivering trustworthy software
Software that we can trust will be reliable, resilient, and counter external
cyberattack
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8. What are the costs of SE?
This is a hard question to answer!
Because it varies quite dramatically for all sorts of systems
If we’re building a critical system in an aircraft , it’s gonna cost an awful lot
per line of code than we’re building an app that’s offered for free in Android
store or itunes
Roughly 60% of software costs are development costs, 40% are testing
costs (updating as things change so the software remains useful for the
buyer of that software )
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9. What are the best…
engineering techniques & methods
All software projects have to be professionally managed and
developed, different techniques are appropriate for different types of
systems
E.g., games should always be developed using a series of prototypes,
whereas safety critical control systems require a complete and
analyzable specification
Therefore you cannot say that one method is better than another
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10. What differences has the web made to SE?
Fundamentally the difference the web has made is that has allowed us to
develop and deliver software in a new way
We can deliver software services rather than systems that are installed
on a user’s own computer
We can access these services remotely
It allows us to build a new kind of distributed system to deliver the
functionality that the user needs
Because of the demands of the web and the need to build highly
distributed systems, this has led to the advances in SE
New ways of reusing software, a new programming language & development
techniques can be used
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Why SE matters?
Why?
Software is everywhere and our society is now totally dependent on
software-intensive systems
Power infrastructure Financial system
telecommunications
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Why?
Feeding and housing a growing world
population
Coping with the problems that come from
people living longer and providing a high
quality of life for our elderly citizens
Dealing with international terrorism, scourge
on all of our societies
We need SE, efficient & effective techniques
of developing complex software systems to
maintain our society and to continue to provide
high quality lives for our citizens
Dealing with the problems in the 21st century can
only be done with software-intensive systems
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Software products
Generic products
Stand-alone systems that are marketed and sold to any customer who wishes
to buy them
E.g. PC software such as graphics programs, project management tools,
CAD(Computer-Aided Designs) software, software for specific markets such as
appointment systems for dentists
Customized products
Software that is commissioned by a specific customer to meet their own needs
E.g., embedded control systems, air traffic control software, traffic
monitoring systems
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Product specification
Generic products
The specification of what the software should do is owned by the software
developer
and decisions on software change are made by the developer
Customized products
The specification of what the software should do is owned by the customer
and they make decisions on software changes
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Essential attributes of good software
Product Description
characteristic
Maintainability Software should be written in such a way so that it can evolve to meet the
changing needs of customers. This is a critical attribute because
software change is an inevitable requirement of a changing business
environment
Dependability & Software dependability includes a range of characteristics including
security reliability, security, and safety. Dependable software shouldn’t cause
physical or economic damage in the event of system failure. Malicious
users shouldn’t be able to access or damage the system
Efficiency Software shouldn’t make wasteful use of system resources such as
memory or processor cycles. Efficiency therefore includes responsiveness,
processing time, memory utilization, etc.
Acceptability Software must be acceptable to the type of users for which it is designed.
This means that it must be understandable, usable, and compatible with
others systems that they use
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SE
SE is an engineering discipline that is concerned with all aspects of
software production from the early stages of system specification
through to maintaining the system after it has gone into use
Engineering discipline
Using appropriate theories and methods to solve problems bearing in mind
organizational and financial constraints
All aspects of software products
Not just technical process of development
Also, project management and development of tools, methods, etc. to support
software production
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Software process activities
Software specification, Where customers and engineers define the
software that is to be produced and the constraints on its operation
Software development, where the software is designed and programmed
Software validation, where the software is checked to ensure that it is
what the customer requires (i.e. do the right things)
Software evolution, where the software is modified to reflect changing
customer and market requirements
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General issues that affect software
Heterogeneity
Increasingly, systems are required to operate as distributed systems across
networks that include different types of computer and mobile devices
Business & social change
Business & society are changing incredibly quickly as emerging economies
develop and new technologies become available
They need to be able to change their existing software and to rapidly develop
new software
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General issues that affect software...
Security & trust
As software is intertwined with all aspects of our lives, it is essential
that we can trust that software
Scale
Software has to be developed across a very wide range of scales,
from very small embedded systems in portable or wearable devices
through to Internet-scale, cloud-based systems that serve a global
community
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SE diversity
There are many different types of software systems and there’s no
universal set of software techniques that is applicable to all of these
The SE methods and tools used depend on the type of application
being developed, the requirements of the customer and the
background of the development team
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Application types
Stand-alone applications
These are application systems that run on a local computer, such as a PC
They include all necessary functionality and do not need to be connected to a
network
Interactive transaction-based applications
Applications that execute on a remote computer and are accessed by users
from their own PCs or terminals
These include web applications such as e-commerce applications
Embedded control systems
These are software control systems
that control and manage hardware devices
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Application types...
Batch processing systems
These are business systems that are designed to
process data in large batches
They process large numbers of individual inputs
to create corresponding outputs
Entertainment systems
These are systems that are primarily for
personal use and which are intended to
entertain the user
Systems for modeling and simulation
These are systems that are developed by
scientists and engineers to model physical
processes or situations, which include many
separate interacting objects
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Application types...
Data collection systems
These are systems that collect data
from their environment using a set
of sensors and send that data to
other systems for processing
Forest fire detection
Systems of systems
These are that are composed of a
number of other software systems
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SE fundamentals
Some fundamental principles applied to all types of software systems,
irrespective of the development techniques used
Systems should be developed using a managed and understood
development process. Of course, different processes are used for different
types of software
Dependability and performance are important for all types of system
Understanding and managing the software specification and requirements
are important
Where appropriate, you should reuse software that has already been
developed rather than rewriting new software
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Internet SE
The web is now a platform for running application and
organizations are increasingly developing web-based systems rather
than local systems
Web services allow application functionality to be accessed over the
web and internet
Cloud computing is an approach to the provision of computer services
where applications run remotely on the cloud
users do not buy software but pay according to use
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Web-based SE
Web-based systems are complex distributed systems but the
fundamental principles of SE discussed previously are applicable to
them (the same way they are applied to other types of system)
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Web SE
Software reuse
Software reuse is the dominant approach for constructing web-based systems
When building these systems, you think about how you can assemble them
from pre-existing software components & systems
Incremental & agile development
Web-based systems should be developed and delivered incrementally
It’s now generally recognized that it’s impractical to specify all the
requirements for such systems in advance
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Web SE...
Service-oriented systems
Software may be implemented using service-oriented SE, where the
software components are stand-alone web services
Rich interfaces
Interface development technologies such as AJAX and HTML5 have emerged
that support the creation of rich interfaces within a web browser
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SE Ethics
What is Ethics?
Ethics & codes of ethics related to professions in computing &
science is fairly simple
it’s behavior that we consciously make, that has positive or negative
impacts on society and citizens and the environment (cultural &
natural) and so on
Generally there are 2 kinds of ethics
Minimalism doesn’t cause harm
Idealism: a fun side of computing which says I can actually prevent
harm, maybe actually do some positive things and then sometimes
get labeled as ethical
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SE ethics
SE involves wider responsibilities than simply the application of
technical skills
Software engineers must behave in an honest and ethically responsible
way if they are to be able to be respected as professionals
Ethical behavior is more than simply upholding the law but involves
following a set of principles that are morally correct
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Issues of professional responsibility
Confidentiality (bảo mật)
Engineers should normally respect the confidentiality of their employers or
clients irrespective of whether or not a formal confidentiality agreement has
been signed
Competence (chức vụ/năng lực/thẩm quyền)
Engineers shouldn’t misrepresent their level of competence
They shouldn’t knowingly accept work which is out with their competence
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Issues of professional responsibility
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 their intellectual property of employers
and clients is protected
Computer misuse
Software engineers shouldn’t 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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Case studies
case studies
A personal insulin pump
An embedded system in an insulin pump used by diabetics to maintain
blood glucose control
A mental health care patients management system
Mentcare: a system used to maintain records of people receiving care for
mental health problems
A wilderness weather station
A data collection system that collects data about weather conditions in
remote areas
iLearn: a digital learning environment
service-oriented systems
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Insulin pump control system
Collects data from a blood sugar sensor and
calculates the amount of insulin required to be
injected
Calculation based on the rate of change of blood
sugar levels
Sends signals to a micro-pump to deliver the correct
dose of insulin
Safety-critical system as low blood sugar levels can
lead to brain malfunctioning, coma and death; high-
blood sugar levels have long-term consequences such
as eye and kidney damage
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Insulin pump hardware architecture
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Essential high-level requirements
The system shall be available to deliver insulin when required
The system shall perform reliably and deliver the correct amount of
insulin to counteract the current level of blood sugar
The system must therefore be designed and implemented to ensure that
the system always meets these requirements
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Mentcare
A patient information system for mental health care
A patient information system to support mental health care is a medical
information system
that maintains information about patients suffering from mental health
problems and the treatments that they have received
Most mental health patients do not require dedicated hospital
treatment
but need to attend specialist clinics regularly where they can meet a doctor who
has detailed knowledge of their problems
To make it easier for patients to attend, these clinics are not just run in
hospitals
they may be held in local medical practices or community centers
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Mentcare
Mentcare is an information system that is intended for use in clinics
It makes use of a centralized database of patient information
but has also been designed to run on a PC,
so that it may be accessed and used from sites that don’t have secure network
connectivity
When the local systems have secure network access, they use patient
information in the database,
they can download and use copies of patient records when they are
disconnected
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Mentcare goals
To generate management information that allows health service
managers to assess performance against local and government targets
To provide medical staff with timely information to support the treatment
of patients
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The organization of the Mentcare system
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Key features of the Mentcare system
Individual care management
Clinicians can support records for patients, edit the information in the
system, view patient history, etc.
The system supports data summaries so that doctors can quickly learn about
their key problems and treatments that have been prescribed
Patient monitoring
The system monitors the records of patients that are involved in treatment
and issues warnings if possible problems are detected
Administrative reporting, the system generates monthly management
reports ...
showing the number of patients treated at each clinic,
the number of patients who have entered and left the care system,
number of patients sectioned/admitted to hospital,
the drugs prescribed and their costs, etc.
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Mentcare system concerns
Privacy
It is essential that patient information is confidential and is never disclosed to
anyone apart from authorized medical staff and the patient themselves
Safety
Some mental illness cause patients to become suicidal or a danger to other
people
Whenever possible, the system should warn medical staff about potentially
suicidal or dangerous patients
The system must be available when needed, otherwise patient safety may
be compromised and it may be impossible to prescribe the correct medication
to patients
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Wilderness weather station
The government of a country with a large area of
wilderness decides to deploy several hundred
weather stations in remote areas
Weather stations collect data from a set of
instruments that...
measure weather parameters such as the wind speed
and directions, the ground and air temperatures, the
barometric pressure and the rainfall over a 24 hour
period
Each of these instruments is controlled by a software
system that takes parameter readings periodically
and manages the data collected from the instruments
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The weather station’s environment
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Weather information system
The weather station system
This is responsible for collecting weather data,
carrying out some initial data processing and
transmitting it to the data management
system
The data management and archiving system
This system collects the data from all of the
wilderness weather stations, carries out
data processing and analysis and archives
the data
The station maintenance system
This system can communicate by satellite with
all wilderness weather stations to monitor
the health of these systems and provide
reports of problems
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iLearn: a digital learning environment
A digital learning environment is a framework in which
a set of general-purpose and specialty designed tools for learning may be
embedded
plus a set of applications that are geared to the needs to the learners using the
system
The tools included in each version of the environment are chosen by
teachers and learners to suit their specific needs
These can be general applications such as spreadsheets
learning management applications such as a Virtual Learning Environment to
mange homework submission and assessment, games and simulations
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iLearn: service-oriented systems
The system is a service-oriented system with all system components
considered to be a replaceable service
This allows the system to be updated incrementally as new services
become available
It also makes it possible to rapidly configure the system to create
versions of the environment for different groups such as very young
children who cannot read, senior students, etc.
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iLearn services
Utility services that provide basic application-independent
functionality and which may be used by other services in the system
Application services that provide specific applications such as email,
conferencing, photo sharing etc. and access to specific educational
content such as scientific films or historical resources
Configuration services that are used to adapt the environment with a
specific set of application services and do define how services are
shared between students, teachers, and their parents
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iLearn architecture
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iLearn service integration
Integrated services are services which offer an API and which can be
accessed by other services through that API
Direct service-to-service communication is therefore possible
Independent services are services which are simply accessed through
a browser interface and which operate independently of other services
Information can only be shared with other services through explicit user
actions such as copy and paste;
re-authentication may be required for each independent service
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Key points
Software engineering is an engineering discipline that is concerned with all
aspects of software production
Essential software product attributes are maintainability, dependability
and security, efficiency and acceptability
The high-level activities of specification, development, validation and
evolution are part of all software process
The fundamental notions of SE are universally applicable to all types of
system development
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