Chapter 1

Question 1

What is software?

Answer 1

Computer programs and associated documentation

Question 2

What are the attributes of good software?

Answer 2

Good software should deliver the required functionality and performance to the user and should be maintainable, dependable and usable

Question 3

What are the fundamental software engineering activities?

Answer 3

Software specification, software development, software validation and software evolution

Question 4

What is the difference between software engineering and computer science?

Answer 4

Computer science focuses on theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software.

Question 5

What is the difference between software engineering and system engineering?

Answer 5

System engineering is concerned with all aspects of computer-based systems development including hardware, software and process engineering. Software engineering is part of this more general process

Question 6

What are the key challenges facing software engineering?

Answer 6

Coping with increasing diversity, demands for reduced delivery times and developing trustworthy software

Question 7

What are the costs of software engineering?

Answer 7

Roughly 60% of software costs are development costs, 40% are testing costs. For custom software, evolution costs often exceed development costs

Question 8

What differences has the Internet made to software engineering?

Answer 8

Not only has the Internet led to the development of massive, highly distributed, service-based systems, it has also supported the creation of an “app” industry for mobile devices which has changed the economics of software.

Question 9

Generic Products

Answer 9

Stand-alone systems that are marketed and sold to any customer who wishes to buy them.

Examples – PC software such as graphics programs, project management tools; software for specific markets such as
appointments systems for dentists.

Question 10

Customized products

Answer 10

Software that is commissioned by a specific customer to meet their own needs.

Examples – embedded control systems, air traffic control software, traffic monitoring systems.

Question 11

Product specification - Generic products

Answer 11

The specification of what the software should do is owned by the software developer and decisions on software change are made by the developer

Question 12

Product specification - Customized products

Answer 12

The specification of what the software should do is owned by the customer for the software and they make decisions on software changes that are required

Question 13

Maintainability

Answer 13

Software should be written in such a way so that it can evolve to meet the changing needs of customers.

Question 14

Dependability and
security

Answer 14

Software dependability includes a range of characteristics including reliability, security and safety. Dependable software should not cause physical or economic damage in the event of system failure. Malicious users should not be able to access or damage the system

Question 15

Efficiency

Answer 15

Software should not make wasteful use of system resources such as memory and processor cycles. Efficiency therefore includes responsiveness, processing time, memory utilisation, etc

Question 16

Acceptability

Answer 16

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 other systems that they use

Question 17

A software process

Answer 17

1. Software specification, where customers and engineers define the software that is to be produced and the constraints on its operation.
2. Software development, where the software is designed and programmed.
3. Software validation, where the software is checked to ensure that it is what the customer requires.
4. Software evolution, where the software is modified to reflect changing customer and market requirements

Question 18

General issues - Heterogeneity

Answer 18

Increasingly, systems are required to operate as distributed systems across networks that include different types of computer and mobile devices. As well as running on general-purpose computers, software may also have to execute on mobile phones and tablets. You often have to integrate new software with older legacy systems written in different programming languages

Question 19

General issues - Business and social change

Answer 19

Business and 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

Question 20

General issues - Security and trust

Answer 20

This is especially true for remote soft-ware systems accessed through a web page or web service interface. We have to make sure that malicious users cannot successfully attack our software and that information security is maintained

Question 21

General issues - Scale

Answer 21

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

Question 22

Stand-alone applications

Answer 22

These are application systems that run on a personal computer or apps that run on a mobile device. Office applications on a PC, CAD programs, photo manipula-tion software, travel apps, productivity apps, and so on

Question 23

Interactive transaction-based applications

Answer 23

These are applications that execute on a remote computer and that are accessed by users from their own computers, phones, or tablets. Web, Business systems

Question 24

Embedded control systems

Answer 24

These are software control systems that control and manage hardware devices. Software in a mobile (cell) phone, software that controls antilock braking in a car, and software in a microwave oven to control the cooking process

Question 25

Batch processing systems

Answer 25

These are business systems that are designed to pro-cess data in large batches. They process large numbers of individual inputs to create corresponding outputs. Examples of batch systems are periodic billing systems, monthly payment

Question 26

Entertainment systems

Answer 26

Games. The quality of the user interaction offered is the most important distinguishing characteristic of enter-tainment systems

Question 27

Systems for modeling and simulation

Answer 27

These are systems that are developed by scientists and engineers to model physical processes or situations, which include many separate, interacting objects. These are often computationally intensive and require high-performance parallel systems for execution

Question 28

Data collection and analysis systems

Answer 28

are systems that collect data from their environment and send that data to other systems for pro-cessing. The software may have to interact with sensors and often is installed in a hostile environment such as inside an engine or in a remote location. Cloud data relations

Question 29

Systems of systems

Answer 29

used in enterprises and other large organ-izations, that are composed of a number of other software systems. Some of these may be generic software products, such as an ERP system