Chapter 1 Flashcards
What is software?
Computer programs and associated documentation
What are the attributes of good software?
Good software should deliver the required functionality and performance to the user and should be maintainable, dependable and usable
What are the fundamental software engineering activities?
Software specification, software development, software validation and software evolution
What is the difference between software engineering and computer science?
Computer science focuses on theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software.
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 more general process
What are the key challenges facing software engineering?
Coping with increasing diversity, demands for reduced delivery times and developing trustworthy software
What are the costs of software engineering?
Roughly 60% of software costs are development costs, 40% are testing costs. For custom software, evolution costs often exceed development costs
What differences has the Internet made to software engineering?
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.
Generic Products
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.
Customized products
Software that is commissioned by a specific customer to meet their own needs.
Examples – embedded control systems, air traffic control software, traffic monitoring systems.
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
Product specification - Customized products
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
Maintainability
Software should be written in such a way so that it can evolve to meet the changing needs of customers.
Dependability and
security
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
Efficiency
Software should not make wasteful use of system resources such as memory and processor cycles. Efficiency therefore includes responsiveness, processing time, memory utilisation, 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 other systems that they use
A software process
- 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.
- Software evolution, where the software is modified to reflect changing customer and market requirements
General issues - Heterogeneity
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
General issues - Business and social change
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
General issues - Security and trust
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
General issues - 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
Stand-alone applications
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
Interactive transaction-based applications
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
Embedded control systems
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
