Cap1 Introduzione Flashcards
What is software?
Computer programs and associated documentation. Software products may be developed for a particular customer or may be developed for a general market.
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 is software engineering?
Software engineering 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 production
Not just technical process of development. Also project management and the development of tools, methods etc. to support software production.
What are the fundamental software engineering 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.
Software evolution, where the software is modified to reflect changing customer and market requirements.
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 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 are the best software engineering techniques and methods?
While all software projects have to be professionally managed and developed, different techniques are appropriate for different types of system. For example, games should always be developed using a series of prototypes whereas safety critical control systems require a complete and analyzable specification to be developed. You can’t, therefore, say that one method is better than another.
What differences has the web made to software engineering?
The web has led to the availability of software services and the possibility of developing highly distributed service-based systems. Web-based systems development has led to important advances in programming languages and software reuse.
Essential attributes of good software
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 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.
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 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.
Security and 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.
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. Numerically, there are probably more embedded systems than any other type of system.
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.
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.
Systems of systems
These are systems that are composed of a number of other software systems
Issues of professional responsibility
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.
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.
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).
