Ch1 updated.pptx

Chapter 1- Introduction 30/10/2014 Chapter 1 Introduction Software engineering ◇ The economies of ALL developed nations are dependent on software. ◇ More and more systems are software controlled ◇ Software engineering is concerned with theories, methods and tools for professiona...

Chapter 1- Introduction 30/10/2014 Chapter 1 Introduction Software engineering ◇ The economies of ALL developed nations are dependent on software. ◇ More and more systems are software controlled ◇ Software engineering is concerned with theories, methods and tools for professional software development. ◇ Expenditure on software represents a significant fraction of GNP in all developed countries. 30/10/2014 Chapter 1 Introduction  Professional software development 30/10/2014 Chapter 1 Introduction Software products ◇ 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; CAD software; 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. 30/10/2014 Chapter 1 Introduction 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 for the software and they make decisions on software changes that are required. 30/10/2014 Chapter 1 Introduction Essential attributes of good software Product characteristic Description 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. 30/10/2014 Chapter 1 Introduction 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. 30/10/2014 Chapter 1 Introduction 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. ◇ Software evolution, where the software is modified to reflect changing customer and market requirements. 30/10/2014 Chapter 1 Introduction 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. 30/10/2014 Chapter 1 Introduction 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. 30/10/2014 Chapter 1 Introduction 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. ◇ Systems of systems ▪ These are systems that are composed of a number of other software systems. 30/10/2014 Chapter 1 Introduction  Software engineering ethics 30/10/2014 Chapter 1 Introduction Software engineering ethics ◇ Software engineering 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 respected as professionals. ◇ Ethical behaviour is more than simply upholding the law but involves following a set of principles that are morally correct. 30/10/2014 Chapter 1 Introduction ACM/IEEE Code of Ethics ◇ The professional societies in the US have cooperated to produce a code of ethical practice. ◇ Members of these organisations sign up to the code of practice when they join. ◇ The Code contains eight Principles related to the behaviour of and decisions made by professional software engineers, including practitioners, educators, managers, supervisors and policy makers, as well as trainees and students of the profession. 30/10/2014 Chapter 1 Introduction Ethical principles 1. PUBLIC - Software engineers shall act consistently with the public interest. 2. CLIENT AND EMPLOYER - Software engineers shall act in a manner that is in the best interests of their client and employer consistent with the public interest. 3. PRODUCT - Software engineers shall ensure that their products and related modifications meet the highest professional standards possible. 4. JUDGMENT - Software engineers shall maintain integrity and independence in their professional judgment. 5. MANAGEMENT - Software engineering managers and leaders shall subscribe to and promote an ethical approach to the management of software development and maintenance. 6. PROFESSION - Software engineers shall advance the integrity and reputation of the profession consistent with the public interest. 7. COLLEAGUES - Software engineers shall be fair to and supportive of their colleagues. 8. SELF - Software engineers shall participate in lifelong learning regarding the practice of their profession and shall promote an ethical approach to the practice of the profession. 30/10/2014 Chapter 1 Introduction 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 processes. ◇ The fundamental notions of software engineering are universally applicable to all types of system development. 30/10/2014 Chapter 1 Introduction Key points ◇ There are many different types of system and each requires appropriate software engineering tools and techniques for their development. ◇ The fundamental ideas of software engineering are applicable to all types of software system. ◇ Software engineers have responsibilities to the engineering profession and society. They should not simply be concerned with technical issues. ◇ Professional societies publish codes of conduct which set out the standards of behaviour expected of their members. 30/10/2014 Chapter 1 Introduction