Slide 1ObjectivesTopics coveredSoftware engineeringSoftware costsFAQs about software engineeringSlide 7What is software?What is software engineering?What is the difference between software engineering and computer science?What is the difference between software engineering and system engineering?What is a software process?What is a software process model?What are the costs of software engineering?Activity cost distributionProduct development costsWhat are software engineering methods?What is CASE (Computer-Aided Software Engineering)What are the attributes of good software?What are the key challenges facing software engineering?Professional and ethical responsibilityIssues of professional responsibilitySlide 23ACM/IEEE Code of EthicsCode of ethics - preambleCode of ethics - principlesSlide 27Slide 28Ethical dilemmasKey pointsSlide 31©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 1An Introduction to Software Engineering©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 2ObjectivesTo introduce software engineering and to explain its importanceTo set out the answers to key questions about software engineeringTo introduce ethical and professional issues and to explain why they are of concern to software engineers©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 3Topics coveredFAQs about software engineeringProfessional and ethical responsibility©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 4Software 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.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 5Software costsSoftware costs often dominate computer system costs. The costs of software on a PC are often greater than the hardware cost.Software costs more to maintain than it does to develop. For systems with a long life, maintenance costs may be several times development costs.Software engineering is concerned with cost-effective software development.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 6FAQs about software engineeringWhat is software?What is software engineering?What is the difference between software engineering and computer science?What is the difference between software engineering and system engineering?What is a software process?What is a software process model?©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 7FAQs about software engineeringWhat are the costs of software engineering?What are software engineering methods?What is CASE (Computer-Aided Software Engineering)What are the attributes of good software?What are the key challenges facing software engineering?©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 8What is software?Computer programs and associated documentation such as requirements, design models and user manuals.Software products may be developed for a particular customer or may be developed for a general market.Software products may be•Generic - developed to be sold to a range of different customers e.g. PC software such as Excel or Word.•Bespoke (custom) - developed for a single customer according to their specification.New software can be created by developing new programs, configuring generic software systems or reusing existing software.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 9What is software engineering?Software engineering is an engineering discipline that is concerned with all aspects of software production.Software engineers should adopt a systematic and organised approach to their work and use appropriate tools and techniques depending on the problem to be solved, the development constraints and the resources available.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 10What is the difference between software engineering and computer science?Computer science is concerned with theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software.Computer science theories are still insufficient to act as a complete underpinning for software engineering (unlike e.g. physics and electrical engineering).©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 11What 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 process concerned with developing the software infrastructure, control, applications and databases in the system.System engineers are involved in system specification, architectural design, integration and deployment.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 12What is a software process?A set of activities whose goal is the development or evolution of software.Generic activities in all software processes are:•Specification - what the system should do and its development constraints•Development - production of the software system•Validation - checking that the software is what the customer wants•Evolution - changing the software in response to changing demands.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1 Slide 13What is a software process model?A simplified representation of a software process, presented from a specific perspective.Examples of process perspectives are•Workflow perspective - sequence of activities;•Data-flow perspective - information flow;•Role/action perspective - who does what.Generic process models•Waterfall;•Iterative development;•Component-based software engineering.©Ian Sommerville 2006 Software Engineering, 8th edition. Chapter 1