CH01-Introduction-Software-engineering.ppt

Click to edit Master title style,Click to edit Master text styles,Second Level,Third Level,Fourth Level,Fifth Level,Chapter 1 Slide,*,Chapter 1,Introduction,Introduction,Getting started with software engineering,Objectives,To introduce software engineering and to explain its importance,To set out the answers to key questions about software engineering,Early experience in building magnitude larger and more complex software systems showed that an informal approach to software development was not good enough.Software development was in crisis.,were sometimes years late,cost much more than originally predicted,unreliable,difficult to maintain,and perform poorly,The notion of software engineering was first proposed in 1968 at a conference held to discuss software crisis.,Software engineering,What is software?,Computer programs and associated documentation,Software engineers are concerned with developing software products.,Software products may be,Generic-developed to be sold to a range of different customers,Bespoke(custom)-developed for a single customer according to their specification,What is software engineering?,Software engineering is an engineering discipline which 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,What 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,What are the costs of software engineering?,Roughly 60%of costs are development costs,40%are testing costs.For custom software,evolution costs often exceed development costs,Costs vary depending on the type of system being developed and the requirements of system attributes such as performance and system reliability,Distribution of costs depends on the development model that is used,What are software engineering methods?,Structured approaches to software development which include system models,notations,rules,design advice and process guidance,Model descriptions,Descriptions of graphical models which should be produced,Rules,Constraints applied to system models,Recommendations,Advice on good design practice,Process guidance,What activities to follow,What are the attributes of good software?,The software should deliver the required functionality and performance to the user and should be maintainable,dependable and usable,Maintainability,Software must evolve to meet changing needs,Dependability,Software must be trustworthy,Efficiency,Software should not make wasteful use of system resources,Usability,Software must be usable by the users for which it was designed,