SW-Week01 PDF - Introduction to Software Engineering

Year: 2024-2025 Fall Semester Introduction to Software Engineering Software and Software Engineering  Course Information Instructors : Dr. Asmaa Saad Dr. Israa Ahmed Dr. Mayar Aly...

Year: 2024-2025 Fall Semester Introduction to Software Engineering Software and Software Engineering  Course Information Instructors : Dr. Asmaa Saad Dr. Israa Ahmed Dr. Mayar Aly Course Assessment : Quizzes – Project - Sections Attendance Midterm Exam - Final Exam 2  Course outline Introduction of software engineering SW process models Agile SW developments Analysis & Design principles UML 3  Lecture Outline Nature of Software Frequent Answers and Questions (FAQs) about software engineering Professional and ethical responsibility 4  Nature of Software – Defining Software Software is: 1) Instructions (computer programs) that when executed provide desired features, function, and performance; 2) Data structures that enable the programs to adequately manipulate information. 3) Documentation that describes the operation and use of the programs. 5  Software Application Domains System software. Application software. Engineering/Scientific software. Embedded software. Product-line software. Web/Mobile applications. AI software (robotics, neural nets, game playing). 6  Legacy Software Why must software change? Software must be adapted to meet the needs of new computing environments or technology. Software must be enhanced to implement new business requirements. Software must be extended to make it interoperable with other more modern systems or databases. Software must be re-architected to make it viable within a network environment. 7  Defining the Software Engineering The IEEE definition: Software Engineering: 1. The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software. 8  Software Engineering Layers 9  Umbrella Activities Software project tracking and control. Risk management. Software quality assurance. Technical reviews. Measurement. Software configuration management. Reusability management. Work product preparation and production. 10  Process Framework Activities Communication. Planning. Modeling. Analysis of requirements. Design. Construction: Code generation. Testing. Deployment. 11  Essence of Software Engineering Practice Polya suggests: 1. Understand the problem (communication and analysis). 2. Plan a solution (modeling and software design). 3. Carry out the plan (code generation). 4. Examine result for accuracy (testing & quality assurance). 12  Understand the Problem Who has a stake in the solution to the problem? That is, who are the stakeholders? What are the unknowns? What data, functions, and features are required to properly solve the problem? Can the problem be fragmented? Is it possible to represent smaller problems that may be easier to understand? Can the problem be represented graphically? 13 Can an analysis model be created?  Plan a Solution Have you seen similar problems before? Are there patterns that are recognizable in a potential solution? Is there existing software that implements the data, functions, and features that are required? Has a similar problem been solved? If so, are elements of the solution reusable? Can subproblems be defined? If so, are solutions readily apparent for the subproblems? Can you represent a solution in a manner that leads to effective implementation? 14 Can a design model be created?  Carryout the Plan Does the solution conform to the plan? Is source code traceable to the design model? Is each component part of the solution provably correct? Has the design and code been reviewed, or better, have correctness proofs been applied to algorithm? 15  Examine the Result Is it possible to test each component part of the solution? Has a reasonable testing strategy been implemented? Does the solution produce results, that conform to the data, functions, and features that are required? Has the software been validated against all stakeholder requirements? 16  Software 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 it than 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. 17  FAQs 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? 18  FAQs 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? 19  What 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. 20  What 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. 21  What 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). 22  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 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. 23  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. 24 What 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. 25  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. 26  Activity cost distribution Waterfall model 0 25 50 75 100 Specificatio n Design Development Integ ration and testing Iterative development 0 25 50 75 1 00 Specificatio n Iterative development System testing Component-based so ftware eng ineering 0 25 50 75 1 00 Specificatio n Development Integ ration and testing Development and evolution costs for long- lifetime sys t ems 0 10 200 30 400 System development System evolution 27  Product development costs 0 25 50 75 100 Specificatio n Development System testing 28  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. 29  What is CASE (Computer-Aided Software Engineering) Software systems that are intended to provide automated support for software process activities. CASE systems are often used for method support. Upper-CASE – Tools to support the early process activities of requirements and design; Lower-CASE – Tools to support later activities such as programming, debugging and testing. 30  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 acceptable. Maintainability – Software must evolve to meet changing needs; Dependability – Software must be trustworthy; Efficiency – Software should not make wasteful use of system resources; Acceptability – Software must accepted by the users for which it was designed. This means it must be understandable, usable and compatible with other systems. 31  What are the key challenges facing software engineering? Heterogeneity, delivery and trust. Heterogeneity – Developing techniques for building software that can cope with heterogeneous platforms and execution environments; Delivery – Developing techniques that lead to faster delivery of software; Trust – Developing techniques that demonstrate that software can be trusted by its users. 32 Professional and ethical responsibility 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. 33 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 out with their competence. 34 Issues of professional responsibility 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). 35  Key points Software engineering is an engineering discipline that is concerned with all aspects of software production. Software products consist of developed programs and associated documentation. Essential product attributes are maintainability, dependability, efficiency and usability. The software process consists of activities that are involved in developing software products. Basic activities are software specification, development, validation and evolution. Methods are organised ways of producing software. They include suggestions for the process to be followed, the notations to be used, rules governing the system descriptions which are produced and design guidelines. 36  Key points CASE tools are software systems which are designed to support routine activities in the software process such as editing design diagrams, checking diagram consistency and keeping track of program tests which have been run. 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. 37