FCI_CSIT_3rd_Software_Engineering_Week1_Amal_Lec.pdf

Mansoura University Faculty of Computers and Information Department of Computer Science First Semester- 2023-2024 Software Engineering [CS311P] Grade: ……3RD YEAR……………. DR……Amal I. Abou ELeneen………….. COURSE OUTLINE Chapter 1: Introduction. Chapter 2: Software...

Mansoura University Faculty of Computers and Information Department of Computer Science First Semester- 2023-2024 Software Engineering [CS311P] Grade: ……3RD YEAR……………. DR……Amal I. Abou ELeneen………….. COURSE OUTLINE Chapter 1: Introduction. Chapter 2: Software Processes. Chapter 3 :Agile Software Development Chapter 4: Requirements Engineering. Chapter 6: Business Model Chapter 5: System Modeling. Chapter 6: Architectural Design Chapter 7: Design and Implementation 2 CHAPTER 1- INTRODUCTION 3  TOPICS COVERED  Professional software development ▪ What is meant by software engineering.  Software engineering ethics ▪ A brief introduction to ethical issues that affect software engineering.  Case studies ▪ An introduction to three examples that are used in later chapters in the book. 4 PROFESSIONAL SOFTWARE DEVELOPMENT 5  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. 6  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 ❖ 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 7  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; 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. 8 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. 9 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 Software dependability includes a range of characteristics security including reliability, security and safety. Malicious users should not be able to access or damage the system. 10 ESSENTIAL ATTRIBUTES OF GOOD SOFTWARE Product characteristic Description 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. 11  SOFTWARE ENGINEERING DIVERSITY  There are many different types of software system and there is no universal set of software techniques that is applicable to all of these.  The software engineering methods and tools used depend on the type of application being developed, the requirements of the customer and the background of the development team. 12  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. 13  APPLICATION TYPES  Entertainment systems ▪ These are systems that are primarily for personal use and which are intended to entertain the user.  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. Some of these may be generic software products, such as an ERP system. 14  SOFTWARE ENGINEERING FUNDAMENTALS  Some fundamental principles apply to all types of software system, irrespective of the development techniques used: ▪ Systems should be developed using a managed and understood development process. Of course, different processes are used for different types of software. ▪ Dependability and performance are important for all types of system. ▪ Understanding and managing the software specification and requirements (what the software should do) are important. ▪ Where appropriate, you should reuse software that has already been developed rather than write new software. 15 SOFTWARE ENGINEERING ETHICS 16  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. 17 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(ability) ▪ Engineers should not misrepresent their level of competence. They should not knowingly accept work which is outwith their competence. 18  ISSUES OF PROFESSIONAL RESPONSIBILITY  Intellectual property rights ‫حقوق الملكيه الفكريه‬ ▪ 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( ‫نشر الفيروسات‬ 19  SOFTWARE PROCESS ACTIVITIES A set of activities whose goal is the development or evolution of software Generic activities in all software processes are  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. 20 PROCESS ACTIVITIES Software specification 21  SOFTWARE SPECIFICATION  The process of establishing what services are required and the constraints on the system’s operation and development.  Requirements engineering process ▪ Requirements elicitation and analysis What do the system stakeholders require or expect from the system? ▪ Requirements specification Defining the requirements in detail ▪ Requirements validation Checking the validity of the requirements 22 THE REQUIREMENTS ENGINEERING PROCESS 23 PROCESS ACTIVITIES Software design and implementation 24  SOFTWARE DESIGN AND IMPLEMENTATION  The process of converting the system specification into an executable system.  Software design ▪ Design a software structure that realises the specification;  Implementation ▪ Translate this structure into an executable program;  The activities of design and implementation are closely related and may be inter-leaved. 25 A GENERAL MODEL OF THE DESIGN PROCESS 26  DESIGN ACTIVITIES  Architectural design, where you identify the overall structure of the system, the principal components (subsystems or modules), their relationships and how they are distributed.  Database design, where you design the system data structures and how these are to be represented in a database.  Interface design, where you define the interfaces between system components.  Component selection and design, where you search for reusable components. If unavailable, you design how it will operate. 27  SYSTEM IMPLEMENTATION  The software is implemented either by developing a program or programs or by configuring an application system.  Design and implementation are interleaved activities for most types of software system.  Programming is an individual activity with no standard process.  Debugging is the activity of finding program faults and correcting these faults. 28 PROCESS ACTIVITIES Software validation 29 SOFTWARE VALIDATION  Verification and validation (V & V) is intended to show that a system conforms to its specification and meets the requirements of the system customer.  Involves checking and review processes and system testing.  System testing involves executing the system with test cases that are derived from the specification of the real data to be processed by the system.  Testing is the most commonly used V & V activity. 30  TESTING STAGES  Component testing ▪ Individual components are tested independently; ▪ Components may be functions or objects.  System testing ▪ Testing of the system as a whole.  Customer testing (Acceptance Testing) ▪ Testing with customer data to check that the system meets the customer’s needs. 31 PROCESS ACTIVITIES Software evolution 32 SOFTWARE EVOLUTION  Changing the system in response to changing customer needs  Software change is inevitable ▪ New requirements emerge when the software is used; ▪ The business environment changes; ▪ Errors must be repaired; ▪ New computers and equipment is added to the system; ▪ The performance or reliability of the system may have to be improved. 33 FREQUENTLY ASKED QUESTIONS ABOUT SOFTWARE ENGINEERING Question Answer 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. What are the fundamental software Software specification, software development, software validation and engineering activities? software evolution. What is the difference between software Computer science focuses on theory and fundamentals; software engineering and computer science? engineering is concerned with the practicalities of developing and delivering useful software. What is the difference between software System engineering is concerned with all aspects of engineering and system engineering? computer-based systems development including hardware, software and process engineering. Software engineering is part of 34 this more general process.  FREQUENTLY ASKED QUESTIONS ABOUT SOFTWARE ENGINEERING Question Answer What are the key challenges facing Coping with increasing diversity, demands for reduced software engineering? delivery times and developing trustworthy software. What are the costs of software Roughly 60% of software costs are development costs, engineering? 40% are testing costs. For custom software, evolution costs often exceed development costs. What are the best software engineering While all software projects have to be professionally techniques and methods? 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. 35 CASE STUDIES 36  CASE STUDIES  A personal insulin pump ▪ An embedded system in an insulin pump used by diabetics to maintain blood glucose control.  A mental health care patient management system ▪ Mentcare.A system used to maintain records of people receiving care for mental health problems.  A wilderness weather station ▪ A data collection system that collects data about weather conditions in remote areas. 37  INSULIN PUMP CONTROL SYSTEM  Collects data from a blood sugar sensor and calculates the amount of insulin required to be injected.  Calculation based on the rate of change of blood sugar levels.  Sends signals to a micro-pump to deliver the correct dose of insulin.  Safety-critical system as low blood sugars can lead to brain malfunctioning, coma and death; high-blood sugar levels have long-term consequences such as eye and kidney damage. 38 INSULIN PUMP HARDWARE ARCHITECTURE 39 MENTCARE: A PATIENT INFORMATION SYSTEM FOR MENTAL HEALTH CARE  A patient information system to support mental health care is a medical information system that maintains information about patients suffering from mental health problems and the treatments that they have received.  Most mental health patients do not require dedicated hospital treatment but need to attend specialist clinics regularly where they can meet a doctor who has detailed knowledge of their problems.  To make it easier for patients to attend, these clinics are not just run in hospitals. They may also be held in local medical practices or community centres. 40  WILDERNESS WEATHER STATION  The government of a country with large areas of wilderness decides to deploy several hundred weather stations in remote areas.  Weather stations collect data from a set of instruments that measure temperature and pressure, sunshine, rainfall, wind speed and wind direction. ▪ The weather station includes a number of instruments that measure weather parameters such as the wind speed and direction, the ground and air temperatures, the barometric pressure and the rainfall over a 24-hour period. Each of these instruments is controlled by a software system that takes parameter readings periodically and manages the data collected from the instruments. 41 REFERENCES  SoftwareEngineering9EditionIanSommerville  SoftwareEngineering10EditionIanSommerville 42