1 se-introduction


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1st & 2nd lecture in the software engineering course

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1 se-introduction

  2. 2. COURSE DETAILSThis Course will cover the following Topics: Introduction. Software Process Models. Requirements Analysis & Specification Design Coding 2
  3. 3. COURSE DETAILS Testing Maintenance Computer Aided Software Engineering (CASE) Software quality assurance Managing Software Projects 3
  4. 4. LEARNING OBJECTIVESAfter successfully completing the modulestudent should be : explain the software engineering principles and techniques that are used in developing quality software products apply software engineering principles and techniques appropriately to develop moderately complex software system 4
  5. 5. ASSESSMENT METHODThe assessment method will be as following: Final Exam: 60% Med-Term Exam:20% Tutorial & Presentation:20% ( including The Lab. Remarks & attendance. 5
  6. 6. COURSE LAB. In the practical part of this course you will learn how to use CASE tools (UML) in addition to do some tutorial related to the course subjects. 6
  7. 7. CONTACT INFO. You can contact me at any time by Email: Aalageed@neelain.edu.sd I will be available at my office on Sat. from 12:00 PM to 2:00 PM 7
  8. 8. COURSE REFERENCES Main Reading:1. Software Engineering by Ian Sommerville, 8th edition, Addison- Wesley, 2006.2. Software Engineering: A practitioners approach by Roger S. Pressman, 6th edition, McGraw-Hill International edition, 2005. 8
  9. 9. COURSE REFERENCES Supplementary Reading1. http://portal.acm.org/citation.cfm?id=11593932. http://www.vnunet.com/vnunet/news/211731 5/air-traffic-system-already-obsolete 9
  10. 10. 1. INTRODUCTIONInstructional Objectives Describe what software is, different types of software and software quality attributes Describe with the problems associated with software and software development Define what software engineering is and explain why it is important State some professional issues related to software development 10
  11. 11. 1.1 SOFTWARE1.1.1. What is software? [Ref.1: pg. 5-6] Computer programs and associated documentation such as requirements, design models and user manuals in addition to data structure. Software products may be developed for a particular customer or may be developed for a general market. 11
  12. 12. 1.1.1 WHAT IS SOFTWARE Software products may be  Generic - developed to be sold to a range of different customers e.g. PC software such as Excel or Word.  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. 12
  13. 13. 1.1 SOFTWARE1.1.2. Types of software [Ref.2: pg. 40-41] System software Application Software. Engineering and scientific software Embedded software Product-line software. Web-based software Artificial intelligence software 13
  14. 14. 1.1 SOFTWARE1.1.3. Characteristics of Software [Ref.2: pg. 36-39][Ref.4] Software is differ form any other thing that human beings build. Software is a logical rather than a physical system element. Therefore software has characteristics that are considerably different than those of hardware. 14
  15. 15. 1.1.3. CHARACTERISTICS OF SOFTWARE Software is developed or engineered; it is not manufactured in the classical sense. Software doesn’t “wear out” 15
  17. 17. 1.1.3. CHARACTERISTICS OF SOFTWARE Although the industry is moving toward component-based construction, most software continues to be custom built 17
  18. 18. 1.1 SOFTWARE1.1.4. Attributes of good software [Ref.1: pg. 34-35] 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; 18
  19. 19. 1.1.4. ATTRIBUTES OF GOOD SOFTWARE 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. 19
  20. 20. SUCCESSFUL SOFTWARE SYSTEM Software development projects have not always been successful. When do we consider a software application successful?  Development completed.  It’s useful.  It’s usable.  And it’s used. 20
  21. 21. REASONS FOR FAILURE Schedule slippage. Cost-over run. Does not solve user’s problem. 21
  22. 22. REASONS FOR FAILURE Ad hoc software development results in such problems:  No planning of development works(e.g no milestones defined).  Deliverables to user not identified.  Poor understanding of user requirements.  No control or review.  Technical incompetence of developers.  Poor understanding of cost and effort by both developer & user. 22
  23. 23. ENGINEERING: OTHER DISCIPLINES Large projects common and successfully done:  Buildings bridges, Dams.  Power plants  Aircrafts Engineering a solution:  To design, develop( build, fabricates) an artifact that meets specifications efficiently, cost- effectively and ensuring quality  Using scientific principles 23
  24. 24. ENGINEERING Requires well-defined approach: repeatable, predictable 24
  25. 25. 1.2. SOFTWARE ENGINEERING1.2.1. What is software engineering? [Ref.1: pg.29] 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. 25
  26. 26. WHAT IS THE DIFFERENCE BETWEEN SOFTWAREENGINEERING 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). 26
  27. 27. WHAT IS THE DIFFERENCE BETWEEN SOFTWAREENGINEERING 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. 27
  28. 28. 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. 28
  29. 29. 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. 29
  30. 30. WHAT IS A SOFTWARE PROCESS MODEL? Generic process models  Waterfall;  Iterative development;  Component-based software engineering. 30
  31. 31. 1.2. SOFTWARE ENGINEERING1.2.2. Software engineering costs [Ref.1: pg. 31-33] 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. 31
  32. 32. 1.2.2. SOFTWARE ENGINEERING COSTS Distribution of costs depends on the development model that is used. 32
  35. 35. 1.2. SOFTWARE ENGINEERING1.2.3. What are the key challenges facingsoftware engineering? [Ref.1: pg. 35-36]Heterogeneity, delivery and trust. Heterogeneity  Developingtechniques for building software that can cope with heterogeneous platforms and execution environments; 35
  36. 36. 1.2.3. WHAT ARE THE KEY CHALLENGESFACING SOFTWARE ENGINEERING? Delivery  Developing techniques that lead to faster delivery of software; Trust  Developing techniques that demonstrate that software can be trusted by its users. 36
  37. 37. 1.2. SOFTWARE ENGINEERING1.2.5. Professional Practice [Ref.1: pg. 36-39; Ref.2: pg.128-149] 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 outwith their competence. 37
  38. 38. 1.2.5. PROFESSIONAL PRACTICE 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. 38
  39. 39. 1.2.5. PROFESSIONAL PRACTICE 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). 39