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CS251 – Software Engineering Lecture 21 Process and Life Cycle

CS251 – Software Engineering Lecture 21 Process and Life Cycle. حكمة اليوم. أفلم يسيروا في الأرض فتكون لهم قلوب يعقلون بها أو آذان يسمعون بها فإنها لا تعمى الأبصار ولكن تعمى القلوب التي في الصدور. Assessment. Midterm exam (5%) Project (15% = 5 + 5 + 5 + 1 + Bonus) Quizzes (10 + 1%)

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CS251 – Software Engineering Lecture 21 Process and Life Cycle

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  1. CS251 – Software EngineeringLecture 21Process and Life Cycle

  2. حكمة اليوم • أفلم يسيروا في الأرض فتكون لهم قلوب يعقلون بها أو آذان يسمعون بها • فإنها لا تعمى الأبصار ولكن تعمى القلوب التي في الصدور

  3. Assessment • Midterm exam (5%) • Project (15% = 5 + 5 + 5 + 1 + Bonus) • Quizzes (10 + 1%) • Lab (5 + 1%) • A1 (5%)

  4. Lecture Outline • SW Lifecycle • SW Process Models

  5. Requirement Analysis Design Implement Testing Where are we now? Process Models Software Configuration Management Software Process

  6. Requirement Analysis Design Implement Testing Where are we now? Process Models Software Configuration Management Software Process

  7. 1. Software Life Cycle • Conception • Feasibility Study / Domain Analysis • Requirements’ Gathering • Overall Design • Detailed Design • Development (Coding, Programming) • Testing (Unit, Integration, Acceptance) • Deployment / Training • Maintenance and Evolution

  8. Process of Building a House Same life cycle Different Process

  9. Software Life Cycle Specification • Conception • Feasibility Study / Domain Analysis • Requirements’ Gathering • Overall Design • Detailed Design • Development (Coding, Programming) • Testing (Unit, Integration, Acceptance) • Deployment / Training • Maintenance and Evolution Development Validation Evolution

  10. Important Terms • Software life-cycle • Phases • Development cycle and evolution cycle • Software process • Discipline, activities, roles, and artifacts • Iterations • Milestones

  11. Software Life Cycle (As in RUP) Inception • Conception • Feasibility Study / Domain Analysis • Requirements’ Gathering • Overall Design • Detailed Design • Development (Coding, Programming) • Testing (Unit, Integration, Acceptance) • Deployment / Training • Maintenance and Evolution Elaboration Construction Transition

  12. Inception Elaboration Construction Transition T I M E Phases of the Development Cycle Inception - Define the scope of project Elaboration - Plan project, specify features, baseline system Construction - Build the product Transition- Transition the product into end user community

  13. Software Process • The set of activities and associatedresults that produce a software product. • Four fundamental process activities: • Software Specification • Software Development • Software Validation • Software Evolution • Can be organized in different ways, described at varying level of details → different software development process models

  14. 2. SE Process • A software process model describes the activities performed to produce a software, the order of these activities, the roles responsible of them and the deliverables produced from each activity. • The distinction between SDLC and SP is a not clear cut.

  15. 1. Waterfall Model • Requirements– defines needed information, function, behavior, performance and interfaces. • Design – data structures, software architecture, interface representations, algorithmic details. • Implementation – source code, database, user documentation, testing.

  16. Waterfall Strengths • Easy to understand, easy to use • Provides structure to inexperienced staff • Milestones are well understood • Sets requirements stability • Good for management control (plan, staff, track) • Works well when quality is more important than cost or schedule

  17. Waterfall Deficiencies • All requirements must be known upfront • Deliverables created for each phase are considered frozen – inhibits flexibility • Can give a false impression of progress • Does not reflect problem-solving nature of software development – iterations of phases • Integration is one big bang at the end • Little opportunity for customer to preview the system (until it may be too late)

  18. When to use the Waterfall Model • Requirements are very well known • Product definition is stable • Technology is understood • Newversion of an existing product • Porting an existing product to a new platform.

  19. 2. Incremental SDLC Model • Construct a partial implementation of a total system • Then slowly add increased functionality • The incremental model prioritizes requirements of the system and then implements them in groups. • Each subsequent release of the system adds function to the previous release, until all designed functionality has been implemented.

  20. Incremental Model Strengths • Develop high-risk or major functions first • Each release delivers an operational product • Customer can respond to each build • Uses “divide and conquer” breakdown of tasks • Lowers initial delivery cost • Initial product delivery is faster • Customers get important functionality early • Risk of changing requirements is reduced

  21. Incremental Model • Each increment is a mini-waterfall. CPSC-4360-01, CPSC-5360-01, Lecture 2

  22. Incremental Model Weaknesses • Requires good planning and design • Requires early definition of a complete and fully functional system to allow for the definition of increments • Well-defined module interfaces are required (some will be developed long before others) • Total cost of the complete system is not lower

  23. When to use the Incremental Model • Risk, funding, schedule, program complexity, or need for early realization of benefits. • Most of the requirements are known up-front but are expected to evolve over time • A need to get basic functionality to the market early • On projects which have lengthy development schedules • On a project with new technology

  24. 3. Spiral SDLC Model • Adds risk analysis, and prototyping to the waterfall model • Each cycle involves the same sequence of steps as the waterfall process model

  25. Spiral QuadrantDetermine objectives, alternatives and constraints • Objectives: functionality, performance, hardware/software interface, critical success factors, etc. • Alternatives: build, reuse, buy, sub-contract, etc. • Constraints: cost, schedule, interface, etc.

  26. Spiral QuadrantEvaluate alternatives, identify and resolve risks • Study alternatives relative to objectives and constraints • Identify risks (lack of experience, new technology, tight schedules, poor process, etc. • Resolve risks (evaluate if money could be lost by continuing system development

  27. Spiral QuadrantDevelop next-level product • Typical activites: • Create a design • Review design • Develop code • Inspect code • Test product

  28. Spiral QuadrantPlan next phase • Typical activities • Develop project plan • Develop configuration management plan • Develop a test plan • Develop an installation plan

  29. Spiral Model Strengths • Provides early indication of insurmountable risks, without much cost • Users see the system early because of rapid prototyping tools • Critical high-risk functions are developed first • The design does not have to be perfect • Users can be closely tied to all lifecycle steps • Early and frequent feedback from users • Cumulative costs assessed frequently

  30. Spiral Model Weaknesses • Time spent for evaluating risks too large for small or low-risk projects • Time spent planning, resetting objectives, doing risk analysis and prototyping may be excessive • The model is complex • Risk assessment expertise is required • Spiral may continue indefinitely • Developers must be reassigned during non-development phase activities • May be hard to define objective, verifiable milestones that indicate readiness to proceed through the next iteration

  31. When to use Spiral Model • When creation of a prototype is appropriate • When costs and risk evaluation is important • For medium to high-risk projects • Long-term project commitment unwise because of potential changes to economic priorities • Users are unsure of their needs • Requirements are complex • New product line • Significant changes are expected (research and exploration)

  32. 4. Agile SDLC’s • Speed up or bypass one or more life cycle phases • Usually less formal and reduced scope • Reduce documentation • Embed quality activities in the development process • Used for time-critical applications

  33. Some Agile Methods • Adaptive Software Development (ASD) • Feature Driven Development (FDD) • Crystal Clear • Dynamic Software Development Method (DSDM) • Rapid Application Development (RAD) • Scrum • Extreme Programming (XP)

  34. Example SPs Rational Unified Process Scrum (Will be covered by Amr Samir) Remember, a SW Development Process defines:activities (or Tasks),their order, roles and deliverables(or Work Products or artifacts).

  35. 1. Rational Unified Process (RUP) • RUP is an iterative software development process framework by the Rational Software Corporation, a division of IBM. • It is not a single concrete prescriptive process, but rather an adaptable process framework, intended to be tailored. • Organizations and software project teams will select the elements of the process that are appropriate for their needs.

  36. UPEDU Is a version of RUP Phases Process Workflows Inception Elaboration Construction Transition Business Modeling Requirements Analysis & Design Implementation Test UPEDU Deployment Supporting Workflows Config & Change Mgmt ProjectManagement Environment http://www.upedu.org/

  37. Weight of Disciplines in Iteration Varies Life Cycle Phases Inception Elaboration Construction Transition Engineering Workflows Requirements Analysis & Design Implementation Test Supporting Workflows Configuration & Change Mgmt Project Management ITERATIONA ITERATION E

  38. M R D I M R D I Artifacts Evolve in the Develop. Cycle Inception Elaboration Construction Transition M R D I M R D I : M Management artifacts : R Requirements artifacts : D Design artifacts : I Implementation artifacts An iteration is a distinct sequence of activities with an established plan and evaluation criteria resulting in an modified artifacts

  39. UPEDU Roles • Project Manager • Reviewer • Any other Stakeholder • Analyst • Designer • Implementer • Integrator • Tester • Change Control Manager • Configuration Manager

  40. UPEDU Implementation Discipline: Activities

  41. UPEDU Implementation Discipline: Artifacts

  42. UPEDU Implementation Discipline: Activities

  43. 2. Scrum • Watch Amr Samir’s video under Acadox (11 min.) • Very important and very nice explanation of Scrum. • Will com in exam

  44. Reviewing Course Objectives1 • Teaching students the disciplined approach to engineering software systems. • Educating the students about the cost of software failures and the importance of software engineering. • Training the students on applying engineering practices in software development. • Introducing learners to the Software Engineering Body of Knowledge.

  45. Course Objectives2 • Training them on the basics of software requirements engineering, modeling, and design, construction and configuration and process management. • Training the students on system modeling using UML. • Training students on teamwork.

  46. Course Objectives3 • Coders - Can pretty much figure out it. It'll work, but it won't be pretty. • Hackers - usually low level folks, skillful, with detailed understanding of some area deeply, often scarily deeply. • Programmer - Write code and understand algorithms. Often work alone and well. • Software Engineer - Are the best generalists, can use lots of different systems and languages and get them to talk to each other. Are true and broad professionals, work with people, and communicate well.

  47. How to Study • Lectures (slides and videos and code) • Readings • Quizzes + Lecture Practice • Labs + Sections • Previous exams and questions

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