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Software Engineering - chp1- software dev methodologies

Software Development methodologies

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Software Engineering - chp1- software dev methodologies

  1. 1. MedTech Chapter 1 – Software Development Methodologies Methods and Methodologies for designing software Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 1 MedTech – Mediterranean Institute of Technology Software Engineering MedTech
  2. 2. MedTech Summary of the Course Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 2 • Introduction to Software Development Methodoogies • Software Development Models • Software Development Methodologies • Ad-hoc • Waterfall • Prototyping • V-Model • Spiral • RAD • Unified Process • Agile
  3. 3. MedTech Software Project • A project is a set of actions planned and executed by a group of people in order to reach a goal, limited by a deadline, and having a certain cost • To manage a project • Define a methodology • Manage concerned people • Manage technical constraints • Manage available means… Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 3 Introduction to Software Development Methodologies
  4. 4. MedTech Software Development Methodology • Also called: • System Development Methodology • Software Development Lifecycle • Software Development Process • A set f activities whose goal is the development or evolution of software • Generic activities in all software processes • Specification • Design • Development • Validation • Evolution Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 4 Introduction to Software Development Methodologies
  5. 5. MedTech Software Lifecycle • Defines all the software development phases, starting from the requirements specification of the client, to the final stages of software creation • These phases are organized with regard to models that guide the engineer in his activities • Linear models • Iterative models • Incremental models • Adaptive models • Extreme models Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 5 Introduction to Software Development Methodologies
  6. 6. MedTech Summary of the Course Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 6 • Introduction to Software Development Methodoogies • Software Development Models • Software Development Methodologies • Ad-hoc • Waterfall • Prototyping • V-Model • Spiral • RAD • Unified Process • Agile
  7. 7. MedTech Software Development Models • Linear Model • A number of dependent phases that are executed in a sequential order with no feedback loops • The solution is only produced at the final phase • Well defined goals, requirements and solution, few scope change requests • Incremental Model • Same as the linear model, except that each phase releases a partial solution or deliverable • Well defined goals, requirements and solution, more agressive schedule • Iterative Model • A number of phases repeated in groups with a feedback loop after each group is completed • The last phase in a group might release a partial or final solution • Well defined goals, not all features known, learn-by-doing strategy Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 7 Introduction to Software Development Methodologies
  8. 8. MedTech Sw. Dev. Models : Incremental vs. Iterative Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 8 Introduction to Software Development Methodologies
  9. 9. MedTech Sw. Dev. Models : Incremental and Iterative Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 9 Introduction to Software Development Methodologies
  10. 10. MedTech Software Development Models • Adaptive Model • Progresses from iteration to iteration based on limited specification of the solution • Each iteration learns from the preceding ones • Attempts to converge on an acceptable solution for the customer • Well defined goals but frequent change requests • Extreme Model • Same as the adaptive model except that the specification of the solution is minimal and the goals are not clearly defined • Goals are unknown, typical R&D projects Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 10 Introduction to Software Development Methodologies
  11. 11. MedTech Summary of the Course Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 11 • Introduction to Software Development Methodoogies • Software Development Models • Software Development Methodologies • Ad-hoc • Waterfall • Prototyping • V-Model • Spiral • RAD • Unified Process • Agile
  12. 12. MedTech Ad-hoc (Big Bang) Methodology • Typically, no methodology at all! • The client states his needs, and the developer just does the work! • Pros • Simple and straightforward • Adequate for small and simple systems • Cons: A big problem if: • The client doesn’t express his needs correctly • The developer doesn’t know how to proceed with the implementation • … and it does not support any changes in the requirements Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 12 Software Development Methodologies
  13. 13. MedTech Waterfall Analysis Design Development Testing Implementation Maintenance Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 13 Software Development Methodologies • Linear Model • Requirementshould be clear before the next step • Testing is done once the code fully developed • A time period is defined for eachstep
  14. 14. MedTech Waterfall • Pros • Requirement is clear before development starts • Each phase is completed in specific period of time, after that it moves to the next phase • As a linea model, it is easy to implement • The amount of required resources are minimal • Each phase requires a proper documentation • Cons • Some phases problems appear when going through the next phases • It is not flexible and does not support any requirements changes • The client sees the resulting product once all the phases are over Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 14 Software Development Methodologies
  15. 15. MedTech Prototyping Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 15 Software Development Methodologies
  16. 16. MedTech Prototyping Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 16 Software Development Methodologies • Remedies to the problem of the waterfall methodology, where we are never sure if the specification will work until you are at the last stage • Creates a prototype of the application: • Incomplete versions of the program • Simulates only a few aspects of the final product • Pros • The customer can be reassured with a sample of his application way before the development is achieved • Cons • A prototype mostly cannot cover all the problems a real application does! • You spend a significant time creating the prototype • Sometimes, the customer is happy with the prototype, and doesn’t go further with the real application!!
  17. 17. MedTech V-Model Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 17 Software Development Methodologies Analysis High Level Design Low Level Design Implementation Acceptance Testing System Testing Integration Testing Unit Testing
  18. 18. MedTech V-Model • Modified version of the waterfall method (linear model) • The stages turn back upwards to verify and validate every step • The test cases are prepared with every step • Tester et developer work in parallel • Pros • Same as those of the waterfall + the tester is involved from the requirement phase • Cons • Rigid • If changes happen midway, not only the requirements documentation, but also the test documentation need to be changed • Is not adequate for short term projects as it requires reviews at each stage Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 18 Software Development Methodologies
  19. 19. MedTech Spiral Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 19 Software Development Methodologies
  20. 20. MedTech Spiral • Linear and Incremental Model + Prototyping • Big emphasis on risk assessment • 4 main phases: • Objective Setting, Risk Analysis, Engineering and Planning • Pros • High amount of risk analysis • Software produced early in the lifecycle • Cons • Can be costly • Risk analysis requires highly specific expertise • Is not adequate for small projects Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 20 Software Development Methodologies
  21. 21. MedTech RAD: Rapid Application Development • First method that fundamentally breaks with the waterfall-based methods • Iterative, incremental and adaptative • Uses minimal planning in favor of rapid prototyping • Massive use of computarized development tools (CASE, GUI builders, DBMS…) • Gathers customer requirements through: • Workshops or focus groups • Early testing of the prototypes using iterative concept • Reuse of existing prototypes • Continuous integration • Used if: • There is a need to produce the system in a short span of time (2-3 months) • There is a high availabilityof designers and a high budget for code generating tools Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 21 Software Development Methodologies
  22. 22. MedTech RAD: Rapid Application Development Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 22 Software Development Methodologies
  23. 23. MedTech RAD: Rapid Application Development • Pros • Reduced development time • Increased reusability of components • Quick initial reviews • Encourages customer feedback • Iteration time can be short using RAD tools • Cons • Depends on a strong team and individual performance • Only applicable for modularizable systems • Inapplicable to cheaper projects as cost of modeling and automated code generation is very high Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 23 Software Development Methodologies
  24. 24. MedTech Unified Process • Iterative and incremental model, use case driven and architecture centered • A software engineering process based on best practices in software development • A disciplines approach to assigning and managing tasks and responsabilities in a development organization • Focused on high-quality software that meets the needs of its end users • Uses the UML notation • Consists of five core workflows and four phases Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 24 Software Development Methodologies
  25. 25. MedTech Unified Process Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 25 Software Development Methodologies
  26. 26. MedTech Unified Process : Terminology Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 26 Software Development Methodologies • Development Cycle • Period of time that elapses from the start of the project until product release • Artifact • Piece of information produced, modified or used by a process • Workflow • Sequence of activities that produces a result of observable value • Phase • Each cycle is broken down into a sequence of four phases • Time during which a well-defined set of objectives is met, artifacts are completed and decisions whether to move to the next step or not are made • Iteration • Inside eahc phase, there may be one or more iterations • Software is developed in each iteration, concluded by a minor milestone • The software product grows incrementally as you iterate over the activities • Milestone • Release point at which an iteration formally ends
  27. 27. MedTech Unified Process : Phases • Inception: 10% Time, 5% Effort • Helps determine the project feasibility, what the customer wants and how to get there • Understand what to build • A vision document • Optional business model • Initial project glossary • Identify key system functionality • An initial use case model (10-20% complete) • One or several prototypes • Understand costs, schedule and risks • Decide what process to follow and what tools to use • Project plan • First Major Milestone: Lifecyle Objective Milestone • Is the project doomed to fail? Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 27 Software Development Methodologies
  28. 28. MedTech Unified Process : Phases • Elaboration : 30% Time, 20% Effort • Define and baseline the architecture of the System to provide a stable basis for the design • Deeper requirements understanding • At least 80% complete use case model • Non functional requirements capturing • Architect consideration • Software architecture description • Executable architectural prototype • Revised risk list and business case • Development case refinement • Coarse grained project plan • Defining iterations & evaluation criteria for each one • Major Milestone: Lifecycle Architecture • Is the project’s plane, vision, architecture are good enough to achieve project goals? Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 28 Software Development Methodologies
  29. 29. MedTech Unified Process : Phases • Construction: 50% Time, 65% Effort • Targets a cost-efficient development of a complete product • Minimize development costs and achieve some degree of parallelism • Iteratively develop a complete product • Software product integrated on the adequate platforms • User manuals • Desciption of the current release • Major Milestone: Initial Operational Capability • Is the product ready to be deployed to a beta test env.? Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 29 Software Development Methodologies
  30. 30. MedTech Unified Process : Phases • Transition: 10% Time, 30% Effort • Transition the software product to the user community • Think about next releases, finish postponed features • Beta testing to validate the new system against user experience • Conversion of operational databases • Training of users and maintainers • Marketing, distribution • Improve performance • Major Milestone: Product Release • Are the objectives met and should we start another development cycle? Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 30 Software Development Methodologies
  31. 31. MedTech Two Track Unified Process • Declination of the Unified Process Methodology • Takes into account the continuous contraints changes during the development • Considers two risks: • Functional inaccuracy: inadequacy to the requirements • Unability to integrate technologies • General principle • Every possible evolution of the system can be decomposed and managed separately, following a functional axis and a technical axis • 2TUP • Unified process (iterative, archi-centered and UC driven) • Two branches (technical and functional), merged into a realization branch Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 31 Software Development Methodologies
  32. 32. MedTech Two Track Unified Process Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 32 Software Development Methodologies Capture ofBusiness requirements Analysis Capture ofTechnical requirements Generic Design Preliminary Design Detailed Design Coding and Tests Recipe Functional Branch Technical Branch Design and Development Branch
  33. 33. MedTech Two Track Unified Process Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 33 Software Development Methodologies
  34. 34. MedTech Agile Approach • Agile movement seeks alternatives to traditional project management • Uses the incremental and iterative model • Regular cadences of work (sprints or iterations) at the end of which the team must present a product increment • Every aspect of development (requirements, design, …) is continually revisited throughout the lifecycle • Possible changes of direction while the project is running: Agility! • Inspect-and-adapt approach Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 34 Software Development Methodologies
  35. 35. MedTech Agile Manifesto : agilemanifesto.org Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 35 Software Development Methodologies Through this work, we have come to value: Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation Responding to change over following a plan That is, while there is value in the items on the right, we value the items on the left more
  36. 36. MedTech Agile Approach : 12 Principles 1. Our highest priority is to satisfy the customer through early and continuous delivery of valuable software. 2. Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage. 3. Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale. 4. Business people and developers must work together daily throughout the project. 5. Build projects around motivated individuals. Give them the environment and support their need, and trust them to get the job done. 6. The most efficient and effective method of conveying information to and within a development team is face-to-face conversation. Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 36 Software Development Methodologies
  37. 37. MedTech Agile Approach : 12 Principles 7. Working software is the primary measure of progress. 8. Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely. 9. Continuous attention to technical excellence and good design enhances agility. 10. Simplicity--the art of maximizing the amount of work not done--is essential. 11. The best architectures, requirements, and designs emerge from self- organizing teams. 12. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly. Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 37 Software Development Methodologies
  38. 38. MedTech Agile Approach Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 38 Software Development Methodologies
  39. 39. MedTech Extreme Programming (XP) • Is an Agile Methodology • Iterative, Incremental and Extreme • Key principles (see http://www.extremeprogramming.org/ ) 1. Planning • User stories are written • Release planning creates the release schedule • Divide the project iterations and start each one with a planning step 2. Managing • Give the team a dedicated workspace • Set a sustainable pace • A stand up meeting starts each day • The project velocity is measured • Move people around • Fix XP when it breaks Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 39 Software Development Methodologies
  40. 40. MedTech Extreme Programming (XP) • Key principles 3. Designing • Simplicity • Choose a system metaphor • Never add functionalities early • Refactor whenever and wherever possible 4. Coding • Customer always available • Code the unit test first • All production code is pair programmed • Integrate often, with a dedicated computer 5. Testing • All code must have unit tests, and must pass them before it is released • When a bug is found, tests are created • Acceptance tests are run often and the score is published Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 40 Software Development Methodologies
  41. 41. MedTech Extreme Programming (XP) Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 41 Software Development Methodologies
  42. 42. MedTech SCRUM A little story to kick it off Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 42 Software Development Methodologies
  43. 43. MedTech SCRUM • Agile Methodology • SCRUM is a team pack in Rugby, everybody in the pack acts together with everyone else to move the ball down the field • A framework for complex software development projects (but not only…) • Actors: • The Scrum Master: is responsible to deliver the expected deliverables. Know how to get things done. • The Product Owner: represent stakeholders in meetings. Know what has to get done. Can prioritize. • The Team: includes (but is not limited to) developers. They commit to deliver. • The Stakeholders: are the sponsor of the project. They might not know what has to be done, they know (most of the times) what they need. Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 43 Software Development Methodologies
  44. 44. MedTech SCRUM • A product owner creates a prioritized wish list called a product backlog. • During sprint planning, the team pulls a small chunk from the top of that wish list, a sprint backlog, and decides how to implement those pieces. • The team has a certain amount of time — a sprint (usually two to four weeks) — to complete its work, but it meets each day to assess its progress (daily Scrum). • Along the way, the ScrumMaster keeps the team focused on its goal. • At the end of the sprint, the work should be potentially shippable: ready to hand to a customer, put on a store shelf, or show to a stakeholder. • The sprint ends with a sprint review and retrospective. • As the next sprint begins, the team chooses another chunk of the product backlog and begins working again. Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 44 Software Development Methodologies
  45. 45. MedTech SCRUM Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 45 Software Development Methodologies
  46. 46. MedTech References Dr. Lilia SFAXI www.liliasfaxi.wix.com/liliasfaxi Slide 46 • A.U. Hakizabera and al. Linear Models vs Agile Models: Making the right model decision, 2010 • S. Balaji and al. WATEERFALL Vs V-MODEL Vs AGILE: A COMPARATIVE STUDY ON SDLC, JITBM, 2012 • N. Munassar and al. A Comparison Between Five Models Of Software Engineering, IJCSI, 2010 • M. Kalali, RUP Overview, 2004 • K. Beck, Extreme Programming Explained, 2000

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