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CSC308B Lecture 02

CSC308B Lecture 02

Software Engineering I
Process Models
(202401) - two-days per week version

Javier Gonzalez-Sanchez

January 21, 2024
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  1. jgs CSC 308 Software Engineering 1 Lecture 02: Process Models

    Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.com Building 14 -227
  2. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2024 |

    3 Key Ideas Large vs Small Human-Centered Together but not scrambled
  3. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2024 |

    6 CSC 308 + CSC 309 Software Engineering Definition
  4. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2024 |

    7 “The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software” – IEEE Software Engineering
  5. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2024 |

    8 “The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software” – IEEE Software Engineering Process
  6. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2024 |

    10 process activity activity activity activity Definitions step step step step step step step step step step step step step step step step step
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    11 § Communication or Requirement § Modeling or Design § Construction or Coding § Testing (Unit, UI, Integration, Stress, Regression) § Deployment or Delivery Summary
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    12 How to connect the activities?
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    14 § Plan-driven all process activities are planned in advance and progress is measured against a plan (a contract). § Agile, planning is incremental and it is easier to change the process to reflect changing customer requirements. Strategy
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    15 Plan-Based Models: • Waterfall • V-model • Incremental • Spiral • Prototype Examples Agile Methodologies: • SCRUM • Kanban • XP (extreme programming) • Feature Driven Development
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    16 Summary Plan-Based Approaches Agile Approaches waterfall V-model Prototyping Kanban XP SCRUM
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    18 • Waterfall • V-model • Incremental • Spiral • Prototype Plan-based Process Models
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    20 § Key idea: Separate and distinct phases of specification and development. A phase has to be complete before moving onto the next phase. § Type: Linear model. § Recommended for: Embedded systems and Large systems(developed by several partner companies) § Disadvantage: difficulty of accommodating change after the process is underway. The Waterfall Model
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    21 The V-Model this arrows point at what we are testing
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    22 § Key idea: It is an extension of Waterfall where instead of moving down in a linear way, the process steps are bent upwards after the coding phase. While tests are just one of five steps in Waterfall, it looks like practically half of the process in V-model. § Type: Linear model. § Recommended for: well-suited for projects that must maintain a strict deadline and meet key milestone dates throughout the process. Example: medical device industry § Disadvantage: same that waterfall The V-Model
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    23 The Incremental Model Option A: Linear Increments (not all colors (activities) are repeated)
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    24 The Incremental Model Option B: Parallel Increments (most than 1 activity at the same time)
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    25 § Key idea: split each activity in pieces. § Type: Iterative model (it could include parallel). § Recommended for: Facilitate getting customer feedback on the development work that has been done. § Disadvantages: (1) it could not cost-effective to produce documents that reflect every version of the system; (2) System structure tends to degrade as new increments are added. Unless time and money is spent on refactoring to improve the software, regular change tends to corrupt its structure. The Incremental Model
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    26 Prototyping Construction of prototype communication Quick plan Modeling Quick design Construction of prototype Deployment delivery & feedback
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    27 § Definition: a prototype is an initial version of a system used to demonstrate concepts and try out design options. § Evolutionary model § Recommended for: a prototype can be used to help with requirements elicitation and validation; or in design processes to explore options and develop a UI design. Prototyping
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    29 § Key idea: High amount of risk analysis hence, avoidance of Risk is enhanced. § Evolutionary model § Recommended for: (1) Good for large and mission-critical projects. (2) Strong approval and documentation control. (3) Significant changes are expected (research and exploration). § Doesn’t work well for smaller projects. § Doesn’t work well when users are unsure of their needs § Doesn’t work well when requirements are complex The Spiral Model
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    31 § 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. Agile Manifesto
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    34 § Product development where a software company is developing a small or medium-sized product for sale. § Several software products and apps nowadays are small or medium-sized; therefore, they are developed using an agile approach § Custom system development within an organization, where there is a clear commitment from the customer to become involved in the development process and where there are few external rules and regulations that affect the software. Applicability
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    35 § The product is broken down into a set of manageable and understandable chunks. § Unstable requirements do not hold up progress. § The whole team have visibility of everything and consequently team communication is improved. § Customers see on-time delivery of increments and gain feedback on how the product works. Pros
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    36 § The informality of agile development is incompatible with the legal approach to contract definition (requirement specification) that is commonly used in large companies. § Agile methods are most appropriate for new software development rather than software maintenance (documentation). Yet the majority of software costs in large companies come from maintaining their existing software systems. § Agile methods are designed for small co-located teams yet much software development now involves worldwide distributed teams. Cons
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    38 § What are the two strategies (approaches) for software development? § What is a process? § What is a process model? § What are the activities involved in Software Development? Summary
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    39 Homework Learn Java (and its libraries) (The Java Tutorial’s link is posted on Canvas)
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    40 Homework Read Software Process Models (PDF available on Canvas)
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  30. jgs CSC 308 Software Engineering 1 Lab 02: Test Yourselves

    Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.com Building 14 -227
  31. jgs CSC 308 Software Engineering I Javier Gonzalez-Sanchez, Ph.D. [email protected]

    Winter 2024 Copyright. These slides can only be used as study material for the class CSC 308 at Cal Poly. They cannot be distributed or used for another purpose.