CSC307 Lecture 02

Introduction to Software Engineering
Process Models
(202406)

In today's class, we explored various software process models, starting with plan-based approaches: the waterfall model (linear and sequential), the V-model (emphasizing testing stages), the prototyping model (iterative with early user feedback), and the spiral model (iterative with risk management). We then introduced the global ideas behind Agile methodologies and contrasted them with plan-based models, highlighting flexibility, iterative progress, and customer collaboration.

Transcript

1. Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.info office: 14 -227 CSC 307 Introduction to Software Engineering Lecture 02. Process Models
2. Previously
3. Homework Read the Syllabus
4. Homework Read Textbook Chapter 1
5. Homework Read the Java Turorials
6. Software Process
7. Software Engineering “The application of a systematic, disciplined, quantifiable approach (process) to the development, operation, and maintenance of software.” – IEEE 7
8. Process 8 Process Activity Task Step
9. Activities 9 Deployment Software Testing Coding, Programming, Developing Software Design Requirement Engineering [+]
10. Activities 10
11. Activities 11
12. Strategies 12 • 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. •
13. Strategies 13
14. Plan-based Process
15. The Waterfall Model 15
16. The Waterfall Model • Key idea: Separate and distinct phases of specification and development. A phase has to be completed before moving on to the next phase. • Type: Linear model. • Recommended for: Embedded systems and Large systems(developed by several partner companies) • Disadvantage: the difficulty of accommodating change after the process is underway. 16
17. The V-Model 17 this arrows point at what we are testing
18. The V-Model • 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 the test is just one of five steps in Waterfall, it looks like practically half of the process in the 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 as waterfall 18
19. The Spiral Model 19
20. The Spiral Model • 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 20
21. Prototyping 21 Constructio n communication Quick plan Modeling Quick design Construction of prototype Deployment delivery & feedback
22. Prototyping • Definition: A prototype is an initial version of a system used to demonstrate concepts and test 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. 22
23. The Incremental Model 23 Option A: Linear Increments (not all colors (activities) are repeated)
24. The Incremental Model 24 Option B: Parallel Increments (most than 1 activity at the same time)
25. The Incremental Model ▪ Key idea: split each activity into 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 be 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 are spent on refactoring to improve the software, regular change tends to corrupt its structure. 25
26. Agile Methods
27. Agile in a Nutshell 27
28. Agile in Action 28
29. Agile Manifesto 29 Agile Manifesto We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value: n Individuals and interactions n Working software n Customer collaboration n Responding to change over processes and tools over comprehensive documentation over contract negotiation over following a plan While there is value in the items on the right, we value the items on the left more.
30. Agile Manifesto 30 Our highest priority is to satisfy the customer through early and continuous delivery of valuable software. Welcome changing requirements, even late in development. Agile processes harness change for the customer’s competitive advantage. Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale. Business people and developers must work together daily throughout the project. Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done. The most efficient and effective method of conveying information to and within a devel- opment team is face-to-face conversation. Working software is the primary measure of progress. Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely. Continuous attention to technical excellence and good design enhances agility. Simplicity – the art of maximizing the amount of work not done – is essential. The best architectures, requirements, and designs emerge from self-organizing teams. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly. The 12 Principles of Agile
31. Agile Manifesto 31 opment team is face-to-face conversation. and adjusts its behavior accordingly. Kent Beck Mike Beedle Arie van Bennekum Alistair Cockburn Ward Cunningham Martin Fowler Robert C. Martin Steve Mellor Dave Thomas James Grenning Jim Highsmith Andrew Hunt Ron Jeffries Jon Kern Brian Marick Ken Schwaber Jeff Sutherland ©2001-2019 The Agile Manifesto Authors. This declaration may be freely copied in any form, but only in its entirety through this notice. THE MANIFESTO AUTHORS Advancing the principles of Agile Learn more at AgileAlliance.org
32. Applicability • Product development is where a software company develops a small or medium-sized product for sale. • Nowadays, several software products and apps are small or medium-sized; therefore, they are developed using an agile approach. • Custom system development within an organization where the customer clearly commits to becoming involved in the development process and where there are few external rules and regulations that affect the software. 32
33. Pros • The product is broken down into a set of manageable and understandable chunks. • Unstable requirements do not hold up progress. • The whole team has visibility of everything, and consequently, team communication is improved. • Customers see on-time delivery of increments and gain feedback on how the product works. 33
34. Cons • 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. 34
35. Questions 35
36. Lab 02. Getting Started with Java Swing (Part II)
37. Previously
38. Paint App 38
43. Lab 01 Make It Work (Submit Code on Canvas)
44. CSC 307 Introduction to Software Engineering Javier Gonzalez-Sanchez, Ph.D. javiergs@calpoly.edu Summer 2024 Copyright. These slides can only be used as study material for the class CSC307 at Cal Poly. They cannot be distributed or used for another purpose.