1. Software Development Process
CSCE 315 – Programming Studio, Fall 2017
Tanzir Ahmed

2. Variety of Software Development Processes
Traditionally covered in Software Engineering
This is just a very brief overview
Many are not “clear cut” ideas
Often modified to incorporate ideas from other models; seldom used in “pure” form
Goal here: to familiarize you with some of the basic terminology/ideas
We will actually follow one approach: Agile/Scrum in project 2

3. Development Processes
More about the process than the actual development
Teamwork/ organization/ management/ collaboration focus
Opinion: Lots of words describing basic ideas/processes
Attempts to give precise definitions, descriptions to imprecise processes
Lots of “religious” arguments about the best way to approach these processes.

4. Waterfall Model of Development
The “traditional”/”baseline" software engineering approach
Series of stages, each a process that converts one product to another
Development “flows” from the top (early processes) through to the bottom

5. Waterfall Model Requirement Customer’s Gathering Needs Requirement
Specification
Analysis
Models,
Business Rules
Design
Software
Architecture
Coding
Software
Testing
Defect-Free
Operations
Ongoing
Maintenance

6. Waterfall Model (another view)
Requirement
Engineering
Customer’s
Needs
Requirement
Specification
Design
Design
Specification
Programming
Executable
Modules
Integration
Integrated
Software
Delivery
Delivered
Product
Maintenance
New
Requirements

7. Waterfall Model Lots of Variation Gets more complex
Key idea: flow “downhill” from one end to other
Gets more complex
Feedback from later stages to earlier ones
Verification and Validation testing in each stage
Or, a separate testing stage after integration
Can extend to incorporate iterative approaches

8. Waterfall Model Good Points Bad Points
Provides clear structured process, especially useful on large projects
Clear requirements, design at beginning can make things much easier and better later on
Tend to have good documentation throughout
Bad Points
Can be tough to know requirements ahead of time
Difficult to evaluate how later parts of system will really work in practice
Requires more discipline by programmers to implement

9. Waterfall
This is the “basis” against which other methods are compared.
The basic ideas are understood as needing to be addressed in other situations, also
The “flow” is somewhat natural from development: you need requirements to develop for, you need software to maintain
It is the one method to be familiar with, if you are familiar with only one method

10. V-model Requirements Analysis User Acceptance Testing System Design
A version of Waterfall, tying the Validation at each level to the earlier stages
Requirements
Analysis
User Acceptance
Testing
System
Design
System
Testing
Architecture
Design
Integration
Testing
Module
Design
Unit
Testing
Coding

11. Iterative Software Development
Rather than produce a single product “all at once”, provide incremental improvements
Deliver pieces of the product at various times
Time is planned to iterate on the design and implementation of the system
Includes user analysis, feedback to improve

12. Iterative Approach Plan and Design Collect Requirements Implement
Test and
Evaluate
Initial
Idea
Deliverable

13. Iterative Methods Prototyping Spiral Model Cleanroom Development
Rational Unified Process

14. Prototyping Deliver early prototypes of the software
Not fully functional, or with poor functionality
Prototypes should allow one to get user feedback
Allows revision of requirements, design
Possible problems:
Can hide difficulties underlying the prototype
Can set expectations too high
Provides early design anchoring (less flexible)
Attachment by user/developer to prototype, not system

15. Spiral Model
Combines iterative and prototype (and waterfall) approaches
Starting from center, (basic requirements), a prototype is created in first iteration
Each successive iterative cycle produces a newer, better prototype (spiraling out)
When good prototype is found, freeze system
Different cycles can use different techniques
Adjust the technique to the risk level in that part of the spiral

16. Cleanroom Development
Devised to put control onto Iterative Methods
Every iteration gets tested on a very large test data set
Provides “hard” statistical data on how reliable the method is
Measure whether iteration has introduced or reduced defects
Introducing defects indicates problem – go back to previous stage and start over

17. Incremental Methods Wide variety and variation in methods
Includes Agile methods – sort of taking over the “incremental” framework
Includes Test Driven Development

18. Agile Software Methods
Newer trend in software development
A favorite in the industry
“Lightweight” in contrast to existing “heavyweight” methods of software development
Heavyweight – Highly regimented methods, typified by the waterfall model
Agile designed to respond/change quickly, but involves much less long-term planning
Many methods fall under the “Agile” heading
Extreme programming
Scrum
Plus, it overlaps with some ideas of iterative development

19. Agile Methods Tend to involve lots of collaboration
Seem to work best with smaller, co-located teams
Good for projects where requirements tend to change
Will be the focus of the next lecture

20. Other Processes
Lots of other variations in development processes, often with different names:
Wikipedia list:
Waterfall, Prototyping, Incremental, Iterative, V- Model, Dual Vee Model, Spiral, IID, Agile, Lean, DevOps
Cleanroom, TSP, PSP, DSDM, MSF, Scrum, Kanban, UP, XP, TDD , ATDD, BDD, FDD, DDD, MDD
Many of these aren’t all that different from each other…