Software Development Process CSCE 315 – Programming Studio, Spring 2019 Robert Lightfoot
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
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.
Where would you like to workafter graduation? • 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.
Development Processes used by popular companies. • Look at a Process Microsoft uses. • Look at a Process NASAuses. • Look at a Process Google uses. • Look at a Process Facebook uses. • Look at a Process Amazon uses. • Look at a Process AT&T uses. • Look at a Process Boeing uses.
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
Waterfall Model Requirement Gathering Customer’s Needs Requirement Specification Analysis Models, Business Rules Design Software Architecture Coding Software Testing Defect-Free Operations Ongoing Maintenance
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
Waterfall Model • Lots of Variation • 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
Waterfall Model • Good 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
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
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
V-model • A version of Waterfall, tying the Validation at each level to the earlier stages User Acceptance Testing Requirements Analysis System Testing System Design Integration Testing Architecture Design Module Design Unit Testing Coding
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
Iterative Approach Plan and Design Collect Requirements Implement Test and Evaluate Initial Idea Deliverable
Iterative Methods • Prototyping • Spiral Model • Cleanroom Development • Rational Unified Process
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
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
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
Incremental Methods • Wide variety and variation in methods • Includes Agile methods – sort of taking over the “incremental” framework • Includes Test Driven Development
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
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
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…