Special Software Development Paradigms Today: HW #5 Next Class: Pressman 17; Demos? Questions? / Team Status Reports / HW#4 Object-Oriented Paradigm Bio Break ( 5 minutes ) Cleanroom Paradigm

Status Reports – 11/01/01 GroupPromised Today Next TimeNext Thur 1. Sliders Improved / more readable GUI 2. Connect Four (Calen, Luis, Suzanne, Lorena) Save & Load functionality 3. Wheel of Fortune Very Rough Draft of Detailed Design Doc. 4. Connect Four (Harry, Kannan, Liwei, Sean) Backend for simple voting implemented. 5. Blackjack Detailed Design Doc #2 6. Mine- sweeper Detailed Design Doc #1; VRD DD#2

Key OO Concepts 1.Data and code are packaged together in a capsule called an object. 2. Information and instructions are passed between objects in the form of messages. 3. Objects of a similar type are grouped together in classes. 4. Objects can inherit characteristics (data and procedures) from other objects in their class.

Advantages of OO Easy to re-use code Easy to extend or maintain code Results in clean, modular designs Easier to spot design defects Great for rapid prototyping

Costs / Risks with OO Time to learn Time to program useful library of classes Tough to keep track of al the classes

Golden Rule of OO Select tools that have already defined most of the classes you will want.

IBM’s Checklist for OO Pilot project identified: new project, flexible schedule OO programming team members identified Available OO tools and methodologies researched OO training complete Class hierarchies of selected tool appropriate to project needs Commitment for more design time up front obtained Project planned to maximize code reuse Rapid prototyping used to gain immediate feedback Feedback and continuous improvement process in place

Waterfall v. Cleanroom Traditional Waterfall Quality often tested in Unit test, function test, system test Division of labor common Serial development of whole product Test cases to uncover coding errors Cleanroom Quality is designed in No unit test; first test is system test Whole team involvement Incremental development & certification Statistical usage testing

Source: Secrets of Software Quality, Kaplan, Clark, & Tang pg. 271

Source: Secrets of Software Quality, Kaplan, Clark, & Tang pg. 277

Three Key Cleanroom Concepts Box structure specification (formal methods), allows… –Boxes encapsulate (aspects of) the system at a given level of abstraction –Black boxes represent external behavior of system –State boxes encapsulate state data and observations –Clear boxes have procedural design for state boxes Correctness verification. Certification refers to components that have undergone statistical usage testing.

Advantages of Cleanroom Zero defects possible < 6 errors/KLoc v errors/KLoc at first test Overall about 10X fewer error at first test Interfaces between increments well-tested MTTF (up to 20X) higher due to statistical usage testing

Costs / Risks with Cleanroom Expensive! (10 – 11 days of training) Time consuming (box spec takes up to 2X as long as regular spec)

IBM’s Checklist for Cleanroom Purpose of Pilot project clear Cleanroom literature selected Pilot project selected Management commitment and funding obtained Experts available for consultation Cleanroom team members identified and educated Conference room scheduled for daily use Product requirements understood and prioritized System environment understood Cleanroom specification written Expected customer usage defined Incremental development plan specified Test plan specified Verifiable designs for procedures and objects Team reviews Results measured and communicated Team recognition Feedback and continuous improvement process in place