SOFTENG PRELIMS

A space probe headed for Venus diverted from its intended flight path shortly after launch. Mission Control destroyed the rocket 293 seconds after liftoff.

Just hours after thousands of fans had left the __________ Coliseum, the steel-latticed roof collapsed under the weight of wet snow.

Control software went haywire and produced intense pressure in the Trans-Siberian gas pipeline, resulting in the largest man-made non-nuclear explosion in Earth’s history.

The Soviet early warning system falsely indicated the United States had launched five ballistic missiles. Fortunately the Soviet duty officer had a “funny feeling in my gut” and reasoned if the U.S. Was really attacking they would launch more than five missiles, so he reported the apparent attack as a false alarm.

Canada’s Therac-25 radiation therapy machine malfunctioned and delivered lethal radiation doses to patients.

: On “Black Monday” (October 19, 1987), the Dow Jones Industrial Average plummeted 508 points, losing 22.6% of its total value. The S&P 500 dropped 20.4%. This was the greatest loss ______ ever suffered in a single day.

A single switch at one of _______ 114 switching centers suffered a minor mechanical problem and shut down the center. When the center came back up, it sent a message to other switching centers, which in turn caused them to shut down and brought down the entire ______ network for 9 hours.

: During the first Gulf War, an American Patriot Missile system in Saudi Arabia failed to intercept an incoming Iraqi Scud missile. The missile destroyed an American Army barracks.

: Intel’s highly-promoted _________ chip occasionally made mistakes when dividing floating-point numbers within a specific range. For example, dividing 4195835.0/3145727.0 yielded 1.33374 instead of 1.33382, an error of 0.006%. Although the bug affected few users, it become a public relations nightmare. With an estimated 5 million defective chips in circulation, Intel offered to replace ________ chips only for consumers who could prove they needed high accuracy. Eventually Intel replaced the chips for anyone who complained.

Europe’s newest unmanned rocket, was intentionally destroyed seconds after launch on its maiden flight. Also destroyed was its cargo of four scientific satellites to study how the Earth’s magnetic field interacts with solar winds.

Human operators attempt to shut off the _______ global computer network. ______ responds by firing U.S. Nuclear missiles at Russia, initiating global nuclear war on what became known as Judgement Day (August 29, 1997).

After a 286-day journey from Earth, the _________________ fired its engines to push into orbit around Mars. The engines fired, but the spacecraft fell too far into the planet’s atmosphere, likely causing it to crash on Mars.

In this ironic case, software used to analyze disasters had a disaster of its own. The New England Journal of Medicine reported increased suicide rates after severe natural disasters. Unfortunately, these results proved to be incorrect.

The U.K. Passport Agency implemented a new Siemens computer system, which failed to issue passports on time for a half million British citizens. The Agency had to pay millions in compensation, staff overtime and umbrellas for people queuing in the rain for passports

One man’s disaster is another man’s fortune, as demonstrated by the infamous _______ bug. Businesses spent billions on programmers to fix a glitch in legacy software. While no significant computer failures occurred, preparation for the _____ bug had a significant cost and time impact on all industries that use computer technology.

A speculative bubble from 1995–2001 fueled a rapid increase in venture capital investments and stock market values in the Internet and technology sectors. The “_________________ began to collapse in early 2000, erasing trillions in stock market value, wiping out thousands of companies and jobs, and launching a global recession.

The ___________worm infected millions of computers and caused more damage than any other computer virus in history. The worm deleted files, changed home pages and messed with the Registry.

_______________by Multidata Systems International miscalculated the proper dosage, exposing patients to harmful and in some cases fatal levels of radiation. The physicians, who were legally required to doublecheck the software’s calculations, were indicted for murder.

Business services giant _______ developed a computer system for U.K.’s Child Support Agency (CSA) that accidentally overpaid 1.9 million people, underpaid another 700,000, had £3.5 billion in uncollected child support payments, a backlog of 239,000 cases, 36,000 new cases “stuck” in the system, and still over 500 documented bugs.

The ________ scrapped its computer systems overhaul after four years of effort. The Virtual Case File project was a massive, integrated software system for agents to share case files and other information.

Instructions (computer programs) that when executed provide desired function and performance

Software system delivered to a customer

Produced by a development organization and sold on the open market to any customer who is able to buy such product

commissioned by a particular customer and developed by some contractor to suit the specific needs of the customer

Characteristics of Software

An engineering discipline that is concerned with all aspects of software production such that high-quality software is produced in a cost-effective manner

4 Layers of Software Engineering

Purposeful collection of interrelated components that work together to achieve some objective.

consists of hardware, software, data, operational processes and organizational policies, people and documentation.

Sequence of steps required to develop or maintain software

4 Software process characteristics

4 Fundamental Process Activities

- basic framework that is applicable to all software projects

Development strategy that encompasses the process, methods and tools

basic process frameworks that are extended and adapted to create more specific processes

4 Generic models

Process phases are distinct and separate

process phases are interleaved

A mathematical system model is formally transformed to an implementation

System is assembled from existing components

Suggested by Mills 1980  In between waterfall and evolutionary  Reduce rework in the development process  Give customers opportunity to delay decisions on detailed requirements until they had some experience on the system

ρ� Can incorporate most other models

Based on the use of commercial-off-the-shelf packages (COTS)

ρ� iterative model created by the Rational Software Corporation (division of IBM)  uses the UML as a primary modeling technique

4 Rational Unified Process Phases (composed of iterations)

ρ� the process of defining, implementing and integrating loosely coupled independent components into systems

Based on the idea of manufacturing semiconductors in a “cleanroom environment”

Hides data implementation and process implementation. It describes how a system responds to stimuli, usually in a formal specification language

shows both data implementation and process implementation; goal is to stepwise refine procedures and to prove them correct

Represents a reasonable alternative to conventional software engineering for certain classes of software and certain types of software projects

ρ� grew out of RAD  embodies the principle that continuous learning and adaptation of the process to the work at hand is the normal state of affairs

3 Adaptive Software Development Phases

Model-driven iteration process based on clientvalued feature perspective, and milestones mark the progress for each feature

Based on the Pareto principle (80-20) that 80% of the business needs are found in 20% of the requirements

5 Project Life Cycle of Dynamic Systems Development Method

Agile method for project management, wrapper model

uses the UML as a primary modeling technique