CS 4001Mary Jean Harrold1 High Cost of Software Failure Denver Airport Baggage System (1995): $280M Ariane 5 Explosion (1996): $7B Mars Rover (2004): Unknown cost Northeast Blackout (2003): $7M-$10M Software bugs are costing the U.S. economy an estimated $59.5 billion each year. Improvements in testing, debugging, and maintenance could reduce this cost by about a third, or $22.5 billion. (from NIST Estimated Planning Report 02-3)
CS 4001Mary Jean Harrold2 High Cost of Software Failure As governments, businesses and other organizations become more reliant on technology, the consequences of software failures are rarely trivial. Entire businesses — and even lives — are at stake. Many experts believe the situation will only worsen as software automates new tasks and more systems interconnect with and rely on other computers. Technical challenges may be surmounted, but managing people never gets easier.
CS 4001Mary Jean Harrold3 Software Disasters are Often People Problems— Bad management, communication or training to blame for failures October 4, 2004
CS 4001Mary Jean Harrold4 Software Disasters are Often People Problems—Another Incident Turbulent skies A breakdown of a radio system linking air traffic controllers to high-altitude planes over Southern California forced federal officials to halt outgoing flights for three hours Tuesday evening at several airports, including Los Angeles International. Though there were a handful of close calls, all 403 planes in the air during the incident managed to land safely. A handful violated rules that dictate how close they are allowed to fly to each other — but the FAA maintained there were no “near misses.”
CS 4001Mary Jean Harrold5 Software Disasters are Often People Problems—Another Incident Turbulent skies (cont’d) The genesis of the problem was the transition in 2001 by Harris Corp. of the Federal Aviation Administration’s Voice Switching Control System from Unix-based servers to Microsoft Corp.’s off- the-shelf Windows Advanced Server By most accounts, the move went well except the new system required regular maintenance to prevent data overload. When that wasn’t done, it turned itself off as it was designed to do. But the backup also failed. In all, the southern California system was down for three hours.
CS 4001Mary Jean Harrold6 Software Disasters are Often People Problems—Another Incident Turbulent skies (cont’d) The lack of robust testing likely contributed to the radio system outage over the skies of parts of California, Nevada, and Arizona.
CS 4001Mary Jean Harrold7 Software Disasters are Often People Problems— Some reasons Too often, he said, programmers are handed a lengthy document explaining the business requirements for a software project and left to interpret it. Unfortunately, developers are least qualified to validate a business requirement. Not enough resources are allocated Lack of strong leadership Poor communication Etc.
CS 4001Mary Jean Harrold8 Discussion Suppose you are responsible for the design and development of a computer system to control an amusement-part ride. Sensors in the seats will determine which seats are occupied, so the software can consider weight and balance. The system will control the speed and time of the ride. The amusement park wants a system where, once the ride starts, a person is not needed to operate it List some important things that can or should be done to ensure the safety of the system. Consider all aspects—development, technical issues, operating instructions, etc.
CS 4001Mary Jean Harrold9 Discussion After making a programming change in a major bank’s computer system, an employee forgot to enter certain commands. As a result, approximately 800K direct deposits received by the bank were not posted to the customer accounts until the next day. 1.In what way is this a “computer error”? 2.What are some potential consequences of the error? 3.If you were the bank president, what would you say in a statement to the news media or your customers?
CS 4001Mary Jean Harrold10 Discussion Software developers are sometimes advised to “design for failure.” Give some examples of what this might mean.
CS 4001Mary Jean Harrold11 Assignment Assignment 8Assignment 8