Informatics 121 Software Design I Lecture 4 Duplication

Informatics 121 Software Design I Lecture 4 Duplication

Informatics 121 Software Design I Lecture 4 Duplication of course material for any commercial purpose without the explicit written permission of the professor is prohibited. SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 1 Discussion There will be discussion this upcoming Friday Please join your designated discussion SDCL

Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 2 Today Two fundamental challenges Software design Design failure Design cycle Design studio 1 SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine

sdcl.ics.uci.edu 3 Two fundamental challenges The nature of software The nature of people SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 4 Nature of software (Brooks) Complexity software is among the most complex people-made artifacts Conformity

software has no laws of nature that simplify its existence; rather, it lives in a world of designed artifacts to which it must conform Changeability software is subject to continuous pressure to change Invisibility because the reality of software is not embedded into space, it is inherently unvisualizable SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 5 Nature of people Diversity

people differ in how they experience the world Indiscernibility experiences are distinctly mental in nature, with tangible reactions and signs not always matching the actual experience Familiarity people tend to be risk averse, sticking to role, organizational, and societal norms and values Volatility with every new exposure, people reinterpret and modify their opinions and expectations SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 6

Software design Predicting the future Making tradeoffs Managing bias Accommodating change Balancing cost, quality, and effort Solving a problem, now and later SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 7 Software design: predicting the future Software design is a predictive activity that must anticipate

the experiences of people account for differing experiences account for shifting experiences Furthermore, when people share their vision for a future change in the world, they tend to be conservative The difficulty lies in how to balance what people perceive they need and what they actually need SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 8 Software design: making tradeoffs Tradeoffs must be made continuously over the course of a design project

a design solution is judged relative to other possible solutions that could have been made it is frequently impossible to quantify the relative virtues of each alternative Furthermore, any given design solution inevitably satisfies certain audiences and certain stakeholders more than others The difficulty lies in how to balance decisions across the needs and anticipated experiences of the various constituent audiences and stakeholders SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 9 Software design: managing bias Bias exists within all stakeholders, and can be a positive or

negative influence audience designer client others Furthermore, bias is typically difficult to detect and address The challenge lies in how to balance benefiting from positive bias while avoiding the effects of negative bias SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 10

Software design: accommodating change Change happens and must be anticipated changing client demands changing context of people, hardware, and software changing understanding of the design problem changing attitudes of the audience Furthermore, the more complete a design solution already is, the more difficult it is to change it The difficulty lies in how to balance accommodating change with making sufficient progress on the design solution SDCL Software Design and Collaboration Laboratory

Department of Informatics, UC Irvine sdcl.ics.uci.edu 11 Software design: balancing cost, quality, effort Quality, cost, and effort are three constraining factors in design, not all of which can be optimized at the same time cost constraints are typically set by other stakeholders cost constraints are typically set before the design project is truly understood Furthermore, there is no stopping rule, since no optimal design solution exists The difficulty lies in how to balance a design solution that is of good enough quality with expectations on cost and effort SDCL Software Design and Collaboration Laboratory

Department of Informatics, UC Irvine sdcl.ics.uci.edu 12 Software design: solving a problem, now and later Software ultimately solves someones problem (or at least fulfills someones need) software does not wear out software provides critical societal infrastructure Because software does not wear out, it very likely will have to accommodate new needs as well as deviations from present needs The difficulty lies in how to balance addressing todays design problem with accommodating future, unknown needs SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine

sdcl.ics.uci.edu 13 Why design To develop the right software for now for later To develop the software right on time within budget on target SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 14

Software design failure: air traffic control Air-Traffic Control System in LA Airport Incident Date: 9/14/2004 Ironic Factor: ***** (IEEE Spectrum) -- It was an air traffic controller's worst nightmare. Without warning, on Tuesday, 14 September, at about 5 p.m. Pacific daylight time, air traffic controllers lost voice contact with 400 airplanes they were tracking over the southwestern United States. Planes started to head toward one another, something that occurs routinely under careful control of the air traffic controllers, who keep airplanes safely apart. But now the controllers had no way to redirect the planes' courses. ... The controllers lost contact with the planes when the main voice communications system shut down unexpectedly. To make matters worse, a backup system that was supposed to take over in such an event crashed within a minute after it was turned on. The outage disrupted about 800 flights across the country. ... Inside the control system unit is a countdown timer that ticks off time in milliseconds. The VCSU uses the timer as a pulse to send out periodic queries to the VSCS. It starts out at the highest possible number that the system's server and its software can handle2 32. It's a number just over 4 billion milliseconds. When the counter reaches zero, the system runs out of ticks and can no longer time itself. So it shuts down. Counting down from 232 to zero in milliseconds takes just under 50 days. The FAA procedure of having a technician reboot the VSCS every 30 days resets the timer to 2 32 almost three weeks before it runs out of digits.

SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 15 Software design failure: air traffic control Air-Traffic Control System in LA Airport Incident Date: 9/14/2004 Ironic Factor: ***** (IEEE Spectrum) -- It was an air traffic controller's worst nightmare. Without warning, on Tuesday, 14 September, at about 5 p.m. Pacific daylight time, air traffic controllers lost voice contact with 400 airplanes they were tracking over the southwestern United States. Planes started to head toward one another, something that occurs routinely under careful control of the air traffic controllers, who keep airplanes safely apart. But now the controllers had no way to redirect the planes' courses. ... The controllers lost contact with the planes when the main voice communications system shut down unexpectedly. To make matters worse, a backup system that was supposed to take over in such an event

crashed within a minute after it was turned on. The outage disrupted about 800 flights across the country. ... Inside the control system unit is a countdown timer that ticks off time in milliseconds. The VCSU uses the timer as a pulse to send out periodic queries to the VSCS. It starts out at the highest possible number that the system's server and its software can handle2 32. It's a number just over 4 billion milliseconds. When the counter reaches zero, the system runs out of ticks and can no longer time itself. So it shuts down. Counting down from 232 to zero in milliseconds takes just under 50 days. The FAA procedure of having a technician reboot the VSCS every 30 days resets the timer to 2 32 almost three weeks before it runs out of digits. SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 16 Software design failure: Mars climate orbiter NASA Mars Climate Orbiter

Incident Date: 9/23/1999 Price Tag: $125 million Ironic Factor: **** WASHINGTON (AP) -- For nine months, the Mars Climate Orbiter was speeding through space and speaking to NASA in metric. But the engineers on the ground were replying in non-metric English. It was a mathematical mismatch that was not caught until after the $125-million spacecraft, a key part of NASA's Mars exploration program, was sent crashing too low and too fast into the Martian atmosphere. The craft has not been heard from since. ... Noel Henners of Lockheed Martin Astronautics, the prime contractor for the Mars craft, said at a news conference it was up to his company's engineers to assure the metric systems used in one computer program were compatible with the English system used in another program. The simple conversion check was not done, he said. SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 17 Software design failure: Mars climate orbiter

NASA Mars Climate Orbiter Incident Date: 9/23/1999 Price Tag: $125 million Ironic Factor: **** WASHINGTON (AP) -- For nine months, the Mars Climate Orbiter was speeding through space and speaking to NASA in metric. But the engineers on the ground were replying in non-metric English. It was a mathematical mismatch that was not caught until after the $125-million spacecraft, a key part of NASA's Mars exploration program, was sent crashing too low and too fast into the Martian atmosphere. The craft has not been heard from since. ... Noel Henners of Lockheed Martin Astronautics, the prime contractor for the Mars craft, said at a news conference it was up to his company's engineers to assure the metric systems used in one computer program were compatible with the English system used in another program. The simple conversion check was not done, he said. SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 18

Software design failure: child support agency EDS Child Support System Is Anything But Since 2004, Electronic Data Systems (EDS) has been maligned throughout much of the U.K. for a massively unpopular software program it built for the Child Support Agency. Complaints are registered frequently. A recap given by Sun Dog Interactive in 2009 revealed that over a five-year span, there were 1.9 million people who had overpaid into the system, 700,000 who had underpaid, and around $7 billion in uncollected child support payments along with a backlog of 239,000 cases and 36,000 new cases stuck in the system. As you can see from the image, its a problem so rampant there is even a website devoted to the agencys screw-ups, fittingly titled CSAHell.com. SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 19 Software design failures

SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 20 Top 10 software failures of 2011 Financial services giant fined $25 million for hiding software glitch that cost investors $217 million Computer system bugs cause Asian banking facilities downtime Cash machine bug benefits customers by giving them extra money Leading smartphones suffer an international blackout Bugs in social networking app for tablet just hours after delayed release 22 people wrongly arrested in Australia due to failures in new NZ $54.5 million courts computer system 50,500 cars recalled after airbag-related software glitch Recall of one million cars addresses fire and rollaway concerns

Telecoms glitch affects 47,000 customers meter readings and costs company NZ $2.7 million Army computer glitches hinder coordinated efforts in insurgent tracking SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 21 Top 15 worst computer software blunders

SDCL St. Marys Mercy Medical Center Kills Its Patients, On Paper Knight Capital Group Loses Nine Figures in 30 Minutes World War III Narrowly Averted AT&T Demonstrates How Not to Upgrade Software World Of Warcraft Creates Literal Computer Virus Apple Maps Goes Nowhere Fast Michigan Dept. of Corrections Grants Prisoners Early Release California Paroles 450 Violent Offenders (Without Supervision) IRS Costs America Close To $300 Million Patriot Missile System Timing Issue Leads To 28 Dead Software Design and Collaboration Laboratory

Department of Informatics, UC Irvine sdcl.ics.uci.edu 22 Design cycle synthesize analyze SDCL Software Design and Collaboration Laboratory evaluate Department of Informatics, UC Irvine sdcl.ics.uci.edu 23 Design cycle

synthesize analyze SDCL Software Design and Collaboration Laboratory goals constraints assumptions decisions ideas Department of Informatics, UC Irvine evaluate sdcl.ics.uci.edu 24

Goals A goal represents an explicit acknowledgment of a desired result that the eventual design solution must achieve Goals may be suggested by any of the stakeholders client other stakeholders audience designer Goals change over time, and may or may not be (partially) addressed by the current state of the design solution SDCL Software Design and Collaboration Laboratory

Department of Informatics, UC Irvine sdcl.ics.uci.edu 25 Example goals The luxury airplane must be 10% more fuel-efficient than its predecessor The library must be able to hold 250,000 books The award must be representative of the professional society that is commissioning it SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 26 Constraints

A constraint represents an explicit acknowledgment of a condition that restricts the design project Constraints may be suggested by any of the stakeholders client other stakeholders audience designer Constraints change over time, and may or may not be (partially) met by the current state of the design project SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine

sdcl.ics.uci.edu 27 Example constraints The luxury airplane must weigh less than 50,000 pounds The library must not violate federal disability laws The award must cost less than $1000 to produce SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 28 Assumptions An assumption represents a fact that is taken for granted, may or may not be true, and influences the design project

Assumptions may be made by any of the stakeholders client other stakeholders audience designer Assumptions change over time, and may or may not be (partially) fulfilled by the current state of the design project SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 29

Example assumptions The average person weighs 85 kilograms The library needs to serve the community with an area stocked with personal computers The professional societys logo is red and white, which therefore must be its preferred colors for the award SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 30 Decisions A decision represents a specific choice of how to further the design solution, typically after some amount of consideration Decisions are the sole responsibility of the designer, though

they can be (heavily) influenced by other stakeholders Decisions change over time, and new decisions may or may not (partially) align with the current state of the design project SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 31 Example decisions The fuselage and wings of the luxury airplane shall be made out of carbon composites The library shall have bookshelves that are not movable The award shall be made out of colored glass SDCL

Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 32 Idea An idea represents a thought or opinion, ranging from highly unformed to fully formed, that potentially shapes the design solution Ideas typically are the sole responsibility of the designer, though they may be inspired by many different sources Ideas change over time, and new ideas may or may not (partially) align with the current state of the design project SDCL Software Design and Collaboration Laboratory

Department of Informatics, UC Irvine sdcl.ics.uci.edu 33 Example ideas What if the luxury airplane had a shower on board? Perhaps the library membership cards should have RFID tags, so a visitor can simply grab the books they want, walk by an automated scanner, and have their books be on loan I am thinking that the award should be a variant of last years award SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 34

Design the software that flies a drone synthesize analyze SDCL Software Design and Collaboration Laboratory goals constraints assumptions decisions ideas Department of Informatics, UC Irvine evaluate

sdcl.ics.uci.edu 35 Design a new version of EEE/Canvas synthesize analyze SDCL Software Design and Collaboration Laboratory goals constraints assumptions decisions ideas Department of Informatics, UC Irvine evaluate

sdcl.ics.uci.edu 36 Design studio 1 Your client is LyftKids, a new company that recognizes the stress of todays parents in having to drop off and pick up their kids all throughout the day at many different places. LyftKids plans to directly work with parents in order to shuttle their kids from place to place on their behalf. The company has sought you out, because you are an excellent designer. All of the software design is in your hands, as LyftKids has the idea protected (meaning no competition), but has no idea how to actually design the software. SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine

sdcl.ics.uci.edu 37 Design studio 1 (part 1) Identify the audience and other stakeholders Identify possible goals, constraints, and assumptions Bring two printed copies to discussion, Friday one for the TAs one for your group Your group will be announced at the start of your discussion SDCL Software Design and Collaboration Laboratory Department of Informatics, UC Irvine sdcl.ics.uci.edu 38

Recently Viewed Presentations

  • PLOT CHARACTERS KEY QUOTES Act 1 Sheila and

    PLOT CHARACTERS KEY QUOTES Act 1 Sheila and

    Eva Smith is the embodiment of young, working-class women who were oppressed by the middle/upper classes. The play demonstrates that when workers do not have full employment rights they cannot fight back. KEY QUOTES. Birling''s. Confidence
  • A Gender Perspective on Recycling Sonia Dias WIEGO/

    A Gender Perspective on Recycling Sonia Dias WIEGO/

    It means to contribute to the emancipation of all people -- men and women. It was with this idea in mind that the Red Lacre, the National Movement of Waste Pickers in Brazil (MNCR), WIEGO began discussing in 2012 the...
  • PRESENT PERFECT TENSE - skopalic.edu.rs

    PRESENT PERFECT TENSE - skopalic.edu.rs

    HAVE/HAS V3 I have helped/gone we have helped/gone You have helped/gone you have helped/gone He has helped/gone they have helped/gone She has helped/gone It has helped/gone INTERROGATIVE We form questions with regular and irregular verbs in the present perfect with...
  • Title

    Title

    Outline. Recap . Introduction. Single-link/ Complete-link . Centroid/ GAAC. Variants. Labeling clusters. Centroid HAC. The similarity of two clusters is the average intersimilarity- the average similarity of documents from the first cluster with documents from the second cluster.
  • The 3 R's of Classroom Management - Mathews Elementary

    The 3 R's of Classroom Management - Mathews Elementary

    Reflection. Tangible. Social. Intrinsic. Give participants time to reflect by themselves and then in their small groups. Allow participants to share out.
  • JIGSAW ( Teaching Technique )

    JIGSAW ( Teaching Technique )

    Jigsaw Technique . A method of organizing classroom activity that makes students dependent on each other to succeed. Breaks classes into heterogeneous groups. Breaks assignments into pieces . The group assembles to complete the (jigsaw) puzzle.
  • The Frankenstein Unit

    The Frankenstein Unit

    In the film, a mad scientists creates a creature with little intelligence who rages against humanity. The Cultural Myth There are over 100 films about Frankenstein. Frankenstein has been used to sell merchandise such as Twix candy bars, Levi's Jeans,...
  • Hosting Capacity for NY - The Joint Utilities of NY

    Hosting Capacity for NY - The Joint Utilities of NY

    Most utilities have models of portions of their distribution system . Vast majority of distribution models. contain only medium voltageassets and all else is an equivalent or approximation. Have fixed controls . Asset and hourly load data is not always...