SoftwareEng1aNotes

SoftwareEng1aNotes - 1 Software Engineering CST IA/IIG/Dip...

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Unformatted text preview: 1 Software Engineering CST IA/IIG/Dip Alan Blackwell OUTLINE OF COURSE The Software Crisis The Software Life Cycle Critical Software Quality Assurance Tools and Methods Large Systems Final lecture given by Dr Robert Brady of Brady plc. on developing packaged software. 2 RESOURCES The newsgroup comp.risks R S Pressman Software Engineering N Leveson Safeware Additional reading: F P Brooks The Mythical Man Month P Newman Computer-Related Risks L R Wiener Digital Woes Finkelstein inquiry reports: London Ambulance Service & CAPSA and its Implementation www.cs.ucl.ac.uk/staff/A.Finkelstein/ Also recommended wide reading in whichever application area(s) interest you (aviation, healthcare, banking,......) The Software Crisis The reality of software development has lagged behind the apparent promise of the hardware Most large projects fail - either abandoned, or do not deliver anticipated benefits LSE Taurus 400 m Denver Airport $ 200 m CONFIRM $ 160 m Some software failures cost lives or cause large material losses Therac 25 Ariane Pentium NY Bank - and Y2K in general Some combine project failure with loss of life, e.g. London Ambulance Service 3 London Ambulance Service Existing manual operation: 999 calls written on forms map reference looked up conveyor belt to central point controller removes duplicates, passes to NE/NW/S district division controller identifies vehicle and puts note in its activation box form passed to radio dispatcher Takes about 3 minutes, and 200 staff (of 2,700 total). some errors (esp. deduplication), some queues (esp. radio), call-backs are laborious to deal with LAS: Project Background Attempt to automate in 1980s failed - the system failed load test Industrial relations poor - pressure to cut costs Decided to go for fully automated system: controller answering 999 call would have on- screen map could send email directly to ambulance Consultancy study to assess feasibility: estimated cost 1.5m, duration 19 months provided a packaged solution could be found excluding an automatic vehicle location system (AVLS) 4 LAS: Award of Tender Idea of a 1.5m system stuck, but AVLS added proviso of packaged solution forgotten new IS director hired tender put out 7 February 1991 completion deadline January 1992 35 firms looked at tender 19 submitted proposals, most said: timescale unrealistic only partial automation possible by January 1992 Tender awarded to consortium: Systems Options Ltd, Apricot and Datatrak bid of 937,463 700K cheaper than next bidder LAS: Design Phase Design work done July main contract August mobile data subcontract September in December told only partial implementation possible in January front end for call taking gazetteer + docket printing by June 91, a progress meeting had minuted: 6 month timescale for 18 month project methodology unclear, no formal meeting program LAS had no full time user on project Systems Options Ltd relied on cozy assurances from subcontractors 5...
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SoftwareEng1aNotes - 1 Software Engineering CST IA/IIG/Dip...

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