Introduction Introduction Introduction Introduction Outline - PDF document

Introduction Introduction Introduction Introduction Outline � Motivation � Failures � Definition and concepts � Process and product properties � Principles � SE Approaches

Motivation Software and the economy � The economies of ALL developed nations are dependent on software. � More and more systems are software controlled � Expenditure on software represents a significant fraction of GNP in all developed countries.

ICT Market – world - 2009 Market sectors - 2009 2000 1800 1600 1400 billion US$ - %of world GNP 1200 1000 800 600 400 200 0 Telecommunications IT Automotive market Sales 1. http :// en . wiserearth org . / article /61670 8 dc dd 5 c 5 a 3 adba 285 f 39 bbf 8145 , last visited : Feb, 17

Sales, 2010 CPUS: 10Gb Mobile phones: 1G Computers: 300M Tv sets: 250M Vehicles: 60M ICT market, per area world ICT market shares Mld$ , yearly variations 5.5% Rest of world 2.735 North America 6.1% 13.9% (Canada USA) 2.592 2.443 Asia – Pacific 36.0% North America 2000 20.6% 4.8% 885.6 (Canada USA) 4.9% 844.7 805.1 3.8% 4.4% Europe (27) 29.5% Europe (15) 779.1 750.6 Rest of world 719.2 North America 14.9% (Canada USA) 32.4% Asia – Pacific 8.6% 7.7% 664.3 616.8 567.9 2006 10.7% 3.3% Rest of world 24.3% 406.4 380.1 350.9 Asia – Pacific 2004 2005 2006 28.5% Europe (25) Fonte: AITech - Assinform / NetConsulting

ICT Diffusion, world Million Units sold - world M Units 2006 - world (2004 vs 2006) 25.0% 1,025 2,700 24.2% Mobile TLC 820 users 2,150 660 1,100 Internet Users 1,080 10.3% 17.3% 224 2006 203 279 173 Broadband 2005 users 210 Telefoni cellulari PC Fonte: AITech - Assinform / NetConsulting 2004 2005 2006 Italy

ICT Market Valori in Milioni di Euro e in % 63.844 +2.0% 62.611 +2.3% 61.180 +2.1% +3.0% 44,040 41,860 43,115 +1.6% +0.9% 19,496 19,804 19,320 2004 2005 2006 IT TLC Fonte: AITech - Assinform / NetConsulting IT Market Valori in milioni di Euro 19.804 19.496 19.320 0,9% 1,6% -0.1% +0.4% 9,289 9,252 9,258 +1.5% +2.7% 4,192 4,082 4,022 -3,7% -3,5% 850 883 915 +3,7% 5,278 5,473 5,125 +3,0% 2004 2005 2006 Hw Assistenza tecnica Software Servizi Fonte: AITech - Assinform / NetConsulting

Diffusion Businesses Families / Individuals 59% 51% 53% Europe 38% 36% 39% 37% Italy 25% 19% 11% 14% 3% Employees who Companies Companies Homes with Homes w Persons with use a PC at work who buy via who sell via Internet access broadband no computer Internet Internet access skill Fonte: Eurostat (2006) Diffusion Companies who buy Imprese on-line Companies who sell on-line UE25 countries UE25 countries Danimarca 34% 52% Irlanda 30% Regno Unito 50% Regno Unito 24% 48% Svezia Germania 23% 44% Paesi Bassi Svezia 23% 37% Irlanda Austria 18% 34% Francia Danimarca 18% 32% Germania Paesi Bassi 16% 30% UE25 Lussemburgo Austria 15% 29% UE25 Belgio 15% Finlandia 23% Finlandia 14% 21% Francia 13% 18% Lituania Slovenia 11% 17% Slovenia Lituania 11% Lussemburgo Repubblica Ceca 17% 9% 16% Polonia Polonia 8% 16% Spagna Belgio 8% 15% Repubblica Ceca Spagna 6% 10% Cipro Cipro 3% Italia 10% Italia 2% 3% Lettonia Lettonia Fonte: ISTAT (2006)

IT (2006) Euro IT expense/ per capita IT per employee IT GNP expense expense USA 3.9% 1,408 2,945 Japan 2.3% 878 1,765 Germany 3.1% 812 1,837 UK 3.1% 983 2,095 France 3.2% 839 2,050 Italy 1.9% 341 878 Spain 1.9% 372 748 Software, innovation, development � Evidence of correlation between ICT diffusion and wealth � Positive correlation IT usage and per capita GNP � Positive correlation productivity increase and ICT usage

Development – IT investment 2003 2004 3,5% USA 6,0% World 3,0% Spain 5,0% 2,5% 4,0% UK ∆ ∆ ∆ ∆ % GNP (2004/2003) ∆ % GNP (2003/02) ∆ ∆ ∆ Japan 2,0% USA UK Spain 1,5% 3,0% Japan 1,0% Europe 2,0% France 0,5% Italy 1,0% France 0,0% Germany Italy Germany -0,5% 0,0% -4,0% -2,0% 0,0% 2,0% 4,0% 6,0% -1,0% 0,0% 1,0% 2,0% 3,0% 4,0% 5,0% ∆ % IT Market (2003/02) ∆ ∆ ∆ ∆ % IT Market(2004/03) ∆ ∆ ∆ Fonte: Assinform / NetConsulting su dati OECD, FMI Development - IT Investment 6% ∆ ∆ % GNP (2006/2005) ∆ ∆ 5% World 4% USA Spain 3% Japan 2% UK 2005/2004 2006/2005 1% France Italy Germany 0% 0.0% 1.0% 2.0% 3.0% 4.0% 5.0% 6.0% 7.0% ∆ % IT Market (2006/2005) ∆ ∆ ∆ Fonte: Assinform / NetConsulting su dati OECD, FMI

R&D investment vs. IT investment Valori % sul PIL SE 5 UK 4 NL FI DK FR IT Expense DE 3 UE EE AT SK CZ LU UH Italy PT SI 2 RO PL LT ES BG GR 1 RD expense 0 1 2 3 4 Fonte: Eurostat Some data to think about Computer use vs GDP

Other data � Internet users growth Internet users (as percentage of population) ICT good exports (See also good imports and service exports ) WEF - ICT development of nations 1 – Denmark Ranking WEF Sweden (world economic forum) Singapore Finland Global IT report 2006-2007 Switzerland www.weforum.org Netherlands United States Iceland United Kingdom Malaysia Norway Malta Canada Portugal Hong Kong SAR United Arab Emirates Taiwan, China Japan Slovenia Australia Chile Germany Spain Austria Hungary Israel Czech Republic Korea, Rep. Tunisia Estonia Qatar Ireland Thailand New Zealand France 40 - Italy Belgium Luxembourg

WEF – ICT development � ICT conductive environment � Regulatory aspects, soft + hard infrastructure � ICT readiness � Individuals, business, government � ICT usage � Individuals, business, government WEF – Global competitiveness World Economic Forum- Global 1- Switzerland competitiveness report 2006-2007 Finland www.weforum.org Sweden Denmark Singapore Malaysia United States Chile Japan Spain Germany Czech Republic Netherlands United Kingdom Tunisia Hong Kong SAR Barbados Norway United Arab Emirates Taiwan, China Slovenia Iceland Portugal Israel Thailand Canada Austria Latvia France Slovak Republic Australia Qatar Belgium Malta Ireland Lithuania Luxembourg New Zealand Hungary Korea, Rep. 45 - Italy Estonia

Global competitiveness � Institutions � Infrastructure � Macroeconomy � Health + primary education � Higher education � Market efficiency � Technological readiness � Business sophistication � Innovation Failures

Ariane V (1996) Ariane V (1996) The European launcher for earth satellites A software defect caused an error in computing the position and speed of the launcher some 30 seconds after launch. The wrong position data caused the controller to send signals to the engines to change the direction of the launcher so swiftly that the structure was subject to high tensions. The tension went over the acceptable thresholds and the safety controller ordered self destruction.

What happened On june 4th 1996, the maiden flight of the Ariane 5 launcher ended in a failure; Only about 40 seconds after initiation of the flight sequence the launcher veered off its flight path, broke up and exploded; The system failure was a direct result of a software failure. The subsystem SRI: computer-based inertial reference system, computes attitude and trajectory of the rocket SRI SRI and sends them to OBC. Redundant. OBC OBC OBC (on board computer): executes Engines flight program, controls engines. Redundant.

The problem Software failure on SRI. Occurred when, in function F, an attempt to convert a 64-bit floating point number to a signed 16-bit integer caused the number to overflow. There was no exception handler associated with the conversion so the system exception management facilities were invoked. These shut down the SRI. The backup SRI had the same software, and behaved in exactly the same way. The OBC received diagnostic commands from shutting down SRI, and interpreted them as normal data, commanding engines to extreme position, resulting in unforeseen stresses on the rocket, that caused separation of the boosters from the main stage, in turn triggering the self- destruct system of the launcher. Why? Why the overflow? Why no exception handling? SRI was reused from Ariane 4. The physical characteristics of Ariane 4 (A smaller vehicle) are such that it has a lower initial acceleration and build up of horizontal velocity than Ariane 5. The value of the variable on Ariane 4 could never reach a level that caused overflow in function F during the launch period. Besides, function F was NOT needed in Ariane 5 (was in Ariane 4). Decisions were made: • Not to remove F as this could introduce new faults; • Not to catch overflow exceptions because the processor was heavily loaded. For dependability reasons, it was thought desirable to have some spare processor capacity.

Mars Polar Lander (2000) A probe expected to land on Mars for scientific exploration A measure of length had to be exchanged between two components developed by two different teams. The two teams used two different unit of measures. The difference was very small and went unnoticed until the probe crashed on Mars The problem Key information is is NOT in the code (or is implicit in the code) Software ≥ code Software engineering is about handling these information