Agenda• Software products• The software industry• Architectural and engineering issues
Why is software important?• Software is a key component in the modern industry, especially in the innovative, emerging technologies• In the next few slides we report the Gartner hype cycle for the emerging technologies from 2005 to 2010
Hype Cycle of emerging technologies (according to Gartner)
DiscussIdentify in the Gartner diagrams thetechnologies which are software-intensive
Software is an industrial productThe world sw industry increased its volume at 10% rates yearly during the ‘90, and at 3% in 2001, now is back at 10%Several technological innovations are based on software(eg. Cellular telephones, Mp3 devices and iTunes, etc.)A cellular telephone includes 5+ MLOC (source Nokia)Windows XP includes 40+ MLOC (Windows 95: 11 MLOC)The developments costs of a software increases with the square of its dimension in LOC [Berra-Meo 2001]
The software industry• According to DataMonitor, the size of the worldwide software industry in 2008 was US$ 303.8 billion, an increase of 6.5% compared to 2007• Americas account for 42.6% of the global software markets value• In 2013, the global software market will have a value of US$ 457 billion, an increase of 50% since 2008
Software• Good: product invisible, intangible, easily duplicated, very expensive to build• Component of a computer system: can be widely (re)used (off the shelf) or commissioned by a specific user• Abstract machine based on an abstract architecture• Service invoked via a well defined interface and based on a communication infrastructure
Software components• COTS: “component off the shelf”• Component based software architectures• Building software by integration• Software component markets – Enterprise Java Beans – Microsoft .NET
Software: the product of a process• Many kinds of software products, many kinds of development processes• Study the process to improve the product• Examples of processes: waterfall, iterative, agile, extreme,…• Software development processes are software too
Many kinds of software• Middleware• Embedded• Open source• Web Services• Mobile (eg. applet)• Data mining (eg. Search engine)• Agents• Social software (eg. Web 2.0)• Software Ecosystems• …
Embedded software• Within only 30 years the amount of software in cars went from 0 to more than 10,000,000 lines of code• More than 2000 individual functions are realized or controlled by software in premium cars, today• 50-70% of the development costs of the software/hardware systems are software costs• (M.Broy, “Challenges in Automotive Software Engineering”, ICSE2006, pp33-42,2006)
Software as a serviceService: the immaterial equivalent of a good• Software is a service at heart, albeit an automated one, but it is sold much like a manufactured good. Customers have to pay large sums of money up front, bear much of the risk that a program may not work as promised, and cannot readily switch vendors. The Economist, 2003
Service oriented architectures• SOA compose different services for complementary domains• They are often base on stacks of service layers• SOA services feature loose coupling that can be “orchestrated” according to some rules of “choreography”
Software ecosystems• A software ecosystem is a set of businesses functioning as a unit and interacting with a shared market for software and services, together with relationships supported by a common technological platform• Eg: Apple Application Store
Software architecture• The discipline of software architecture is centered on the idea of reducing the design complexity of software systems through abstraction and separation of concerns• The discipline has developed a number of design styles and patterns that help in designing or integrating software intensive systems• However, it is hard to find sw architects who agree on the right way to architect a software system• Wrong decisions in crafting the software architecture are a major cause of project cancellation
Software engineering• Software Engineering is a discipline studying the methods to produce software, the theories at their basis, and the tools effective to develop and measure the qualities of software systems• Software engineering deals with limited resources• It is a discipline strongly empirical, that is based on experience and past projects (“Coloro che non conoscono la storia, sono condannati a ripeterla”)
Main problems• Methods to analyze and design a software product• Architectural and design patterns• Software development processes and their models• Software development tools and environments• Economic issues• Products and process standards
Producing software is difficult• Complexity derives from – Very fast technical innovation – Strong international competition – Psychological issues – Organizational issues – Professionals not trained on sw design and development• Typical failures: bad project management, wrong requirements, mediocre design• Stakeholders with contrasting interests• New projects start with high risks, scarcely analyzed
Productivity is low• Analyzing 13.522 sw development projects in USA: – 66% out all projects fail (no useful result) – 82% out all projects need more time than initially planned – 48% out all projects produce products lacking some function required by the customers – 55 G$ wasted in one year Standish Report 2003
StakeholdersTypical stakeholders in a sw process – Designers – Management – Technicians – Decisors – Users – Funding people – …Each stakeholder has a specific viewpoint on the product and its development process
Process• Development processes are created and adapted to different project situations• Both products and processes can be evaluated for their quality• Software needs several different layers of development process: – Industrial lifecycle – Design lifecycle (reqs, build, test) – Module lifecycle – Operational lifecycle (eg.: portal)
The software process• Software process: set of roles, activities, and artifacts necessary to create a software product• Possible roles: designer, developer, tester, maintenance, ecc.• Possible artifacts: source code, executables, specifications, comments, test suite, etc.
Models for the software process• Waterfall model (planned, linear)• Spiral model (planned, iterative)• Agile model (unplanned, user driven)
Activities• Each organization differs in products it builds and the way it develops them; however, most development processes include: – Specification – Design – Verification and validation – Evolution• The development activities must be modeled to be managed and supported by automatic tools
Productivity differences• For the same 104 projects Cusumano got the following data: India Japan US Europe Total No. of Projects 24 27 31 22 104 LOC/programmer month 209 469 270 436 374 Defects/KLOC (12 mon. 0.263 0.020 0.400 0.225 0.150 after delivery)
Standards• Many institutions define international product or process standards for the global software industry• Their goal is usually to improve the quality of software products and their development processes
Software standards• Standard IEEE: development methods• Standard OMG: UML and CORBA• Standard W3C: Web technologies• Standard OASIS: Business Process
IEEE Standards on Software• IEEE 828 - Standard for Glossary of Sw Eng Terminology• IEEE 830 - Practice for Sw Reqs Specifications• IEEE 1016 - Practice for Sw Design Descriptions• IEEE 1012 - Sw Verification and Validation• IEEE 1062 - Sw Acquisition• IEEE 1063 - Sw User Documentation• IEEE 1233 - Developing System Reqs Specifications• IEEE 12207 - Standard for Sw Life Cycle Processes• IEEE 1471 - Practice for Architectural Descriptions www.computer.org/standards!
Summary• Software is a business, but it is not like other businesses• Software products are both the programs and their documentation, included process documentation• A software process is a set of roles and activities to develop a software product• Software engineers should use effective tools and methods based on principles scientifically and ethically correct
Questions• What is “software architecture”?• What is a “service oriented architecture”?• What are the main problems in software architecting?• What is an architecture-centered software process?• Where can I find a specific paper on a specific software architecture topic?
ReferencesTextbook:Taylor & Medvidović & Dashofy,Software Architecture: Foundations, Theory, and Practice,Wiley 2009Additional textbooks:Quian & Fu, Software Architecture and Design Illuminated,Bartlett & Jones 2009Reekie and McAdam A Software Architecture Primer, 2006
ReferencesAdditional textbook on software engineering:Pressman, Software Engineering, McGraw Hill, 6th ed., 2005Additional textbook on UML:Arlow & Neustadt, UML2 and Unified Process, McGraw Hill,2007
Journals (via Internet inside UniBo network):IEEE Transactions on Software EngineeringACM Trans. on Sw Engineering and MethodologyIEEE SoftwareIEEE Internet Computing(online) Journal of Object Technology www.jot.fm scholar.google.com!
Reference web sitesSite of the textbook: www.softwarearchitecturebook.comIASA (int. assoc. of sw architects): www.iasahome.orgMajor web sites:www.sei.cmu.edu/architecture/!www.handbookofsoftwarearchitecture.com!www.bredemeyer.com!Blogsblog.softwarearchitecture.com!