http://www.dis.uniroma1.it/~santucci/SW_Engineering/Materials/. • References on
the course webpage. • Roger S. Pressman : “Software Engineering A.
Software Engineering Introduction
Lecturer: Giuseppe Santucci
Summary • Some useful pieces of information • Introduction to Software Engineering • Standardization of Software Process
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Software Engineering Classes • Course homepage • http://www.dis.uniroma1.it/~santucci/SW_Engineering/Index.html
• Address: via Ariosto 25 • Monday 14:15 15.30 - 15.45 17.15 Room: A2 • Friday 10.30-11.45 Room A2 – Please have always a look at news on the teaching homepage • Giuseppe Santucci teaching home page (news, exams, etc.) – http://www.dis.uniroma1.it/~santucci/didattica.html – Or Google giuseppe santucci 3
Exams • • • •
Two “regular” dates in June-July One “recovery” date in September Two “recovery” dates January-February Exercises and theoretical questions (true/false) – On the course homepage you will find examples of test questions
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Materials • Lecture notes – slides presented during classes – Available online at the course homepage – http://www.dis.uniroma1.it/~santucci/SW_Engineering/Material/
• References on the course webpage • Roger S. Pressman : “Software Engineering A Practitioner’s approach”
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How to communicate with me • Office Hours: Tuesday 14.30-16.30 Via Ariosto 25 room B218 • After classes
–Always have a look at news before coming !
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Course (rough) Outline Introduction and basic concepts • Software process models • Software Process Standardization • Software Processes • Agile Methodologies and Extreme Programming • Project Management (exam’s exercises) Methods for testing • Software Testing and Quality • Static and Dynamic Testing • Black-Box testing (exam’s exercises) • White-Box Testing (exam’s exercises) Cost estimation in software engineering • Function point and COCOMO II (exam’s exercises)
Requirements analysis and specification • Basic definitions • Types of applications and specification languages • Types of models
Measure theory foundations exam’s exercises • Definitions and overview on statistics basic concepts • Quality of metrics • Systematic and random errors • Inferential statistics • Analysis of variance (ANOVA) Exercises
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Software • Software: – is the collection of computer programs, procedures, rules, and associated documentation and data resulting from intellectual creations
• Software product – is the complete set of programs, procedures, and associated documentation delivered to a customer, typically released for sale
• Software components – A software component is a software product element offering a predefined service or event, and able to communicate with other components
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Manufacture vs Software products • There is a big difference between manufactured products and software products • Manufactured products: – they are built and eventually wore out – once designed, their fabrication can be delegated to external industries without affecting the characteristics of the result – parameters and techniques used for describing it are well known, reliable and effective
• Software products – they are developed and do not wear out – starting from the same design and specification details, two different people would produce two completely different products – how to describe their functional and quality characteristics is still an open issue
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Worsening and damages of hw and sw % damages sw (theory)
% damages hw
time
time
% damage sw
Changes sw
time
Classification of Software • This is an example taken from the model North American Product Classification System NAPCS • System Software – – – – –
Operating System Network Software Database Management Development tools and programming language software Other system software
• Application Software – – – – – –
General business productivity applications Home use applications Cross-industry application Vertical market application Utilities Other application 11
Examples of System Software • Operating System – Client and network operating systems
• Network Software – Network management software – Server software – Security and encryption software
• Development tools and programming language software – Software testing tools – Program development tools 12
Examples of Application Software • General Business productivity applications – – – – – –
Office suite applications Word processors Spreadsheets Simple databases Graphics applications Project management software
• Home use applications – Games – Home education 13
Examples of Application Software • Cross-industry application software – – – – –
Professional accounting software Human resource management Customer relations management software Geographic Information System software Web page/site design software
• Vertical market application software – Software for a specific industry (manufacturing, healthcare, telecom, etc.)
• Utilities software – – – – –
Compression programs Antivirus Search engines File viewers Voice recognition software
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Software development Is there a problem? • Some slides taken from MIT Open Course Ware
Risks and success percentage • Development of large applications in excess of 5000 function points (~500,000 LOC) is one of the most risky business undertakings in the modern world • Risks of cancellation or major delays rise rapidly as overall application size increases • Failure or cancellation rate of large software systems is over 20% • Average cancelled project in U.S. is about a year behind schedule and has consumed 200% of expected budget • Of completed projects, 2/3 experience schedule delays and cost overruns (Caper Jones) 16
Death March Projects • A project whose “project parameters” exceed the norm by at least 50% – The scheduled has been compressed to less than half the amount estimated – The staff has been reduced to half of people needed – The budget and associated resources have been cut in half – The functionality, features, performance requirements of the project are twice what they would be under normal circumstances
(Edward Yurdon) 17
Death March Projects cont.d • In other words: • A death march project is one for which an unbiased, objective risk assessment determines that the likelihood of failure is more than 50 % (Edward Yurdon)
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Death March Projects cont.d • Why? • Because corporation are insane and do the same thing again and again! (Edward Yurdon)
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Understanding the problem
Development costs are only the top of the iceberg
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Understanding the problem cont.d
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Software Engineering
What is Software Engineering? • SWE is a methodological discipline. It studies development methods, the theories such methods are based on, effective tools and metrics for measuring the quality of complex software systems • SWE is also an empirical discipline. It is based on personal experiences and past project stories If you don’t know the history you will re-do it 23
Software Engineering • Designing, building and maintaining large software systems (I.Sommerville)
•
Multi-person construction of multi-version software
(D.L. Parnas)
•
Technological and managerial discipline of software products that are developed and modified on time and within cost estimates
(R. Fairley)
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Software Engineering • The establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines. [NATO1969] • The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software. [IEEE Std 610.12-1990] • The systematic activities involved in the design, implementation and testing of software to optimize its production and support. [Canadian Standards Association]
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Software Engineering cont.d • The term software engineering first appeared in the 1968 NATO Software Engineering Conference • It was meant to provoke thought regarding the current software crisis at the time – Software crisis refers to the difficulty of writing correct, understandable, and verifiable computer programs
• The major cause of the software crisis is that the machines have became several orders of magnitude more powerful! To put it quite bluntly: as long as there were no machines, programming was no problem at all; when we had a few weak computers, programming became a mild problem, and now we have gigantic computers, programming has become an equally gigantic problem. (Edsger Dijkstra)
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Software Engineering subdisciplines •
•
•
•
•
Software requirements – the elicitation, analysis, specification, and validation of requirements for software Software design – the design of software is usually done with Computer-Aided Software Engineering (CASE) tools and use standards for the format, such as the Unified Modeling Language (UML) Software development – the construction of software through the use of programming languages Software testing – Black box – White box Software maintenance – software systems often have problems and need enhancements for a long time after they are first completed. This subfield deals with those problems 27
Software Engineering sub-disciplines cont.d • Software configuration management – since software systems are very complex, their configuration (such as versioning and source control) have to be managed in a standardized and structured method
• Software engineering management – the management of software systems borrows heavily from project management, but there are nuances encountered in software not seen in other management disciplines
• Software development process – the process of building software is hotly debated among practitioners with the main paradigms being agile or waterfall
• Software engineering tools, see Computer Aided Software Engineering • Software quality
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Software Development Process
Software Development Process • A set of structured and organized activities that are needed in order to develop a software product – – – –
Analysis Design and Development Validation and Testing Evolution and Maintenance • Corrective (20%): error resolution • Adaptive (20%): changes and new requirements • Improving (50%): non-functional and secondary functional requirements • Preventing (10%): refactoring 30
Software Process Related Activities • • • • • • • •
Project Management Project Revision (Contract revision) Quality Assurance Configuration Management Documentation Management Reusability Measures Risk Management 31
Principles of Software Engineering • • • • • • •
Changes foreseeing Rigorous and formal approach Separation of concerns Modularity Abstraction Generality Incremental approach 32
Standardization of Software Process • CMMI • ISO 12207 • ISO 9000
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Capability Maturity Model Integration • Created and maintained by the Software Engineering Institute of the Carnegie Mellon University • Replaces the CMM which is not maintained anymore • It is a process improvement approach that provides organizations with the essential elements of effective processes 34
ISO 12207 • Produced by the International Organization for Standardization • It establishes a common framework for software life cycle processes that can be referenced by the software industry • It also provides a process that can be employed for defining, controlling, and improving software life cycle processes 35
ISO 9000 • Produced by the International Organization for Standardization • It specifies fundamentals of quality management systems • It is intended to be applicable to all organizations, regardless of type, size and product provided
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