2. Motivation

3.  Computer programs and associated documentation  Software products may be developed for a particular customer or may be developed for a general market  Software products may be › Generic - developed to be sold to a range of different customers › Custom - developed for a single customer according to their specification

4. Software has number of attributes which decide whether it is a good or bad. The definition of a good software changes with the person who evaluates it. The software is required by the customer, used by the end users of an organization and developed by software engineer. Each one will evaluate the different attributes differently in order to decide whether the software is good.

5. The software should deliver the required functionality and performance to the user and should be maintainable, dependable and usable. Maintainability › Software must evolve to meet changing needs  Dependability › Software must be trustworthy  Efficiency › Software should not make wasteful use of system resources  Usability › Software must be usable by the users for which it was designed

6.  Software has a dual role. It is a product, but also a vehicle for delivering a product.  Software is a logical rather than a physical system element.  Software has characteristics that differ considerably from those of hardware.  - Software is developed or engineered, it is not manufactured in the classical sense.  - Software doesn’t “wear out”.  - Most software is custom-built, rather than being assembled from existing components.

7.  System Software- A collection of programs written to service other programs at system level. For example, compiler, operating systems.  Real-time Software- Programs that monitor/analyze/control real world events as they occur.  Business Software- Programs that access, analyze and process business information.  Engineering and Scientific Software - Software using “number crunching” algorithms for different science and applications. System simulation, computer-aided design.

8.  Embedded Software-: Embedded software resides in read-only memory and is used to control products and systems for the consumer and industrial markets. It has very limited and esoteric functions and control capability.  Artificial Intelligence (AI) Software: Programs make use of AI techniques and methods to solve complex problems. Active areas are expert systems, pattern recognition, games

9.  Internet Software : Programs that support internet accesses and applications. For example, search engine, browser, e-commerce software, authoring tools.  Software Tools and CASE environment : Tools and programs that help the construction of application software and systems. For example, test tools, version control tools.

10. Software can have a huge impact in any aspect of society. Importance of software

11. Where can you find software?

12. Some popular ones…

15. And even in…

16. Conclusion Software is Almost Everywhere.

21. The final Software doesn´t fulfill the needs of the customer. Hard to extend and improve: if you want to add a functionality later is mission impossible. Bad documentation. Bad quality: frequent errors, hard to use,... More time and costs than expected Common issues

23. But That never happens, right?

24. Wrong!

25. Problems in software development

26. Requirements Software Here is the problem!!

27.  Cost: $10 Billion, millions of dollars more than planned  Time: 3 years late  Quality: First launch of Columbia was cancelled because of a synchronization problem with the Shuttle's 5 onboard computers. › Error was traced back to a change made 2 years earlier when a programmer changed a delay factor in an interrupt handler from 50 to 80 milliseconds. › The likelihood of the error was small enough, that the error caused no harm during thousands of hours of testing.  Substantial errors still exist. › Astronauts are supplied with a book of known software problems "Program Notes and Waivers".

28. Ariane 5 Flight 501 Cause: design errors in the software

29. Chaos Report

30. It is not enough to do your best: you must Know what to do, and THEN do your best. -- W. Edwards Deming Conclusion Programming is NOT enough!

31. And Since… A clever person solves a problem. A wise person avoids it. - Albert Einstein

32. Solution

33. Software Engineering The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software. -Wikipedia What is it?

34. ???

35. Software Engineering The study and application of methodologies to develop quality software that fulfill customer needs. What is it?

36.  “ A systematic approach to the analysis, design, implementation and maintenance of software.” (The Free On-Line Dictionary of Computing)  “ The systematic application of tools and techniques in the development of computer-based applications.” (Sue Conger in The New Software Engineering)  “ Software Engineering is about designing and developing high-quality software.” (Shari Lawrence Pfleeger in Software Engineering -- The Production of Quality Software)

37. Although hundreds of authors have developed personal definitions of software engineering, a definition proposed by Fritz Bauer[NAU69] provides a basis:  “[Software engineering is] the establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines.” The IEEE [IEE93] has developed a more comprehensive definition when it states:  “Software Engineering: (1) The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software. (2) The study of approaches as in (1).”

39. By “Systematic” we mean Following a well-defined sequence of activities, - in which desired outputs (deliverables) are well-defined - by using well-defined inputs ( i.e. documented syntax, semantics, context and other relevant properties of the input) - in a well-defined process (e.g. using organizational standards for interprocess communication, data formats, error handling etc.) - whose outputs are in turn used similarly as inputs in subsequent process(es), - until the final output is achieved, - and where the correctness of the output is verifiable. Note: The “inputs” and “outputs” most often refer to requirements, software specifications, the software itself, documentation, test inputs/outputs and similar software artifacts. Back Back

40. Software Engineering - Introduction 40  Each process is followed using organizational principles (e.g. who manages whom, who is responsible for what?),  Intermediate results are carefully documented, as well as final results,  Actions are traceable as to their causes, individuals involved, time of occurrence and circumstances. Back

41. Software Engineering - Introduction 41  The size and extent of the required effort (size of output code, data, documentation, manpower, duration, budget for development, expected error rate and user support) are predictable within justifiable and acceptable bounds

42.  Computer science is concerned with theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software  Computer science theories are currently insufficient to act as a complete underpinning for software engineering

43. Software Engineering Objective To produce software that is: On time: is deliver at the established date. Reliable: doesn´t crash. Complete: good documentation, fulfill customer needs.

44. The team

45. Stages for software development Requirements Analysis Software Design Implementation Testing Maintenance

46. 1. Requirements Analysis Find out what the client want the software to do

47. 2. Design Planning the software solution

48. 3. Implementation Code!!!

49. 4. Testing Executing the application trying to find software bugs

50. 5. Maintenance Any activity oriented to change an existing software product.

56.  Major Goals: - To increase software productivity and quality. - To effectively control software schedule and planning. - To reduce the cost of software development. - To meet the customers’ needs and requirements. - To enhance the conduction of software engineering process. - To improve the current software engineering practice. - To support the engineers’ activities in a systematic and efficient manner.

57.  Programming 1. The process of translating a problem from its physical environment into a language that a computer can understand and obey. ( Webster’s New World Dictionary of Computer Terms) 2. The art of debugging a blank sheet of paper. 3. A pastime similar to banging one's head against a wall, but with fewer opportunities for rewards. (2 and 3 from The New Hacker’s Dictionary)  Software Engineering (according to Fritz Bauer) “The establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines.”

58. Computer ScienceSoftware Engineering is concerned with Computer science theories are currently insufficient to act as a complete underpinning for software engineering, BUT it is a foundation for practical aspects of software engineering  theory  fundamentals  the practicalities of developing  delivering useful software

59.  Software engineering is part of System engineering  System engineering is concerned with all aspects of computer-based systems development including › hardware, › software and › process engineering  System engineers are involved in system specification architectural design integration and deployment