Software engineering (SE) is the application of a systematic, disciplined, quantifiable approach to the design, development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software. In layman's terms, it is the act of using insights to conceive, model and scale a solution to a problem. The first reference to the term is the 1968 NATO Software Engineering Conference and was meant to provoke thought regarding the perceived "software crisis" at the time. Software development, a much used and more generic term, does not necessarily subsume the engineering paradigm. The generally accepted concepts of Software Engineering as an engineering discipline have been specified in the Guide to the Software Engineering Body of Knowledge (SWEBOK). The SWEBOK has become an internationally accepted standard ISO/IEC TR 19759:2005.
For those who wish to become recognized as professional software engineers, the IEEE offers two certifications (Certified Software Development Associate and Certified Software Development Professional). The IEEE certifications do not use the term Engineer in their title for compatibility reasons. In some parts of the US such as Texas, the use of the term Engineer is regulated only to those who have a Professional Engineer license. Further, in the United States starting from 2013, the NCEES Professional Engineer exam will be available for Software Engineering.
When the first digital computers appeared in the early 1940s, the instructions to make them operate were wired into the machine. Practitioners quickly realized that this design was not flexible and came up with the "stored program architecture" or von Neumann architecture. Thus the division between "hardware" and "software" began with abstraction being used to deal with the complexity of computing.
Programming languages started to appear in the 1950s and this was also another major step in abstraction. Major languages such as Fortran, ALGOL, and COBOL were released in the late 1950s to deal with scientific, algorithmic, and business problems respectively. E.W. Dijkstra wrote his seminal paper, "Go To Statement Considered Harmful", in 1968 and David Parnas introduced the key concept of modularity and information hiding in 1972 to help programmers deal with the ever increasing complexity of software systems. A software system for managing the hardware called an operating system was also introduced, most notably by Unix in 1969. In 1967, the Simula language introduced the object-oriented programming paradigm.
These advances in software were met with more advances in computer hardware. In the mid-1970s, the microcomputer was introduced, making it economical for hobbyists to obtain a computer and write software for it. This in turn led to the now famous Personal Computer (PC). The Software Development Life Cycle or SDLC was also starting to appear as a consensus for centralized construction of software in the mid-1980s. The late 1970s and early 1980s saw the introduction of several new Simula-inspired object-oriented programming languages, including Smalltalk, Objective-C, and C++.
Open-source software started to appear in the early 90s in the form of Linux and other software introducing the "bazaar" or decentralized style of constructing software. Then the World Wide Web and the popularization of the Internet hit in the mid 90s, changing the engineering of software once again. Distributed systems gained sway as a way to design systems, and the Java programming language was introduced with its own virtual machine as another step in abstraction. Programmers collaborated and wrote the Agile Manifesto, which favored more lightweight processes to create cheaper and more timely software.
The current definition of software engineering is still being debated by practitioners today as they struggle to come up with ways to produce software that is "cheaper, better, faster". Cost reduction has been a primary focus of the IT industry since the 1990s. Total cost of ownership represents the costs of more than just acquisition. It includes things like productivity impediments, upkeep efforts, and resources needed to support infrastructure.
Legal requirements for the licensing or certification of professional software engineers vary around the world. In the UK, the British Computer Society licenses software engineers and members of the society can also become Chartered Engineers (CEng), while in some areas of Canada, such as Alberta, Ontario, and Quebec, software engineers can hold the Professional Engineer (P.Eng) designation and/or the Information Systems Professional (I.S.P.) designation. In Canada, there is a legal requirement to have P.Eng when one wants to use the title "engineer" or practice "software engineering". In the USA, beginning in 2013, the path for licensure of software engineers will become a reality. As with the other engineering disciplines, the requirements consist of earning an ABET accredited bachelor’s degree in Software Engineering (or any non-ABET degree and NCEES credentials evaluation), passing the Fundamentals of Engineering Exam, having at least four years of demonstrably relevant experience, and passing the Software Engineering PE Exam. In some states, such as Florida, Texas, Washington, and other, software developers cannot use the title "Professional Engineer" unless they are licensed professional engineers who have passed the PE Exam and possess a valid licence to practice. This license has to be periodically renewed, which is known as continuous education, to ensure engineers are kept up to date with latest techniques and safest practices.
The IEEE Computer Society and the ACM, the two main US-based professional organizations of software engineering, publish guides to the profession of software engineering. The IEEE's Guide to the Software Engineering Body of Knowledge - 2004 Version, or SWEBOK, defines the field and describes the knowledge the IEEE expects a practicing software engineer to have. Currently, the SWEBOK v3 is being produced and will likely be released in mid-2013. The IEEE also promulgates a "Software Engineering Code of Ethics".
In 2004, the U. S. Bureau of Labor Statistics counted 760,840 software engineers holding jobs in the U.S.; in the same time period there were some 1.4 million practitioners employed in the U.S. in all other engineering disciplines combined. Due to its relative newness as a field of study, formal education in software engineering is often taught as part of a computer science curriculum, and many software engineers hold computer science degrees.
Many software engineers work as employees or contractors. Software engineers work with businesses, government agencies (civilian or military), and non-profit organizations. Some software engineers work for themselves as freelancers. Some organizations have specialists to perform each of the tasks in the software development process. Other organizations require software engineers to do many or all of them. In large projects, people may specialize in only one role. In small projects, people may fill several or all roles at the same time. Specializations include: in industry (analysts, architects, developers, testers, technical support, middleware analysts, managers) and in academia (educators, researchers).
Most software engineers and programmers work 40 hours a week, but about 15 percent of software engineers and 11 percent of programmers worked more than 50 hours a week in 2008. Injuries in these occupations are rare. However, like other workers who spend long periods in front of a computer terminal typing at a keyboard, engineers and programmers are susceptible to eyestrain, back discomfort, and hand and wrist problems such as carpal tunnel syndrome.
The field's future looks bright according to Money Magazine and Salary.com, which rated Software Engineer as the best job in the United States in 2006. In 2012, software engineering was again ranked as the best job in the United States, this time by CareerCast.com.
The Software Engineering Institute offers certifications on specific topics like Security, Process improvement and Software architecture. Apple, IBM, Microsoft and other companies also sponsor their own certification examinations. Many IT certification programs are oriented toward specific technologies, and managed by the vendors of these technologies. These certification programs are tailored to the institutions that would employ people who use these technologies.
Broader certification of general software engineering skills is available through various professional societies. As of 2006[update], the IEEE had certified over 575 software professionals as a Certified Software Development Professional (CSDP). In 2008 they added an entry-level certification known as the Certified Software Development Associate (CSDA). The ACM had a professional certification program in the early 1980s, which was discontinued due to lack of interest. The ACM examined the possibility of professional certification of software engineers in the late 1990s, but eventually decided that such certification was inappropriate for the professional industrial practice of software engineering. In 2012, Validated Guru began offering the Certified Software Developer (VGCSD) certification; which is heavily influenced by the global community.
In the U.K. the British Computer Society has developed a legally recognized professional certification called Chartered IT Professional (CITP), available to fully qualified Members (MBCS). Software engineers may be eligible for membership of the Institution of Engineering and Technology and so qualify for Chartered Engineer status. In Canada the Canadian Information Processing Society has developed a legally recognized professional certification called Information Systems Professional (ISP). In Ontario, Canada, Software Engineers who graduate from a Canadian Engineering Accreditation Board (CEAB) accredited program, successfully complete PEO's (Professional Engineers Ontario) Professional Practice Examination (PPE) and have at least 48 months of acceptable engineering experience are eligible to be licensed through the Professional Engineers Ontario and can become Professional Engineers P.Eng. The PEO does not recognize any online or distance education however; and does not consider Computer Science programs to be equivalent to software engineering programs despite the tremendous overlap between the two. This has sparked controversy and a certification war. It has also held the number of P.Eng holders for the profession exceptionally low. The vast majority of working professionals in the field hold a degree in CS, not SE. Given the difficult certification path for holders of non-SE degrees, most never bother to pursue the license.
Impact of globalization 
The initial impact of outsourcing, and the relatively lower cost of international human resources in developing third world countries led to a massive migration of software development activities from corporations in North America and Europe to India and later: China, Russia, and other developing countries. This approach had some flaws, mainly the distance / timezone difference that prevented human interaction between clients and developers, but also the lower quality of the software developed by the outsourcing companies and the massive job transfer. This had a negative impact on many aspects of the software engineering profession. For example, some students in the developed world avoid education related to software engineering because of the fear of offshore outsourcing (importing software products or services from other countries) and of being displaced by foreign visa workers. Although statistics do not currently show a threat to software engineering itself; a related career, computer programming does appear to have been affected. Nevertheless, the ability to smartly leverage offshore and near-shore resources via the follow-the-sun workflow has improved the overall operational capability of many organizations. When North Americans are leaving work, Asians are just arriving to work. When Asians are leaving work, Europeans are arriving to work. This provides a continuous ability to have human oversight on business-critical processes 24 hours per day, without paying overtime compensation or disrupting a key human resource, sleep patterns.
While global outsourcing has several advantages, global - and generally distributed - development can run into serious difficulties resulting from the distance between developers. This includes but is not limited to language, communication, cultural or corporate barriers. Handling global development successfully is subject to active research of the software engineering community.
A knowledge of computer programming is a pre-requisite to becoming a software engineer. In 2004 the IEEE Computer Society produced the SWEBOK, which has been published as ISO/IEC Technical Report 19759:2004, describing the body of knowledge that they believe should be mastered by a graduate software engineer with four years of experience. Many software engineers enter the profession by obtaining a university degree or training at a vocational school. One standard international curriculum for undergraduate software engineering degrees was defined by the CCSE, and updated in 2004. A number of universities have Software Engineering degree programs; as of 2010[update], there were 244 Campus programs, 70 Online programs, 230 Masters-level programs, 41 Doctorate-level programs, and 69 Certificate-level programs in the United States.
In addition to university education, many companies sponsor internships for students wishing to pursue careers in information technology. These internships can introduce the student to interesting real-world tasks that typical software engineers encounter every day. Similar experience can be gained through military service in software engineering.
Comparison with other disciplines 
Major differences between software engineering and other engineering disciplines, according to some researchers, result from the costs of fabrication.
Software Process 
A set of activities that leads to the production of a software product is known as software process. Although most of the software are custom build, the software engineering market is being gradually shifted towards component based. Computer-aided software engineering (CASE) tools are being used to support the software process activities. However, due to the vast diversity of software processes for different types of products, the effectiveness of CASE tools is limited. There is no ideal approach to software process that has yet been developed. Some fundamental activities, like software specification, design, validation and maintenance are common to all the process activities.
A software process model is an abstraction of software process. These are also called process paradigms. Various general process models are waterfall model, evolutionary development model and component-based software engineering model. These are widely used in current software engineering practice. For large systems, these are used together.
Waterfall model 
The waterfall model was one of the first published model for the software process. This model divides software processes in various phases. These phases are:
- Requirements analysis
- Software design
- Unit testing
- Component testing
- System testing
Theoretically the activities should be performed individually but in practice, they often overlap. During the maintenance stage, the software is put into use. During this, additional problems might be discovered and the need of new feature may arise. This may require the software to undergo the previous phases once again.
Software engineering can be divided into ten subdisciplines. They are:
- Software requirements: The elicitation, analysis, specification, and validation of requirements for software.
- Software design: The process of defining the architecture, components, interfaces, and other characteristics of a system or component. It is also defined as the result of that process.
- Software construction: The detailed creation of working, meaningful software through a combination of coding, verification, unit testing, integration testing, and debugging.
- Software testing: The dynamic verification of the behavior of a program on a finite set of test cases, suitably selected from the usually infinite executions domain, against the expected behavior.
- Software maintenance: The totality of activities required to provide cost-effective support to software.
- Software configuration management: The identification of the configuration of a system at distinct points in time for the purpose of systematically controlling changes to the configuration, and maintaining the integrity and traceability of the configuration throughout the system life cycle.
- Software engineering management: The application of management activities—planning, coordinating, measuring, monitoring, controlling, and reporting—to ensure that the development and maintenance of software is systematic, disciplined, and quantified.
- Software engineering process: The definition, implementation, assessment, measurement, management, change, and improvement of the software life cycle process itself.
- Software engineering tools and methods: The computer-based tools that are intended to assist the software life cycle processes, see Computer Aided Software Engineering, and the methods which impose structure on the software engineering activity with the goal of making the activity systematic and ultimately more likely to be successful.
- Software quality: The degree to which a set of inherent characteristics fulfills requirements.
Related disciplines 
Systems engineering 
Systems engineers deal primarily with the overall system requirements and design, including hardware and human issues. They are often concerned with partitioning functionality to hardware, software or human operators. Therefore, the output of the systems engineering process serves as an input to the software engineering process.
Computer software engineers 
Computer Software Engineers are usually systems level (software engineering, information systems) computer science or software level computer engineering graduates. This term also includes general computer science graduates with a few years of practical on the job experience involving software engineering.
See also 
- Bachelor of Science in Information Technology
- Bachelor of Software Engineering
- List of software engineering conferences
- List of software engineering publications
- Software craftsmanship
- Abran et al. 2004, pp. 1–1
- ACM (2006). "Computing Degrees & Careers". ACM. Retrieved 2010-11-23.
- Laplante, Phillip (2007). What Every Engineer Should Know about Software Engineering. Boca Raton: CRC. ISBN 978-0-8493-7228-5. Retrieved 2011-01-21.
- Sommerville 2008, p. 26
- Peter, Naur; Brian Randell (7–11 October 1968). "Software Engineering: Report of a conference sponsored by the NATO Science Committee" (PDF). Garmisch, Germany: Scientific Affairs Division, NATO. http://homepages.cs.ncl.ac.uk/brian.randell/NATO/nato1968.PDF. Retrieved 2008-12-26.
- Randell, Brian (10 August 2001). "The 1968/69 NATO Software Engineering Reports". Brian Randell's University Homepage. The School of the Computer Sciences, Newcastle University. Retrieved 2008-10-11. "The idea for the first NATO Software Engineering Conference, and in particular that of adopting the then practically unknown term "software engineering" as its (deliberately provocative) title, I believe came originally from Professor Fritz Bauer."
- "ISO/IEC TR 19759:2005". Retrieved 2012-04-01.
- "NCEES Software Engineering Exam Specifications". Retrieved 2012-04-01.
- Leondes (2002). intelligent systems: technology and applications. CRC Press. ISBN 978-0-8493-1121-5.
- Dijkstra, E. W. (March 1968). "Go To Statement Considered Harmful". Communications of the ACM 11 (3): 147–148. doi:10.1145/362929.362947. Retrieved 2009-08-10.
- Parnas, David (December 1972). "On the Criteria To Be Used in Decomposing Systems into Modules". Communications of the ACM 15 (12): 1053–1058. doi:10.1145/361598.361623. Retrieved 2008-12-26.
- Raymond, Eric S. The Cathedral and the Bazaar. ed 3.0. 2000.
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- "''IEEE-USA Offers Study Guide for Software Engineering Licensure Exam''". Retrieved 2012-11-05.
- "''NCEES Principles and Practice of Engineering Examination Software Engineering Exam Specifications''" (pdf). Retrieved 2012-11-05.
- "'SWEBOK Guide Version 3'". Retrieved 2012-11-14.
- "''Software Engineering Code of Ethics''" (PDF). Retrieved 2012-03-25.
- Bureau of Labor Statistics, U.S. Department of Labor, USDL 05-2145: Occupational Employment and Wages, November 2004, Table 1.
- "Software Engineering". Retrieved 2008-02-01.
- "Computer Software Engineers and Computer Programmers". Retrieved 2009-12-17.
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- "Best and Worst Jobs of 2012". online.wsj.com. Retrieved 2012.
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- ACM (July 17, 2000). "A Summary of the ACM Position on Software Engineering as a Licensed Engineering Profession". Association for Computing Machinery (ACM). Retrieved 2009-03-03. "At its meeting in May 2000, the Council further concluded that the framework of a licensed professional engineer, originally developed for civil engineers, does not match the professional industrial practice of software engineering. Such licensing practices would give false assurances of competence even if the body of knowledge were mature; and would preclude many of the most qualified software engineers from becoming licensed."[dead link]
- Canadian Information Processing Society. "I.S.P. Designation". Retrieved 2007-03-15.
- "Professional Engineers Ontario: Welcome to PEO's website". Peo.on.ca. Retrieved 2012-03-25.
- Patrick Thibodeau (2006-05-05). "As outsourcing gathers steam, computer science interest wanes". Computerworld.com. Retrieved 2012-03-25.
- "Computer Programmers". Bls.gov. Retrieved 2012-03-25.
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- Abran, Alain, ed. (2005) . "Chapter 1: Introduction to the Guide". Guide to the Software Engineering Body of Knowledge. Los Alamitos: IEEE Computer Society. ISBN 0-7695-2330-7. Retrieved 2010-09-13. "The total volume of cited literature is intended to be suitable for mastery through the completion of an undergraduate education plus four years of experience."
- "SE2004 Software Engineering Curriculum". Sites.computer.org. 2003-09-30. Retrieved 2012-03-25.
-  Degree programs in Software Engineering
- Young, Michal; Faulk, Stuart (2010). "Sharing What We Know About Software Engineering" (PDF). Proceedings of the FSE/SDP workshop on Future of software engineering research (FoSER '10). ACM. pp. 439–442. doi:10.1145/1882362.1882451. ISBN 978-1-4503-0427-6. Retrieved 2011-02-25. "The essential distinction between software and other engineered artifacts has always been the absence of fabrication cost. In conventional engineering of physical artifacts, the cost of materials and fabrication has dominated the cost of design and placed a check on the complexity of artifacts that can be designed. When one bottleneck is removed, others appear, and software engineering has therefore faced the essential challenges of complexity and the cost of design to an extent that conventional engineering has not. Software engineering has focused on issues in managing complexity, from process to modular design to cost-effective verification, because that is the primary leverage point when the costs of materials and fabrication are nil."
- Sommerville 2008, p. 86
- Sommerville 2008, p. 87
- Sommerville 2008, p. 89
- *Software Construction
- Abran, Alain; Moore, James W.; Bourque, Pierre; Dupuis, Robert; Tripp, Leonard L. (2004). Guide to the Software Engineering Body of Knowledge. IEEE. ISBN 0-7695-2330-7.
- Sommerville, Ian (2008). Software Engineering (7 ed.). Pearson Education. ISBN 978-81-7758-530-8. Retrieved 10 January 2013.
Further reading 
- Ghezzi, Carlo; Mehdi Jazayeri, Dino Mandrioli (2003) . Fundamentals of Software Engineering (2nd (International) ed.). Pearson Education @ Prentice-Hall.
- Jalote, Pankaj (2005) . An Integrated Approach to Software Engineering (3rd ed.). Springer. ISBN 0-387-20881-X.
- Pressman, Roger S (2005). Software Engineering: A Practitioner's Approach (6th ed.). Boston, Mass: McGraw-Hill. ISBN 0-07-285318-2.
- Sommerville, Ian (2007) . Software Engineering (8th ed.). Harlow, England: Pearson Education. ISBN 0-321-31379-8.
|Wikimedia Commons has media related to: Software engineering|
|Wikibooks has a book on the topic of: Introduction to Software Engineering|
- Guide to the Software Engineering Body of Knowledge
- Computer Software Engineers - Definition and statistics from the U.S. Bureau of Labor Statistics
- A Student's Guide to Software Engineering Projects - a free online guide for students taking SE project courses
- The Open Systems Engineering and Software Development Life Cycle Framework OpenSDLC.org the integrated Creative Commons SDLC
- Function Oriented vs Object Oriented Software Engineering