Software engineering: Meaning (information, definition, explanation, facts)

Software engineering (SE) is the profession concerned with creating and maintaining software applications by applying computer science and other technologies and practices.

Software applications are used in wide range of activities, from industry to entertainment. Software applications improve user productivity and quality of life. Application software examples: office suites, video games, and the world wide web. System software examples: embedded systems and operating systems.

Technologies and practices help developers by improving productivity and quality. SE examples: databases, languages, libraries, patterns, processes, and tools. CS examples: algorithms and data structures.

The SE community includes 630,000 practitioners and educators in the U.S. and an estimated 1,400,000 practitioners in the E.U., Asia, and elsewhere; and is about 60% the size of traditional engineering. American SE pioneers include Kent Beck, Barry Boehm, Fred Brooks, Watts Humphrey, and David Parnas.

Related terms: software engineer.

Meanings of words

As of 2004, in common parlance the term software engineering is used with at least three distinct meanings:

• As the usual contemporary term for the broad range of activities that was formerly called programming or systems analysis;
• As the broad term for the technical analysis of all aspects of the practice, as opposed to the theory of computer programming;
• As the term embodying the advocacy of a specific approach to computer programming, one that urges that it be treated as an engineering profession rather than an art or a craft, and advocates the codification of recommended practices in the form of software engineering methodologies.

A profession, which cares with creation of software with software engineering called software engineer, programmer or developer.

See also in this article Education, Practice.

People from many different educational backgrounds make important contributions to SE. The fraction of practitioners who earn computer science or software engineering degrees has been slowly rising. Today, about 1/2 of all software engineers earn computer science or software engineering degrees. For comparison, about 3/4 of all traditional engineers earn engineering degrees.

Software : About half of all practitioners today have computer science degrees, which are the most relevant degrees that are widely available. A small, but growing, number of practitioners have software engineering degrees. As of 2004, in the U.S., about 2,000 universities offer computer science degrees and about 50 universities offer software engineering degrees. Most SE practitioners will earn computer science degrees for decades to come, though someday, this may change.

Domain : Some practitioners have degrees in application domains, bringing important domain knowledge and experience to projects. In MIS, some practitioners have business degrees. In embedded systems, some practitioners have electrical or computer engineering degrees, because embedded software often requires a detailed understanding of hardware. In medical software, some practitioners have medical informatics, general medical, or biology degrees.

Other : Some practitioners have mathematics, science, engineering, or other technical degrees. Some have philosophy, or other non-technical degrees. And, some have no degrees. Note that Barry Boehm earned degrees in mathematics and Edsger Dijkstra earned degrees in physics.

Graduate software engineering degrees have been available from dozens of universities for a decade or so. Undergraduate software engineering degrees are being established at many universities. A standard curriculum for undergraduate software engineering degrees was recently defined by the CCSE.

Practitioners specialize in many roles in industry (analysts, developers, testers, technical support, managers) and academia (educators, researchers).

Most software engineers work as employees or contractors. Software engineers work with businesses, government agencies (civilian or military), and non-profit agencies (a school or .org like Wikipedia). Some software engineers work for themselves as free agents.

There is considerable debate over the future employment prospects for Software Engineers and other IT Professionals. For example, an online futures market called the Future of IT Jobs in America attempts to answer the question as to whether there will be more IT jobs, including software engineers, in 2012 than there were in 2002.

Is SE a branch of computer science, a branch of traditional engineering, or a field that stands on its own? There is considerable debate over this.

Branch of computer science : Many believe that software engineering is a part of computer science, because of their close historical connections and their relationship to mathematics. They advocate keeping SE a part of computer science.

Branch of engineering : Others advocate making SE a part of traditional engineering. This is especially true for people who want to emulate other elements of engineering, such as licensing.

Freestanding field : Recently, software engineering has been finding its own identity and emerging as an important freestanding field. Practitioners are slowly realizing that they form a huge community in their own right.

This article attempts to be neutral on this issue, but errs on the side of being independent to clarify the differences between fields. See also Comparing software engineering and related fields

Software engineering resembles mathematics, science, engineering, and art in many different ways. There is considerable debate over which is closest. These diverse influences explain why some see software engineering as its own field.

Mathematics : Programs have many mathematical properties. For example the correctness and complexity of many algorithms are mathematical concepts that can be rigorously proven. Programs are finite, so in principle, developers could know many things about a program in a mathematical way. However, computability theory proves that not everything useful about a program can be proven. Mathematics works best for small pieces of code and has difficulty scaling up. Edsger Dijkstra has argued that software engineering is a branch of mathematics.

Science : Programs have many scientific properties, that are shown by measurement. For example, the performance and scalabiliy of programs under various workloads is shown by measuring them. The effectiveness of caches, bigger processors, faster networks, newer databases are scientific issues. Mathematical equations can sometimes be deduced from the measurements. Scientific approaches work best for system-wide analysis, but often are meaningless when comparing different small fragments of code.

Engineering : Programs are built as a sequence of projects by people. These projects are constrained by technology, budget, and schedule. Others want practitioners follow one of the many software engineering processes. Software Engineering is considered by many to be an engineering discipline because there are pragmatic approaches and expected characteristics of the engineer. Proper analysis, documentation, and commented code are signs of an engineer. David Parnas has argued that software engineering is engineering.

Art : Programs contain many artistic elements. User interfaces are designed to be aesthetically pleasing to users. Completed code should be aesthetically pleasing to programmers. Many goals of good design are NP-complete or worse (such as minimizing the number of lines of code, minimizing number of variables, etc.), which means they are not decidable by either man or computer, and they must be decided by one's own sense of aesthetics. Even the decision of whether a variable name or class name is clear and simple is an artistic question. People who write code and do not follow the doctines of engineering are more rightfully called software artists. (non-scientific craft) Donald Knuth famously argued that programming is an art.

Performance : The act of writing software requires that developers summon the energy to find the answers they need while they are at the keyboard. Creating software is a performance that resembles what athletes do on the field, and actors and musicians do on stage. When you consider how to develop software, some argue that you need artistic inspiration to spark the creation of the code. Sometimes a creative spark is needed to create the architecture or develop a piece of code.

In the U.S., software drove about 1/4 of all increase in GDP during the 1990s (about $90 billion per year), and 1/6 of all productivity growth (efficiency within GDP) during the late 1990s (about $33 billion per year). Software engineering drove $1 trillion of economic and productivity growth over the last decade. See also software engineering economics.

Software engineering changes world culture, wherever people use computers. Email, the world-wide web, and instant messaging enable people to interact in new ways. Software lowers the cost and improves the quality of health-care, fire departments, and other important social services.

Successful projects where software engineering methods have been applied include Linux, the space shuttle software, and automatic teller machines. When it is cheaper to run a business or agency with software applications than without, businesses and agencies often invest in computers, software, and personnel.

Many debates are raging within SE. As software becomes more pervasive, we all recognize the need for better software, but we disagree on how.

Technologies and Practices : What is the best way to make more and better software? SEs advocate many different technologies and practices, with much disagreement. This debate has gone on for 60 years and may continue forever.

Licensing : What will SEs do about licensing? Licensing is a polarizing issue. Some fiercely advocate it; others staunchly oppose it.

Professionalism : What will SEs do about professionalism and ethics?

Success : Is SE a success or a failure? Some look to the enormous economic growth and productivity gains enabled by software and claim that software engineering is a huge success. Others point to the ongoing problems with crashing operating systems and computer viruses and claim that software engineering has failed. How can we reconcile these points of view?

Software Engineering utopia vs Bazaar practise : '[SE advocates] have climbed a social ladder for a few decades and are now fighting against a tide of open source software that seems to be bringing bazaar anarchy and taking the well-deserved control out of their hands. Part of this is their utopia of "software engineering" by some magic cathedral approach which has never worked and whose failure the authors of these utopias tend to blame on the lack of control that copyright offers them over their projects. The strange thing here is that they have had the chance to put all these things into practise in their university haven. But, strangely enough, the more successful university projects are carried out in a bazaar-like open-source manner.' -- Hartmut Pilch

See also Debates within software engineering.

Aspect-oriented programming and agile methods are important emerging SE technologies and practices.

Aspects : Aspects help programmers deal with ilities by providing tools to add or remove boilerplate code from many areas in the source code. Aspects describe how all objects or functions should behave in particular circumstances. For example, aspects can add debugging, logging, or locking control into all objects of particular types. Researchers are currently working to understand how to use aspects to design general-purpose code. Related concepts include generative programming and templates.

Agile : Agile software development guides software development projects that evolve rapidly with changing expectations and competitive markets. The heavy, document-driven processes (like CMM and ISO 9000) are fading in importance. Some people believe that companies and agencies export many of the jobs that can be guided by heavy-weight processes. Related concepts include extreme programming and lean software development.

The Future of Software Engineering conference (FOSE) held at the ICSE 2000 documented the state of the art of SE in 2000 and listed many problems to be solved over the next decade. The Feyerabend project attempts to discover the future of software engineering by seeking and publishing innovative ideas.

The biggest and oldest conference devoted to software engineering is the International Conference on Software Engineering (ICSE). This conference meets every year to discuss improvements in research, education, and practice.

Conferences dedicated to inform undergraduate students like the annual Canadian University Software Engineering Conference (CUSEC) are also very promising for the future generation. It is completely organized by undergraduate students and lets different Canadian Universities interrested in Software Engineering host the conference each year. Past guests includes Kent Beck, Joel Spolsky, Philippe Kruchten, Hal Helms, Craig Larman as well as university professors and students.

The most known (and possibly oldest) process is the waterfall where you (roughly) analyze the problem, design a solution approach, architect a software framework to that solution, develop code, test, deploy, and maintain. That is a disciplined pragmatic approach. The problem is that adequate experience to analyze and specify large systems is almost never available.

Without the engineering approach, the code can be difficult to maintain or debug, but an engineering approach does not guarantee quality code without bugs.

Art is an application of creative process. Actually, engineering is a creative act, too.

• History of software engineering
• Criticism of software engineering
• Debates within software engineering
• Software engineering demographics
• Comparing software engineering and related fields
• List of software engineering topics
• Important publications in software engineering
• Wikipedia articles on software engineering