Software Engineering (SE) is the design, development, and documentation of software by applying technologies and practices from computer science, project management, engineering, application domains, interface design, digital asset management and other fields.The term software engineering was popularized after 1968during the 1968 NATO Software Engineering Conference (held in Garmisch, Germany) by its chairman F.L. Bauer, and has been in widespread use since.The term software engineering has been commonly used with a variety of distinct meanings:
- As the informal contemporary term for the broad range of activities that was formerly called programming and systems analysis
- As the broad term for all aspects of the practice of computer programming, as opposed to the theory of computer programming, which is called computer science
- As the term embodying the advocacy of a specific approach to computer programming, one that urges that it be treated as an engineering discipline rather than an art or a craft, and advocates the codification of recommended practices in the form of software engineering methodologies.
- Software engineering is “(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,” and “(2) the study of approaches as in (1).” – IEEE Standard 610.12
The Need for Software EngineeringSoftware is often found in products and situations where very high reliability is expected, even under demanding conditions, such as monitoring and controlling nuclear power plants, or keeping a modern airliner aloft Such applications contain millions of lines of code, making them comparable in complexity to the most complex modern machines. For example, a modern airliner has several million physical parts (and the space shuttle about ten million parts), while the software for such an airliner can run to 4 million lines of code.See also List of software engineering topics (thematic) and List of software engineering topics (alphabetical).What is the Nature of SE?Software engineering resembles many different fields in many different ways. The following paragraphs make some simple comparisons.
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 rigorous mathematical way. The use of mathematics within software engineering is often called formal methods. However, computability theory shows that not everything useful about a program can be proven. Mathematics works best for small pieces of code and has difficulty scaling up.
Engineering Software Engineering is considered by many to be an engineering discipline because there are pragmatic approaches and expected characteristics of engineers. Proper analysis, documentation, and commented code are signs of an engineer. David Parnas has argued that software engineering is engineering. Programs have many properties that can be measured. For example, the performance and scalability of programs under various workloads can be measured. The effectiveness of caches, bigger processors, faster networks, newer databases are engineering issues. Mathematical equations can sometimes be deduced from the measurements. Mathematical approaches work best for system-wide analysis, but often are meaningless when comparing different small fragments of code.
Manufacturing Programs are built in as a sequence of steps. By properly defining and carrying out those steps, much like a manufacturing assembly line, advocates hope to improve the productivity of developers and the quality of final programs. This approach inspires the many different processes and methodologies. While others, such as the authors of the Programmer’s Stone, contend this view “[is] in fact claiming to be able to implement an Artificial Intelligence that simulates a production line designer”.
Project management Commercial (and many non-commercial) software projects require management. There are budgets and schedules to set. People to hire and lead. Resources (office space, computers) to acquire. All of this fits more appropriately within the purview of management.
Audio and Visual art Programs contain many artistic elements, akin to writing or painting. User interfaces should be aesthetically pleasing and provide optimal audio and visual communication to end-users. What is considered “good design” is often subjective, and may be decided by one’s own sense of aesthetics. Because graphic artists create graphic elements for graphical user interfaces, graphic design often overlaps interaction design in the position of an interface designer.
User interfaces may require technical understanding including graphical integration with code, computer animation technology, automation of graphic production, integrating graphics with sound editing technology, and mathematical application. One could say that “audiovisual engineering” is required.
User interfaces with user-read text and voice may also be enhanced from professional copywriting and technical writing.
Code should be aesthetically pleasing to programmers. Even the decision of whether a variable name or class name is clear and simple is an artistic question. Donald Knuth asserted that programming is an art.
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. Some argue that SEs need inspiration to spark the creation of code. Sometimes a creative spark is needed to create the architecture or to develop a unit of code to solve a particularly intractable problem. Others argue that discipline is the key attribute. Pair programming emphasizes this point of view. Both Kent Beck and Watts Humphrey have argued this emphasis. See also Performance Engineering.
Branch of Which Field?Is SE (or should SE be) a branch of programming, a branch of computer science, a branch of traditional engineering, or a field that stands on its own? There is considerable debate over this. This has important implications for professionalism, licensing, and ethics. Licensing is a polarizing issue: some fiercely advocate it while others staunchly oppose it.
Branch of programming Programming emphasizes writing code, independent of projects and customers. Software engineering emphasizes writing code in the context of projects and customers by making plans and delivering applications. As a branch of programming, SE would probably have no significant licensing or professionalism issues.
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. Both computer science and software engineering care about programs. Computer science emphasizes the theoretical, eternal truths while software engineering emphasizes practical, everyday usefulness. Some argue that computer science is to software engineering as physics and chemistry are to traditional engineering. As a branch of computer science, SE would probably have few licensing or professionalism concerns.
Branch of engineering Some SE academics and practitioners, such as David Parnas and Steve McConnell, have advocated treating SE an engineering discipline. Advocates for this view argue that the practice of engineering involves the use of mathematics, science, and the technology of the day, to build trustworthy products that are “fit for purpose”, a description that applies as well to SE as to any other engineering discipline. As a branch of engineering, SE would probably adopt the engineering model of licensing and professionalism.
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. Software engineering may need to create a form of regulation/licensing appropriate to its own circumstances. It is arguable that licensing (in the United States) is inappropriate because the creation of software represents a form of writing, and requiring people to be licensed in order to write computer programs may be a violation of the First Amendment. Requiring software engineers to be licensed by a government bureaucracy would make persons who create software without a license into criminals, even if they give their software away, same as practicing medicine or law without a license, even for free, is a criminal offense.