History of Software Engineering

 

History  Of Software 

The term programming was commonly used through the mid-1960s, and referred essentially to the task of coding a computer. The term software engineering—referring to the highly disciplined, systematic approach to software development and maintenance—came into existence after a NATO-sponsored conference in 1968. At that conference, the difficulties and pitfalls of designing complex systems were explored in depth, and a search for solutions began that concentrated on better methodologies and tools. The most prominent of these tools were languages reflecting procedural, modular, and object-oriented styles of programming. Since 1968, the development of software engineering has been intimately tied to these tools’ emergence and improvement, as well as to efforts for systematizing or automating program documentation and testing. Ultimately, analytic verification and correctness proofs were supposed to replace testing, but that has not happened.

The 1960s and the origin of software engineering

It is unfortunate that people dealing with computers often have little interest in the history of their subject. As a result, many concepts and ideas are propagated and advertised as being new, when in fact they existed decades ago, perhaps under a different name. I believe it worthwhile to occasionally consider the past and to investigate how computing terms and concepts originated. I regard the late 1950s as a period essential to the era of computing. At that time, large computers became available to research institutions and universities. Computers were then used primarily in engineering and the natural sciences, but they soon became indispensable in business, too. The time when they were accessible only to a few insiders in laboratories, when they frequently broke down whenever one wanted to use them, belonged to the past. Computers’ emergence from the closed laboratory of electrical engineers into the public domain meant that computers’ use, in particular their programming, became an activity of many. As a result, a new profession was born, and all kinds of companies began to hire programmers. The actual computers, however, remained hidden, enclosed within special rooms built to house them in those same companies. Programmers would write code and bring their programs to a counter where a dispatcher would pick up the programs and queue them for processing.

Programming as a mathematical discipline

In 1967, Robert W. Floyd had suggested the idea of assertions of states, of truths always valid at given points in a program.10 It led to Hoare’s seminal paper titled ‘‘An Axiomatic Basis of Computer Programming,’’ postulating the so-called Hoare logic.11 A few years later, in 1975, Dijkstra deduced from it the calculus of predicate transformers.12 Programming was obtaining a mathematical basis. Programs were no longer just code for controlling computers, but static texts that could be subjected to mathematical reasoning. Although these developments were recognized at some universities, they passed virtually unnoticed in industry. Indeed, Hoare’s logic and Dijkstra’s predicate transformers were explained on interesting but small algorithms such as multiplication of integers, binary search, and greatest common divisor. But industry was plagued by large, even gargantuan, systems. It was not obvious that mathematical theories would ever solve real problems when the analysis of simple algorithms was demanding enough.

Era of the personal workstation 

However, another development influenced the computing field more profoundly than all programming languages. It was the workstation, whose first incarnation, the Alto, was built in 1975 by the Xerox PARC lab.16 In contrast to the aforementioned microcomputers, the workstation was powerful enough to allow serious software development, complex computations, and the use of a compiler for an advanced programming language. Most important, the Alto pioneered the bit-mapped, high-resolution display and the pointing device called a mouse, which together brought about a revolutionary change in computer usage. Along with the Alto, the concept of a local area network was introduced, and that of central servers for (laser) printing, large-scale file storage, and email service. It is no exaggeration at all to claim that the modern computing era started in 1975 with the Alto. The Alto caused nothing less than a revolution, albeit slowly, and as a result many people today have no idea how computing was done before 1975, without personal, highly interactive workstations. The influence of these developments on software engineering cannot be overestimated.

Abundance of computer power

The period since 1985 has, until a few years ago, chiefly been characterized by enormous advances in hardware technology. Today, even tiny computers, such as mobile telephones, have 100 times more power and capacity than the biggest of 20 years ago. It is fair to say that semiconductor and disk technologies have recently determined all advances. Who, for example, would have dreamed in 1990 of memory sticks holding several gigabytes of data, of tiny disks with dozens-of-gigabytes capacity, of processors with clock rates of several gigahertz? Such speedy development has vastly widened the area of computer applications. This has happened particularly in connection with communications technology. It is now hard to believe that before 1975 computer and communications technologies were considered separate fields. 

Wasteful software

Whereas the incredible increase in the power of hardware was very beneficial for a wide spectrum of applications (we think of administrations, banks, railways, airlines, guidance systems, engineering, science), the same cannot be claimed for software engineering. Surely, software engineering has profited too from the many sophisticated development tools. But the quality of its products hardly reflects signs of great progress. No wonder: after July–September 2008 37 all, the increase of power was itself the reason for the terrifying growth of complexity. Whatever progress was made in software methodology was quickly compensated for by still higher complexity of the software tasks. This is reflected by Martin Reiser’s ‘‘law’’: ‘‘Software is getting slower faster than hardware is getting faster.’’17 Indeed, new problems have been tackled that are so difficult that engineers often have to be admired more for their optimism and courage than for their success.

Personal reflections 

What can we do to release this logjam? There is little point in reading history unless we are willing to learn from it. Therefore, I dare to reflect on the past and will try to draw some conclusions. A primary effort must be education concerning a sense of quality. Programmers must become engaged crusaders against homemade complexity. The cancerous growth of complexity is not a thing to be admired; it must be fought wherever possible.18 Programmers must be given time and afforded respect for work of high quality. This is crucial, ultimately more effective than more and better tools and rules. Let us embark on a global effort to prevent software from becoming known as softwaste! Recently I have become acquainted with a few projects where large, commercial operating systems were discarded in favor of the Oberon system, whose principal design objective had been perspicuity and concentration on the essentials.