Key Software Trend: Object Technology
One of the authors, HMD, remembers the great frustration felt in the 1960s by software development organizations, especially those working on large-scale projects. During his undergraduate years, he had the privilege of working summers at a leading computer ven- dor on the teams developing timesharing, virtual-memory operating systems. This was a great experience for a college student. But, in the summer of 1967, reality set in when the company “decommitted” from producing as a commercial product the particular system on which hundreds of people had been working for many years. It was difficult to get this thing called software right—software is “complex stuff.”
Improvements to software technology did emerge, with the benefits of structured pro- gramming (and the related disciplines of structured systems analysis and design) being realized in the 1970s. Not until the technology of object-oriented programming became widely used in the 1990s, though, did software developers feel they had the necessary tools for making major strides in the software development process.
What are objects and why are they special? Actually, object technology is a packaging scheme that helps us create meaningful software units. These can be large and are highly focused on particular applications areas. There are date objects, time objects, paycheck objects, invoice objects, audio objects, video objects, file objects, record objects and so on. In fact, almost any noun can be reasonably represented as an object.
We live in a world of objects. Just look around you. There are cars, planes, people, animals, buildings, traffic lights, elevators and the like. Before object-oriented languages appeared, procedural programming languages (such as Fortran, COBOL, Pascal, BASIC and C) were focused on actions (verbs) rather than on things or objects (nouns). Program- mers living in a world of objects programmed primarily using verbs. This made it awkward to write programs. Now, with the availability of popular object-oriented languages, such as C++, Java, Visual Basic and C#, programmers continue to live in an object-oriented world and can program in an object-oriented manner. This is a more natural process than procedural programming and has resulted in significant productivity gains.
A key problem with procedural programming is that the program units do not effec- tively mirror real-world entities, so these units are not particularly reusable. It’s not unusual for programmers to “start fresh” on each new project and have to write similar software “from scratch.” This wastes time and money, as people repeatedly “reinvent the wheel.” With object technology, the software entities created (called classes), if properly designed, tend to be reusable on future projects. Using libraries of reusable componentry can greatly reduce effort required to implement certain kinds of systems (compared to the effort that would be required to reinvent these capabilities on new projects).
Software Engineering Observation 1.2
Extensive class libraries of reusable software components are available on the Internet. Many of these libraries are free. 1.2
Software Engineering Observation 1.3
Some organizations report that the key benefit object-oriented programming gives them is not software that is reusable but, rather, software that is more understandable, better organized and easier to maintain, modify and debug. This can be significant, because perhaps as much as 80 percent of software cost is associated not with the original efforts to develop the software, but with the continued evolution and maintenance of that software throughout its lifetime. 1.3