Object-Oriented Systems in Real Life

Object-oriented development is expected to provide many benefits, but observations of industrial practice show that there are many problems to overcome. This paper discusses two issues: (1) The architectural issue of how to connect database, application, and screen objects. (2) To what extent expected benefits such as seamless transition from analysis to design, improved usability, etc. can be obtained. The architectural issue appears to have a significant influence on the expected benefits. The paper is based on studies of about seven experienced, but very different, development teams, plus a lot of casual observations. I will present the three basic architectures that I found in practice and discuss their advantages and problems. Surprisingly, only one team had a solid architecture that solved most of the problems. 1. Background The term "object-oriented " has been used as a catchword in recent years. We hear about OO user interfaces, OO design, OO languages, etc. Managers have heard about all the benefits of object-orientation: better user interfaces, reuse of code, cheaper development, and so on. In spite of the claimed advantages, little detail has been published about real-life object-oriented systems. In the early eighties, I was leading an object-oriented project. Since then, I have been following the spread of OO and often wondered what benefit OO actually gave, particularly in business applications. Some developers of business applications have told me in private that their managers expected great benefits, but they could not themselves see the advantages. In contrast, developers of technical systems could tell about real benefits after some trials. As a response to these comments, I published a critical article in the Danish version of ComputerWorld. It sparked a heavy debate and brought me into contact with many developers claiming they had successful OO projects. Typically they had more than five years of OO experience. Through many interviews and studies of about seven different developmen