Seamlessness is a promise often used to promote object orientation, and the use of object orientation in the different domains and in the different stages of the software development process has brought great improvements in seamlessness.

Where can we find seamlessness? And are there different kinds of seamlessness? In this paper we look at seamlessness starting with the different models found in large software developments. To give a common base for the discussion a model architecture is presented and different aspects of seamlessness are defined. We then show on a general level, where object orientation has already brought some seamlessness, where it will hopefully bring a higher degree of seamlessness in the future and where it cannot bring seamlessness due to restrictions inherent to the model architecture. The emphasis of the discussion is not to present a complete theoretical treatment but rather to help software developers to judge the many claims about seamlessness.