Enhancing Java']Java with support for simultaneous independent extensibility of collaborating objects

In this paper, we identify and describe problems which developers face when building dynamic upgradeable component systems using conventional object-oriented programming languages. The identified problems are caused by the absence of proper language support for dynamic evolution of objects and their respective collaborations. The most prominent problem is that of simultaneous independent extensibility, which materialize as part of continuously upgrading a running system. We examine recent advances, within the domain of object-oriented language technology, which touch upon the identified problems and discuss how far they bring us toward a unified solution. Finally, we present Lasagne/J, a language extension, which adds support for simultaneous independent extensibility to Java.