Modularity for the changing meaning of changing

In the past, modular structures for software systems have rested upon several assumptions that may no longer characterize the changing world of dynamic computing. Important among these assumptions is that the decision to use or reuse a particular component is made at the time a client is developed. But the advent of a variety of modern software architectures like SOA, mobile/ubiquitous computing, grids, and AOSD emphasize deferring these decisions about component choice until run-time. The presumption of development-time choice has had deep influence on many of the characteristics of programming languages. We explore the impact of the change of implementation selection from development-time to run-time on programming language constructs and middleware, and conclude that there is a model for software that satisfies the needs of future, more dynamic environments in a way that can be achieved as a compatible extension of today's common object-oriented languages.