The increasing popularity of wireless devices, such as mobile phones, personal digital assistants, watches and the like, is enabling new classes of applications that present challenging problems to designers. Applications have to be aware of, and adapt to, frequent variations in the context of execution, such as fluctuating network bandwidth, decreasing battery power changes in location or device capabilities, and so on. In this paper, we argue that middleware solutions for wired distributed systems cannot be used in a mobile setting, as the principle of transparency that has driven their design runs counter to the new degrees of awareness imposed by mobility. We propose a synergy of reflection and code mobility as a means for middleware to give applications the desired level of flexibility to react to changes happening in the environment, including those that have not necessarily been foreseen by middleware designers. We use the sharing and processing of images as an application scenario to highlight the advantages of our approach.
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