A Case-Study in Encoding Configuration Languages: Multiple Class Loaders.

Abstract

The contribution of the paper is twofold. First, we define a toy language, called MCL, which provides a very abstract view of the mechanism of dynamic class loading with multiple loaders as in Java. The aim is to study this feature in isolation, allowing a better understanding; moreover, this also shows a stratified approach, which, dierently from the Java approach based on reflection, distinguishes between the language at the user level and the configuration language. This approach is less flexible but allows to statically check type safety, hence provides an intermediate solution between the rigid approach based only on the class path and that which allows loaders to depend on execution of user applications, which can be intricate and error-prone. The second contribution is related to a recent stream of work aiming at defining simple and powerful calculi providing a common foundation for systems supporting dynamic reconfiguration. We use MCL as an extended case-study, by defining an encoding in one of these kernel calculi, and prove the correctness of the translation.