Simulating upgrades of complex systems: The case of Free and Open Source Software

AbstractContext grade of complex systems is intrinsically difficult and requires techniques, algorithms, and methods which are both expressive and computationally feasible in order to be used in practice. In the case of FOSS (Free and Open Source Software) systems, many upgrade errors cannot be discovered by current upgrade managers and then a system upgrade can potentially lead the system to an inconsistent and incoherent state. ive jective of this paper is to propose an approach to simulate the upgrade of complex systems in order to predict errors before they affect the real system. proach promotes the use of model-driven engineering techniques to simulate the upgrade of complex systems. The basic idea is to have a model-based description of the system to be upgraded and to make use of model transformations to perform the upgrade on a source model so to obtain a target model representing the state of the upgraded system. s vide an implementation of the simulator, which is tailored to FOSS systems. The architecture of the simulator is distribution independent so that it can be easily instantiated to specific distributions. The simulator takes into account also pre and post-installation scripts that equip each distribution package. This feature is extremely important since maintainer scripts are full-fledged programs that are run with system administration rights. sions per shows the kind of errors the simulator is able to predict before upgrading the real system, and how the approach improves the state of the art of package managers while integrated in real Linux distribution installations.