Module Reload through Dynamic Update - The Case of NetBeans

Recent versions of the NetBeans IDE allow us to easily reload NetBeans modules in an instance of a running program. Though overcoming some of the dynamic component-replacement issues, simply running NetBeans´ install/uninstall hooks, can lead to dangling object references and hard-to-track class cast exceptions. These problems are caused by Java´s class-loading scheme which considers class objects of the same class definition as distinct types when loaded by different class loaders. In this paper we apply a novel dynamic update approach to NetBeans´ reload feature which overcomes these shortcomings, thus confirming its general validity. Hence, developers of NetBeans application modules, as well as NetBeans IDE modules, will experience a significant improvement as our approach allows transparent evolution of both code and state.