Enhanced OSGi Bundle Updates to Prevent Runtime Exceptions

Explicit declaration of provided and required features facilitates easier updates of components within an application. A necessary precondition is that sufficient and correct meta-data about the component and its features is available. In this paper we describe a method that ensures safe OSGi bundle updates and package bindings despite potentially errorneous meta-data. It uses subtype checks on feature types, implemented as user-space enhancements of the standard bundle update process. The method was successfully applied in the Knopflerfish and Apache Felix frameworks and the paper discusses the general experiences with the OSGi framework gained during the implementation.