JavAdaptor : flexible runtime updates of Java applications

Software is changed frequently during its life cycle. New requirements come, and bugs must be \ufb01xed. To update an application, it usually must be stopped, patched, and restarted. This causes time periods of unavailability, which is always a problem for highly available applications. Even for the development of complex applications, restarts to test new program parts can be time consuming and annoying. Thus, we aim at dynamic software updates to update programs at runtime. There is a large body of research on dynamic software updates, but so far, existing approaches have shortcomings either in terms of \ufb02exibility or performance. In addition, some of them depend on speci\ufb01c runtime environments and dictate the program\u2019s architecture. We present JAVA DAPTOR, the \ufb01rst runtime update approach based on Java that (a) offers \ufb02exible dynamic software updates, (b) is platform independent, (c) introduces only minimal performance overhead, and (d) does not dictate the program architecture. JAVA DAPTOR combines schema changing class replacements by class renaming and caller updates with Java HotSwap using containers and proxies. It runs on top of all major standard Java virtual machines. We evaluate our approach\u2019s applicability and performance in non-trivial case studies and compare it with existing dynamic software update approaches