Handling consistent dynamic updates on distributed systems

While updating a software system, it is paramount to safeguard the consistency of execution and let as many operations as possible execute undisturbed in order to minimise disruption. This paper proposes a framework that supports transparent dynamic updates of distributed systems consisting of Java classes. This framework aims at: (i) ensuring the consistency of the execution flow, and (ii) handling coordination issues concerning the update of the distributed parts. The operations of the framework are transparent with respect to the system to be updated, thanks to appropriate selective rewriting of bytecode performed at load-time. Consistency of the execution flow has been obtained by devising appropriate means to check and selectively block execution on components of the running system.