Verifying the Design of Dynamic Software Updating in the OTS/CafeOBJ Method

Dynamic Software Updating (DSU) is a technique for updating running software systems without incurring downtime. However, a challenging problem is how to design a correct dynamic update so that the system after being updated will run as expected instead of causing any inconsistencies or even crashes. The OTS/CafeOBJ method is an effective and practical approach to specifying and verifying the design of software. In this paper, we propose an algebraic way of specifying and verifying the design of dynamic updates in the OTS/CafeOBJ method. By verifying the design of a dynamic update, we can (1) gain a better understanding of the update, e.g., how the behavior of the running system is affected by the update, (2) identify updating points where the dynamic update can be safely applied, (3) detect potential errors, and hence (4) design a safer dynamic update.