Escape capsule: Explicit state is robust and scalable

Software is modular, and so is run-time state. We argue that by allowing individual layers of the software stack to store isolated runtime state, we cripple the ability of systems to effectively scale or respond to failures. Given the strong desire to build elastic and highly available applications for the cloud, we propose Slice, an abstraction that allows applications to declare appropriate granularities of scale-oriented state, and allows layers to contribute the appropriate layer-specific data to those containers. Slices can be transparently migrated and replicated between application instances, thereby simplifying design of elastic and highly available systems, while retaining the modularity of modern software.