Increasing the Efficiency of Code Offloading in n-tier Environments with Code Bubbling

Code offloading strives for increasing the energy efficiency and execution speed of mobile applications on resource-constrained mobile devices. First approaches only considered a code offloading between two (or three) tiers, executing code either locally on a mobile device or remotely on a powerful server. However, new execution environments comprise multiple tiers, containing highly distributed heterogeneous resources. To this end, we present our Code Bubbling Offload System (CoBOS) that targets n-tier environments containing highly distributed heterogeneous resources with different performance characteristics and cost implications. In such n-tier environments, it is very costly for a resource-constrained mobile device to gather a global view on available resources, why we propose the novel concept of code bubbling. Code bubbling moves code dynamically and adaptively toward more powerful and more distant tiers, enabling an efficient and scalable code offloading in n-tier environments. Each tier makes autonomous decisions to execute code in the tier or forward it further to the next tier. To support such a recursive escalation of code along autonomous tiers, CoBOS offloads self-contained offload requests that possess all information required for a decision-making and processing. Our real-world evaluation shows that CoBOS decreases execution time by 83% and energy consumption by 77% for code offloading in n-tier environments.