Mobile Apps with Dynamic Bindings between the Fog and the Cloud

The back-ends of mobile apps usually use services executed on remote (e.g., cloud) machines. The transmission latency may though make the usage of remote machines a less efficient solution for data that need short analysis time. Thus, apps should further use machines located near the network edge, i.e., on the Fog. However, the combination of the Fog and the Cloud introduces the research question of when and how the right binding of the front-end to an edge instance or a remote instance of the back-end can be decided. Such a decision should not be made at the development or the deployment time of apps, because the response time of the instances may not be known ahead of time or cannot be guaranteed. To make such decisions at run-time, we contribute the conceptual model and the algorithmic mechanisms of an autonomic controller as a service. The autonomic controller predicts the response time of edge/remote instances of the back-end and dynamically decides the binding of the front-end to an instance. The evaluation results of our approach on a real-world app for a large number of datasets show that the autonomic controller makes efficient binding-decisions in the majority of the datasets, decreasing significantly the response time of the app.