# Virtual Replication of IoT Hubs in the Cloud:
## 2 Related Work
The adoption of Virtualization Technologies for Wireless Sensor Networks has been studied and evaluated in several aspects during last years. In [11] the researchers present the implementation of a testbed where physical, simulated, and emulated sensor nodes cooperate and interact in real time extending the experimentation capabilities of a deployment. With the arrival of the IoT revolution, this technologies have been enriched with new features and functionalities in order to augment the proposed platforms and solutions. For example the authors of [12] introduce an interesting and innovative platform supporting different aspects of Wireless Sensor Network virtualization in order to handle the heterogenous requirements typical of IoT applications. In [13] the authors present a scalable virtual sensor framework to support the build of logical data flows related to either physical sensors or custom virtual sensors. Although the presented approach is interesting, the presented technology is not applied on the Edge to handle synchronization between local and remote environment. The authors of [14] propose the use Virtual IoT Devices on the Edge for local data processing, management of physical devices, and quick actuation. The Cloud is envisioned only as a way to access the Edge infrastructure remotely but without the introduction of Gateway and/or Objects replicas and the related synchronization procedures. A suitable lightweight alternative to VMs is represented by containers, which provide a more flexible environment for \"disposable applications\", like the IoT Hub. Container platforms like Docker [15; 16; 17] are gaining increasing attention also for edge and Fog computing applications. In this challenging scenario, the possibility of moving from centralized to decentralized paradigm to offload the processing to the edge reducing application response time and improving overall user experience will play a fundamental role in Internet of Things. In [18; 19], the authors present how a container-based architecture could be efficiently used for dynamic networking application. In [20], an interesting comparison about existing lightweight and hypervisor-based approaches for edge computing and efficient networking is presented. Furthermore, in [21] a novel approach for the application of a lightweight virtualization technology (such as Docker) to constrained devices with a negligible overhead is presented. In this work, a containerized version of the IoT Hub, based on Docker, will be considered. The authors of [22] present the use of virtualization techniques in the context of IoT Gateway management. In particular, they introduce the concept of Gateway-as-a-Service, a lightweight instance that can be shared between different users thanks to the use of virtualization techniques. This interesting work is focused on the adoption of virtualization techniques (e.g., Virtual Machines and Containers) on the Edge but does not take into account the virtualization and synchronization of gateways and Smart Objects with the Cloud and how this procedure can be seamless for users and services both on local and remote environments.