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In this paper, we investigate extensions for Conflict-Free Replicated Data Types (CRDTs) that permit their use in failure-prone, heterogeneous, resource-constrained, distributed, multi-tier (cloud/edge/device) cloud deployments such as the Internet-of-Things (IoT), while addressing multiple CRDT limitations. Specifically, we employ distributed logging to implement robust, strong eventual consistency of replicas. Our approach also enables uniform reversal of operations and precludes the requirement of exactly-once delivery and idempotence imposed by operation-based CRDTs. Moreover, it exposes CRDT versions for use in debugging and history-based programming. We evaluate our approach for commonly used CRDTs and show that it enables higher operation throughput (up to 1.8x) versus conventional CRDTs for the workloads we consider. 

Co-location of processing infrastructure and IoT devices at the edge is used to reduce response latency and long-haul network use for IoT applications. As a result, edge clouds for many applications (e.g. agriculture, ecology, and smart city deployments) must operate in remote, unattended, and environmentally harsh settings, introducing new challenges. One key challenge is heat exposure, which can degrade the performance, reliability, and longevity of electronics. For edge clouds, these problems are exacerbated because they increasingly perform complex workloads, such as machine learning, to affect data-driven actuation and control of devices and systems in the environment. The goal of our work is to protect edge clouds from overheating. To enable this, we develop a heat-budget-based scheduling system, called Sparta, which leverages dynamic voltage and frequency scaling (DVFS) to adaptively control CPU temperature. Sparta takes machine learning applications, datasets, and a temperature threshold as input. It sets the initial frequency of the CPU based on historical data and then dynamically updates it, according to the applications’ execution profile and ambient temperature, to safeguard edge devices. We find that for a suite of machine learning applications and deployment temperatures, Sparta is able to maintain CPU temperature below the threshold 94% of the time while facilitating improvements in execution time by 1.04x − 1.32x over competitive approaches. 

We present CAPLets, an authorization mechanism that extends capability based security to support fine grained access control for multi-scale (sensors, edge, cloud) IoT deployments. To enable this, CAPLets uses a strong cryptographic construction to provide integrity while preserving computational efficiency for resource constrained systems. Moreover, CAPLets augments capabilities with dynamic, user defined constraints to describe arbitrary access control policies. We introduce an application specific, turing complete virtual machine, CapVM, alongside with eBPF and Wasm, to describe constraints. We show that CAPLets is able to express permissions and requirements at a fine grain, facilitating construction of non-trivial access control policies. We empirically evaluate the efficiency and flexibility of CAPLets abstractions using resource constrained devices and end-to-end IoT deployments, and compare it against related mechanisms in wide use today. Our empirical results show that CAPLets is an order of magnitude faster and more energy efficient than current IoT authorization systems. 

We present MSDBench – a set of benchmarks designed to illuminate the effects of deployment choices and operating system ab- stractions on microservices performance in IoT settings. The microser- vices architecture has emerged as a mainstay set of design principles for cloud-hosted, network-facing applications. Their utility as a design pattern for “The Internet of Things” (IoT) is less well understood. We use MSDBench to show the performance impacts of different deploy- ment choices and isolation domain assignments for Linux and Ambience, an experimental operating system specifically designed to support mi- croservices for IoT. These results indicate that deployment choices can have a dramatic impact on microservices performance, and thus, MSD- Bench is a useful tool for developers and researchers in this space. 

Serverless computing is an emerging event-driven programming model that accelerates the development and deployment of scalable web services on cloud computing systems. Though widely integrated with the public cloud, serverless computing use is nascent for edge-based, IoT deployments. In this work, we design and develop STOIC (Serverless TeleOperable HybrId Cloud), an IoT application deployment and offloading system that extends the serverless model in three ways. First, STOIC adopts a dynamic feedback control mechanism to precisely predict latency and dispatch workloads uniformly across edge and cloud systems using a distributed serverless framework. Second, STOIC leverages hardware acceleration (e.g. GPU resources) for serverless function execution when available from the underlying cloud system. Third, STOIC can be configured in multiple ways to overcome deployment variability associated with public cloud use. Finally, we empirically evaluate STOIC using real-world machine learning applications and multi-tier IoT deployments (edge and cloud). We show that STOIC can be used for training image processing workloads (for object recognition) – once thought too resource intensive for edge deployments. We find that STOIC reduces overall execution time (response latency) and achieves placement accuracy that ranges from 92% to 97%. 

Serverless computing is a promising new event- driven programming model that was designed by cloud vendors to expedite the development and deployment of scalable web services on cloud computing systems. Using the model, developers write applications that consist of simple, independent, stateless functions that the cloud invokes on-demand (i.e. elastically), in response to system-wide events (data arrival, messages, web requests, etc.). In this work, we present STOIC (Serverless TeleOperable HybrId Cloud), an application scheduling and deployment system that extends the serverless model in two ways. First, it uses the model in a distributed setting and schedules application functions across multiple cloud systems. Second, STOIC sup- ports serverless function execution using hardware acceleration (e.g. GPU resources) when available from the underlying cloud system. We overview the design and implementation of STOIC and empirically evaluate it using real-world machine learning applications and multi-tier (e.g. edge-cloud) deployments. We find that STOIC’s combined use of edge and cloud resources is able to outperform using either cloud in isolation for the applications and datasets that we consider. 

We present Centaurus a scalable, open source, clustering service for K-means clustering of correlated, multidimensional data. Centaurus provides users with automatic deployment via public or private cloud resources, model selection (using Bayesian information criterion), and data visualisation. We apply Centaurus to a real-world, agricultural analytics application and compare its results to the industry standard clustering approach. The application uses soil electrical conductivity (EC) measurements, GPS coordinates, and elevation data from a field to produce a map of differing soil zones (so that management can be specialised for each). We use Centaurus and these datasets to empirically evaluate the impact of considering multiple K-means variants and large numbers of experiments. We show that Centaurus yields more consistent and useful clusterings than the competitive approach for use in zone-based soil decision-support applications where a hard decision is required.