An Experimental Evaluation of Machine-to-Machine Coordination Middleware

Abstract

The vision of the Internet-of-Things (IoT) embodies the seamless discovery, configuration, and interoperability of networked devices in various settings, ranging from home automation and multimedia to autonomous vehicles and manufacturing equipment. As these applications become increasingly critical, the middleware coping with Machine-to-Machine (M2M) communication and coordination has to deal with fault tolerance and increasing complexity, while still abiding to resource constraints of target devices.In this report, we focus on configuration management and coordination of services in a M2M scenario. On one hand, we consider Zoo-Keeper, originally developed for cloud data centers, offering a simple file-system abstraction, and embodying replication for fault-tolerance and scalability based on a consensus protocol. On the other hand, we consider the Devices Profile for Web Services (DPWS) stack with replicated services based on our implementation of the Raft consensus protocol. We show that the latter offers adequate performance for the targeted applications while providing increasing flexibility.for this is that it has become cost-effective to equip most devices with a considerable amount of processing and networking resources, making Ethernet networking and mainstream operating systems (e.g. Linux) ubiquitous and increasing the variety and complexity of functions performed. The second driver is the increasing diversity as previously closed systems are opened up to multiple vendors and become full fledged service ecosystems. Finally, these systems play increasingly important roles in day-to-day life, raising more vehemently the issue of dependability.Service-oriented architectures (SOA) have been a mainstay in enterprise computing, addressing similar needs, and there is now a growing interest in services for systems of connected devices. The Devices Profile for Web Services (DPWS) addresses this with a set of protocols that resource constrained devices should implement in order to achieve seamless networking and interoperability through Web Services. It assumes that each device behaves as a standard hosting service, providing basal functionality, and exposing one or more hosted services that offer device specific functionality. It includes basic SOAP, WSDL, HTTP binding, WS-Addressing, and WS-Security that are at the core of Web Services capabilities and interoperability. It also includes WS-Eventing, to allow event notification, and SOAP-over-UDP, which enables the usage of UDP as a transport for SOAP messages and enables network level multicast, thus paving the way for dynamic discovery in WS-Discovery [3], WS-MetadataExchange, and WS-Policy. These protocols allow a client to discover devices in the network, and to learn about their services, resources and characteristics. Multiple open source implementations of the DPWS exist [2, 1], and the Windows operating systems are shipped with a built-in DPWS framework, thus rendering this specification available in most personal computers and in many devices such as se...