CacheL: A cache algorithm using leases for node data in the Internet of Things (Best Paper Award)

Wireless Sensor Networks (WSNs) allow applications to interact with the physical world using sensing nodes deployed in an Internet of Things (IoT). Many WSN sensing nodes have constrained computing and memory capabilities. This paper details a new cache algorithm suitable for use on constrained nodes and its use in an architecture incorporating caching and the flow of data from sensors to services, possibly Cloud-based. This cache algorithm is influenced by the Clock paging algorithm and manages the leases of cached data in its replacement policy, removing the need for a separate process for this. This paper presents implementations of the algorithm in C on the Contiki OS and Java, compares its performance to LRU and considers its suitability for use on constrained WSN nodes

A holistic architecture using peer to peer (P2P) protocols for the internet of things and wireless sensor networks

Wireless Sensor Networks (WSNs) interact with the physical world using sensing and/or actuation. The wireless capability of WSN nodes allows them to be deployed close to the sensed phenomenon. Cheaper processing power and the use of micro IP stacks allow nodes to form an “Internet of Things” (IoT) integrating the physical world with the Internet in a distributed system of devices and applications. Applications using the sensor data may be located across the Internet from the sensor network, allowing Cloud services and Big Data approaches to store and analyse this data in a scalable manner, supported by new approaches in the area of fog and edge computing. Furthermore, the use of protocols such as the Constrained Application Protocol (CoAP) and data models such as IPSO Smart Objects have supported the adoption of IoT in a range of scenarios. IoT has the potential to become a realisation of Mark Weiser’s vision of ubiquitous computing where tiny networked computers become woven into everyday life. This presents the challenge of being able to scale the technology down to resource-constrained devices and to scale it up to billions of devices. This will require seamless interoperability and abstractions that can support applications on Cloud services and also on node devices with constrained computing and memory capabilities, limited development environments and requirements on energy consumption. This thesis proposes a holistic architecture using concepts from tuple-spaces and overlay Peer-to-Peer (P2P) networks. This architecture is termed as holistic, because it considers the flow of the data from sensors through to services. The key contributions of this work are: development of a set of architectural abstractions to provide application layer interoperability, a novel cache algorithm supporting leases, a tuple-space based data store for local and remote data and a Peer to Peer (P2P) protocol with an innovative use of a DHT in building an overlay network. All these elements are designed for implementation on a resource constrained node and to be extensible to server environments, which is shown in a prototype implementation. This provides the basis for a new P2P holistic approach that will allow Wireless Sensor Networks and IoT to operate in a self-organising ad hoc manner in order to deliver the promise of IoT

Using a DHT in a Peer to Peer architecture for the Internet of Things

A challenging aspect of The Internet of Things (IoT) is to provide an architecture that can handle the range of IoT elements ranging from Cloud-based applications to constrained nodes in Wireless Sensor Networks (WSNs). Such an architecture must be scalable, allow seamless operation across networks and devices with little human intervention. This paper describes a set of abstractions and an architecture for the flow of data from sensors to applications supported by a Distributed Hash Table (DHT) and our novel Holistic Peer to Peer (HPP) Application Layer protocol to handle node ids, capabilities, services and sensor data. We show that this architecture can operate in a constrained node by presenting a `C' implementation running on the Contiki3.0 OS and consider the effectiveness of its use of a DHT and its abstractions

OMA LWM2M in a holistic architecture for the Internet of Things

Wireless Sensor Networks (WSNs) allow applications to interact with the physical world using nodes in an Internet of Things (IoT). Application level protocols such as the Constrained Application Protocol (CoAP) and data models such as IPSO Smart Objects and the Open Mobile Alliance Lightweight Specification (OMA LWM2M) have the potential to provide greater application interoperability and to ease the difficulties imposed by the heterogeneous nature, limited development environments and interfaces of existing solutions. This paper describes an architecture using a tuple-space based library for the flow of data from sensors to applications with defined service abstractions. It also compares the OMA LWM2M Information Model and the DMTF Common Information Model. It presents a `C' implementation of the OMA LWM2M model on our tuple-space running on the Contiki3.0 OS and considers the effectiveness of our architecture and its integration with existing CoAP and OMA LWM2M implementations