A Novel Approach to Load Balancing in P2P Overlay Networks for Edge Systems

Edge computing aims at addressing some limitations of cloud computing by bringing computation towards the edge of the system, i.e., closer to the client. There is a panoply of devices that can be integrated into future edge computing platforms, from local datacenters and ISP points of presence, to 5G towers, and even, multiple user devices like smartphones, laptops, and IoT devices. For all of these devices to communicate fruitfully, we need to build systems that enable the seamless interaction and cooperation among these diverse devices. However, creating and maintaining these systems is not trivial since there are numerous types of devices with different capacities. This resource heterogeneity has to be taken into account so that different types of machines contribute to the management of the distributed infrastructure differently, and the operation of the overall system becomes more efficient. In this work, we addressed the challenges identified above by exploring unstructured overlay networks, that have been shown to be possible to manage efficiently and in a fully decentralized way, while being highly robust to failures. To that end, we devised a solution that adapts the number of neighbors of each device (i.e., how many other devices that device knows) according to the capacity of that device and the distribution of capacities of the other devices in the network, as to ensure that the load is fairly distributed between them and, as a consequence, improve the operation of other services atop the unstructured overlay network, for instance, reducing the latencies experienced when broadcasting information. This solution can be easily integrated into most existing peer-to-peer distributed systems, requiring just a slight adaptation to their membership protocol. To show the correction and benefits of our proposal, we evaluated it by comparing it with state of the art decentralized solutions to manage unstructured overlay networks, combining both simulation (to observe the performance of the solution at large scale) and prototype deployments in realistic distributed infrastructures.A computação de periferia visa abordar algumas limitações da computação em nuvem, trazendo a computação para mais perto do cliente. Há uma enorme variedade de dispositivos que podem ser integrados em futuras plataformas de computação de periferia, de data centers locais e pontos de presença de ISPs a torres 5G e até mesmo dispositivos de cliente, como smartphones, laptops e dispositivos IoT. Para que todos esses dispositivos comuniquem de forma proveitosa entre si, precisamos construir sistemas que possibilitem a interação e cooperação eficaz entre eles. No entanto, criar e manter esses sistemas não é trivial, uma vez que existem vários tipos de dispositivos com diferentes capacidades. Essa heterogeneidade de recursos deve ser levada em consideração para que diferentes tipos de máquinas contribuam para o gerenciamento da infraestrutura distribuída de forma distinta e a operação do sistema se torne mais eficiente. Neste trabalho, enfrentámos os desafios identificados acima explorando redes sobrepostas não estruturadas, que se têm mostrado possíveis de gerenciar de forma eficiente e totalmente descentralizada, sendo altamente resistentes a falhas. Para tal, concebemos uma solução que adapta o número de vizinhos de cada dispositivo (ou seja, quantos outros dispositivos aquele dispositivo conhece) de acordo com a sua capacidade e a capacidade dos demais dispositivos da rede, de forma a garantir que a carga seja proporcionalmente distribuída entre eles e, como consequência, reduzindo as latências experienciadas por esses dispositivos. Esta solução pode ser facilmente integrada num sistema distribuído entre-pares existente, exigindo apenas uma ligeira adaptação ao seu protocolo de filiação. Avaliámos a nossa solução comparando-a com outras soluções descentralizadas de última geração, combinando simulação (para observar o desempenho da soluç

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved