Airborne Network Data Availability Using Peer to Peer Database Replication on a Distributed Hash Table

The concept of distributing one complex task to several smaller, simpler Unmanned Aerial Vehicles (UAVs) as opposed to one complex UAV is the way of the future for a vast number of surveillance and data collection tasks. One objective for this type of application is to be able to maintain an operational picture of the overall environment. Due to high bandwidth costs, centralizing all data may not be possible, necessitating a distributed storage system such as mobile Distributed Hash Table (DHT). A difficulty with this maintenance is that for an Airborne Network (AN), nodes are vehicles and travel at high rates of speed. Since the nodes travel at high speeds they may be out of contact with other nodes and their data becomes unavailable. To address this the DHT must include a data replication strategy to ensure data availability. This research investigates the percentage of data available throughout the network by balancing data replication and network bandwidth. The DHT used is Pastry with data replication using Beehive, running over an 802.11 wireless environment, simulated in Network Simulator 3. Results show that high levels of replication perform well until nodes are too tightly packed inside a given area which results in too much contention for limited bandwidth

APRE: A Replication Method for Unstructured P2P Networks

We present APRE, a replication method for structureless Peer-to-Peer overlays. The goal of our method is to achieve real-time replication of even the most sparsely located content relative to demand. APRE adaptively expands or contracts the replica set of an object in order to improve the sharing process and achieve a low load distribution among the providers. To achieve that, it utilizes search knowledge to identify possible replication targets inside query-intensive areas of the overlay. We present detailed simulation results where APRE exhibits both efficiency and robustness relative to the number of requesters and the respective request rates. The scheme proves particularly useful in the event of flash crowds, managing to quickly adapt to sudden surges in load

Investigation of Third Party Rights Service and Shibboleth Modification to Introduce the Service

Shibboleth is an architecture to support inter-institutional sharing of electronic resources that are subject to access control. Codifying copyright in Shibboleth authorization policies is difficult because of the copyright exceptions which can be highly subjective. Third Party Rights Service is a high-level concept that has been suggested as a solution to approximate the exceptions of copyright law. In this thesis, I investigate the components of the Third Party Rights Service. I design and analyze a modified Shibboleth architecture based on these components. The resulting architecture allows for the phased addition of the resources to make use of the Third Party Rights Service, while keeping the existing resources in Shibboleth

Practical Load Balancing for Content Requests in Peer-to-Peer Networks

Abstract—This paper studies the problem of loadbalancing the demand for content in a peer-to-peer network across heterogeneous peer nodes that hold replicas of the content. Previous decentralized load balancing techniques in distributed systems base their decisions on periodic updates containing information about load or available capacity observed at the serving entities. We show that these techniques do not work well in the peer-to-peer context; either they do not address peer node heterogeneity, or they suffer from significant load oscillations. We propose a new decentralized algorithm, Max-Cap, based on the maximum inherent capacities of the replica nodes and show that unlike previous algorithms, it is not tied to the timeliness or frequency of updates. Yet, Max-Cap can handle the heterogeneity of a peer-to-peer environment without suffering from load oscillations. I

Individuazione di hot spot in distributed hash table

In questo lavoro di tesi, si propone un algoritmo per l'individuazione dei nodi sovraccarichi all'interno di un hot spot. La tecnica proposta utilizza l'analisi dinamica del traffico di rete per eseguire stime del carico