Firefly-inspired Heartbeat Synchronization in Overlay Networks

Heartbeat synchronization strives to have nodes in a distributed system generate periodic, local “heartbeat” events approximately at the same time. Many useful distributed protocols rely on the existence of such heart-beats for driving their cycle-based execution. Yet, solving the problem in environments where nodes are unreliable and messages are subject to delays and failures is non-trivial. We present a heartbeat synchronization protocol for overlay networks inspired by mathematical models of flash synchronization in certain species of fireflies. In our protocol, nodes send flash messages to their neighbors when a local heartbeat triggers. They adjust the phase of their next heartbeat based on incoming flash messages using an algorithm inspired by mathematical models of firefly synchronization. We report simulation results of the protocol in various realistic failure scenarios typical in overlay networks and show that synchronization emerges even when messages can have significant delay subject to large jitter

Self-Synchronization in Duty-cycled Internet of Things (IoT) Applications

In recent years, the networks of low-power devices have gained popularity. Typically these devices are wireless and interact to form large networks such as the Machine to Machine (M2M) networks, Internet of Things (IoT), Wearable Computing, and Wireless Sensor Networks. The collaboration among these devices is a key to achieving the full potential of these networks. A major problem in this field is to guarantee robust communication between elements while keeping the whole network energy efficient. In this paper, we introduce an extended and improved emergent broadcast slot (EBS) scheme, which facilitates collaboration for robust communication and is energy efficient. In the EBS, nodes communication unit remains in sleeping mode and are awake just to communicate. The EBS scheme is fully decentralized, that is, nodes coordinate their wake-up window in partially overlapped manner within each duty-cycle to avoid message collisions. We show the theoretical convergence behavior of the scheme, which is confirmed through real test-bed experimentation.Comment: 12 Pages, 11 Figures, Journa

Organic Design of Massively Distributed Systems: A Complex Networks Perspective

The vision of Organic Computing addresses challenges that arise in the design of future information systems that are comprised of numerous, heterogeneous, resource-constrained and error-prone components or devices. Here, the notion organic particularly highlights the idea that, in order to be manageable, such systems should exhibit self-organization, self-adaptation and self-healing characteristics similar to those of biological systems. In recent years, the principles underlying many of the interesting characteristics of natural systems have been investigated from the perspective of complex systems science, particularly using the conceptual framework of statistical physics and statistical mechanics. In this article, we review some of the interesting relations between statistical physics and networked systems and discuss applications in the engineering of organic networked computing systems with predictable, quantifiable and controllable self-* properties.Comment: 17 pages, 14 figures, preprint of submission to Informatik-Spektrum published by Springe

Organic Design of Massively Distributed Systems: A Complex Networks Perspective

The vision of Organic Computing addresses challenges that arise in the design of future information systems that are comprised of numerous, heterogeneous, resource-constrained and error-prone components. The notion organic highlights the idea that, in order to be manageable, such systems should exhibit self-organization, self-adaptation and self-healing characteristics similar to those of biological systems. In recent years, the principles underlying these characteristics are increasingly being investigated from the perspective of complex systems science, particularly using the conceptual framework of statistical physics and statistical mechanics. In this article, we review some of the interesting relations between statistical physics and networked systems and discuss applications in the engineering of organic overlay networks with predictable macroscopic propertie

Rapid and Round-free Multi-pair Asynchronous Push-Pull Aggregation

As various distributed algorithms and services demand overall information on large scale networks, the protocols that aggregate data over networks are essential, and the quality of aggregations determines the quality of those distributed algorithms and services. Though a variety of aggregation protocols have been proposed, gossip-based iterative aggregations have outstanding advantages especially in accuracy, result distribution, topology-independence, and resilience to network churns. However, most of iterative aggregations, especially push-pull style aggregations, suffer from two synchronization constraints: synchronized rounds and synchronized communication. Namely, iterative protocols generally need prior configurations to synchronize rounds over all nodes, and messages should be exchanged in a synchronous way in order to ensure accurate estimates in push-pull or push-sum protocols. This paper proposes multi-pair asynchronous push-pull aggregation (MAPPA), which liberates the push-pull aggregations from the synchronization constraints, and pursues a way to accelerate the aggregation speed. MAPPA considerably reduces aggregation times, and shows an improvement in fault-tolerance. Thanks to topology independence, inherent from gossip mechanisms, and its rapidness, MAPPA is resilient to network churns, and thus suitable for dynamic networks

P2PSim - ein Framework zur Simulation der Heterogenität und Volatilität von Ressourcen in Peer-to-Peer Desktop Grids

Das folgende Dokument beschreibt die Entwicklung eines Frameworks, mit dessen Hilfe die Heterogenität und die Volatilität von Ressourcen in Peer-to-Peer Desktop Grids simuliert werden kann. Da diese Simulation auf einem Rechencluster stattfinden soll, auf dem die Ressourcen (die Rechenknoten) weder Heterogenität noch Volatilität aufweisen, wird eine Möglichkeit entwickelt, diese künstlich herzustellen. Die auf dem Cluster installierte Software „Virtual Box“ ermöglicht es, jedem Rechenknoten eine virtuelle Gastmaschine zuzuordnen. Diese virtuellen Maschinen sind individuell konfigurierbar hinsichtlich der Heterogenität (Geschwindigkeit des Prozessors und Größe des Arbeitsspeichers). Darüber hinaus lassen sich die virtuellen Maschinen einzeln jederzeit starten und wieder stoppen, wodurch sich eine beliebige Volatilität herstellen lässt. Um für die Simulation eine realistische Verteilung von verschiedenen Prozessorgeschwindigkeiten und Arbeitsspeichergrößen zu erreichen, wird für die Generierung dieser Werte auf eine umfassende Sammlung von Systemaufzeichnungen aus parallelen und verteilten Systemen zurückgegriffen. Hierbei handelt es sich um das Failure Trace Archive, aus dem sich nach Analyse aller zugrunde liegenden Daten die Datenbank des SETI@home - Projektes (Verteiltes Rechnen) als verwendbar erwiesen hat. Für die Konfiguration der virtuellen Maschinen liegen aus der genannten Datenbank mehrere 10.000 Datensätze vor. In dieser Arbeit wird die vollständige Implementierung der Lösung beschrieben um sie für Anwender und Interessierte nachvollziehbar zu machen. Neben der Analyse und Aufbereitung der SETI-Datenbank wird die gesamte Systemarchitektur, Funktionsweise und das Zusammenspiel der unterschiedlichen Komponenten beschrieben. Darüber hinaus werden im Detail einige wichtige Vorgehensweisen beleuchtet, wie Programmaktionen mit Hilfe der Linux-Shell (bash) ausgeführt werden. Anschließend wird dem Anwender eine Installations- und Konfigurationsanleitung für eine virtuelle Maschine auf einem Rechencluster gegeben, die im Folgenden als Vorlage für alle weiteren automatisch generierten Instanzen von virtuellen Maschinen dient, die an der Simulation teilnehmen. Zum Schluss wird die Verwendung von P2PSim im Detail beschrieben

MediaSync: Handbook on Multimedia Synchronization

This book provides an approachable overview of the most recent advances in the fascinating field of media synchronization (mediasync), gathering contributions from the most representative and influential experts. Understanding the challenges of this field in the current multi-sensory, multi-device, and multi-protocol world is not an easy task. The book revisits the foundations of mediasync, including theoretical frameworks and models, highlights ongoing research efforts, like hybrid broadband broadcast (HBB) delivery and users' perception modeling (i.e., Quality of Experience or QoE), and paves the way for the future (e.g., towards the deployment of multi-sensory and ultra-realistic experiences). Although many advances around mediasync have been devised and deployed, this area of research is getting renewed attention to overcome remaining challenges in the next-generation (heterogeneous and ubiquitous) media ecosystem. Given the significant advances in this research area, its current relevance and the multiple disciplines it involves, the availability of a reference book on mediasync becomes necessary. This book fills the gap in this context. In particular, it addresses key aspects and reviews the most relevant contributions within the mediasync research space, from different perspectives. Mediasync: Handbook on Multimedia Synchronization is the perfect companion for scholars and practitioners that want to acquire strong knowledge about this research area, and also approach the challenges behind ensuring the best mediated experiences, by providing the adequate synchronization between the media elements that constitute these experiences

Multi-robot behaviors with bearing-only sensors and scale-free coordinates

This thesis presents a low-cost multi-robot system for large populations of robots, a new coordinate system for the robot based on angles between robots and a series of experiments validating robot performance. The new robot platform, the r-one will serve as an educational, outreach and research platform for robotics. I consider the robot's bearing-only sensor model, where each robot is capable of measuring the bearing, but not the distance, to each of its neighbors. This work also includes behaviors demonstrating the efficiency of this approach with this bearing-only sensor model. The new local coordinate systems based on angular information is introduced as scale-free coordinate system . Each robot produces its own local scale-free coordinates to determine the relative positions of its neighbors up to an unknown scaling factor. The computation of scale-free coordinates is analyzed with hardware and simulation validation. For hardware, the scale-free algorithm is tailored to low-cost systems with limited communication bandwidth and sensor resolution. The algorithm also uses a noise sensitivity model to reduce the impact of noise on the computed scale-free coordinates. I validate the algorithm with static and dynamic motion experiments