Dependable, Adaptive, and Trustworthy Distributed Systems13th DADS Track of the
33rd ACM Symposium on Applied Computing
12th DADS 2017
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April 9 - 13, 2018
The Symposium on Applied Computing has been a primary gathering forum for applied computer scientists, computer engineers, software engineers, and application developers from around the world. SAC 2018 is sponsored by the ACM Special Interest Group on Applied Computing and the SRC Program is sponsored by Microsoft Research.
The track provides a forum for scientists and engineers in academia and industry to present and discuss their latest research findings on selected topics in dependable, adaptive and trustworthy distributed systems and services.
The track comprises the following session:
Towards a Model for Comprehending and Reasoning about PoW-based Blockchain Network Sustainability
Sotirios Liaskos and Bo Wang
Blockchain networks have been claimed to have the potential of fundamentally changing the way humans perform economic transactions with each other. In such networks, trust-enabling agents and activities, that were traditionally arranged in a centralized fashion, are replaced by a network of nodes which collectively yet independently witness and establish the non-repudiability of transactions. Most often, a proof-of-work (PoW) requirement ensures that participants invest resources for joining the network, incentivizing conformance to the network rules, while making it highly infeasible for malicious agents to construct an alternative version of the transaction history. Nevertheless, there is limited work on how such complex networks behave under different external and internal conditions and what guarantees their sustainability, i.e., their continuous operation. Focusing on public PoW-based blockchain platforms, in this paper we sketch a model that is aimed at supporting the comprehension and reasoning about the factors that affect behavior of a blockchain network.
Secure Publish and Subscribe Systems with Efficient Revocation
Sana Belguith, Shujie Cui, Muhammad Rizwan Asghar and Giovanni Russello
User revocation is one of the main security issues in publish and subscribe (pub/sub) systems. Indeed, to ensure data confidentiality, the system should be able to remove malicious subscribers without affecting the functionalities and decoupling of authorised subscribers and publishers. To revoke a user, there are solutions, but existing schemes inevitably introduce high computation and communication overheads, which can ultimately affect the system capabilities. In this paper, we propose a novel revocation technique for pub/sub systems that can efficiently remove compromised subscribers without requiring regeneration and redistribution of new keys as well as re-encryption of existing data with those keys. Our proposed solution is such that a subscriber's interest is not revealed to curious brokers and published data can only be accessed by the authorised subscribers. Finally, the proposed protocol is secure against the collusion attacks between brokers and revoked subscribers.
Adaptive Information Distribution for Dynamic Sets
Matthias Prellwitz, Helge Parzyjegla, Steffen Steiner and Gero Mühl
While ubiquitous computing is becoming an integral part of our daily lives, developing applications for dynamic device ensembles is still a challenging and cumbersome task. Besides other reasons (e. g., heterogeneity), a major obstacle for application development is that the developer often does not know at design time which and how many devices will be available when the user deploys the application in his personal environment. To tackle this problem, a new programming abstraction called dynamic sets was proposed. A dynamic set allows an application to interact transparently with a set of remote objects in the same way it interacts with a single object. To achieve this, the developer programs against a proxy that replicates the calls to the objects and aggregates the return values. However, if an application is calling methods with high frequency, this can waste large amounts of network and computing resources. In this paper, we propose three adaptive heuristics tackling this problem for methods that only return information about the objects’ state. The heuristics dynamically switch between push and pull communication and use unicast as well as multicast communication to optimize resource usage. We discuss and prove algorithm details and present an evaluation based on simulations that shows that our approach can indeed reduce resource usage substantially.
EcoVMBroker: Energy-aware Scheduling for Multi-layer Datacenters
Rodrigo Fernandes, Jose Simao and Luís Veiga
The cloud relies on efficient algorithms to find resources for jobs by fulfilling the job’s requirements and at the same time optimise an objective function. Utility is a measure of the client satisfaction that can be seen as an objective function maximised by schedulers based on the agreed service level agreement (SLA). We propose EcoVMBroker which can reduce energy consumption save by using dynamic voltage frequency scaling (DVFS) and applying reductions of utility, different for classes of users and across ranges of resource allocations. Using efficient data structures and a hierarchical architecture, we created a scalable solution for the fast growing heterogeneous cloud. EcoVMBroker proved that we can delegate work in a hierarchical datacenter, make decisions based on summaries of resource usage collected from several nodes and still be efficient.
Dynamic Adaptation of Byzantine Consensus Protocols
Carlos Carvalho, Daniel Porto, Luís Rodrigues, Manuel Bravo and Alysson Bessani
The problem of distributed consensus in the presence of Byzantine faults has received particular attention in recent decades. Today a variety of solution to this problem exist, each optimized for particular execution conditions. Given that, in most cases, real systems operate under dynamic conditions, it is important to develop mechanisms that allow the protocols to be adapted at runtime or to switch between different protocols so that is possible to optimize the system to the current conditions. The problem of dynamic adaptation of consensus protocols is not new, but the literature is scarce for the Byzantine case and there is no comprehensive comparison of existing solutions. This work has two complementary objectives. First, it studies how the different dynamic adaptation techniques proposed for the crash failure model can be applied in the presence of Byzantine faults. Second, it presents a comparative study of the performance of these switching algorithms in practice. For that purpose, we have implemented the switching algorithms in a common software framework, based on the open source BFT-SMaRt package. Using this common framework we have performed an extensive evaluation that offers useful insights on the practical effects of different mechanisms used to support the run-time switching among Byzantine protocols.
Details see SAC poster page.
Safe and Efficient Fleet Operation for Autonomous Machines: An Actor-based Approach
Ali Jafari, Jayasoorya Jayanthi Surendran Nair, Stephan Baumgart and Marjan Sirjani
The development of distributed embedded systems has grown increasingly and their use has become a significant part of human life. In this paper, we formally model and verify run-time requirements of an application consisting of complex electrified machines called HX autonomous haulers, developed by Volvo Construction Equipment. These haulers are designed for material transport at a quarry site. They operate in a fleet, and loading, unloading and battery charging are performed in a cyclic manner. To model the fleet control, we use Timed Rebeca, an actor-based modeling language, and to analyze the system performance, we use an approach based on model checking. We run a set of experiments to find the improved configuration in which the total time for machines to complete one operating cycle is minimized.
Modeling and Verifying SDN with Multiple Controllers
Lili Xiao, Shuangqing Xiang and Huibiao Zhu
SDN (Software Defined Network) with multiple controllers draws more attention for the increasing scale of the network. The architecture can handle what SDN with single controller is not able to address. In order to understand what this architecture can accomplish and face precisely, we analyze it with formal methods. In this paper, applying CSP (Communicating Sequential Processes), we model the routing service of SDN under multi-controller architecture, in particular HyperFlow and Kandoo architecture based on OpenFlow protocol. By using model checker PAT (Process Analysis Toolkit), we verify that the models satisfy three properties, covering deadlock freeness, consistency and fault tolerance. In addition, for studying the security of those models, some extension is added. We find that the models are capable of coping with Denial of Service and may suffer from Information Disclosure. Moreover, a fake path and an inconsistent message could be present in SDN network.
Trigger Correlation for Dynamic System Reconfiguration
Mahin Abbasipour, Ferhat Khendek and Maria Toeroe
Service providers aim at optimizing resource utilisation while respecting the Service Level Agreements (SLAs) entered with customers. Dynamic reconfiguration is a mechanism for rearranging, allocating and deallocating resources as workload varies. Rearranging, adding or deallocating resources are performed by actions according to elasticity rules triggered by certain conditional events, like threshold violations, called triggers. At runtime, more than one trigger may be generated at a time. Handling them independently may jeopardize certain properties such as availability; moreover, it may harm the stability of the system. In this paper we propose a model based approach for runtime correlation of triggers and the execution of their related elasticity rule actions. This approach is part of an overall framework for SLA compliance management and dynamic reconfiguration.
Karl M. Göschka (Main contact chair)
University of Applied Sciences Technikum Wien
Embedded Systems Institute
A-1200 Vienna, Austria
phone: +43 664 180 6946
fax: +43 664 188 6275
goeschka (at) technikum-wien dot at
Universidade do Minho
Computer Science Department
Campus de Gualtar
4710-057 Braga, Portugal
phone: +351 253 604 452 / Internal: 4452
fax: +351 253 604 471
rco (at) di dot uminho dot pt
Imperial College London
Department of Computing
South Kensington Campus
180 Queen's Gate
London SW7 2AZ, United Kingdom
phone: +44 (20) 7594 8314
fax: +44 (20) 7581 8024
prp (the at sign goes here) doc (dot) ic (dot) ac (dot) uk
University of Auckland
Department of Computer Science
Private Bag 92019
Auckland 1142, New Zealand
phone: +64 9 373 7599 ext. 86137
g dot russello at auckland dot ac dot nz
|September 25, 2017 (11:59PM Pacific Time) - extended||Paper submission|
|November 17, 2017||Author notification|
|December 9, 2017||Camera-ready papers|
For general information about SAC, please visit: http://www.sigapp.org/sac/sac2018/
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