@inproceedings{564, abstract = {{We consider the problem of resource discovery in distributed systems. In particular we give an algorithm, such that each node in a network discovers the add ress of any other node in the network. We model the knowledge of the nodes as a virtual overlay network given by a directed graph such that complete knowledge of all nodes corresponds to a complete graph in the overlay network. Although there are several solutions for resource discovery, our solution is the first that achieves worst-case optimal work for each node, i.e. the number of addresses (O(n)) or bits (O(nlogn)) a node receives or sendscoincides with the lower bound, while ensuring only a linearruntime (O(n)) on the number of rounds.}}, author = {{Kniesburges, Sebastian and Koutsopoulos, Andreas and Scheideler, Christian}}, booktitle = {{Proceedings of 20th International Colloqium on Structural Information and Communication Complexity (SIROCCO)}}, pages = {{165--176}}, title = {{{A Deterministic Worst-Case Message Complexity Optimal Solution for Resource Discovery}}}, doi = {{10.1007/978-3-319-03578-9_14}}, year = {{2013}}, } @inproceedings{371, abstract = {{In this work we present the first distributed storage system that is provably robust against crash failures issued by an adaptive adversary, i.e., for each batch of requests the adversary can decide based on the entire system state which servers will be unavailable for that batch of requests. Despite up to \gamma n^{1/\log\log n} crashed servers, with \gamma>0 constant and n denoting the number of servers, our system can correctly process any batch of lookup and write requests (with at most a polylogarithmic number of requests issued at each non-crashed server) in at most a polylogarithmic number of communication rounds, with at most polylogarithmic time and work at each server and only a logarithmic storage overhead. Our system is based on previous work by Eikel and Scheideler (SPAA 2013), who presented IRIS, a distributed information system that is provably robust against the same kind of crash failures. However, IRIS is only able to serve lookup requests. Handling both lookup and write requests has turned out to require major changes in the design of IRIS.}}, author = {{Scheideler, Christian and Setzer, Alexander and Eikel, Martina}}, booktitle = {{Proceedings of the 18th International Conference on Principles of Distributed Systems (OPODIS)}}, pages = {{107----122}}, title = {{{RoBuSt: A Crash-Failure-Resistant Distributed Storage System}}}, doi = {{10.1007/978-3-319-14472-6_8}}, year = {{2014}}, } @article{378, abstract = {{The Chord peer-to-peer system is considered, together with CAN, Tapestry and Pastry, as one of the pioneering works on peer-to-peer distributed hash tables (DHT) that inspired a large volume of papers and projects on DHTs as well as peer-to-peer systems in general. Chord, in particular, has been studied thoroughly, and many variants of Chord have been presented that optimize various criteria. Also, several implementations of Chord are available on various platforms. Though Chord is known to be very efficient and scalable and it can handle churn quite well, no protocol is known yet that guarantees that Chord is self-stabilizing, i.e., the Chord network can be recovered from any initial state in which the network is still weakly connected. This is not too surprising since it is known that the Chord network is not locally checkable for its current topology. We present a slight extension of the Chord network, called Re-Chord (reactive Chord), that turns out to be locally checkable, and we present a self-stabilizing distributed protocol for it that can recover the Re-Chord network from any initial state, in which the n peers are weakly connected, in O(nlogn) communication rounds. We also show that our protocol allows a new peer to join or an old peer to leave an already stable Re-Chord network so that within O(logn)^2) communication rounds the Re-Chord network is stable again.}}, author = {{Kniesburges, Sebastian and Koutsopoulos, Andreas and Scheideler, Christian}}, journal = {{Theory of Computing Systems}}, number = {{3}}, pages = {{591--612}}, publisher = {{Springer}}, title = {{{Re-Chord: A Self-stabilizing Chord Overlay Network}}}, doi = {{10.1007/s00224-012-9431-2}}, year = {{2014}}, } @article{387, abstract = {{This article studies the design of medium access control (MAC) protocols for wireless networks that are provably robust against arbitrary and unpredictable disruptions (e.g., due to unintentional external interference from co-existing networks or due to jamming). We consider a wireless network consisting of a set of n honest and reliable nodes within transmission (and interference) range of each other, and we model the external disruptions with a powerful adaptive adversary. This adversary may know the protocol and its entire history and can use this knowledge to jam the wireless channel at will at any time. It is allowed to jam a (1 − )-fraction of the timesteps, for an arbitrary constant > 0 unknown to the nodes. The nodes cannot distinguish between the adversarial jamming or a collision of two or more messages that are sent at the same time. We demonstrate, for the first time, that there is a local-control MAC protocol requiring only very limited knowledge about the adversary and the network that achieves a constant (asymptotically optimal) throughput for the nonjammed time periods under any of the aforementioned adversarial strategies. The derived principles are also useful to build robust applications on top of the MAC layer, and we present an exemplary study for leader election, one of the most fundamental tasks in distributed computing.}}, author = {{Awerbuch, Baruch and Richa, Andrea W. and Scheideler, Christian and Schmid, Stefan and Zhang, Jin}}, journal = {{Transactions on Algorithms}}, number = {{4}}, publisher = {{ACM}}, title = {{{Principles of Robust Medium Access and an Application to Leader Election}}}, doi = {{10.1145/2635818}}, year = {{2014}}, } @article{1858, author = {{Jacob, Riko and W. Richa, Andrea and Scheideler, Christian and Schmid, Stefan and Täubig, Hanjo}}, journal = {{J. ACM}}, number = {{6}}, pages = {{36:1----36:26}}, title = {{{SKIP*: A Self-Stabilizing Skip Graph}}}, doi = {{10.1145/2629695}}, year = {{2014}}, } @inproceedings{1863, author = {{Derakhshandeh, Zahra and Dolev, Shlomi and Gmyr, Robert and W. Richa, Andrea and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{26th ACM Symposium on Parallelism in Algorithms and Architectures, SPAA'14, Prague, Czech Republic - June 23 - 25, 2014}}, isbn = {{978-1-4503-2821-0}}, pages = {{220----222}}, publisher = {{ACM}}, title = {{{Brief announcement: amoebot - a new model for programmable matter}}}, doi = {{10.1145/2612669.2612712}}, year = {{2014}}, } @inproceedings{446, abstract = {{This paper considers the problem of how to efficiently share a wireless medium which is subject to harsh external interference or even jamming. While this problem has already been studied intensively for simplistic single-hop or unit disk graph models, we make a leap forward and study MAC protocols for the SINR interference model (a.k.a. the physical model). We make two contributions. First, we introduce a new adversarial SINR model which captures a wide range of interference phenomena. Concretely, we consider a powerful, adaptive adversary which can jam nodes at arbitrary times and which is only limited by some energy budget. The second contribution of this paper is a distributed MAC protocol which provably achieves a constant competitive throughput in this environment: we show that, with high probability, the protocol ensures that a constant fraction of the non-blocked time periods is used for successful transmissions.}}, author = {{Ogierman, Adrian and Richa, Andrea W. and Scheideler, Christian and Schmid, Stefan and Zhang, Jin}}, booktitle = {{Proceedings of the 33rd Annual IEEE International Conference on Computer Communications (INFOCOM)}}, pages = {{2751----2759}}, title = {{{Competitive MAC under adversarial SINR}}}, doi = {{10.1109/INFOCOM.2014.6848224}}, year = {{2014}}, } @inproceedings{459, abstract = {{In this survey article, we discuss two algorithmic research areas that emerge from problems that arise when resources are offered in the cloud. The first area, online leasing, captures problems arising from the fact that resources in the cloud are not bought, but leased by cloud vendors. The second area, Distributed Storage Systems, deals with problems arising from so-called cloud federations, i.e., when several cloud providers are needed to fulfill a given task.}}, author = {{Kniesburges, Sebastian and Markarian, Christine and Meyer auf der Heide, Friedhelm and Scheideler, Christian}}, booktitle = {{Proceedings of the 21st International Colloquium on Structural Information and Communication Complexity (SIROCCO)}}, pages = {{1--13}}, title = {{{Algorithmic Aspects of Resource Management in the Cloud}}}, doi = {{10.1007/978-3-319-09620-9_1}}, year = {{2014}}, } @article{464, abstract = {{Topological self-stabilization is an important concept to build robust open distributed systems (such as peer-to-peer systems) where nodes can organize themselves into meaningful network topologies. The goal is to devise distributed algorithms where nodes forward, insert, and delete links to neighboring nodes, and that converge quickly to such a desirable topology, independently of the initial network configuration. This article proposes a new model to study the parallel convergence time. Our model sheds light on the achievable parallelism by avoiding bottlenecks of existing models that can yield a distorted picture. As a case study, we consider local graph linearization—i.e., how to build a sorted list of the nodes of a connected graph in a distributed and self-stabilizing manner. In order to study the main structure and properties of our model, we propose two variants of a most simple local linearization algorithm. For each of these variants, we present analyses of the worst-case and bestcase parallel time complexities, as well as the performance under a greedy selection of the actions to be executed. It turns out that the analysis is non-trivial despite the simple setting, and to complement our formal insights we report on our experiments which indicate that the runtimes may be better in the average case.}}, author = {{Gall, Dominik and Jacob, Riko and Richa, Andrea W. and Scheideler, Christian and Schmid, Stefan and Täubig, Hanjo }}, journal = {{Theory of Computing Systems}}, number = {{1}}, pages = {{110--135}}, publisher = {{Springer}}, title = {{{A Note on the Parallel Runtime of Self-Stabilizing Graph Linearization}}}, doi = {{10.1007/s00224-013-9504-x}}, year = {{2014}}, } @inproceedings{393, abstract = {{A fundamental problem for peer-to-peer systems is to maintain connectivity while nodes are leaving, i.e., the nodes requesting to leave the peer-to-peer system are excluded from the overlay network without affecting its connectivity. There are a number of studies for safe node exclusion if the overlay is in a well-defined state initially. Surprisingly, the problem is not formally studied yet for the case in which the overlay network is in an arbitrary initial state, i.e., when looking for a self-stabilizing solution for excluding leaving nodes. We study this problem in two variants: the Finite Departure Problem (FDP) ) and the Finite Sleep Problem (FSP). In the FDP the leaving nodes have to irrevocably decide when it is safe to leave the network, whereas in the FSP, this leaving decision does not have to be final: the nodes may resume computation if necessary. We show that there is no self-stabilizing distributed algorithm for the FDP, even in a synchronous message passing model. To allow a solution, we introduce an oracle called NIDEC and show that it is sufficient even for the asynchronous message passing model by proposing an algorithm that can solve the FDP using NIDEC. We also show that a solution to the FSP does not require an oracle.}}, author = {{Foreback, Dianne and Koutsopoulos, Andreas and Nesterenko, Mikhail and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 16th International Symposium on Stabilization, Safety, and Security of Distributed Systems}}, pages = {{48----62}}, title = {{{On Stabilizing Departures in Overlay Networks}}}, doi = {{10.1007/978-3-319-11764-5_4}}, year = {{2014}}, }