@misc{556, author = {{Nickel, Tobias}}, publisher = {{Universität Paderborn}}, title = {{{Analyse von Benutzeranforderungen von Service-Kompositionen mittels Modelchecking}}}, year = {{2013}}, } @techreport{557, abstract = {{Since the last two decades, the water consumption in Germany is decreasing, which causes the water tanks and pipes in a water supply system to work inefficiently. This paper proposes an approach for a decision support system, which helps to decide how to plan new water tanks and resize existing tanks in water supply systems. The approach uses a combination of network reduction, mathematical optimization and hydraulic simulation. The mathematical optimization model is a nonconvex Mixed Integer Quadratically Constrained Program (MIQCP), which is solved by a piecewise linearization. As this may lead to many binary variables and therefore high computational times, the size of the water supply system model is reduced before building the optimization model. By applying several network reduction techniques there may occur some hydraulic differences between the original network model and the reduced network model. To make sure that the solution obtained in the optimization process is feasible in the original water supply system, the solution is verified by a hydraulic simulation tool.}}, author = {{Hallmann, Corinna}}, publisher = {{Universität Paderborn}}, title = {{{An Approach for a Decision Support Systems to optimize Water Tanks in Water Supply Systems by combining Network Reduction, Optimization and Simulation}}}, year = {{2013}}, } @proceedings{558, editor = {{Flocchini, Paola and Gao, Jie and Kranakis, Evangelos and Meyer auf der Heide, Friedhelm}}, location = {{Sophia Antipolis, France}}, publisher = {{Springer}}, title = {{{Algorithms for Sensor Systems - 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics}}}, doi = {{10.1007/978-3-642-45346-5}}, volume = {{8243}}, year = {{2013}}, } @inproceedings{559, abstract = {{Distributed hash tables are very versatile to use, as distributed storage is a desirable feature for various applications. Typical structured overlays like Chord, Pastry or Kademlia consider only homogeneous nodes with equal capacities, which does not resemble reality. In a practical use case, nodes might get overloaded by storing popular data. In this paper, we present a general approach to enable capacity awareness and load-balancing capability of homogeneous structured overlays. We introduce a hierarchical second structured overlay aside, which allows efficient capacity-based access on the nodes in the system as hosting mirrors. Simulation results show that the structured overlay is able to store various contents, such as of a social network, with only a negligible number of overloaded peers. Content, even if very popular, is hosted by easily findable capable peers. Thus, long-existing and well-evaluated overlays like Chord or Pastry can be used to create attractive DHT-based applications.}}, author = {{Wette, Philip and Graffi, Kalman}}, booktitle = {{Proceedings of the Conference on Networked Systems (NetSys)}}, pages = {{35--42}}, title = {{{Adding Capacity-Aware Storage Indirection to Homogeneous Distributed Hash Tables}}}, doi = {{10.1109/NetSys.2013.9}}, year = {{2013}}, } @inproceedings{560, abstract = {{In the last decades, development turned from monolithic software products towards more flexible software components that can be provided on world-wide markets in form of services. Customers request such services or compositions of several services. However, in many cases, discovering the best services to address a given request is a tough challenge and requires expressive, gradual matching results, considering different aspects of a service description, e.g., inputs/ouputs, protocols, or quality properties. Furthermore,in situations in which no service exactly satifies the request, approximate matching which can deal with a certain amount of fuzziness becomes necessary. There is a wealth of service matching approaches, but it is not clear whether there is a comprehensive, fuzzy matching approach which addresses all these challenges. Although there are a few service matchingsurveys, none of them is able to answer this question. In this paper, we perform a systematic literature survey of 35 (outof 504) service matching approaches which consider fuzzy matching. Based on this survey, we propose a classication,discuss how different matching approaches can be combined into a comprehensive matching method, and identify future research challenges.}}, author = {{Platenius, Marie and von Detten, Markus and Becker, Steffen and Schäfer, Wilhelm and Engels, Gregor}}, booktitle = {{Proceedings of the 16th International ACM Sigsoft Symposium on Component-Based Software Engineering}}, pages = {{143--152}}, title = {{{A Survey of Fuzzy Service Matching Approaches in the Context of On-The-Fly Computing}}}, doi = {{10.1145/2465449.2465454}}, year = {{2013}}, } @article{561, abstract = {{We present a privacy-friendly architecture for a future cloud computing scenario where software licensing and software payment plays a major role. We show how digital rights management as a technical solution for software licensing can be achieved in a privacy-friendly manner. In our scenario, users who buy software from software providers and execute it at computing centres stay anonymous. At the same time, our approach guarantees that software licenses are bound to users and that their validity is checked before execution. Thus, DRM constitutes an incentive for software providers to take part in such a future cloud computing scenario. We employ a software re-encryption scheme so that computing centres are not able to build profiles of their users – not even under a pseudonym. We make sure that malicious users are unable to relay software to others. }}, author = {{Petrlic, Ronald and Sekula, Stephan and Sorge, Christoph}}, journal = {{International Journal of Grid and Utility Computing}}, number = {{4}}, pages = {{265--277}}, publisher = {{InderScience}}, title = {{{A privacy-friendly Architecture for future Cloud Computing}}}, doi = {{10.1504/IJGUC.2013.057120}}, year = {{2013}}, } @inproceedings{562, abstract = {{In Distributed Cloud Computing, applications are deployed across many data centres at topologically diverse locations to improved network-related quality of service (QoS). As we focus on interactive applications, we minimize the latency between users and an application by allocating Cloud resources nearby the customers. Allocating resources at all locations will result in the best latency but also in the highest expenses. So we need to find an optimal subset of locations which reduces the latency but also the expenses – the facility location problem (FLP). In addition, we consider resource capacity restrictions, as a resource can only serve a limited amount of users. An FLP can be globally solved. Additionally, we propose a local, distributed heuristic. This heuristic is running within the network and does not depend on a global component. No distributed, local approximations for the capacitated FLP have been proposed so far due to the complexity of the problem. We compared the heuristic with an optimal solution obtained from a mixed integer program for different network topologies. We investigated the influence of different parameters like overall resource utilization or different latency weights.}}, author = {{Keller, Matthias and Pawlik, Stefan and Pietrzyk, Peter and Karl, Holger}}, booktitle = {{Proceedings of the 6th International Conference on Utility and Cloud Computing (UCC) workshop on Distributed cloud computing}}, pages = {{429--434}}, title = {{{A Local Heuristic for Latency-Optimized Distributed Cloud Deployment}}}, doi = {{10.1109/UCC.2013.85}}, year = {{2013}}, } @inproceedings{563, abstract = {{Dominating set based virtual backbones are used for rou-ting in wireless ad-hoc networks. Such backbones receive and transmit messages from/to every node in the network. Existing distributed algorithms only consider undirected graphs, which model symmetric networks with uniform transmission ranges. We are particularly interested in the well-established disk graphs, which model asymmetric networks with non-uniform transmission ranges. The corresponding graph theoretic problem seeks a strongly connected dominating-absorbent set of minimum cardinality in a digraph. A subset of nodes in a digraph is a strongly connected dominating-absorbent set if the subgraph induced by these nodes is strongly connected and each node in the graph is either in the set or has both an in-neighbor and an out-neighbor in it. We introduce the first distributed algorithm for this problem in disk graphs. The algorithm gives an O(k^4) -approximation ratio and has a runtime bound of O(Diam) where Diam is the diameter of the graph and k denotes the transmission ratio r_{max}/r_{min} with r_{max} and r_{min} being the maximum and minimum transmission range, respectively. Moreover, we apply our algorithm on the subgraph of disk graphs consisting of only bidirectional edges. Our algorithm gives an O(ln k) -approximation and a runtime bound of O(k^8 log^∗ n) , which, for bounded k , is an optimal approximation for the problem, following Lenzen and Wattenhofer’s Ω(log^∗ n) runtime lower bound for distributed constant approximation in disk graphs.}}, author = {{Markarian, Christine and Meyer auf der Heide, Friedhelm and Schubert, Michael}}, booktitle = {{Proceedings of the 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics (ALGOSENSORS)}}, pages = {{217--227}}, title = {{{A Distributed Approximation Algorithm for Strongly Connected Dominating-Absorbent Sets in Asymmetric Wireless Ad-Hoc Networks}}}, doi = {{10.1007/978-3-642-45346-5_16}}, year = {{2013}}, } @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{528, abstract = {{Cold-boot attacks exploit the fact that DRAM contents are not immediately lost when a PC is powered off. Instead the contents decay rather slowly, in particular if the DRAM chips are cooled to low temperatures. This effect opens an attack vector on cryptographic applications that keep decrypted keys in DRAM. An attacker with access to the target computer can reboot it or remove the RAM modules and quickly copy the RAM contents to non-volatile memory. By exploiting the known cryptographic structure of the cipher and layout of the key data in memory, in our application an AES key schedule with redundancy, the resulting memory image can be searched for sections that could correspond to decayed cryptographic keys; then, the attacker can attempt to reconstruct the original key. However, the runtime of these algorithms grows rapidly with increasing memory image size, error rate and complexity of the bit error model, which limits the practicability of the approach.In this work, we study how the algorithm for key search can be accelerated with custom computing machines. We present an FPGA-based architecture on a Maxeler dataflow computing system that outperforms a software implementation up to 205x, which significantly improves the practicability of cold-attacks against AES.}}, author = {{Riebler, Heinrich and Kenter, Tobias and Sorge, Christoph and Plessl, Christian}}, booktitle = {{Proceedings of the International Conference on Field-Programmable Technology (FPT)}}, keywords = {{coldboot}}, pages = {{386--389}}, publisher = {{IEEE}}, title = {{{FPGA-accelerated Key Search for Cold-Boot Attacks against AES}}}, doi = {{10.1109/FPT.2013.6718394}}, year = {{2013}}, } @inproceedings{505, abstract = {{In this paper we introduce “On-The-Fly Computing”, our vision of future IT services that will be provided by assembling modular software components available on world-wide markets. After suitable components have been found, they are automatically integrated, configured and brought to execution in an On-The-Fly Compute Center. We envision that these future compute centers will continue to leverage three current trends in large scale computing which are an increasing amount of parallel processing, a trend to use heterogeneous computing resources, and—in the light of rising energy cost—energy-efficiency as a primary goal in the design and operation of computing systems. In this paper, we point out three research challenges and our current work in these areas.}}, author = {{Happe, Markus and Kling, Peter and Plessl, Christian and Platzner, Marco and Meyer auf der Heide, Friedhelm}}, booktitle = {{Proceedings of the 9th IEEE Workshop on Software Technology for Future embedded and Ubiquitous Systems (SEUS)}}, publisher = {{IEEE}}, title = {{{On-The-Fly Computing: A Novel Paradigm for Individualized IT Services}}}, doi = {{10.1109/ISORC.2013.6913232}}, year = {{2013}}, } @article{2519, author = {{Haake, Claus-Jochen and Martini, Jan Thomas}}, issn = {{0926-2644}}, journal = {{Group Decision and Negotiation}}, number = {{4}}, pages = {{657--680}}, publisher = {{Springer Nature}}, title = {{{Negotiating Transfer Prices}}}, doi = {{10.1007/s10726-012-9286-6}}, volume = {{22}}, year = {{2012}}, } @article{2521, author = {{Haake, Claus-Jochen and Krieger, Tim and Minter, Steffen}}, issn = {{1612-4804}}, journal = {{International Economics and Economic Policy}}, number = {{4}}, pages = {{583--612}}, publisher = {{Springer Nature}}, title = {{{On the institutional design of burden sharing when financing external border enforcement in the EU}}}, doi = {{10.1007/s10368-012-0226-3}}, volume = {{10}}, year = {{2012}}, } @inproceedings{568, abstract = {{A major goal of the On-The-Fly Computing project is the automated composition of individual services based on services that are available in dynamic markets. Dependent on the granularity of a market, different alternatives that satisfy the requested functional requirements may emerge. In order to select the best solution, services are usually selected with respect to their quality in terms of inherent non-functional properties. In this paper, we describe our idea of how to model this service selection process as a Markov Decision Process, which we in turn intend to solve by means of Reinforcement Learning techniques in order to control the underlying service composition process. In addition, some initial issues with respect to our approach are addressed.}}, author = {{Jungmann, Alexander and Kleinjohann, Bernd}}, booktitle = {{Proceedings of the 9th IEEE International Conference on Service Computing (SCC)}}, pages = {{701--702}}, title = {{{Towards the Application of Reinforcement Learning Techniques for Quality-Based Service Selection in Automated Service Composition}}}, doi = {{10.1109/SCC.2012.76}}, year = {{2012}}, } @inproceedings{569, abstract = {{Today's real-time embedded systems operate in frequently changing environments on which they react by self-adaptations. Such an approach needs adequate modeling support of these reconfigurations to enable verification of safety properties, e.g., by timed model checking. Component-based development of such systems realizes these self-adaptations by structural reconfigurations of components and their connectors. However, component models proposed in literature do not support reconfigurable components in real-time embedded context but focus on other domains like business information systems. In this paper, we present an extension of our modeling language MechatronicUML to support structural reconfigurations taking the specific requirements of our domain into account. Based on the proposed extension we outline our research roadmap to achieve verification and realization of systems modeled in MechatronicUML.}}, author = {{Becker, Steffen and Heinzemann, Christian and Priesterjahn, Claudia }}, booktitle = {{Proceedings of the 15th ACM SigSoft International Symposium on Component-Based Software Engineering (CBSE)}}, pages = {{23----28}}, title = {{{Towards Modeling Reconfiguration in Hierarchical Component Architectures}}}, doi = {{10.1145/2304736.2304742}}, year = {{2012}}, } @article{570, abstract = {{This article studies the construction of self-stabilizing topologies for distributed systems. While recent research has focused on chain topologies where nodes need to be linearized with respect to their identiers, we explore a natural and relevant 2-dimensional generalization. In particular, we present a local self-stabilizing algorithm DStab which is based on the concept of \local Delaunay graphs" and which forwards temporary edges in greedy fashion reminiscent of compass routing. DStab constructs a Delaunay graph from any initial connected topology and in a distributed manner in time O(n3) in the worst-case; if the initial network contains the Delaunay graph, the convergence time is only O(n) rounds. DStab also ensures that individual node joins and leaves aect a small part of the network only. Such self-stabilizing Delaunay networks have interesting applications and our construction gives insights into the necessary geometric reasoning that is required for higherdimensional linearization problems.Keywords: Distributed Algorithms, Topology Control, Social Networks}}, author = {{Jacob, Riko and Ritscher, Stephan and Scheideler, Christian and Schmid, Stefan}}, journal = {{Theoretical Computer Science}}, pages = {{137--148}}, publisher = {{Elsevier}}, title = {{{Towards higher-dimensional topological self-stabilization: A distributed algorithm for Delaunay graphs}}}, doi = {{10.1016/j.tcs.2012.07.029}}, year = {{2012}}, } @inproceedings{571, abstract = {{The paradigm shift from purchasing monolithic software solutions to a dynamic composition of individual solutions entails many new possibilities yet great challenges, too. In order to satisfy user requirements, complex services have to be automatically composed of elementary services. Multiple possibilities of composing a complex service inevitably emerge. The problem of selecting the most appropriate services has to be solved by comparing the different service candidates with respect to their quality in terms of inherent non-functional properties while simultaneously taking the user requirements into account. We are aiming for an integrated service rating and ranking methodology in order to support the automation of the underlying decision-making process. The main contribution of this paper is a first decomposition of the quality-based service selection process, while emphasizing major issues and challenges, which we are addressing in the On-The-Fly Computing project.}}, author = {{Jungmann, Alexander and Kleinjohann, Bernd}}, booktitle = {{Proceedings of the 4th International Conferences on Advanced Service Computing (SERVICE COMPUTATION)}}, pages = {{43--47}}, title = {{{Towards an Integrated Service Rating and Ranking Methodology for Quality Based Service Selection in Automatic Service Composition}}}, year = {{2012}}, } @inproceedings{572, abstract = {{Service-oriented computing (SOC) promises to solve many issues in the area of distributed software development, e.g. the realization of the loose coupling pattern in practice through service discovery and invocation. For this purpose, service descriptions must comprise structural as well as behavioral information of the services otherwise an accurate service discovery is not possible. We addressed this issue in our previous paper and proposed a UML-based rich service description language (RSDL) providing comprehensive notations to specify service requests and offers.However, the automatic matching of service requests and offers specified in a RSDL for the purpose of service discovery is a complex task, due to multifaceted heterogeneity of the service partners. This heterogeneity includes the use of different underlying ontologies or different levels of granularity in the specification itself resulting in complex mappings between service requests and offers. In this paper, we present an automatic matching mechanism for service requests and offers specified in a RSDL that overcomes the underlying heterogeneity of the service partners.}}, author = {{Huma, Zille and Gerth, Christian and Engels, Gregor and Juwig, Oliver}}, booktitle = {{Proceedings of the ACM/IEEE 15th International Conference on Model Driven Engineering Languages and Systems (MoDELS)}}, pages = {{709----725}}, title = {{{Towards an Automatic Service Discovery for UML-based Rich Service Descriptions}}}, doi = {{10.1007/978-3-642-33666-9_45}}, year = {{2012}}, } @inproceedings{573, abstract = {{In software markets of the future, customer-specific software will be developed on demand from distributed software and hardware services available on world-wide markets. Having a request, services have to be automatically discovered and composed. For that purpose, services have to be matched based on their specifications. For the accurate matching, services have to be described comprehensively that requires the integration of different domain-specific languages (DSLs) used for functional, non-functional, and infrastructural properties. Since different service providers use plenty of language dialects to model the same service property, their integration is needed for the matching. In this paper, we propose a framework for integration of DSLs. It is based on a parameterized abstract core language that integrates key concepts needed to describe a service. Parts of the core language can be substituted with concrete DSLs. Thus, the framework serves as a basis for the comprehensive specification and automatic matching of services.}}, author = {{Arifulina, Svetlana}}, booktitle = {{Proceedings of the Doctoral Symposium of the 5th International Conference on Software Language Engineering 2012, Dresden, Germany (SLE (Doctoral Symposium))}}, editor = {{W. Eisenecker, Ulrich and Bucholdt, Christian}}, pages = {{23----26}}, title = {{{Towards a Framework for the Integration of Modeling Languages}}}, year = {{2012}}, } @article{574, abstract = {{We present Tiara — a self-stabilizing peer-to-peer network maintenance algorithm. Tiara is truly deterministic which allows it to achieve exact performance bounds. Tiara allows logarithmic searches and topology updates. It is based on a novel sparse 0-1 skip list. We then describe its extension to a ringed structure and to a skip-graph.Key words: Peer-to-peer networks, overlay networks, self-stabilization.}}, author = {{Clouser, Thomas and Nesterenko, Mikhail and Scheideler, Christian}}, journal = {{Theoretical Computer Science}}, pages = {{18--35}}, publisher = {{Elsevier}}, title = {{{Tiara: A self-stabilizing deterministic skip list and skip graph}}}, doi = {{10.1016/j.tcs.2011.12.079}}, year = {{2012}}, }