@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}}, } @inproceedings{394, abstract = {{Service Oriented Architectures (SOAs) enable the reuse and substitution of software services to develop highly flexible software systems. To benefit from the growing plethora of available services, sophisticated service discovery approaches are needed that bring service requests and offers together. Such approaches rely on rich service descriptions, which specify also the behavior of provided/requested services, e.g., by pre- and postconditions of operations. As a base for the specification a data schema is used, which specifies the used data types and their relations. However, data schemas are typically heterogeneous wrt. their structure and terminology, since they are created individually in their diverse application contexts. As a consequence the behavioral models that are typed over the heterogeneous data schemas, cannot be compared directly. In this paper, we present an holistic approach to normalize rich service description models to enable behavior-aware service discovery. The approach consists of a matching algorithm that helps to resolve structural and terminological heterogeneity in data schemas by exploiting domain-specific background ontologies. The resulting data schema mappings are represented in terms of Query View Transformation (QVT) relations that even reflect complex n:m correspondences. By executing the transformation, behavioral models are automatically normalized, which is a prerequisite for a behavior-aware operation matching.}}, author = {{Schwichtenberg, Simon and Gerth, Christian and Huma, Zille and Engels, Gregor}}, booktitle = {{Proceedings of the 10th European Conference on Modelling Foundations and Applications (ECMFA)}}, pages = {{180--195}}, title = {{{Normalizing Heterogeneous Service Description Models with Generated QVT Transformations}}}, doi = {{10.1007/978-3-319-09195-2_12}}, year = {{2014}}, } @inproceedings{395, abstract = {{We consider a multilevel network game, where nodes can improvetheir communication costs by connecting to a high-speed network.The n nodes are connected by a static network and each node can decideindividually to become a gateway to the high-speed network. The goalof a node v is to minimize its private costs, i.e., the sum (SUM-game) ormaximum (MAX-game) of communication distances from v to all othernodes plus a fixed price α > 0 if it decides to be a gateway. Between gatewaysthe communication distance is 0, and gateways also improve othernodes’ distances by behaving as shortcuts. For the SUM-game, we showthat for α ≤ n − 1, the price of anarchy is Θ (n/√α) and in this rangeequilibria always exist. In range α ∈ (n−1, n(n−1)) the price of anarchyis Θ(√α), and for α ≥ n(n − 1) it is constant. For the MAX-game, weshow that the price of anarchy is either Θ (1 + n/√α), for α ≥ 1, orelse 1. Given a graph with girth of at least 4α, equilibria always exist.Concerning the dynamics, both games are not potential games. For theSUM-game, we even show that it is not weakly acyclic.}}, author = {{Abshoff, Sebastian and Cord-Landwehr, Andreas and Jung, Daniel and Skopalik, Alexander}}, booktitle = {{Proceedings of the 10th International Conference on Web and Internet Economics (WINE)}}, pages = {{435--440}}, title = {{{Multilevel Network Games}}}, doi = {{10.1007/978-3-319-13129-0_36}}, year = {{2014}}, } @misc{396, author = {{Bano, Dorina}}, publisher = {{Universität Paderborn}}, title = {{{Modeling and Matching of Reputation of Services in On-The-Fly Computing}}}, year = {{2014}}, } @inproceedings{397, abstract = {{We present a factor $14D^2$ approximation algorithm for the minimum linear arrangement problem on series-parallel graphs, where $D$ is the maximum degree in the graph. Given a suitable decomposition of the graph, our algorithm runs in time $O(|E|)$ and is very easy to implement. Its divide-and-conquer approach allows for an effective parallelization. Note that a suitable decomposition can also be computed in time $O(|E|\log{|E|})$ (or even $O(\log{|E|}\log^*{|E|})$ on an EREW PRAM using $O(|E|)$ processors). For the proof of the approximation ratio, we use a sophisticated charging method that uses techniques similar to amortized analysis in advanced data structures. On general graphs, the minimum linear arrangement problem is known to be NP-hard. To the best of our knowledge, the minimum linear arrangement problem on series-parallel graphs has not been studied before.}}, author = {{Scheideler, Christian and Eikel, Martina and Setzer, Alexander}}, booktitle = {{Proceedings of the 12th Workshop on Approximation and Online Algorithms (WAOA)}}, pages = {{168----180}}, title = {{{Minimum Linear Arrangement of Series-Parallel Graphs}}}, year = {{2014}}, } @inproceedings{399, abstract = {{Ensuring memory access security is a challenge for reconfigurable systems with multiple cores. Previous work introduced access monitors attached to the memory subsystem to ensure that the cores adhere to pre-defined protocols when accessing memory. In this paper, we combine access monitors with a formal runtime verification technique known as proof-carrying hardware to guarantee memory security. We extend previous work on proof-carrying hardware by covering sequential circuits and demonstrate our approach with a prototype leveraging ReconOS/Zynq with an embedded ZUMA virtual FPGA overlay. Experiments show the feasibility of the approach and the capabilities of the prototype, which constitutes the first realization of proof-carrying hardware on real FPGAs. The area overheads for the virtual FPGA are measured as 2x-10x, depending on the resource type. The delay overhead is substantial with almost 100x, but this is an extremely pessimistic estimate that will be lowered once accurate timing analysis for FPGA overlays become available. Finally, reconfiguration time for the virtual FPGA is about one order of magnitude lower than for the native Zynq fabric.}}, author = {{Wiersema, Tobias and Drzevitzky, Stephanie and Platzner, Marco}}, booktitle = {{Proceedings of the International Conference on Field-Programmable Technology (FPT)}}, pages = {{167--174}}, title = {{{Memory Security in Reconfigurable Computers: Combining Formal Verification with Monitoring}}}, doi = {{10.1109/FPT.2014.7082771}}, year = {{2014}}, } @misc{400, author = {{Bunse, Mirko}}, publisher = {{Universität Paderborn}}, title = {{{Measuring Transformation-induced Uncertainty in Service Matching: A Feasibility Study}}}, year = {{2014}}, } @inproceedings{401, abstract = {{Service matching approaches determine to what extent a provided service matches a requester's requirements. This process is based on service specifications describing functional (e.g., signatures) as well as non-functional properties (e.g., privacy policies). However, we cannot expect service specifications to be complete as providers do not want to share all details of their services' implementation. Moreover, creating complete specifications requires much effort. In this paper, we propose a novel service matching approach taking into account a service's signatures and privacy policies. In particular, our approach applies fuzzy matching techniques that are able to deal with incomplete service specifications. As a benefit, decision-making based on matching results is improved and service matching becomes better applicable in practice.}}, author = {{Platenius, Marie Christin and Arifulina, Svetlana and Petrlic, Ronald and Schäfer, Wilhelm}}, booktitle = {{Proceedings of the 4th International Workshop on Adaptive Services for the Future Internet}}, pages = {{6--17}}, title = {{{Matching of Incomplete Service Specifications Exemplified by Privacy Policy Matching}}}, doi = {{10.1007/978-3-319-14886-1_2}}, year = {{2014}}, } @inproceedings{402, abstract = {{Various approaches in service engineering are based on servicemarkets where brokers use service matching in order to performservice discovery. For matching, a broker translates the specifications ofproviders' services and requesters' requirements into her own specificationlanguage, in order to check their compliance using a matcher. Thebroker's success depends on the configuration of her language and itsmatcher because they in uence important properties like the effort forproviders and requesters to create suitable specifications as well as accuracyand runtime of matching. However, neither existing service specification languages, nor existing matching approaches are optimized insuch way. Our approach automatically provides brokers with an optimalconfiguration of a language and its matcher to improve her success ina given market with respect to her strategy. The approach is based onformalized configuration properties and a predefined set of configurationrules.}}, author = {{Arifulina, Svetlana and Platenius, Marie Christin and Gerth, Christian and Becker, Steffen and Engels, Gregor and Schäfer, Wilhelm}}, booktitle = {{Proceedings of the 12th International Conference on Service Oriented Computing (ICSOC 2014)}}, editor = {{Franch, Xavier and Ghose, AdityaK. and Lewis, GraceA. and Bhiri, Sami}}, pages = {{543--550}}, title = {{{Market-optimized Service Specification and Matching}}}, doi = {{10.1007/978-3-662-45391-9_47}}, year = {{2014}}, } @misc{403, author = {{Martin Lohre, Tobias}}, publisher = {{Universität Paderborn}}, title = {{{Machtverteilungen von Koalitionen im Fokus der politischen Realität}}}, year = {{2014}}, } @misc{404, author = {{van Straaten, Dirk}}, publisher = {{Universität Paderborn}}, title = {{{Kooperative Verhandlungen im duopolistischen Wettbewerb - eine spieltheoretische Analyse}}}, year = {{2014}}, } @misc{405, author = {{Degraf, Olga}}, publisher = {{Universität Paderborn}}, title = {{{Koalitionsbildung bei mehrdimensionalen Verhandlungsproblemen}}}, year = {{2014}}, } @inproceedings{407, abstract = {{Automated programming aims at automatically assembling a new software artifact from existing software modules. Although automated programming was revitalized through automated software composition in the last decade, the problem cannot be considered solved. Automated software composition is widely accepted as being a planning task, but the problem is that it has very special properties that other planning problems do not have and that are commonly overseen. These properties usually imply that the composition problem cannot be solved with standard planning tools. This paper gives a brief and intuitive description of the planning problem that most approaches are based on. It points out special properties of this problem and explains why it is not adequate to solve the problem with classical planning tools as done by most existing approaches.}}, author = {{Mohr, Felix}}, booktitle = {{Proceedings of the 29th International Conference on Automated Software Engineering (ASE)}}, pages = {{ 895----898}}, title = {{{Issues of Automated Software Composition in AI Planning}}}, doi = {{10.1145/2642937.2653470}}, year = {{2014}}, } @inproceedings{408, abstract = {{Verification of hardware and software usually proceeds separately, software analysis relying on the correctness of processors executing instructions. This assumption is valid as long as the software runs on standard CPUs that have been extensively validated and are in wide use. However, for processors exploiting custom instruction set extensions to meet performance and energy constraints the validation might be less extensive, challenging the correctness assumption.In this paper we present an approach for integrating software analyses with hardware verification, specifically targeting custom instruction set extensions. We propose three different techniques for deriving the properties to be proven for the hardware implementation of a custom instruction in order to support software analyses. The techniques are designed to explore the trade-off between generality and efficiency and span from proving functional equivalence over checking the rules of a particular analysis domain to verifying actual pre and post conditions resulting from program analysis. We demonstrate and compare the three techniques on example programs with custom instructions, using stateof-the-art software and hardware verification techniques.}}, author = {{Jakobs, Marie-Christine and Platzner, Marco and Wiersema, Tobias and Wehrheim, Heike}}, booktitle = {{Proceedings of the 11th International Conference on Integrated Formal Methods (iFM)}}, editor = {{Albert, Elvira and Sekerinski, Emil}}, pages = {{307--322}}, title = {{{Integrating Software and Hardware Verification}}}, doi = {{10.1007/978-3-319-10181-1_19}}, year = {{2014}}, } @inproceedings{409, abstract = {{Service markets provide software components in the formof services. In order to enable a service discovery that satisfies servicerequesters and providers best, markets need automatic service matching:approaches for comparing whether a provided service satisfies a servicerequest. Current markets, e.g., app markets, are limited to basic keywordbasedsearch although many better suitable matching approaches aredescribed in literature. However, necessary architectural decisions forthe integration of matchers have a huge impact on quality propertieslike performance or security.Architectural decisions wrt. servicematchers have rarely been discussed,yet, and systematic approaches for their integration into service marketsare missing. In this paper, we present a systematic integration approachincluding the definition of requirements and a discussion on architecturaltactics. As a benefit, the decision-making process of integrating servicematchers is supported and the overall market success can be improved.}}, author = {{Platenius, Marie Christin and Becker, Steffen and Schäfer, Wilhelm}}, booktitle = {{Proceedings of the 8th European Conference on Software Architecture (ECSA 2014)}}, editor = {{Avgeriou, Paris and Zdun, Uwe}}, pages = {{210--217}}, title = {{{Integrating Service Matchers into a Service Market Architecture}}}, doi = {{10.1007/978-3-319-09970-5_19}}, year = {{2014}}, } @article{410, abstract = {{One goal of service-oriented computing is to realize future markets of composed services. In such markets, service providers offer services that can be flexibly combined with each other. However, although crucial for decision-making, market participants are usually not able to individually estimate the quality of traded services in advance. To overcome this problem, we present a conceptual design for a reputation system that collects and processes user feedback on transactions, and provides this information as a signal for quality to participants in the market. Based on our proposed concept, we describe the incorporation of reputation information into distinct decision-making processes that are crucial in such service markets. In this context, we present a fuzzy service matching approach that takes reputation information into account. Furthermore, we introduce an adaptive service composition approach, and investigate the impact of exchanging immediate user feedback by reputation information. Last but not least, we describe the importance of reputation information for economic decisions of different market participants. The overall output of this paper is a comprehensive view on managing and exploiting reputation information in markets of composed services using the example of On-The-Fly Computing.}}, author = {{Jungmann, Alexander and Brangewitz, Sonja and Petrlic, Ronald and Platenius, Marie Christin}}, journal = {{International Journal On Advances in Intelligent Systems (IntSys)}}, number = {{3&4}}, pages = {{572----594}}, publisher = {{IARIA}}, title = {{{Incorporating Reputation Information into Decision-Making Processes in Markets of Composed Services}}}, volume = {{7}}, year = {{2014}}, } @misc{411, author = {{Taherinajafabadi, Vahide}}, publisher = {{Universität Paderborn}}, title = {{{Improving Service Specifications for the Service Matching on a Service Market}}}, year = {{2014}}, } @inproceedings{412, abstract = {{In this paper we present and analyze HSkip+, a self-stabilizing overlay network for nodes with arbitrary heterogeneous bandwidths. HSkip+ has the same topology as the Skip+ graph proposed by Jacob et al. [PODC 2009] but its self-stabilization mechanism significantly outperforms the self-stabilization mechanism proposed for Skip+. Also, the nodes are now ordered according to their bandwidths and not according to their identifiers. Various other solutions have already been proposed for overlay networks with heterogeneous bandwidths, but they are not self-stabilizing. In addition to HSkip+ being self-stabilizing, its performance is on par with the best previous bounds on the time and work for joining or leaving a network of peers of logarithmic diameter and degree and arbitrary bandwidths. Also, the dilation and congestion for routing messages is on par with the best previous bounds for such networks, so that HSkip+ combines the advantages of both worlds. Our theoretical investigations are backed by simulations demonstrating that HSkip+ is indeed performing much better than Skip+ and working correctly under high churn rates.}}, author = {{Feldotto, Matthias and Scheideler, Christian and Graffi, Kalman}}, booktitle = {{Proceedings of the 14th IEEE International Conference on Peer-to-Peer Computing (P2P)}}, pages = {{1--10}}, title = {{{HSkip+: A Self-Stabilizing Overlay Network for Nodes with Heterogeneous Bandwidths}}}, doi = {{10.1109/P2P.2014.6934300}}, year = {{2014}}, } @misc{413, author = {{Eusterholz, Fabian}}, publisher = {{Universität Paderborn}}, title = {{{Horizontale Fusionen: Theorie und Praxis am Beispiel zweier Entscheidungen des Bundeskartellamtes}}}, year = {{2014}}, } @misc{414, author = {{Jochheim, Janek}}, publisher = {{Universität Paderborn}}, title = {{{Hiding software components using functional encryption}}}, year = {{2014}}, }