Institut für Parallele und Verteilte Systeme (IPVS)

Publikationen

Eine Übersicht der Publikationen des Instituts für Parallele und Verteilte Systeme

Publikationen VS: Bibliographie 2015 BibTeX

 
@inproceedings {INPROC-2015-59,
   author = {Simon Gansel and Stephan Schnitzer and Ahmad Gilbeau-Hammoud and Viktor Friesen and Frank D{\"u}rr and Kurt Rothermel and Christian Maih{\"o}fer and Ulrich Kr{\"a}mer},
   title = {{Context-aware Access Control in Novel Automotive HMI Systems}},
   booktitle = {Proceedings of 11th International Conference on Information Systems Security, ICISS 2015, Kolkata, India},
   editor = {Sushil Jajodia and Chandan Mazumdar},
   publisher = {Springer International Publishing},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {118--138},
   type = {Konferenz-Beitrag},
   month = {Dezember},
   year = {2015},
   isbn = {10.1007/978-3-319-26961-0_8},
   language = {Englisch},
   cr-category = {D.4.6 Operating Systems Security and Protection},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-59/INPROC-2015-59.pdf,     http://link.springer.com/chapter/10.1007%2F978-3-319-26961-0_8},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {The growing relevance of vehicular applications like media player, navigation system, or speedometer using graphical presentation has lead to an increasing number of displays in modern cars. This effectuates the desire for flexible sharing of all the available displays between several applications. However, automotive requirements include many regulations to avoid driver distraction to ensure safety. To allow for safe sharing of the available screen surface between the many safety-critical and non-safety-critical applications, adequate access control systems are required. We use the notion of $\backslash$emph{contexts} to dynamically determine, which application is allowed to access which display area. A context can be derived from vehicle sensors (e.g., the current speed), or be an application-specific state (e.g., which menu item is selected). We propose an access control model that is inherently aware of the context of the car and the applications. It provides delegation of access rights to display areas by applications. We implemented a proof-of-concept implementation that demonstrates the feasibility of our concept and evaluated the latency introduced by access control. Our results show that the delay reacting on dynamic context changes is small enough for automotive scenarios.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-59&engl=0}
}
@inproceedings {INPROC-2015-54,
   author = {Simon Gansel and Stephan Schnitzer and Riccardo Cecolin and Frank D{\"u}rr and Kurt Rothermel and Christian Maih{\"o}fer},
   title = {{Efficient Compositing Strategies for Automotive HMI Systems}},
   booktitle = {10th IEEE International Symposium on Industrial Embedded Systems (SIES), Siegen, Germany, 2015},
   address = {Siegen},
   publisher = {IEEE},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {1--10},
   type = {Konferenz-Beitrag},
   month = {Juni},
   year = {2015},
   doi = {10.1109/SIES.2015.7185036},
   keywords = {CPU execution time; automotive HMI systems; automotive embedded platforms; cache-hybrid compositing; graphical functions; off-screen buffers; power consumption; vehicular applications},
   language = {Englisch},
   cr-category = {D.4.9 Systems Programs and Utilities,     H.5.2 Information Interfaces and Presentation User Interfaces,     I.3.6 Computer Graphics Methodology and Techniques},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-54/INPROC-2015-54.pdf,     http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7185036&isnumber=7185026},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {The relevance of graphical functions in vehicular applications has increased significantly during the last years. Modern cars are equipped with multiple displays used by different applications such as speedometer, navigation system, or media players. The rendered output of the applications is stored in so-called off-screen buffers and then bitblitted to the screen buffer at the respective window sizes and positions. To guarantee the visibility of the potentially overlapping windows, the compositing has to match the z-order of the windows. To this end, two common compositing strategies Tile compositing and Full compositing are used, each having performance issues depending on how windows overlap. Since automotive embedded platforms are restricted in power consumption, installation space, and hardware cost, their performance is limited which effectuates the need for highly efficient bitblitting. In order to increase the performance in compositing the windows, we propose Hybrid Compositing which predicts the required bitblitting time and chooses the most efficient strategy for each pair of overlapping windows. Using various scenarios we show that our approach is faster than the other strategies. In addition, we propose CacheHybrid Compositing which reduces the CPU execution time of our approach by up to 66 \%. In case of an automotive scenario we show that our optimized approach saves up to 51 \% bitblitting time compared to existing approaches.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-54&engl=0}
}
@inproceedings {INPROC-2015-49,
   author = {Thomas Kohler and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Update Consistency in Software-defined Networking based Multicast Networks}},
   booktitle = {Proceedings of the 2015 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN), San Francisco, USA, November 18-21, 2015},
   address = {San Francisco, USA},
   publisher = {IEEE Computer Society},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {177--183},
   type = {Konferenz-Beitrag},
   month = {September},
   year = {2015},
   doi = {10.1109/NFV-SDN.2015.7387424},
   keywords = {Software-defined Networking; Multicast communication; Computer network management; Concurrency Control},
   language = {Englisch},
   cr-category = {C.2.1 Network Architecture and Design,     C.2.3 Network Operations,     C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-49/INPROC-2015-49.pdf,     http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7387424},
   contact = {thomas.kohler@ipvs.uni-stuttgart.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {When applying updates on distributed network elements with SDN, intra-update states may violate desired network properties, such as drop- and loop-freeness. Current stateless approaches cannot guarantee the constancy of arbitrary network invariants (correctness) in general, yet update procedures guaranteeing certain invariants do exist. In this paper, we investigate on update consistency for the case of multicast routing and show that there is no correct update procedure w.r.t. both drop- and duplicate-freeness. We show that certain updates of multicast routes inherently raise a concurrency issue, which necessarily results in the occurrence of either drops or duplicates. Furthermore, we present a generic update procedure for multicast routing updates that identifies concurrency-relevant update steps. This procedure allows for the selection of an update strategy, such that either drops or duplicates are avoided. These effects can severely degrade network performance or quality of experience. To investigate the implications of drops and duplicates, we evaluate their frequencies and impact for wide-area network scenarios both, analytically and empirically, through direct measurement in the data plane under update.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-49&engl=0}
}
@inproceedings {INPROC-2015-48,
   author = {Florian Berg and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Increasing the Efficiency of Code Offloading through Remote-side Caching}},
   booktitle = {Proceedings of the IEEE 11th International Conference on Wireless and Mobile Computing, Networking and Communications: WiMob'15; Abu-Dhabi, United Arab Emirates (UAE), October 19-21, 2015},
   publisher = {IEEE Computer Society},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {573--580},
   type = {Konferenz-Beitrag},
   month = {Oktober},
   year = {2015},
   doi = {10.1109/WiMOB.2015.7348013},
   keywords = {Mobile Cloud Computing; Code Offloading; Distributed Execution; Data Replication; Function Caching},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems},
   ee = {http://dx.doi.org/10.1109/WiMOB.2015.7348013},
   contact = {Florian.Berg@ipvs.uni-stuttgart.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {End users execute today on their smart phones different kinds of mobile applications like calendar apps or high-end mobile games, differing in local resource usage. Utilizing local resources of a smart phone heavily, like playing high-end mobile games, drains its limited energy resource in few hours. To prevent the limited energy resource from a quick exhaustion, smart phones benefit from executing resource-intensive application parts on a remote server in the cloud (code offloading). During the remote execution on the remote server, a smart phone waits in idle mode until it receives a result. However, code offloading introduces computation and communication overhead, which decreases the energy efficiency and induces monetary cost. For instance, sending or receiving execution state information to or from a remote server consumes energy. Moreover, executing code on a remote server instance in a commercial cloud causes monetary cost. To keep consumed energy and monetary cost low, we present in this paper the concept of remote-side caching for code offloading, which increases the efficiency of code offloading. The remote-side cache serves as a collective storage of results for already executed application parts on remote servers, avoiding the repeated execution of previously run application parts. The smart phone queries the remote-side cache for corresponding results of resource-intensive application parts. In case of a cache hit, the smart phone gets immediately a result and continues the application execution. Otherwise, it migrates the application part and waits for a result of the remote execution. We show in our evaluation that the use of a remote-side cache decreases energy consumption and monetary cost for mobile applications by up to 97\% and 99\%, respectively.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-48&engl=0}
}
@inproceedings {INPROC-2015-42,
   author = {Thomas Bach and Muhammad Adnan Tariq and Christian Mayer and Kurt Rothermel},
   title = {{Utilizing the Hive Mind - How to Manage Knowledge in Fully Distributed Environments}},
   booktitle = {OTM 2015 Conferences},
   address = {Rhodos},
   publisher = {Springer Verlag},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {1--18},
   type = {Konferenz-Beitrag},
   month = {Oktober},
   year = {2015},
   keywords = {Knowledge retrieval; Distributed knowledge; Confidence-based indexing; Indexing; Query routing; Knowledge},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-42/INPROC-2015-42.pdf},
   contact = {thomas.bach@ipvs.uni-stuttgart.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {By 2020, the Internet of Things will consist of 26 Billion connected devices. All these devices will be collecting an innumerable amount of raw observations, for example, GPS positions or communication patterns. In order to benefit from this enormous amount of information, machine learning algorithms are used to derive knowledge from the gathered observations. This benefit can be increased further, if the devices are enabled to collaborate by sharing gathered knowledge. In a massively distributed environment, this is not an easy task, as the knowledge on each device can be very heterogeneous and based on a different amount of observations in diverse contexts. In this paper, we propose two strategies to route a query for specific knowledge to a device that can answer it with high confidence. To that end, we developed a confidence metric that takes the number and variance of the observations of a device into account. Our routing strategies are based on local routing tables that can either be learned from previous queries over time or actively maintained by interchanging knowledge models. We evaluated both routing strategies on real world and synthetic data. Our evaluations show that the knowledge retrieved by the presented approaches is up to 96.7 \% as accurate as the global optimum.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-42&engl=0}
}
@inproceedings {INPROC-2015-41,
   author = {Naresh Ganesh Nayak and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Software-defined Environment for Reconfigurable Manufacturing Systems}},
   booktitle = {Proceedings of the 5th International Conference on Internet of Things (IoT 2015)},
   address = {Seoul, South Korea},
   publisher = {IEEE},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   type = {Konferenz-Beitrag},
   month = {Oktober},
   year = {2015},
   keywords = {Time-sensitive networks; Industry 4.0; Quality of service; Genetic Algorithm; Software-defined networks},
   language = {Englisch},
   cr-category = {C.2.1 Network Architecture and Design,     C.2.3 Network Operations},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-41/INPROC-2015-41.pdf},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Conventional manufacturing systems like assembly lines cannot handle the constantly changing requirements of a modern-day manufacturer, which are driven by volatile market demands. In a bid to satisfy such requirements, modern manufacturing systems, comprising innumerable cyber-physical systems (CPS), aim to be reconfigurable. CPS implement production processes through an ICT infrastructure networked with sensors and actuators embedded in the shop floor. Reconfigurability, in context of manufacturing systems, must include the entire system of networked components and hence requires a flexible ICT infrastructure. Providing flexible ICT infrastructures, often, comes at the cost of diluted quality of service (QoS) guarantees. This, however, is not an option for manufacturing systems, most of which require strict QoS guarantees to function correctly. To overcome this obstacle, we propose a new software-defined environment (SDE) for reconfigurable manufacturing systems with real-time properties in this paper. Software-defined environment is an emerging technology that provides flexible ICT infrastructures modifiable using software. Our contributions include an SDE-based system architecture for dynamically configuring the underlying infrastructure for a manufacturing system. In particular, we focus on configuring the network for the time-sensitive communication flows essential for realising CPS. Moreover, we propose a pair of routing algorithms to calculate routes for these flows while configuring the network.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-41&engl=0}
}
@inproceedings {INPROC-2015-36,
   author = {Christoph Dibak and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Numerical Analysis of Complex Physical Systems on Networked Mobile Devices}},
   booktitle = {Proceedings of the 12th IEEE International Conference on Mobile Ad hoc and Sensor Systems (MASS 2015); Dallas, USA, October 19-22 2015},
   address = {Dallas},
   publisher = {IEEE},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {1--9},
   type = {Konferenz-Beitrag},
   month = {Oktober},
   year = {2015},
   keywords = {mobile cloud computing; numerical applications; mobile cyber-physical systems; augmented reality},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems,     C.4 Performance of Systems,     G.1.0 Numerical Analysis General},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-36/INPROC-2015-36.pdf},
   contact = {Christoph Dibak christoph.dibak@ipvs.uni-stuttgart.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Recently, a new class of mobile applications has appeared that takes into account the behavior of physical phenomenon. Prominent examples of such applications include augmented reality applications visualizing physical processes on a mobile device or mobile cyber-physical systems like autonomous vehicles or robots. Typically, these applications need to solve partial differential equations (PDE) to simulate the behavior of a physical system. There are two basic strategies to numerically solve these PDEs: (1) offload all computations to a remote server; (2) solve the PDE on the resource-constrained mobile device. However, both strategies have severe drawbacks. Offloading will fail if the mobile device is disconnected, and resource constraints require to reduce the quality of the solution. Therefore, we propose a new approach for mobile simulations using a hybrid strategy that is robust to communication failures and can still benefit from powerful server resources. The basic idea of this approach is to dynamically decide on the placement of the PDE solver based on a prediction of the wireless link availability using Markov Chains. Our tests based on measurement in real cellular networks and real mobile devices show that this approach is able to keep deadline constraints in more than 61 \% of the cases compared to a pure offloading approach, while saving up to 74 \% of energy compared to a simplified approach.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-36&engl=0}
}
@inproceedings {INPROC-2015-22,
   author = {Sukanya Bhowmik and Muhammad Adnan Tariq and Boris Koldehofe and Andre Kutzleb and Kurt Rothermel},
   title = {{Distributed Control Plane for Software-defined Networks: A Case Study Using Event-based Middleware}},
   booktitle = {Proceedings of the 9th International Conference on Distributed Event-based Systems, Oslo, Norway, June 29 - July 3, 2015},
   publisher = {ACM},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {1--12},
   type = {Konferenz-Beitrag},
   month = {Juni},
   year = {2015},
   isbn = {http://doi.acm.org/10.1145/2675743.2771835},
   language = {Englisch},
   cr-category = {C.2.1 Network Architecture and Design,     C.2.4 Distributed Systems,     D.2.11 Software Engineering Software Architectures},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-22/INPROC-2015-22.pdf},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Realizing a communication middleware in a software-defined network can leverage significant performance gains in terms of latency, throughput and bandwidth efficiency. For example, filtering operations in an event-based middleware can be performed highly efficiently in the TCAM memory of switches enabling line-rate forwarding of events. A key challenge in a software-defined network, however, is to ensure high responsiveness of the control plane to dynamically changing communication interactions. In this paper, we propose a methodology for both vertical and horizontal scaling of the distributed control plane that is capable of improving the responsiveness by enabling concurrent network updates in the presence of high dynamics while ensuring consistent changes to the data plane of a communication middleware. In contrast to existing scaling approaches that aim for a general-purpose distributed control plane, our approach uses knowledge of the application semantics that is already available in the design of the data plane of a communication middleware, e.g. subscriptions and advertisements in an event-based middleware. By proposing a methodology for an application-aware control distribution, we show, in the context of PLEROMA, an event-based middleware, that application-awareness is significantly beneficial in avoiding the synchronization bottlenecks for ensuring consistency in the presence of concurrent network updates and thus greatly improves the responsiveness of the control plane.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-22&engl=0}
}
@inproceedings {INPROC-2015-06,
   author = {Zohaib Riaz and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Optimized Location Update Protocols for Secure and Efficient Position Sharing}},
   booktitle = {Proceedings of the 2nd International Conference on Networked Systems: NetSys 2015; Cottbus, Germany, March 9-13, 2015},
   publisher = {IEEE Computer Society},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {1--8},
   type = {Konferenz-Beitrag},
   month = {M{\"a}rz},
   year = {2015},
   language = {Englisch},
   cr-category = {C.2.0 Computer-Communication Networks, General,     K.4.1 Computers and Society Public Policy Issues},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-06/INPROC-2015-06.pdf},
   contact = {zohaib.riaz@ipvs.uni-stuttgart.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Abstract{\^a}€”Although location-based applications have seen fast growth in the last decade due to pervasive adoption of GPS enabled mobile devices, their use raises privacy concerns. To mitigate these concerns, a number of approaches have been proposed in literature, many of which rely on a trusted party to regulate user privacy. However, trusted parties are known to be prone to data breaches [1]. Consequently, a novel solution, called Position Sharing, was proposed in [2] to secure location privacy in fully non-trusted systems. In Position Sharing, obfuscated position shares of the actual user location are distributed among several location servers, each from a different provider, such that there is no single point of failure if the servers get breached. While Position Sharing can exhibit useful properties such as graceful degradation of privacy, it incurs significant communication overhead as position shares are sent to several location servers instead of one. To this end, we propose a set of location update protocols to minimize the communication overhead of Position Sharing while maintaining the privacy guarantees that it originally provided. As we consider the scenario of frequent location updates, i.e., movement trajectories, our protocols additionally add protection against an attack based on spatio-temporal correlation in published locations. By evaluating on a set of real-world GPS traces, we show that our protocols can reduce the communication overhead by 75\% while significantly improving the security guarantees of the original Position Sharing algorithm.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-06&engl=0}
}
@inproceedings {INPROC-2015-05,
   author = {Thomas Bach and Muhammad Adnan Tariq and Boris Koldehofe and Kurt Rothermel},
   title = {{A Cost Efficient Scheduling Strategy to Guarantee Probabilistic Workflow Deadlines}},
   booktitle = {Proceedings of the International Conference on Networked Systems},
   address = {Cottbus, Germany},
   publisher = {IEEE Computer Society},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {1--8},
   type = {Konferenz-Beitrag},
   month = {M{\"a}rz},
   year = {2015},
   keywords = {robust workflow execution; parallel service execution; service execution},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2015-05/INPROC-2015-05.pdf},
   contact = {thomas.bach@ipvs.uni-stuttgart.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Today, workflows are widely used to model business processes. A recent trend is to use them to model applications in heterogeneous, large-scale distributed systems. In such systems, many, possibly mobile, providers offer independent and interchangeable services that can be used to satisfy the different activities of a workflow. Due to varying server loads, failures, and changing network characteristics, the response time of these services is highly volatile. Thus, it is hard to ensure the timely and reliable execution of workflows depending on such services. A common approach is to invoke several services in parallel to increase the probability of success. This, however, can easily lead to overprovisioning and high cost when needlessly invoked services have to be compensated. In this paper, we investigate the search space between parallel and sequential invocation of services. We propose to invoke independent services staggered over time to ensure timely workflow execution at minimal cost. Evaluations show that our approach reduces the execution cost by up to 85 \% while it guarantees to fulfill activity deadlines with 99.9 \% probability.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2015-05&engl=0}
}
@article {ART-2015-02,
   author = {Ruben Mayer and Boris Koldehofe and Kurt Rothermel},
   title = {{Predictable Low-Latency Event Detection with Parallel Complex Event Processing}},
   journal = {IEEE Internet of Things Journal},
   publisher = {IEEE},
   pages = {1--13},
   type = {Artikel in Zeitschrift},
   month = {Januar},
   year = {2015},
   keywords = {Complex Event Processing, Stream Processing, Data Parallelization, Self-Adaptation, Quality of Service},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems,     C.4 Performance of Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/ART-2015-02/ART-2015-02.pdf},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {The tremendous number of sensors and smart objects being deployed in the Internet of Things pose the potential for IT systems to detect and react to live-situations. For using this hidden potential, Complex Event Processing (CEP) systems offer means to efficiently detect event patterns (complex events) in the sensor streams and therefore help in realizing a “distributed intelligence” in the Internet of Things. With the increasing number of data sources and the increasing volume at which data is produced, parallelization of event detection is crucial to limit the time events need to be buffered before they actually can be processed. In this article, we propose a pattern-sensitive partitioning model for data streams that is capable of achieving a high degree of parallelism in detecting event patterns which formerly could only be consistently detected in a sequential manner or at a low parallelization degree. Moreover, we propose methods to dynamically adapt the parallelization degree to limit the buffering imposed on event detection in the presence of dynamic changes to the workload. Extensive evaluations of the system behavior show that the proposed partitioning model allows for a high degree of parallelism and that the proposed adaptation methods are able to meet a buffering limit for event detection under high and dynamic workloads.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2015-02&engl=0}
}
@article {ART-2015-01,
   author = {Pericle Perazzo and Pavel Skvortsov and Gianluca Dini},
   title = {{On Designing Resilient Location-Privacy Obfuscators}},
   journal = {The Computer Journal},
   publisher = {Oxford University Press},
   type = {Artikel in Zeitschrift},
   month = {Februar},
   year = {2015},
   doi = {10.1093/comjnl/bxv009},
   keywords = {location-based service; privacy; obfuscation; sharing},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems,     H.3.5 Online Information Services},
   ee = {http://comjnl.oxfordjournals.org/content/early/2015/02/11/comjnl.bxv009.abstract},
   contact = {Pericle Perazzo pericle.perazzo@iet.unipi.it, Pavel Skvortsov skvortsov@hlrs.de, Gianluca Dini gianluca.dini@iet.unipi.it},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {The success of location-based services is growing together with the diffusion of GPS-equipped smart devices. As a consequence, privacy concerns are raising year by year. Location privacy is becoming a major interest in research and industry world, and many solutions have been proposed for it. One of the simplest and most flexible approaches is obfuscation, in which the precision of location data is artificially degraded before disclosing it. In this paper, we present an obfuscation approach capable of dealing with measurement imprecision, multiple levels of privacy, untrusted servers, and adversarial knowledge of the map. We estimate its resistance against statistical-based deobfuscation attacks, and we improve it by means of three techniques, namely extreme vectors, enlarge-and-scale, and hybrid vectors.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2015-01&engl=0}
}
 
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