@inproceedings {INPROC-2010-81,
   author = {Ralph Lange and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Indexing Source Descriptions based on Defined Classes}},
   booktitle = {Proceedings of the 14th International Database Engineering and Applications Symposium (IDEAS '10). Montreal, QC, Canada. August 2010},
   publisher = {ACM},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {245--256},
   type = {Conference Paper},
   month = {August},
   year = {2010},
   keywords = {heterogeneous information systems; source descriptions; indexing of source descriptions; defined classes; tree-based index structure},
   language = {English},
   cr-category = {H.2.5 Heterogeneous Databases,
                   H.3.3 Information Search and Retrieval},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-81/INPROC-2010-81.pdf,
      http://doi.acm.org/10.1145/1866480.1866514},
   contact = {ralph.lange@ipvs.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Scaling heterogeneous information systems (HIS) to thousands of sources poses
      particular challenges to source discovery. It requires a powerful formalism for
      describing the contents of the sources in a concise manner and for formulating
      compatible queries as well as a suitable structure for indexing and retrieving
      the source descriptions efficiently.
      
      We propose an extended logic-based description formalism for large-scale HIS
      with structured sources and a shared ontology. The formalism refines existing
      approaches that describe the sources by constraints on the attribute value
      ranges in several ways: It allows for complex, nested descriptions based on
      defined classes. It supports alternative descriptions to express that a source
      may be discovered by different combinations of constraints. Finally, it allows
      to adjust between positive matching, similar to keyword-based discovery, and
      negative matching, as used in existing logic-based approaches.
      
      We further propose the SDC-Tree for indexing such source descriptions. To allow
      for efficient discovery, the SDC-Tree features multidimensional indexing
      capabilities for the different attributes and the IS-A hierarchy of the shared
      ontology, but also incorporates the existence or absence of constraints. For
      this purpose, it supports three different types of node split operations which
      exploit the expressiveness of the description formalism. Therefore, we also
      propose a generic split algorithm which can be used with arbitrary ontologies.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-81&engl=1}
}

@inproceedings {INPROC-2010-80,
   author = {Hannes Wolf and Klaus Herrmann and Kurt Rothermel},
   title = {{Robustness in Context-Aware Mobile Computing}},
   booktitle = {IEEE International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob'2010)},
   address = {Niagara Falls, Canada},
   publisher = {IEEE Communications Society},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {46--53},
   type = {Conference Paper},
   month = {October},
   year = {2010},
   doi = {10.1109/WIMOB.2010.5645026},
   language = {English},
   cr-category = {H.4.1 Office Automation,
                   I.5.1 Pattern Recognition Models},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-80/INPROC-2010-80.pdf,
      http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5645026},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {High level context recognition and situation detection are an enabling
      technologies for unobtrusive mobile computing systems. Significant progress has
      been made in processing and managing context information, leading to
      sophisticated frameworks, middlewares, and algorithms. Despite great
      improvements, context aware systems still require a significantly increased
      recognition accuracy for high-level context information on uncertain sensor
      data to enable the robust execution of context-aware applications. Recently
      Adaptable Pervasive Workflows (APF)s have been presented as innovative
      programming paradigm for mobile context-aware applications. We propose a novel
      Flow Context System (FlowCon) that builds upon APFs. FlowCon uses structural
      information from the APF to increase accuracy of uncertain high-level context
      information up to 49$\backslash$\%. This way we make an important step to enable robust
      execution of mobile context-aware applications.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-80&engl=1}
}

@inproceedings {INPROC-2010-78,
   author = {A. Bucchiarone and A. Marconi and M. Pistore and S. F{\"o}ll and K. Herrmann and C. Hiesinger and S. Marinovic},
   title = {{An Overall Process for Self-Adaptive Pervasive Systems}},
   booktitle = {Proceedings of the Second International Conference on Adaptive and Self-adaptive Systems and Applications : ADAPTIVE 2010 ; Lisbon, Portugal, November 21-26, 2010},
   publisher = {Elsevier},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--6},
   type = {Conference Paper},
   month = {November},
   year = {2010},
   language = {German},
   cr-category = {D.2.9 Software Engineering Management,
                   D.2.11 Software Engineering Software Architectures},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Self-adaptive pervasive systems often implement adaptation in a centralised
      manner, where one component holds all the necessary knowledge to identify when
      and how the system needs to adapt. In self-adaptive pervasive systems, composed
      of autonomous components with different authorities (such as security,
      distribution, etc.), this approach cannot be implemented as composing a
      centralised knowledge is not feasible and it also obstructs the system's
      ability to dynamically change its components. A simple alternative would be to
      allow each component to adapt independently but this can quickly give rise to
      conflicts, race conditions and oscillations between multiple independent
      adaptations. To avoid these problems, we propose to coordinate individual
      adaptations so that each component's adaptation goals are satisfied. Each
      component proposes an adaptation which is reviewed by other components who may
      propose their own adaptations that they may need to do. This continues until a
      complete adaptation plan is agreed upon. In cases where certain individual
      adaptations conflict with some components' goals, components are instructed to
      seek alternative proposals. The Adaptation Manager component is in charge of
      the negotiation process and it also has the authority to resolve certain
      conflicts between adaptations. Our approach is evaluated in the context of
      pervasive workflow systems where the failure probability and execution times
      are assessed.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-78&engl=1}
}

@inproceedings {INPROC-2010-71,
   author = {Bilal Hameed and Imran Ahmed Khan and Frank D{\"u}rr and Kurt Rothermel},
   title = {{An RFID Based Consistency Management Framework for Production Monitoring In a Smart Real-Time Factory}},
   booktitle = {Proceedings of 2010 Internet of Things Conference (To Appear).},
   address = {Tokyo, Japan},
   publisher = {IEEE},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--8},
   type = {Conference Paper},
   month = {November},
   year = {2010},
   language = {English},
   cr-category = {C.2 Computer-Communication Networks,
                   C.2.1 Network Architecture and Design},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {The use of RFID devices for real-time production monitoring in modern factories
      is impeded by the inherent unreliability of RFID devices. In this paper we
      present a consistency stack that conceptually divides the different consistency
      issues in production monitoring into separate layers. In addition to this we
      have built a consistency management framework to ensure consistent real-time
      production monitoring, using unreliable RFID devices. In detail, we deal with
      the problem of detecting object sequences by a set of unreliable RFID readers
      that are installed along production lines. We propose a probabilistic sequence
      detection algorithm that assigns probabilities to objects detected by RFID
      devices and provides probabilistic guarantees regarding the real-time sequences
      of objects on the production lines.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-71&engl=1}
}

@inproceedings {INPROC-2010-69,
   author = {Andreas Benzing and Boris Koldehofe and Marco V{\"o}lz and Kurt Rothermel},
   title = {{Multilevel Predictions for the Aggregation of Data in Global Sensor Networks}},
   booktitle = {Proceedings of the 14th IEEE/ACM International Symposium on Distributed Simulation and Real Time Applications},
   publisher = {IEEE},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {169--178},
   type = {Conference Paper},
   month = {October},
   year = {2010},
   keywords = {Global Sensor Networks; Distributed Stream Processing; Predictors},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-69/INPROC-2010-69.pdf,
      http://ieeexplore.ieee.org/search/srchabstract.jsp?tp=&arnumber=5636734},
   contact = {andreas.benzing@ipvs.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Real-time simulations are one challenging application domain that is expected
      to introduce high requirements to global sensor applications. Besides having
      hard constraints on latency bounds at which data needs to be processed,
      simulation applications will impose high requirements with respect to available
      bandwidth. Predictors, originally introduced in the domain of wireless sensor
      networks for energy saving, are one appealing solution to provide real-time
      estimates and at the same time significantly reduce the data rates. While in
      the setting of wireless sensor networks many prediction models have been
      analyzed, their behavior and use is unclear when applied to distributed data
      streams where aggregation results are typically processed over multilevel
      hierarchies.
      
      In the context of weather simulations, we propose a distributed R-Tree-based
      aggregation algorithm that allows for efficient reuse of aggregate queries. In
      the setting of real temperature readings taken from weather stations during one
      month, we study the trade-off between updates of the prediction model and the
      precision of the predicted values. Our evaluations indicate that even in
      situations where complex prediction models are expected to perform best, simple
      prediction models give higher benefits with respect to saving bandwidth while
      providing similar data accuracy.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-69&engl=1}
}

@inproceedings {INPROC-2010-65,
   author = {Daniel Fischer and Klaus Herrmann and Kurt Rothermel},
   title = {{GeSoMo - A General Social Mobility Model for Delay Tolerant Networks}},
   booktitle = {Proceedings of the 7th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (MASS '10)},
   publisher = {IEEE},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--9},
   type = {Conference Paper},
   month = {November},
   year = {2010},
   language = {German},
   cr-category = {C.2.1 Network Architecture and Design,
                   C.4 Performance of Systems,
                   I.6.0 Simulation and Modeling General},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Simulation is a fundamental means for evaluating mobile applications based on
      ad-hoc networks. This has led to the design of a large number of mobility
      models for simulating realistic user movement under physical constraints
      (obstacles, acceleration, inertia etc.). In recent years, the new breed of
      social mobility models (SMMs) has risen. These SMMs model the $\backslash$emph{social
      aspects of human mobility}, i.e. which users meet, when and how often. Such
      information is indispensable for the simulation of a wide range of
      socially-aware communication protocols mostly based on delay-tolerant networks,
      including opportunistic ad-hoc routing and data dissemination systems. Each SMM
      needs a model of the relations between a set of relevant people (called social
      network model -- SNM) in order to simulate their mobility. Existing SMMs lack
      flexibility since each of them is implicitly restricted to a specific,
      simplifying SNM.
      
      We present GeSoMo, a new SMM that separates the core mobility model from the
      structural description of the social network underlying the simulation. This
      simple and elegant design principle gives GeSoMo generalizing power: Arbitrary
      existing and future SNMs can be used without changing GeSoMo itself. Our
      evaluation results show that GeSoMo produces simulations that are coherent with
      a broad range of empirical data describing real-world human social behavior and
      mobility.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-65&engl=1}
}

@inproceedings {INPROC-2010-63,
   author = {Harald Weinschrott and Frank D{\"u}rr and Kurt Rothermel},
   title = {{StreamShaper: Coordination Algorithms for Participatory Mobile Urban Sensing}},
   booktitle = {Proceedings of the 7th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (MASS'10)},
   address = {San Francisco, CA, USA},
   publisher = {IEEE},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {1--10},
   type = {Conference Paper},
   month = {November},
   year = {2010},
   language = {English},
   cr-category = {C.2 Computer-Communication Networks},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-63/INPROC-2010-63.pdf,
      http://www.comnsense.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {In this paper we introduce mechanisms for automated mapping of urban areas that
      provide a virtual sensor abstraction to the applications. We envision a
      participatory system that exploits widely available devices as mobile phones to
      cooperatively read environmental conditions as air quality or noise pollution,
      and map these measurements to stationary virtual sensors. We propose spatial
      and temporal coverage metrics for measuring the quality of acquired sensor data
      that reflect the conditions of urban areas and the uncontrolled movement of
      nodes. To achieve quality requirements and efficiency in terms of energy
      consumption, this paper presents two algorithms for coordinating sensing. The
      first is based on a central control instance, which assigns sensing tasks to
      mobile nodes based on movement predictions. The second algorithm is based on
      coordination of mobile nodes in an ad-hoc network. By extensive simulations, we
      show that these algorithms achieve a high quality of readings, which is about
      95\% of the maximum possible. Moreover, the algorithms achieve a very high
      energy efficiency allowing for drastic savings compared to uncoordinated
      sensing.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-63&engl=1}
}

@inproceedings {INPROC-2010-60,
   author = {Faraz Memon and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Index Recommendation Tool for Optimized Information Discovery Over Distributed Hash Tables}},
   booktitle = {Proceedings of the 35th International Conference on Local Computer Networks (LCN '10)},
   address = {Dever, CO, USA},
   publisher = {IEEE Computer Society},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--8},
   type = {Conference Paper},
   month = {October},
   year = {2010},
   language = {English},
   cr-category = {C.2.1 Network Architecture and Design,
                   E.1 Data Structures,
                   E.2 Data Storage Representations,
                   H.3.1 Content Analysis and Indexing},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-60/INPROC-2010-60.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Peer-to-peer (P2P) networks allow for efficient information discovery in
      large-scale distributed systems. Although point queries are well supported by
      current P2P systems -- in particular systems based on distributed hash tables
      (DHTs) --, providing efficient support for more complex queries remains a
      challenge. Our research focuses on the efficient support for multi-attribute
      range (MAR) queries over DHT-based information discovery systems.
      Traditionally, the support for MAR queries over DHTs has been provided either
      by creating an individual index for each data attribute or by creating a single
      index using the combination of all data attributes. In contrast to these
      approaches, we propose to create a set of indices over selected attribute
      combinations. In order to limit the overhead induced by index maintenance, the
      total number of created indices has to be limited. Thus, the resulting problem
      is to create a limited number of indices such that the overall system
      performance is optimal for MAR queries. In this paper, we propose an index
      recommendation tool that implements heuristic solutions to this NP-hard
      problem. Our evaluations show that these heuristics lead to a close-to-optimal
      system performance for MAR queries.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-60&engl=1}
}

@inproceedings {INPROC-2010-57,
   author = {Stamatia Rizou and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Providing QoS Guarantees for Large-Scale Operator Networks}},
   booktitle = {Proceedings of the 12th IEEE International Conference on High Performance Computing and Communications},
   address = {Melbourne, VIC, Australia},
   publisher = {IEEE Computer Society Press},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {337--345},
   type = {Conference Paper},
   month = {September},
   year = {2010},
   doi = {10.1109/HPCC.2010.53},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-57/INPROC-2010-57.pdf,
      http://dx.doi.org/10.1109/HPCC.2010.53},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Application areas like global sensor networks and data stream processing
      involve the on-line processing of large amounts of data in an overlay network
      of operators on top of the Internet infrastructure. Trying to fulfill QoS
      guarantees in such networks is a challenging task that should be realized under
      the requirement for optimal usage of common resources in the network. Therefore
      in this paper, we formalize a constrained optimization problem for the
      placement of operators in an overlay network which strives for satisfying user
      QoS constraints subject to latency, while minimizing the network load induced
      by the deployment of the operators in the network. Since the initial problem is
      NP-hard, we solve at a first step the problem in an intermediate continuous
      latency space and then we map the continuous solution to its discrete variant.
      Our evaluations provide an analysis about the inherent interdepedence between
      the two metrics, network usage and latency, subject to this paper and
      furthermore shows that our algorithm achieves a good balance between the user
      requirements and the usage of the network resources.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-57&engl=1}
}

@inproceedings {INPROC-2010-56,
   author = {Stamatia Rizou and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Solving the Multi-operator Placement Problem in Large-Scale Operator Networks}},
   booktitle = {Proceedings of the 19th International Conference on Computer Communication Networks},
   address = {Zurich, Switzerland},
   publisher = {IEEE Communications Society},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {1--6},
   type = {Conference Paper},
   month = {August},
   year = {2010},
   doi = {10.1109/ICCCN.2010.5560127},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-56/INPROC-2010-56.pdf,
      http://dx.doi.org/10.1109/ICCCN.2010.5560127},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Processing streams of data in an overlay network of operators distributed over
      a wide-area network is a common idea shared by different applications such as
      distributed event correlation systems and large-scale sensor networks. In order
      to utilize network resources efficiently and allow for the parallel deployment
      of a large number of large-scale operator networks, suitable placement
      algorithms are vital that place operators on physical nodes. In this paper, we
      present a distributed placement algorithm that minimizes the bandwidth-delay
      product of data streams between operators of the network in order to reduce the
      induced network load. Since the fundamental optimization problem is NP-hard, we
      propose a heuristic solution. First, we calculate an optimal solution in an
      intermediate continuous search space, called latency space. Subsequently the
      continuous solution is mapped to the physical network. Our evaluations show
      that this algorithm reduces the resulting network load significantly compared
      to state of the art algorithms and achieves results close to the optimum.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-56&engl=1}
}

@inproceedings {INPROC-2010-46,
   author = {Stefan F{\"o}ll and Klaus Herrmann and Christian Hiesinger},
   title = {{Flow-Based Context Prediction}},
   booktitle = {Proceedings of the 7th International Conference on Pervasive Services (ICPS 2010), Berlin, Germany, July 13-15, 2010},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--1},
   type = {Conference Paper},
   month = {July},
   year = {2010},
   keywords = {Context prediction, Markov model, workflows, context awareness, probabilistic user behaviour},
   language = {English},
   cr-category = {G.3 Probability and Statistics,
                   I.2.6 Artificial Intelligence Learning},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-46/INPROC-2010-46.pdf},
   contact = {stefan.foell@ipvs.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Context prediction has been recognized as an enabler for proactive pervasive
      services that anticipate future situations already ahead of time. Traditional
      context predictors are limited by their agnostic view on the targeted
      application domain when analysing context histories of past user behaviour.
      Awareness about the processes in which an entity is involved can provide rich
      information to foresee future context changes more accurately. We present an
      approach for context prediction in pervasive environments that are
      characterized by context-aware workflows. In order to benefit from the explicit
      knowledge about human behaviour in these environments, we devise a context
      predictor that learns the relationship of context changes with the flow of
      activities performed by humans. This relationship is encoded as a probabilistic
      state transition system that can be explored to determine the most likely paths
      of future context occurrences. Our evaluation shows that our enhanced predictor
      is able to extract patterns from context histories that are inaccessible to
      history-only predictors and significantly improves the prediction accuracy.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-46&engl=1}
}

@inproceedings {INPROC-2010-43,
   author = {Stamatia Rizou and Kai H{\"a}ussermann and Frank D{\"u}rr and Nazario Cipriani and Kurt Rothermel},
   title = {{A system for distributed context reasoning.}},
   booktitle = {Proceedings of ICAS’10: International Conference on Autonomous and Autonomic Systems},
   publisher = {IEEE Computer Society Conference Publishing Services},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {84--89},
   type = {Conference Paper},
   month = {March},
   year = {2010},
   isbn = {978-0-7695-3970-6},
   doi = {10.1109/ICAS.2010.21},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-43/INPROC-2010-43.pdf,
      http://dx.doi.org/10.1109/ICAS.2010.21},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems;
                  University of Stuttgart, Institute of Parallel and Distributed Systems, Applications of Parallel and Distributed Systems},
   abstract = {Context aware systems use context information to adapt their behaviour
      accordingly. In order to derive high level context information from low level
      context, such as sensor values, context reasoning methods that correlate
      observable context information, are necessary. Several context reasoning
      mechanisms have been proposed in the literature. Usually these mechanisms are
      centralized, leading to suboptimal utilization of network resources and poor
      system performance in case of large-scale scenarios. Therefore to increase the
      scalability of context reasoning systems the development of methods that
      distribute the reasoning process is necessary. Existing distributed approaches
      are method specific and do not provide a generic formalization for distributed
      reasoning. In this paper we introduce a novel system which enables distributed
      context reasoning in a generic way that is independent of the reasoning
      algorithm.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-43&engl=1}
}

@inproceedings {INPROC-2010-38,
   author = {Gerald G. Koch and M. Adnan Tariq and Boris Koldehofe and Kurt Rothermel},
   title = {{Event processing for large-scale distributed games}},
   booktitle = {Proceedings of the 4th International Conference on Distributed Event-Based Systems (DEBS'10)},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {103--104},
   type = {Conference Paper},
   month = {July},
   year = {2010},
   doi = {http://doi.acm.org/10.1145/1827418.1827440},
   isbn = {978-1-60558-927-5},
   keywords = {Cordies; SpoVNet; CEP},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-38/INPROC-2010-38.pdf,
      http://doi.acm.org/10.1145/1827418.1827440},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Novel peer-to-peer-based multiplayer online games are instantiated in an ad-hoc
      manner without the support of dedicated infrastructure and maintain their state
      in a distributed manner. Although their employed communication paradigms
      provide efficient access to sections of distributed state, such communication
      fails if the participants need to access large subsets of the application state
      in order to detect high-level situations. We propose a demonstration that shows
      how multiplayer online games can benefit from using publish/subscribe
      communication and complex event processing alongside their traditional
      communication paradigm.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-38&engl=1}
}

@inproceedings {INPROC-2010-32,
   author = {Lars Geiger and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Aggregation of User Contexts in Context-based Communication}},
   booktitle = {Proceedings of the 6th Euro-NF Conference on Next Generation Internet (NGI 2010)},
   address = {Paris},
   publisher = {IEEE Xplore},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {1--8},
   type = {Conference Paper},
   month = {June},
   year = {2010},
   language = {English},
   cr-category = {C.2.1 Network Architecture and Design,
                   C.2.2 Network Protocols,
                   C.2.4 Distributed Systems,
                   C.2.6 Internetworking},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-32/INPROC-2010-32.pdf,
      http://dx.doi.org/10.1109/NGI.2010.5534466},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {A context-based communication system enables the indirect addressing and
      routing of messages according to the users' contexts. This provides, for
      example, the means to send a message to all students on campus who attend a
      certain class, with information about an upcoming exam. However, for a targeted
      forwarding of messages towards users, the routers need information about the
      context of connected users. Global knowledge, i.e., each router knowing about
      every user, is not scalable, though, because of the necessary update messages
      to keep this information up-to-date.
      
      To address this challenge, a router can aggregate similar contexts and only
      provide such an aggregated view to neighboring routers. In this paper, we
      present an approach to aggregate similar contexts, based on a similarity
      measure for user contexts. The algorithm can be adjusted according to the
      observed messages and user contexts in the system by specifying a similarity
      threshold to determine when contexts are aggregated.
      
      The aggregation of user contexts improves the scalability of our approach by
      significantly reducing the load of context updates by up to 30\%, depending on
      the usage of the system. This improvement comes at the cost of a negligible
      increase in false positive messages due to the loss of information used for
      forwarding messages.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-32&engl=1}
}

@inproceedings {INPROC-2010-31,
   author = {Muhammad Adnan Tariq and Gerald Georg Koch and Boris Koldehofe and Imran Khan and Kurt Rothermel},
   title = {{Dynamic publish/subscribe to meet subscriber-defined delay and bandwidth constraints}},
   booktitle = {The Sixteenth International Conference on Parallel Computing (Euro-Par 2010)},
   publisher = {Springer},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {458--470},
   type = {Conference Paper},
   month = {August},
   year = {2010},
   keywords = {Content-based; P2P; Event-based; Bandwidth; End-to-end Delay; Spatial indexing; QoS},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-31/INPROC-2010-31.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Current distributed publish/subscribe systems assume that all participants have
      similar QoS requirements and equally contribute to the system’s resources.
      However, in many real-world applications, the message delay tolerance of
      individual peers may differ widely. Disseminating messages according to
      individual delay requirements not only allows for the satisfaction of
      user-specific needs but also significantly improves the utilization of the
      resources in a publish/subscribe system. In this paper, we propose a
      peer-to-peer-based approach to satisfy the individual delay requirements of
      subscribers in the presence of bandwidth constraints. Our approach allows
      subscribers to dynamically adjust the granularity of their subscriptions
      according to their bandwidth constraints and delay requirements. Subscribers
      maintain the publish/subscribe overlay in a decentralized manner by
      establishing connections to peers that provide messages meeting exactly their
      subscription granularity and complying to their delay requirements. Evaluations
      show that for practical workloads, the proposed system scales up to a large
      number of subscribers and performs robustly in a very dynamic setting.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-31&engl=1}
}

@inproceedings {INPROC-2010-30,
   author = {Andreas Grau and Klaus Herrmann and Kurt Rothermel},
   title = {{NETplace: Efficient Runtime Minimization of Network Emulation Experiments}},
   booktitle = {Proceeding of the International Symposium on Performance Evaluation of Computer and Telecommunication Systems (SPECTS'10) [Best Paper Award]},
   address = {Ottawa, Canada},
   publisher = {IEEE Communications Society},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {265--272},
   type = {Conference Paper},
   month = {July},
   year = {2010},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-30/INPROC-2010-30.pdf,
      http://www.ipvs.uni-stuttgart.de/abteilungen/vs/abteilung/mitarbeiter/andreas.grau_infos/spects10bestpaper.jpg,
      http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5589304},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Network emulation is an efficient method for evaluating distributed
      applications and communication protocols by combining the benefits of real
      world experiments and network simulation. The process of network emulation
      involves execution of thousands of connected virtual nodes running the software
      under test in a controlled environment. Along with the quality of the
      experiment results, the runtime of network experiments strongly influences the
      convenience of users and operators of emulation testbeds. The goal of this
      paper is, therefore, to minimize the experiment runtime of network emulations.
      
      In order to achieve this goal, we make the following contributions in this
      paper: First, we present a highly scalable emulation architecture to
      efficiently support network emulation testbeds with multicore CPUs. Second, we
      propose a detailed and generic cost model for the communication costs of
      emulation testbeds. Third, we present an efficient placement strategy
      (NETplace) to assign virtual nodes to physical nodes of the testbed while
      minimizing the runtime of network experiments. Therefore, we combine graph
      partitioning and greedy approaches. Our evaluations show that our placement
      strategy outperforms existing methods by reducing the experiment runtime up to
      64\%.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-30&engl=1}
}

@inproceedings {INPROC-2010-24,
   author = {Muhammad Adnan Tariq and Boris Koldehofe and Ala Altaweel and Kurt Rothermel},
   title = {{Providing basic security mechanisms in broker-less publish/subscribe systems}},
   booktitle = {Proceedings of the 4th International Conference on Distributed Event-Based Systems (DEBS'10), 2010},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {38--49},
   type = {Conference Paper},
   month = {July},
   year = {2010},
   keywords = {Content-based; P2P; Broker-less; Security; Identity-based encryption; IBE; Attribute-based encryption; Clustering},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-24/INPROC-2010-24.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {The provisioning of basic security mechanisms such as authentication and
      confidentiality is highly challenging in a content-based publish/subscribe
      system. Authentication of publishers and subscribers is difficult to achieve
      due to the loose coupling of publishers and subscribers. Similarly,
      confidentiality of events and subscriptions conflicts with contentbased
      routing. In particular, content-based approaches in broker-less environments do
      not address confidentiality at all. This paper presents a novel approach to
      provide confidentiality and authentication in a broker-less content-based
      publish-subscribe system. By adapting the pairing-based cryptography mechanisms
      to the needs of publish/subscribe authentication of publisher and subscriber as
      well as confidentiality of events is ensured. Furthermore, an algorithm to
      cluster subscribers according to their subscriptions preserves a weak notion of
      subscription confidentiality. Our approach provides fine grained key management
      and the cost for encryption, decryption and routing is in the order of
      subscribed attributes. Moreover, the simulation results verify that supporting
      security is affordable with respect to the cost for overlay construction and
      event dissemination latencies, thus preserving scalability of the system.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-24&engl=1}
}

@inproceedings {INPROC-2010-22,
   author = {Bj{\"o}rn Schilling and Boris Koldehofe and Udo Pletat and Kurt Rothermel},
   title = {{Distributed Heterogeneous Event Processing: Enhancing Scalability and Interoperability of CEP in an Industrial Context}},
   booktitle = {Proceedings of the 4th ACM International Conference on Distributed Event-Based Systems (DEBS); Cambridge, United Kingdom, July 12-15, 2010},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {150--159},
   type = {Conference Paper},
   month = {July},
   year = {2010},
   isbn = {1827418.1827453},
   language = {German},
   cr-category = {C.2.1 Network Architecture and Design,
                   C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-22/INPROC-2010-22.pdf,
      http://portal.acm.org/citation.cfm?doid=1827418.1827453},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Although a significant amount of research has investigated the benefits of
      distributed CEP in terms of scalability and extensibility, there is an ongoing
      reluctance in deploying distributed CEP in an industrial context. In this paper
      we present the DHEP system developed together with the IBM laboratory in
      B{\"o}blingen. It addresses some of the key problems in increasing the acceptance
      of distributed CEP, for example supporting interoperability between
      heterogeneous event processing systems. We present the concepts behind the DHEP
      system and show how those concepts help to achieve scalable and extensible
      event processing in an industrial context. Moreover, we verify in an evaluation
      study that the additional cost imposed by the DHEP system is moderate and
      'affordable' for the benefits provided.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-22&engl=1}
}

@inproceedings {INPROC-2010-21,
   author = {Gerald Georg Koch and Boris Koldehofe and Kurt Rothermel},
   title = {{Cordies: Expressive event correlation in distributed systems}},
   booktitle = {Proceedings of the 4th International Conference on Distributed Event-Based Systems (DEBS'10)},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {26--37},
   type = {Conference Paper},
   month = {July},
   year = {2010},
   isbn = {978-1-60558-927-5},
   doi = {10.1145/1827418.1827424},
   keywords = {Cordies; distributed complex event processing; restriction graph; correlation description},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-21/INPROC-2010-21.pdf,
      http://doi.acm.org/10.1145/1827418.1827424},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Complex Event Processing (CEP) is the method of choice for the observation of
      system states and situations by means of events. A number of systems have been
      introduced that provide CEP in selected environments. Some are restricted to
      centralised systems, or to system with synchronous communication, or to a
      limited space of event relations that are defined in advance. Many modern
      systems, though, are inherently distributed and asynchronous, and require a
      more powerful CEP. We present Cordies, a distributed system for the detection
      of correlated events that is designed for the operation in large-scale,
      heterogeneous networks and adapts dynamically to changing network conditions.
      With its expressive language to describe event relations, it is suitable for
      environments where neither the event space nor the situations of interest are
      predefined but are constantly adapted.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-21&engl=1}
}

@inproceedings {INPROC-2010-18,
   author = {Andreas Benzing and Boris Koldehofe and Kurt Rothermel},
   title = {{Distributed Diagnostic Simulations for the Smart Grid}},
   booktitle = {Accepted Poster at the 1st International Conference on Energy-Efficient Computing and Networking: E-Energy 2010},
   publisher = {Online},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--3},
   type = {Conference Paper},
   month = {April},
   year = {2010},
   keywords = {Diagnostic Simulation; Global Sensor Grid},
   language = {German},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-18/INPROC-2010-18.pdf},
   contact = {andreas.benzing@ipvs.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Energy efficiency is usually achieved by reducing the energy consumption as far
      as possible. With the growing amount of renewable energy sources, energy
      efficient usage also has to consider what kind of and when power is consumed.
      By matching the availability of electrical power with the current demands, the
      amount of unused energy and therefore overall energy production can be reduced.
      The so called smart grid aims to provide this matching with a broad deployment
      of smart meters to acquire the current demand. However, current approaches to
      the smart grid cannot handle the huge amount of sensors and energy sources
      involved in a scalable way. Most data acquisition systems focus on the lookup
      and reading of single sensors and therefore do not fit the requirements of a
      large scale power grid simulation. We propose a Global Sensor Grid (GSG) which
      provides consumers with data preprocessed to their needs instead of delivering
      raw sensor data. With this decoupling from the actual sensors, multiple
      consumers can benefit from improvements in data acquisition and avoidance of
      the redundant processing of data by each consumer. By integrating so-called
      diagnostic simulations into the GSG, gaps in sensor coverage can be filled with
      higher precision than normal interpolation.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-18&engl=1}
}

@inproceedings {INPROC-2010-17,
   author = {Frank D{\"u}rr and Harald Weinschrott and Kurt Rothermel},
   title = {{Geocast Routing of Symbolically Addressed Messages in Wireless Mesh Networks}},
   booktitle = {Proceedings of the 8th IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops '10)},
   address = {Mannheim, Germany},
   publisher = {IEEE Computer Society},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {552--557},
   type = {Workshop Paper},
   month = {March},
   year = {2010},
   language = {English},
   cr-category = {C.2.2 Network Protocols},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-17/INPROC-2010-17.pdf,
      http://dx.doi.org/10.1109/PERCOMW.2010.5470499},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Geocast protocols can be used to send messages to all receivers in a geographic
      target area. In this paper we present geocast routing algorithms for Wireless
      Mesh Networks that are tailored to symbolic addressing using symbolic location
      names like floor or room numbers. Since in particular indoors no geometric
      information is available, our algorithms use symbolic location models to derive
      directional information for routing. Moreover, we show how to integrate
      geometric and symbolic geographic routing algorithms into a hybrid routing
      approach which is applicable to larger areas consisting of symbolically and
      geometrically defined locations.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-17&engl=1}
}

@inproceedings {INPROC-2010-16,
   author = {Harald Weinschrott and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Symbolic Routing for Location-based Services in Wireless Mesh Networks}},
   booktitle = {Proceedings of the IEEE 24nd International Conference on Advanced Information Networking and Applications},
   publisher = {IEEE Computer Society},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {1--8},
   type = {Conference Paper},
   month = {April},
   year = {2010},
   language = {English},
   cr-category = {C.2.2 Network Protocols},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-16/INPROC-2010-16.pdf,
      http://dx.doi.org/10.1109/AINA.2010.71},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Wireless Mesh Networks are cost-efficient medium-scale networks that have the
      potential to serve as an infrastructure for advanced location-based services.
      As a basis for these services we present a routing algorithm that allows to
      address intuitive symbolic coordinates. This algorithm is based on a
      proactively maintained geographic routing structure that mimics the structure
      of a symbolic location model. Message forwarding is done greedily along short
      paths defined by a symbolic location model and if this fails, through an
      hierarchical overlay network built by selected mesh routers. We show how a
      geocast communication mechanism that allows to send messages to all hosts
      within a specific location can be implemented with this routing algorithm. In
      extensive evaluations we show that a low proactive routing overhead allows to
      achieve high message delivery rates even in case of mobility. Moreover, we show
      that the paths achieved are only 25\% longer than the theoretic optimal paths
      for a wide range of simulation settings.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-16&engl=1}
}

@inproceedings {INPROC-2010-15,
   author = {Ralph Lange and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Efficient Tracking of Moving Objects using Generic Remote Trajectory Simplification (Demo Paper)}},
   booktitle = {Proceedings of the 8th IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops '10). Mannheim, Germany. March 2010},
   publisher = {IEEE Computer Society},
   institution = {University of Stuttgart : Collaborative Research Center SFB 627 (Nexus: World Models for Mobile Context-Based Systems), Germany},
   pages = {829--831},
   type = {Workshop Paper},
   month = {March},
   year = {2010},
   keywords = {Remote trajectory simplification; tracking; dead reckoning; moving objects database; MOD; line simplification},
   language = {English},
   cr-category = {H.2.8 Database Applications},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-15/INPROC-2010-15.pdf,
      http://dx.doi.org/10.1109/PERCOMW.2010.5470553},
   contact = {ralph.lange@ipvs.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Position information of moving objects plays a vital role in many pervasive
      applications. Therefore, moving objects databases (MODs), which can manage
      trajectory data of a number objects, are used in many pervasive systems. A
      crucial problem with MODs is how to efficiently track a remote object's
      trajectory in real-time, i.e. how to continuously report the sensed trajectory
      data to the MOD with minimal effort. For this purpose, we present a
      prototypical implementation of the Generic Remote Trajectory Simplification
      (GRTS) protocol, which optimizes storage consumption, processing, and
      communication costs. Our prototypical system includes a fully functional MOD as
      well as map-based mobile applications for subnotebooks and smartphones to
      illustrate the functioning of GRTS.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-15&engl=1}
}

@inproceedings {INPROC-2010-118,
   author = {Frank D{\"u}rr and Marius Wernke and Pavel Skvortsov and Kurt Rothermel},
   title = {{Towards a Position Sharing Approach for Location-based Services}},
   booktitle = {Proceedings of the W3C Workshop on Privacy for Advanced Web APIs},
   publisher = {Online},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--3},
   type = {Workshop Paper},
   month = {July},
   year = {2010},
   language = {English},
   cr-category = {C.2.4 Distributed Systems,
                   H.3.5 Online Information Services},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-118/INPROC-2010-118.pdf,
      http://www.w3.org/2010/api-privacy-ws/papers/privacy-ws-16.pdf,
      http://www.priloc.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {In partially-trusted system environments like the WWW, the management of
      private user positions is a great challenge. On the one hand, location-based
      services of different partially-trusted providers have to be provided with
      position information. On the other hand, location servers, which are
      responsible for the management of user positions, might as well be operated by
      only partially-trusted providers. Therefore, in order to protect his privacy, a
      user might only want to store position information of limited precision on
      location servers, and also provide location-based services with position
      information of limited precision.
      
      In this position paper, we sketch a novel position sharing approach that
      enables the user to tightly control the precision of position information
      stored on servers and provided to location-based services. This approach is
      based on the idea of distributing position information among a set of servers
      of different providers such that a compromised server only reveals information
      of strictly limited precision.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-118&engl=1}
}

@inproceedings {INPROC-2010-116,
   author = {Faraz Memon and Daniel Tiebler and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Optimized Information Discovery using Self-adapting Indices over Distributed Hash Tables}},
   booktitle = {Proceedings of 29th International Performance Computing and Communications Conference (IPCCC'10)},
   address = {Albuquerque, New Mexico, USA},
   publisher = {IEEE},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--9},
   type = {Conference Paper},
   month = {December},
   year = {2010},
   language = {English},
   cr-category = {C.2.1 Network Architecture and Design,
                   E.1 Data Structures,
                   E.2 Data Storage Representations,
                   H.3.1 Content Analysis and Indexing},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-116/INPROC-2010-116.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Distributed Hash Table (DHT)-based peer-to-peer information discovery systems
      have emerged as highly scalable systems for information storage and discovery
      in massively distributed networks. Originally DHTs supported only point
      queries. However, recently they have been extended to support more complex
      queries, such as multi-attribute range (MAR) queries. Generally, the support
      for MAR queries over DHTs has been provided either by creating an individual
      index for each data attribute or by creating a single index using the
      combination of all data attributes. In contrast to these approaches, we propose
      to create and modify indices using the attribute combinations that dynamically
      appear in MAR queries in the system.
      
      In this paper, we present an adaptive information discovery system that adapts
      the set of indices according to the dynamic set of MAR queries in the system.
      The main contribution of this paper is a four-phase scalable index adaptation
      process. Our evaluations show that the adaptive information discovery system
      continuously optimizes the overall system performance for MAR queries.
      Moreover, compared to a non-adaptive system, the adaptive information discovery
      system shows several orders of magnitude improved performance.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-116&engl=1}
}

@inproceedings {INPROC-2010-06,
   author = {Stephan Schuhmann and Klaus Herrmann and Kurt Rothermel},
   title = {{Efficient Resource-Aware Hybrid Configuration of Distributed Pervasive Applications}},
   booktitle = {Proceedings of the 8th International Conference on Pervasive Computing (Pervasive 2010); Helsinki, Finland, May 17-20, 2010},
   publisher = {Springer-Verlag},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   series = {Lecture Notes in Computer Science},
   volume = {6030},
   pages = {373--390},
   type = {Conference Paper},
   month = {May},
   year = {2010},
   keywords = {Adaptivity; Components; Distributed Application Configuration; Heterogeneous Environments; Middleware; Pervasive Applications},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-06/INPROC-2010-06.pdf,
      http://www.springerlink.com/content/x6607vl0w9753683/},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {As the size and complexity of Pervasive Computing environments increases,
      configuration and adaptation of distributed applications gains importance.
      These tasks require automated system support, since users must not be
      distracted by the (re-)composition of applications. In homogeneous ad hoc
      scenarios, relying on decentralized configuration schemes is obviously
      mandatory, while centralized approaches may help to reduce latencies in weakly
      heterogeneous infrastructure-based environments. However, in case of strongly
      heterogeneous pervasive environments including several resource-rich and
      resource-weak devices, both approaches may lead to suboptimal results
      concerning configuration latencies: While the resource-weak devices represent
      bottlenecks for decentralized configuration, the centralized approach faces the
      problem of not utilizing parallelism. Instead, a hybrid approach that involves
      only the subset of resource-rich devices is capable of rendering configuration
      and adaptation processes more efficiently. In this paper, we present such a
      resource-aware hybrid scheme that effectively reduces the time required for
      configuration processes. This is accomplished by a balanced-load clustering
      scheme that exploits the computational power of resource-rich devices, while
      avoiding bottlenecks in (re-)configurations. We present real-world evaluations
      which confirm that our approach reduces configuration latencies in
      heterogeneous environments by more than 30 \% compared to totally centralized
      and totally decentralized approaches. This is an important step towards
      seamless application configuration.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-06&engl=1}
}

@article {ART-2010-03,
   author = {Sven Schulz and Wolfgang Blochinger and Mathias Poths},
   title = {{Orbweb - A Network Substrate for Peer-to-Peer Grid Computing Platforms based on Open Standards}},
   journal = {Journal of Grid Computing},
   address = {Heidelberg},
   publisher = {Springer-Verlag},
   volume = {8},
   number = {1},
   pages = {77--107},
   type = {Article in Journal},
   month = {June},
   year = {2010},
   doi = {10.1007/s10723-009-9121-8},
   language = {English},
   cr-category = {C.2.1 Network Architecture and Design,
                   C.2.2 Network Protocols,
                   C.2.4 Distributed Systems,
                   C.2.6 Internetworking},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {In this paper, we propose to use the open industrial-strength eXtensible
      Messaging and Presence Protocol (XMPP) to build a network substrate for
      Peer-to-Peer Grid computing called Orbweb. We describe how to employ XMPP to
      tackle domain-specific challenges, including high scalability, support for
      volatility, NAT/Firewall traversal, and protocol efficiency. Where XMPP fails
      to meet these requirements, we contribute pertinent extensions. In particular,
      we boost the scalability of XMPP by taking load of the XMPP servers through
      dynamically negotiated direct Peer-to-Peer communication channels between XMPP
      peers. We pave the way for scalable group membership management by substituting
      the existing XMPP Multi-User Chat protocol for one that does not suffer from
      limitations imposed by a everyone knows everyone visibility model and allows
      for selecting a membership model that matches the requirements of a given
      application. As efficient multicasting is an essential prerequisite for many
      distributed algorithms and the centralized XMPP multicast is of limited
      scalability, we adapt the well-known Bimodal Multicast protocol to work in a
      highly volatile Peer-to-Peer Grid computing environment. Finally, we show how
      to improve the protocol efficiency of XMPP by leveraging a standardized binary
      encoding of the XML Information Set for XMPP packet transmission. To
      substantiate the applicability of our approach and the effectiveness of our
      extensions, we describe how some important higher-level services used in
      Peer-to-Peer Grid Computing can be implemented on top of Orbweb and provide a
      detailed experimental analysis.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2010-03&engl=1}
}