@inproceedings {INPROC-2013-67,
   author = {Simon Gansel and Stephan Schnitzer and Frank D{\"u}rr and Kurt Rothermel and Christian Maih{\"o}fer},
   title = {{Towards Virtualization Concepts for Novel Automotive HMI Systems}},
   booktitle = {Proceedings of 4th IFIP TC 10 International Embedded Systems Symposium, IESS 2013, Paderborn, Germany, June 17-19, 2013.},
   publisher = {Springer Berlin Heidelberg},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   series = {Embedded Systems: Design, Analysis and Verification},
   volume = {403},
   pages = {193--204},
   type = {Conference Paper},
   month = {June},
   year = {2013},
   isbn = {978-3-642-38853-8},
   isbn = {10.1007/978-3-642-38853-8_18},
   keywords = {Virtualization; Automotive HMI},
   language = {English},
   cr-category = {H.5.2 Information Interfaces and Presentation User Interfaces,
                   J.7 Computers in Other Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-67/INPROC-2013-67.pdf,
      http://link.springer.com/chapter/10.1007%2F978-3-642-38853-8_18},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Many innovations in the automotive industry are based on electronics and
      software, which has led to a steady increase of electronic control units (ECU)
      in cars. This brought up serious scalability and complexity issues in terms of
      cost, installation space, and energy consumption. In order to tackle these
      problems, there is a strong interest to consolidate ECUs using virtualization
      technologies. However, current efforts largely neglect legal constraints and
      certification issues and the resulting technical requirements.
      
      In this paper, we focus on the consolidation of graphics hardware through
      virtualization, which received a lot of interest in the car industry due to the
      growing relevance of HMI systems such as head unit and instrument cluster in
      modern cars. First, we investigate relevant ISO standards and legal
      requirements and derive seven technical requirements for a virtualized
      automotive HMI system. Based on these requirements, we present the concept for
      a Virtualized Automotive Graphics System (VAGS) that allows for the
      consolidation of mixed-criticality graphics ECUs.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-67&engl=1}
}

@inproceedings {INPROC-2013-62,
   author = {Kirak Hong and Beate Ottenw{\"a}lder and Umakishore Ramachandran},
   title = {{Scalable Spatio-temporal Analysis on Distributed Camera Networks}},
   booktitle = {Proceedings of the 7th International Symposium on Intelligent Distributed Computing (IDC 2013)},
   publisher = {Springer International Publishing},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   series = {Studies in Computational Intelligence},
   volume = {511},
   pages = {131--140},
   type = {Conference Paper},
   month = {September},
   year = {2013},
   doi = {10.1007/978-3-319-01571-2_16},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-62/INPROC-2013-62.pdf,
      http://link.springer.com/chapter/10.1007/978-3-319-01571-2_16},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Technological advances and the low cost of sensors enable the deployment of
      large-scale camera networks in airports and metropolises. A well-known
      technique, called spatio-temporal analysis, enables detecting anomalies such as
      an individual entering into a restricted area without permission.
      Spatio-temporal analysis requires a large amount of system resources to infer
      locations of occupants in real-time. In particular, state update becomes a
      bottleneck due to computation and communication overhead to update possibly
      large application state. In this paper we propose a system design and
      mechanisms for scalable spatio-temporal analysis. We present a distributed
      system architecture including smart cameras and distributed worker nodes in the
      cloud to enable real-time spatio-temporal analysis on large-scale camera
      networks. Furthermore we propose and implement a couple of selective update
      mechanisms to further improve scalability of our system by reducing the
      communication cost for state update.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-62&engl=1}
}

@inproceedings {INPROC-2013-59,
   author = {Marius Wernke and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Protecting Movement Trajectories through Fragmentation}},
   booktitle = {Proceedings of the Tenth Annual International Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services (MobiQuitous '13)},
   address = {Tokyo, Japan},
   publisher = {ICST},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--12},
   type = {Conference Paper},
   month = {December},
   year = {2013},
   keywords = {Location based applications; position sharing; privacy},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-59/INPROC-2013-59.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Location-based applications (LBAs) like geo-social networks, points of interest
      finders, and real-time traffic monitoring applications have entered people's
      daily life. Advanced LBAs rely on location services (LSs) managing movement
      trajectories of multiple users in a scalable fashion. However, exposing
      trajectory information raises user privacy concerns, in particular if LSs are
      non-trusted. For instance, an attacker compromising an LS can use the retrieved
      user trajectory for stalking, mugging, or to trace user movement. To limit the
      misuse of trajectory data, we present a new approach for the secure management
      of trajectories on non-trusted servers. Instead of providing the complete
      trajectory of a user to a single LS, we split up the trajectory into a set of
      fragments and distribute the fragments among LSs of different providers. By
      distributing fragments, we avoid a single point of failure in case of
      compromised LSs, while different LBAs can still reconstruct the trajectory
      based on user-defined access rights.
      
      In our evaluation, we show the effectiveness of our approach by using real
      world trajectories and realistic attackers using map knowledge and statistical
      information to predict and reconstruct the user's movement.
      
      Location management, fragmentation, trajectories, privacy},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-59&engl=1}
}

@inproceedings {INPROC-2013-57,
   author = {Susanne Becker and Michael Peter and Dieter Fritsch and Damian Philipp and Patrick Baier and Christoph Dibak},
   title = {{Combined grammar for the modeling of building interiors}},
   booktitle = {ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences},
   address = {Kapstadt, S{\"u}dafrika},
   publisher = {International Society for Photogrammetry and Remote Sensing},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   series = {ISPRS Acquisition and Modelling of Indoor and Enclosed Environments},
   volume = {II-4/W1},
   pages = {1--6},
   type = {Conference Paper},
   month = {December},
   year = {2013},
   keywords = {Public Sensing; Opportunistic Sensing; Smartphone; Indoor; Mapping},
   language = {German},
   cr-category = {J.5 Arts and Humanities,
                   C.2.4 Distributed Systems},
   contact = {Susanne Becker susanne.becker@ifp.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {As spatial grammars have proven successful and efficient to deliver LoD3
      models, the next challenge is their extension to indoor applications, leading
      to LoD4 models. Therefore, a combined indoor grammar for the automatic
      generation of indoor models from erroneous and incomplete observation data is
      presented. In building interiors where inaccurate observation data is
      available, the grammar can be used to make the reconstruction process robust,
      and verify the reconstructed geometries. In unobserved building interiors, the
      grammar can generate hypotheses about possible indoor geometries matching the
      style of the rest of the building. The grammar combines concepts from L-systems
      and split grammars. It is designed in such way that it can be derived from
      observation data fully automatically. Thus, manual predefinitions of the
      grammar rules usually required to tune the grammar to a specific building
      style, become obsolete. The potential benefit of using our grammar as support
      for indoor modeling is evaluated based on an example where the grammar has been
      applied to automatically generate an indoor model from erroneous and incomplete
      traces gathered by foot-mounted MEMS/IMU positioning systems.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-57&engl=1}
}

@inproceedings {INPROC-2013-52,
   author = {Damian Philipp and Jaroslaw Stachowiak and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Model-Driven Public Sensing in Sparse Networks}},
   booktitle = {Proceedings of the 10th International Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services},
   publisher = {Springer},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   series = {LNCS},
   pages = {1--12},
   type = {Conference Paper},
   month = {December},
   year = {2013},
   keywords = {model-driven; energy optimization; public sensing; opportunistic sensing; adaptive algorithm; mobility},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-52/INPROC-2013-52.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Public Sensing (PS) is a recent trend for building large-scale sensor data
      acquisition systems using commodity smartphones. Limiting the energy drain on
      participating devices is a major challenge for PS, as otherwise people will
      stop sharing their resources with the PS system. Existing solutions for
      limiting the energy drain through model-driven optimizations are limited to
      dense networks where there is a high probability for every point of interest to
      be covered by a smartphone. In this work, we present an adaptive model-driven
      PS system that deals with both dense and sparse networks. Our evaluations show
      that this approach improves data quality by up to 41 percentage points while
      enabling the system to run with a greatly reduced number of participating
      smartphones. Furthermore, we can save up to 81\% of energy for communication and
      sensing while providing data matching an error bound of 1°C up to 96\% of the
      time.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-52&engl=1}
}

@inproceedings {INPROC-2013-51,
   author = {Marius Wernke and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Speed Protection Algorithms for Privacy-aware Location Management}},
   booktitle = {Proceedings of the IEEE 9th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob 2013).},
   address = {Lyon, France},
   publisher = {IEEE Xplore},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {355--362},
   type = {Conference Paper},
   month = {October},
   year = {2013},
   keywords = {Location-based applications; location-based services; speed protection; movement trajectory; location management; location privacy},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-51/INPROC-2013-51.pdf,
      www.ieeexplore.ieee.org,
      www.PriLoc.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Nowadays, millions of users share their complete movement trajectory online
      when using real-time traffic monitoring applications, pay-as-you-drive
      insurances, or when sharing their last road trip with friends. However, many
      users still hesitate to use location-based applications as they are not willing
      to reveal, for instance, their driving behavior or the occurrence of a speeding
      violation.
      
      Therefore, we present novel speed protection algorithms protecting users from
      revealing a violation of given speed limits when using location-based
      applications. Our algorithms support time-based and distance-based position
      updates. To protect positions indicating a speeding violation, we either adjust
      temporal information by delaying position updates or adjust their spatial
      information. We evaluate our algorithms by using real world traces and show
      that the protected movement trajectory of the user is of high quality even
      after removing speeding violations.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-51&engl=1}
}

@inproceedings {INPROC-2013-35,
   author = {Patrick Baier and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Efficient Distribution of Sensing Queries in Public Sensing Systems}},
   booktitle = {Proceedings of the 10th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (MASS 2013)},
   publisher = {IEEE Computer Society},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--9},
   type = {Conference Paper},
   month = {October},
   year = {2013},
   language = {German},
   cr-category = {C.2 Computer-Communication Networks},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-35/INPROC-2013-35.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {The advent of mobile phones paved the way for a new paradigm for gathering
      sensor data termed Public Sensing (PS). PS uses built-in sensors of mobile
      devices to opportunistically gather sensor data. For instance, the microphones
      of a crowd of mobile phones can be used to capture sound samples, which can be
      used to construct a city noise map.
      
      A great challenge of PS is to reduce the energy consumption of mobile devices
      since otherwise users might not be willing to participate. One crucial part in
      the overall power consumption is the energy required for the communication
      between the mobile devices and the infrastructure. In particular, the
      communication required for sending sensing queries to mobile devices has been
      largely neglected in the related work so far.
      
      Therefore, in this paper, we address the problem of minimizing communication
      costs for the distribution of sensing queries. While existing systems simply
      broadcast sensing queries to all devices, we use a selective strategy by
      addressing only a subset of devices. In order not to negatively affect the
      quality of sensing w.r.t. completeness, this subset is carefully chosen based
      on a probabilistic sensing model that defines the probability of mobile devices
      to successfully perform a given sensing query.
      
      Our evaluations show that with our optimized sensing query distribution, the
      energy consumption can be reduced by more than 70\% without significantly
      reducing the quality of sensing.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-35&engl=1}
}

@inproceedings {INPROC-2013-33,
   author = {Patrick Baier and Frank D{\"u}rr and Kurt Rothermel},
   title = {{Opportunistic Position Update Protocols for Mobile Devices}},
   booktitle = {Proceedings of the International Joint Conference on Pervasive and Ubiquitous Computing (UbiComp 2013)},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {1--9},
   type = {Conference Paper},
   month = {September},
   year = {2013},
   language = {English},
   cr-category = {C.2 Computer-Communication Networks},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-33/INPROC-2013-33.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Many location-based applications such as geo-social networks rely on location
      services storing mobile object positions. To update positions on location
      servers, position update protocols are used. On the one hand, these protocols
      decide when an update has to be sent to ensure a certain quality of position
      information. On the other hand, they try to minimize the energy consumption of
      the mobile device by reducing communication to a minimum.
      
      In this paper, we show how to improve the energy efficiency of different update
      protocols by taking the energy characteristics of the mobile network interface
      into account. In particular, we show that the energy consumption can be reduced
      on average by 70\% using an opportunistic update strategy sending position
      updates together with messages of other applications. We present a Markov model
      to predict the arrival of messages and an online optimization algorithm
      calculating an optimized schedule to send position updates.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-33&engl=1}
}

@inproceedings {INPROC-2013-31,
   author = {Kirak Hong and David Lillethun and Umakishore Ramachandran and Beate Ottenw{\"a}lder and Boris Koldehofe},
   title = {{Mobile Fog: A Programming Model for Large-Scale Applications on the Internet of Things}},
   booktitle = {Proceedings of the 2nd MCC Workshop on Mobile Cloud Computing},
   address = {Hong Kong, China},
   publisher = {ACM Press},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {15--20},
   type = {Conference Paper},
   month = {August},
   year = {2013},
   doi = {10.1145/2491266.2491270},
   keywords = {fog computing; cloud computing; programming model; Internet of Things; future Internet applications; situation awareness applications},
   language = {English},
   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-2013-31/INPROC-2013-31.pdf,
      http://doi.acm.org/10.1145/2491266.2491270},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {The ubiquitous deployment of mobile and sensor devices is creating a new
      environment, namely the Internet of Things(IoT), that enables a wide range of
      future Internet applications. In this work, we present Mobile Fog, a high level
      programming model for future Internet applications that are geospatially
      distributed, large-scale, and latency-sensitive. We analyze use cases for the
      programming model with camera network and connected vehicle applications to
      show the efficacy of Mobile Fog We also evaluate application performance
      through simulation.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-31&engl=1}
}

@inproceedings {INPROC-2013-29,
   author = {Kirak Hong and David Lillethun and Umakishore Ramachandran and Beate Ottenw{\"a}lder and Boris Koldehofe},
   title = {{Opportunistic Spatio-temporal Event Processing for Mobile Situation Awareness}},
   booktitle = {Proceedings of the 7th ACM International Conference on Distributed Event-Based Systems (DEBS)},
   address = {Arlington, Texas, USA},
   publisher = {ACM Press},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {195--206},
   type = {Conference Paper},
   month = {June},
   year = {2013},
   doi = {10.1145/2488222.2488266},
   keywords = {mobility; complex event processing; situation awareness},
   language = {English},
   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-2013-29/INPROC-2013-29.pdf,
      http://doi.acm.org/10.1145/2488222.2488266},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {With the proliferation of mobile devices and sensors, mobile situation
      awareness is becoming an important class of applications. The key requirement
      of this class of applications is low-latency processing of events stemming from
      sensordata in order to provide timely situational information to mobile
      users.To satisfy the latency requirement, we propose a spatio-temporal event
      processing system that uses prediction-based continuous query handling. Our
      system predicts future query regions for moving consumers and starts processing
      events early so that the live situational information is available when the
      consumer reaches the future location. In contrast to existing systems, our
      system provides timely information about a consumer's current position by
      hiding computation latency for processing recent events. To evaluate our
      system, we measure the quality of results and timeliness of live situational
      information with various query parameters. Our evaluation shows that we can
      achieve highly meaningful query results with near-zero latency in most cases.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-29&engl=1}
}

@inproceedings {INPROC-2013-28,
   author = {Beate Ottenw{\"a}lder and Boris Koldehofe and Kurt Rothermel and Umakishore Ramachandran},
   title = {{MigCEP: Operator Migration for Mobility Driven Distributed Complex Event Processing}},
   booktitle = {Proceedings of the 7th ACM International Conference on Distributed Event-Based Systems (DEBS)},
   address = {Arlington, Texas, USA},
   publisher = {ACM Press},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {183--194},
   type = {Conference Paper},
   month = {June},
   year = {2013},
   doi = {10.1145/2488222.2488265},
   keywords = {complex event processing; migration; mobility},
   language = {English},
   cr-category = {C.2.1 Network Architecture and Design,
                   C.2.4 Distributed Systems,
                   E.1 Data Structures},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-28/INPROC-2013-28.pdf,
      http://doi.acm.org/10.1145/2488222.2488265},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {A recent trend in communication networks --- sometimes referred to as fog
      computing --- offers to execute computational tasks close to the access points
      of the networks. This enables real-time applications, like mobile Complex Event
      Processing (CEP), to significantly reduce end-to-end latencies and bandwidth
      usage. Most work studying the placement of operators in such an environment
      completely disregards the migration costs. However, the mobility of users
      requires frequent migration of operators, together with possibly large state
      information, to meet latency restrictions and save bandwidth in the
      infrastructure.
      
      This paper presents a placement and migration method for providers of
      infrastructures that incorporate cloud and fog resources. It ensures
      application-defined end-to-end latency restrictions and reduces the network
      utilization by planning the migration ahead of time. Furthermore, we present
      how the application knowledge of the CEP system can be used to improve current
      live migration techniques for Virtual Machines to reduce the required bandwidth
      during the migration. Our evaluations show that we safe up to 49\% of the
      network utilization with perfect knowledge about a users mobility pattern and
      up to 27\% of the network utilization when considering the uncertainty of those
      patterns.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-28&engl=1}
}

@inproceedings {INPROC-2013-27,
   author = {Boris Koldehofe and Frank D{\"u}rr and Muhammad Adnan Tariq},
   title = {{Event-based Systems Meet Software-defined Networking}},
   booktitle = {Proceedings of the 7th ACM International Conference on Distributed Event-Based Systems (DEBS)},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Germany},
   pages = {271--280},
   type = {Conference Paper},
   month = {June},
   year = {2013},
   doi = {10.1145/2488222.2488270},
   keywords = {Software-defined Networking, Event-based Systems, Content-based Routing, Publish/Subscribe, Network Virtualization},
   language = {English},
   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-2013-27/INPROC-2013-27.pdf,
      http://dx.doi.org/10.1145/2488222.2488270},
   department = {University of Stuttgart, Institute of Parallel and Distributed High-Performance Systems, Distributed Systems},
   abstract = {Software-defined networking (SDN) is a recent development in the area of
      communication networks with tremendous support by key players building the next
      generation of computer hardware and software. This development will have
      significant impact on how communication middleware---in particular, future
      distributed event-based systems---can be designed. While currently the
      communication middleware has no possibility to directly influence the
      properties of its underlying communication channels on the network layer, SDN
      enables communication middleware to control and flexibly adapt the forwarding
      of communication flows in the underlying network. In addition to the immediate
      implication to local area networks such as data center networks, campus
      networks, or company networks, novel trends like network virtualization may
      even support Internet-wide distributed applications to benefit from SDN in the
      future. This paper gives an introduction on how to utilize SDN-concepts for
      improving the performance of event-based middleware and to test their behavior.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-27&engl=1}
}

@inproceedings {INPROC-2013-26,
   author = {Boris Koldehofe and Ruben Mayer and Umakishore Ramachandran and Kurt Rothermel and Marco V{\"o}lz},
   title = {{Rollback-Recovery without Checkpoints in Distributed Event Processing Systems}},
   booktitle = {Proceedings of the 7th ACM International Conference on Distributed Event-Based Systems (DEBS)},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {27--38},
   type = {Conference Paper},
   month = {June},
   year = {2013},
   doi = {10.1145/2488222.2488259},
   keywords = {Reliability; Recovery; Complex Event Processing},
   language = {English},
   cr-category = {C.2.4 Distributed Systems,
                   C.4 Performance of Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-26/INPROC-2013-26.pdf,
      http://dx.doi.org/10.1145/2488222.2488259},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Reliability is of critical importance to many applications involving
      distributed event processing systems. Especially the use of stateful operators
      makes it challenging to provide efficient recovery from failures and to ensure
      consistent event streams. Even during failure-free execution, state-of-the-art
      methods for achieving reliability incur significant overhead at run-time
      concerning computational resources, event traffic, and event detection time.
      This paper proposes a novel method for rollback-recovery that allows for
      recovery from multiple simultaneous operator failures, but eliminates the need
      for persistent checkpoints. Thereby, the operator state is preserved in
      savepoints at points in time when its execution solely depends on the state of
      incoming event streams which are reproducible by predecessor operators. We
      propose an expressive event processing model to determine savepoints and
      algorithms for their coordination in a distributed operator network.
      Evaluations show that very low overhead at failure-free execution in comparison
      to other approaches is achieved.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-26&engl=1}
}

@inproceedings {INPROC-2013-23,
   author = {Muhammad Adnan Tariq and Boris Koldehofe and Kurt Rothermel},
   title = {{Efficient content-based routing with network topology inference}},
   booktitle = {Proceedings of the 7th ACM International Conference on Distributed Event-Based Systems (DEBS)},
   address = {Arlington, Texas, USA},
   publisher = {ACM},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {51--62},
   type = {Conference Paper},
   month = {June},
   year = {2013},
   doi = {10.1145/2488222.2488262},
   keywords = {QoS; quality of service; network inference; underlay awareness; delay; bandwidth; content-based; publish/subscribe; event-based},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-23/INPROC-2013-23.pdf,
      http://doi.acm.org/10.1145/2488222.2488262},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Content-based publish/subscribe has gained high popularity for large-scale
      dissemination of dynamic content. Yet it is highly challenging to enable
      communication-efficient dissemination of content in such systems, especially in
      the absence of a broker infrastructure. This paper presents a novel approach
      that exploits the knowledge of event traffic, user subscriptions and topology
      of the underlying physical network to perform efficient routing in a
      publish/subscribe system. In particular, mechanisms are developed to discover
      the underlay topology among subscribers and publishers in a distributed manner.
      The information of the topology and the proximity between the subscribers to
      receive similar events is then used to construct a routing overlay with low
      communication cost. Our evaluations show that for internet-like topologies the
      proposed inference mechanisms are capable of modeling an underlay in an
      efficient and accurate manner. Furthermore, the approach yields a significant
      reduction in routing cost in comparison to the state of the art.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-23&engl=1}
}

@inproceedings {INPROC-2013-22,
   author = {Frank D{\"u}rr},
   title = {{Improving the Efficiency of Cloud Infrastructures with Elastic Tandem Machines}},
   booktitle = {Proceedings of the 6th International Conference on Cloud Computing (Cloud 2013)},
   address = {Santa Clara, CA, 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 = {June},
   year = {2013},
   keywords = {cloud computing; infrastructure as a service; efficiency; energy, elasticity; scaling; system on a chip; software-defined networking; green computing},
   language = {English},
   cr-category = {C.2.3 Network Operations,
                   C.2.4 Distributed Systems,
                   C.2.1 Network Architecture and Design,
                   C.4 Performance of Systems,
                   C.5 Computer System Implementation,
                   H.3.4 Information Storage and Retrieval Systems and Software},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-22/INPROC-2013-22.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {In this paper, we propose a concept for improving the energy efficiency and
      resource utilization of cloud infrastructures by combining the benefits of
      heterogeneous machine instances. The basic idea is to integrate low-power
      system on a chip (SoC) machines and high-power virtual machine instances into
      so-called Elastic Tandem Machine Instances (ETMI). The low-power machine serves
      low load and is always running to ensure the availability of the ETMI. When
      load rises, the ETMI scales up automatically by starting the high-power
      instance and handing over traffic to it. For the non-disruptive transition from
      low-power to high-power machines and vice versa, we present a handover
      mechanism based on software-defined networking technologies. Our evaluations
      show the applicability of low-power SoC machines to serve low load efficiently
      as well as the desired scalability properties of ETMIs.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-22&engl=1}
}

@inproceedings {INPROC-2013-04,
   author = {Damian Philipp and Jaroslaw Stachowiak and Patrick Alt and Frank D{\"u}rr and Kurt Rothermel},
   title = {{DrOPS: Model-Driven Optimization for Public Sensing Systems}},
   booktitle = {2013 IEEE International Conference on Pervasive Computing and Communications (PerCom 2013)},
   address = {San Diego, CA, USA},
   publisher = {IEEE Computer Society},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {185--192},
   type = {Conference Paper},
   month = {March},
   year = {2013},
   doi = {10.1109/PerCom.2013.6526731},
   keywords = {Data acquisition; Distributed computing; Wireless sensor networks; Public Sensing; Opportunistic Sensing; Smartphone; Model-Driven Data Acquisition; Quality aware; Adaptive, autonomic and context-aware computing; Energy-efficient and green pervasive computing; Innovative pervasive computing applications; Pervasive opportunistic communications and applications; Participatory, opportunistic and social sensing; Sensors and RFID in pervasive systems; Smart devices and intelligent environments},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-04/INPROC-2013-04.pdf,
      http://www.comnsense.de,
      http://dx.doi.org/10.1109/PerCom.2013.6526731},
   contact = {Damian Philipp damian.philipp@ipvs.uni-stuttgart.de},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {The proliferation of modern smartphones has given rise to Public Sensing, a new
      paradigm for data acquisition systems utilizing smartphones of mobile
      participants. In this paper, we present DrOPS, a system for improving the
      efficiency of data acquisition in Public Sensing systems. DrOPS utilizes a
      model-driven approach, where the number of required readings from mobile
      smartphones is reduced by inferring readings from the model. Furthermore, the
      model can be used to infer readings for positions where no sensor is available.
      The model is directly constructed from the observed phenomenon in an online
      fashion. Using such models together with a client-specified quality bound, we
      can significantly reduce the effort for data acquisition while still reporting
      data of required quality to the client. To this effect, we develop a set of
      online learning and control algorithms to create and validate the model of the
      observed phenomenon and present a sensing task execution system utilizing our
      algorithms in this paper. Our evaluations show that we obtain models in a
      matter of just hours or even minutes. Using the model-driven approach for
      optimizing the data acquisition, we can save up to 80\% of energy for
      communication and provide inferred temperature readings for uncovered positions
      matching an error-bound of 1°C up to 100\% of the time.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-04&engl=1}
}

@inproceedings {INPROC-2013-01,
   author = {Bj{\"o}rn Schilling and Boris Koldehofe and Kurt Rothermel and Umakishore Ramachandran},
   title = {{Access Policy Consolidation for Complex Event Processing}},
   booktitle = {IEEE Conference on Networked Systems (NetSys)},
   publisher = {IEEE},
   institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
   pages = {92--101},
   type = {Conference Paper},
   month = {March},
   year = {2013},
   doi = {10.1109/NetSys.2013.18},
   keywords = {Event processing; Complex event processing; CEP; Security; Access Control; Bayesian network},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-01/INPROC-2013-01.pdf},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {In distributed complex event processing, event streams are processed over a
      chain of subsequent operators. For large-scale applications like a logistic
      chain these operators may be hosted by different entities and thus are spread
      over different security domains. Current approaches for complex event
      processing cannot preserve the privacy of an operator’s incoming event streams.
      An adversary may infer the original input stream from its legally received
      event streams.
      
      In this paper we present a fine-grained access management for complex event
      processing. We show how to enforce privacy of events throughout the chain of
      dependent operators by specifying appropriate access policies and proposing an
      algorithm for policy consolidation. Furthermore, we introduce the calculation
      of obfuscation achieved in a correlation step. This allows us to ignore access
      requirements once a sufficient obfuscation level has been achieved, the
      proposed algorithms is capable to reduce the required overhead in the
      enforcement of access policies. We prove correctness and evaluate the cost in
      establishing policy consolidation.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-01&engl=1}
}

@article {ART-2013-13,
   author = {Hannes Wolf and Klaus Herrmann and Kurt Rothermel},
   title = {{Dealing with uncertainty: Robust workflow navigation in the healthcare domain}},
   journal = {ACM Transactions on Intelligent Systems and Technology (TIST)},
   address = {New York, NY, USA},
   publisher = {ACM},
   volume = {4},
   number = {4},
   type = {Article in Journal},
   month = {September},
   year = {2013},
   doi = {10.1145/2508037.2508046},
   issn = {2157-6904},
   language = {English},
   cr-category = {C.2.4 Distributed Systems,
                   H.4.1 Office Automation},
   ee = {http://doi.acm.org/10.1145/2508037.2508046},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Processes in the healthcare domain are characterized by coarsely predefined
      recurring procedures that are flexibly adapted by the personnel to
      suite-specific situations. In this setting, a workflow management system that
      gives guidance and documents the personnel's actions can lead to a higher
      quality of care, fewer mistakes, and higher efficiency. However, most existing
      workflow management systems enforce rigid inflexible workflows and rely on
      direct manual input. Both are inadequate for healthcare processes. In
      particular, direct manual input is not possible in most cases since (1) it
      would distract the personnel even in critical situations and (2) it would
      violate fundamental hygiene principles by requiring disinfected doctors and
      nurses to touch input devices. The solution could be activity recognition
      systems that use sensor data (e.g., audio and acceleration data) to infer the
      current activities by the personnel and provide input to a workflow (e.g.,
      informing it that a certain activity is finished now). However,
      state-of-the-art activity recognition technologies have difficulties in
      providing reliable information. We describe a comprehensive framework tailored
      for flexible human-centric healthcare processes that improves the reliability
      of activity recognition data. We present a set of mechanisms that exploit the
      application knowledge encoded in workflows in order to reduce the uncertainty
      of this data, thus enabling unobtrusive robust healthcare workflows. We
      evaluate our work based on a real-world case study and show that the robustness
      of unobtrusive healthcare workflows can be increased to an absolute value of up
      to 91\% (compared to only 12\% with a classical workflow system). This is a major
      breakthrough that paves the way towards future IT-enabled healthcare systems.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2013-13&engl=1}
}

@article {ART-2013-04,
   author = {Anders Gidenstam and Boris Koldehofe and Marina Papatriantafilou and Philippas Tsigas},
   title = {{Scalable group communication supporting configurable levels of consistency}},
   journal = {Concurrency and Computation: Practice and Experience},
   publisher = {John Wiley \& Sons, Ltd.},
   volume = {25},
   number = {5},
   pages = {649--671},
   type = {Article in Journal},
   month = {January},
   year = {2013},
   doi = {10.1002/cpe.1801},
   keywords = {Distributed Systems, Group Communication, Consistency},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Group communication is deployed in many evolving Internet-scale cooperative
      applications such as multiplayer online games and virtual worlds to efficiently
      support interaction on information relevant to a potentially very large number
      of users or objects. Especially peer-to-peer based group communication
      protocols have evolved as a promising approach to allow intercommunication
      between many distributed peers. Yet, the delivery semantics of robust and
      scalable protocols such as gossiping is not sufficient to support consistency
      semantics beyond eventual consistency because no relationship on the order of
      events is enforced. On the other hand, traditional consistency models provided
      by reliable group communication providing causal or even total order are
      restricted to support only small groups. This article proposes the cluster
      consistency model which bridges the gap between traditional and current
      approaches in supporting both scalability and ordered event delivery. We
      introduce a dynamic and fault tolerant cluster management method that can
      coordinate concurrent access to resources in a peer-to-peer system and can be
      used to establish fault-tolerant configurable cluster consistency with
      predictable reliability, running on top of decentralised probabilistic
      protocols supporting scalable group communication. This is achieved by a
      general two-layered architecture that can be applied on top of the standard
      Internet communication layers and offers a modular, layered set of services to
      the applications that need them. Further, we present a fault-tolerant method
      implementing causal cluster consistency with predictable reliability, running
      on top of decentralised probabilistic protocols supporting group communication.
      This paper provides analytical and experimental evaluation of the properties
      regarding the fault tolerance of the approach. Furthermore, our experimental
      study, conducted by implementing and evaluating the two-layered architecture on
      top of standard Internet transport services, shows that the approach scales
      well, imposes an even load on the system, and provides high-probability
      reliability guarantees.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2013-04&engl=1}
}

@article {ART-2013-02,
   author = {Marius Wernke and Frank D{\"u}rr and Kurt Rothermel},
   title = {{PShare: Ensuring location privacy in non-trusted systems through multi-secret sharing}},
   journal = {Pervasive and Mobile Computing},
   publisher = {Elsevier},
   pages = {1--17},
   type = {Article in Journal},
   month = {February},
   year = {2013},
   doi = {10.1016/j.pmcj.2013.01.001},
   keywords = {Location-based applications; Privacy; Position sharing; Location management},
   language = {English},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/ART-2013-02/ART-2013-02.pdf,
      http://www.priloc.de,
      http://dx.doi.org/10.1016/j.pmcj.2013.01.001},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Location-based applications such as Facebook Places, Foursquare, or Loopt
      typically use location services to manage mobile object positions. However,
      exposing precise user positions raises user privacy concerns, especially if
      location service providers are not fully trusted. To enable the secure
      management of private user positions in non-trusted systems, we present two
      novel position sharing approaches based on the concept of multi-secret sharing.
      We improve existing geometric position sharing approaches [1, 2] by considering
      continuous position updates and by increasing the robustness against various
      attacks. Furthermore, we present the first position sharing approach for
      symbolic location models.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2013-02&engl=1}
}

@article {ART-2013-01,
   author = {Stephan Schuhmann and Klaus Herrmann and Kurt Rothermel and Yazan Boshmaf},
   title = {{Adaptive Composition of Distributed Pervasive Applications in Heterogeneous Environments}},
   journal = {ACM Transactions on Autonomous and Adaptive Systems},
   publisher = {ACM},
   volume = {8},
   number = {2},
   pages = {1--21},
   type = {Article in Journal},
   month = {July},
   year = {2013},
   doi = {10.1145/2491465.2491469},
   issn = {1556-4665},
   keywords = {Adaptivity; Algorithms; Automation; Components; Design; Heterogeneity; Hybrid Configuration; Management; Measurement; Middleware; Partial Configurations; Pervasive Applications; Service Composition},
   language = {English},
   cr-category = {C.2.4 Distributed Systems,
                   D.2.11 Software Engineering Software Architectures},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/ART-2013-01/ART-2013-01.pdf,
      http://doi.acm.org/10.1145/2491465.2491469},
   department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Distributed Systems},
   abstract = {Complex pervasive applications need to be distributed for two main reasons: due
      to the typical resource restrictions of mobile devices, and to use local
      services to interact with the immediate environment. To set up such an
      application, the distributed components require spontaneous composition. Since
      dynamics in the environment and device failures may imply the unavailability of
      components and devices at any time, finding, maintaining, and adapting such a
      composition is a nontrivial task. Moreover, the speed of such a configuration
      process directly influences the user since in the event of a configuration, the
      user has to wait. In this article, we introduce configuration algorithms for
      homogeneous and heterogeneous environments. We discuss a comprehensive approach
      to pervasive application configuration that adapts to the characteristics of
      the environment: It chooses the most efficient configuration method for the
      given environment to minimize the configuration latency. Moreover, we propose a
      new scheme for caching and reusing partial application configurations. This
      scheme reduces the configuration latency even further such that a configuration
      can be executed without noticeable disturbance of the user.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2013-01&engl=1}
}