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  • 51.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Broadening the Audience: Popularity Dynamics and Scalable Content Delivery2012Ingår i: Advances in secure and networked information systems: the ADIT perspective ; Festschrift in honor of professor Nahid Shahmehri / [ed] Patrick Lambrix, Linköping: Linköping University Electronic Press, 2012, s. 139-144Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    The Internet is playing an increasingly important role in today’s society and people are beginning to expect instantaneous access to information and content wherever they are. As content delivery is consuming a majority of the Internet bandwidth and its share of bandwidth is increasing by the hour, we need scalable and efficient techniques that can support these user demands and efficiently deliver the content to the users. When designing such techniques it is important to note that not all content is the same or will reach the same popularity. Scalable techniques must handle an increasingly diverse catalogue of contents, both with regards to diversity of content (as service are becoming increasingly personalized, for example) and with regards to their individual popularity. The importance of understanding content popularity dynamics is further motivated by popular contents widespread impact on opinions, thoughts, and cultures. This article will briefly discuss some of our recent work on capturing content popularity dynamics and designing scalable content delivery techniques

  • 52.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Optimized eeeBond: Energy Efficiency with non-Proportional Router Network Interfaces2016Ingår i: PROCEEDINGS OF THE 2016 ACM/SPEC INTERNATIONAL CONFERENCE ON PERFORMANCE ENGINEERING (ICPE'16), ACM Digital Library, 2016, s. 215-223Konferensbidrag (Refereegranskat)
    Abstract [en]

    The recent Energy Efficient Ethernet (EEE) standard and the eBond protocol provide two orthogonal approaches that allow significant energy savings on routers. In this paper we present the modeling and performance evaluation of these two protocols and a hybrid protocol. We first present eeeBond, pronounced ``triple-e bond'', which combines the eBond capability to switch between multiple redundant interfaces with EEE's active/idle toggling capability implemented in each interface. Second, we present an analytic model of the protocol performance, and derive closed-form expressions for the optimized parameter settings of both eBond and eeeBond. Third, we present a performance evaluation that characterizes the relative performance gains possible with the optimized protocols, as well as a trace-based evaluation that validates the insights from the analytic model. Our results show that there are significant advantages to combine eBond and EEE. The eBond capability provides good savings when interfaces only offer small energy savings when in short-term sleep states, and the EEE capability is important as short-term sleep savings improve.

  • 53.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Arlitt, Martin
    Towards More Effective Utilization of Computer Systems2011Ingår i: Proc. ACM/SPEC International Conference on Performance Engineering (ICPE ’10), Karlsruhe, Germany, March 2011., ACM , 2011, s. 235-246Konferensbidrag (Refereegranskat)
  • 54.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dan, Gyorgy
    KTH Royal Institute of Technology, Stockholm.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Sydney, Australia,.
    Tradeoffs in Cloud and Peer-assisted Content Delivery Systems2012Ingår i: Peer-to-Peer Computing (P2P), 2012: , IEEE , 2012, s. 249-260Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the proliferation of cloud services, cloud-based systems can become a cost-effective means of on-line content delivery. In order to make best use of the available cloud bandwidth and storage resources, content distributors need to have a good understanding of the tradeoffs between various system design choices. In this work we consider a peer-assisted content delivery system that aims to provide guaranteed average download rate to its customers. We show that bandwidth demand peaks for contents with moderate popularity, and identify these contents as candidates for cloud-based service. We then consider dynamic content bundling and cross-swarm seeding, which were recently proposed to improve download performance, and evaluate their impact on the optimal choice of cloud service use. We find that much of the benefits from peer seeding can be achieved with careful torrent inflation, and that hybrid policies that combine bundling and peer seeding often reduce the delivery costs by 20% relative to only using seeding. Furthermore, all these peer-assisted policies reduce the number of files that would need to be pushed to the cloud. Finally, we show that careful system design is needed if locality is an important criterion when choosing cloud-based service provisioning.

  • 55.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dan, György
    KTH Royal Institute of Technology, Sweden.
    Arlitt, Martin
    NICTA, Australia.
    Mahanti, Anirban
    HP Labs, USA.
    A Longitudinal Characterization of Local and Global BitTorrent Workload Dynamics2012Ingår i: Passive and Active Measurement: 13th International Conference, PAM 2012, Vienna, Austria, March 12-14th, 2012. Proceedings / [ed] Nina Taft; Fabio Ricciato, Springer Berlin/Heidelberg, 2012, s. 252-262Konferensbidrag (Refereegranskat)
    Abstract [en]

    This book constitutes the refereed proceedings of the 13th International Conference on Passive and Active Measurement, PAM 2012, held in Vienna, Austria, in March 2012. <br>The 25 revised full papers presented were carefully reviewed and selected from 83 submissions. The papers were arranged into eight sessions traffic evolution and analysis, large scale monitoring, evaluation methodology, malicious behavior, new measurement initiatives, reassessing tools and methods, perspectives on internet structure and services, and application protocols.

  • 56.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Eager, Derek
    University of Saskatchewan, Canada.
    Ephemeral Content Popularity at the Edge and Implications for On-Demand Caching2017Ingår i: IEEE Transactions on Parallel and Distributed Systems, ISSN 1045-9219, E-ISSN 1558-2183, Vol. 28, nr 6, s. 1621-1634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ephemeral content popularity seen with many content delivery applications can make indiscriminate on-demand caching in edge networks highly inefficient, since many of the content items that are added to the cache will not be requested again from that network. In this paper, we address the problem of designing and evaluating more selective edge-network caching policies. The need for such policies is demonstrated through an analysis of a dataset recording YouTube video requests from users on an edge network over a 20-month period. We then develop a novel workload modelling approach for such applications and apply it to study the performance of alternative edge caching policies, including indiscriminate caching and cache on kth request for different k. The latter policies are found able to greatly reduce the fraction of the requested items that are inserted into the cache, at the cost of only modest increases in cache miss rate. Finally, we quantify and explore the potential room for improvement from use of other possible predictors of further requests. We find that although room for substantial improvement exists when comparing performance to that of a perfect "oracle" policy, such improvements are unlikely to be achievable in practice.

  • 57.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eager, Derek
    University of Saskatchewan, Canada.
    Gopinathan, Ajay
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Li, Zongpeng
    University of Calgary, Canada.
    Caching and optimized request routing in cloud-based content delivery systems2014Ingår i: Performance evaluation (Print), ISSN 0166-5316, E-ISSN 1872-745X, Vol. 79, s. 38-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Geographically distributed cloud platforms enable an attractive approach to large-scale content delivery. Storage at various sites can be dynamically acquired from (and released back to) the cloud provider so as to support content caching, according to the current demands for the content from the different geographic regions.  When storage is sufficiently expensive that not all content should be cached at all sites, two issues must be addressed: how should requests for content be routed to the cloud provider sites, and what policy should be used for caching content using the elastic storage resources obtained from the cloud provider.  Existing approaches are typically designed for non-elastic storage and little is known about the optimal policies when minimizing the delivery costs for distributed elastic storage.

    In this paper, we propose an approach in which elastic storage resources are exploited using a simple dynamic caching policy, while request routing is updated periodically according to the solution of an optimization model.  Use of pull-based dynamic caching, rather than push-based placement, provides robustness to unpredicted changes in request rates.  We show that this robustness is provided at low cost \textendash{} even with fixed request rates, use of the dynamic caching policy typically yields content delivery cost within 10\% of that with the optimal static placement.  We compare request routing according to our optimization model to simpler baseline routing policies, and find that the baseline policies can yield greatly increased delivery cost relative to optimized routing.  Finally, we present a lower-cost approximate solution algorithm for our routing optimization problem that yields content delivery cost within 2.5\% of the optimal solution.

  • 58.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Eager, Derek
    University of Saskatchewan, Canada.
    Krishnamoorthi, Vengatanathan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Polishchuk, Tatiana
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Optimized Adaptive Streaming of Multi-video Stream Bundles2017Ingår i: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 19, nr 7, s. 1637-1653Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In contrast to traditional video, multi-view video streaming allows viewers to interactively switch among multiple perspectives provided by different cameras. One approach to achieve such a service is to encode the video from all of the cameras into a single stream, but this has the disadvantage that only a portion of the received video data will be used, namely that required for the selected view at each point in time. In this paper, we introduce the concept of a multi-video stream bundle that consists of multiple parallel video streams that are synchronized in time, each providing the video from a different camera capturing the same event or movie. For delivery we leverage the adaptive features and time-based chunking of HTTP-based adaptive streaming, but now employing adaptation in both content and rate. Users are able to change their viewpoint on-demand and the client player adapts the rate at which data are retrieved from each stream based on the users current view, the probabilities of switching to other views, and the users current bandwidth conditions. A crucial component of such a system is the prefetching policy. For this we present an optimization model as well as a simpler heuristic that can balance the playback quality and the probability of playback interruptions. After analytically and numerically characterizing the optimal solution, we present a prototype implementation and sample results. Our prefetching and buffer management solution is shown to provide close to seamless playback switching when there is sufficient bandwidth to prefetch the parallel streams.

  • 59.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Li, Xiaolin Andy
    University of Florida, USA.
    Singhal, Mukesh
    University of California, Merced, USA.
    Wang, Mea
    University of Calgary, Canada.
    Guest Editorial - Cloud and Big Data2014Ingår i: Journal of Communications, ISSN 1796-2021, E-ISSN 1796-2021, Vol. 9, nr 4, s. i-iiiArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the current digital age, massive amounts of data are generated in many different ways and forms. The data may be collected from everything from personal web logs to purposefully placed sensors. Today, companies and researchers use this data for everything from targeted personalized ads based on social data to solving important scientific problems that may help future generations of word citizens. Regardless if measured in monetary profit or other measures, the value of this data has proven valuable for many purposes and has led us into the Big Data era. Due to the large volume of data, Big Data requires significant storage, processing, and bandwidth resources. To date, the Cloud provides the largest collection of disk storage, CPU power, and network bandwidth, which makes it a natural choice for housing the Big Data.

  • 60.
    Carlsson, Niklas
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Williamson, Carey
    University of Calgary, Canada.
    Hirt, Andreas
    University of Calgary, Canada.
    Jacobson, Micheal
    University of Calgary, Canada.
    Performance Modeling of Anonymity Protocols2012Ingår i: Performance evaluation (Print), ISSN 0166-5316, E-ISSN 1872-745X, Vol. 69, nr 12, s. 643-661Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anonymous network communication protocols provide privacy for Internet-based communication. In this paper, we focus on the performance and scalability of anonymityprotocols. In particular, we develop performance models for two anonymityprotocols from the prior literature (Buses and Taxis), as well as our own newly proposed protocol (Motorcycles). Using a combination of experimental implementation, simulation, and analysis, we show that: (1) the message latency of the Buses protocol is O(N2), scaling quadratically with the number of participants; (2) the message latency of the Taxis protocol is O(N), scaling linearly with the number of participants; and (3) the message latency of the Motorcycles protocol is O(log2N), scaling logarithmically with the number of participants. Motorcycles can provide scalable anonymous network communication, without compromising the strength of anonymity provided by Buses or Taxis.

  • 61.
    Cheatham, Michelle
    et al.
    Wright State University, USA.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Euzenat, Jerome
    INRIA, France; Univ. Grenoble Alpes, Grenoble, France.
    Faria, Daniel
    Instituto Gulbenkian de Ciencia, Lisbon, Portugal.
    Ferrara, Alfio
    Universita degli studi di Milano, Italy.
    Flouris, Giorgios
    Institute of Computer Science-FORTH, Heraklion, Greece.
    Fundulaki, Irini
    Institute of Computer Science-FORTH, Heraklion, Greece.
    Granada, Roger
    IRIT, France; Universite Toulouse II, Toulouse, France.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Jimenez-Ruiz, Ernesto
    University of Oxford, UK.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Montanelli, Stefano
    Universita degli studi di Milano, Italy.
    Pesquita, Catia
    LASIGE, Faculdade de Ciencias, Universidade de Lisboa, Portugal .
    Saveta, Tzanina
    Institute of Computer Science-FORTH, Heraklion, Greece.
    Shvaiko, Pavel
    TasLab, Informatica Trentina, Trento, Italy.
    Solimando, Allesandro
    INRIA-Saclay, France; Univ. Paris-Sud, Orsay, France.
    Trojahn, Cassia
    IRIT, France; Universite Toulouse II, Toulouse, France.
    Zamazal, Ondrej
    University of Economics, Prague, Czech Republic.
    Results of the Ontology Alignment Evaluation Initiative 20152015Ingår i: Ontology Matching, 2015, s. 60-115Konferensbidrag (Refereegranskat)
  • 62.
    Chen, Bi
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Tan, He
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Structure-Based Filtering for Ontology Alignment2006Ingår i: Proceedings of the IEEE WETICE Workshop on Semantic Technologies in Collaborative Applications, Institute of Electrical and Electronics Engineers (IEEE), 2006, s. 364-369Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ontologies are an important technology for the Semantic Web and many ontologies have already been developed. Many ontologies also contain overlapping information and to be able to use them together effectively, we need to align them. Some of the current alignment techniques use information about the structure of the ontologies, but they have not produced good results in evaluations. We propose an approach where, in contrast to the other approaches, structural information is used as a filtering method in the alignment process. We evaluate the approach in terms of quality and performance.

  • 63.
    Chiatti, Agnese
    et al.
    Politecnico di Torino, Italy.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Cerquitelli, Tania
    Politecnico di Torino, Italy.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Reducing the search space in ontology alignment using clustering techniques and topic identification2015Ingår i: Proceedings of the 8th International Conference on Knowledge Capture, New York: ACM Digital Library, 2015, s. 21-Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the current challenges in ontology alignment is scalability and one technique to deal with this issue is to reduce the search space for the generation of mapping suggestions. In this paper we develop a method to prune that search space by using clustering techniques and topic identification. Further, we provide experiments showing that we are able to generate partitions that allow for high quality alignments with a highly reduced effort for computation and validation of mapping suggestions for the parts of the ontologies in the partition. Other techniques will still be needed for finding mappings that are not in the partition.

  • 64.
    Chiesa, Marco
    et al.
    Catholic University of Louvain, Belgium.
    Nikolaevskiy, Ilya
    Aalto University, Finland.
    Mitrovic, Slobodan
    Ecole Polytech Federal Lausanne, Switzerland.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten. ITMO University, Russia.
    Madry, Aleksander
    MIT, MA 02139 USA.
    Schapira, Michael
    Hebrew University of Jerusalem, Israel.
    Shenker, Scott
    University of Calif Berkeley, CA 94720 USA; Int Comp Science Institute, CA 94704 USA.
    On the Resiliency of Static Forwarding Tables2017Ingår i: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 25, nr 2, s. 1133-1146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fast reroute and other forms of immediate failover have long been used to recover from certain classes of failures without invoking the network control plane. While the set of such techniques is growing, the level of resiliency to failures that this approach can provide is not adequately understood. In this paper, we embarked upon a systematic algorithmic study of the resiliency of forwarding tables in a variety of models (i.e., deterministic/probabilistic routing, with packet-headerrewriting, with packet-duplication). Our results show that the resiliency of a routing scheme depends on the "connectivity" k of a network, i.e., the minimum number of link deletions that partition a network. We complement our theoretical result with extensive simulations. We show that resiliency to four simultaneous link failures, with limited path stretch, can be achieved without any packet modification/duplication or randomization. Furthermore, our routing schemes provide resiliency against k - 1 failures, with limited path stretch, by storing log(k) bits in the packet header, with limited packet duplication, or with randomized forwarding technique.

  • 65.
    Chisalita, Ioan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Adaptive dissemination of safety data among moving vehicles2006Ingår i: 17th IEEE Personal, Indoor and Mobile Radio Communication Symposium,2006, Helsinki, Finland: IEEE , 2006Konferensbidrag (Refereegranskat)
  • 66.
    Chisalita, Ioan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Emergency information dissemination in mobile networks for vehicles2006Ingår i: International Conference on Wireless Information Networks and Systems, part of the 3rd International Joint Conference on e-Business and Telecommunications,2006, Setubal, Portugal: WINSYS/ICETE , 2006Konferensbidrag (Refereegranskat)
  • 67.
    Chisalita, Ioan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    On the design of safety communication systems for vehicles2007Ingår i: IEEE transactions on systems, man and cybernetics. Part A. Systems and humans, ISSN 1083-4427, E-ISSN 1558-2426, Vol. 37, nr 6, s. 933-945Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Statistics show that the number of casualties due to traffic accidents exceeds one million each year. For the development of systems that prevent vehicle collisions, vehicular communication is considered a promising technology. This paper focuses on design aspects of communication systems that support the development of collaborative active safety systems such as collision warning and collision avoidance. We introduce a design method for safety communication systems that includes a set of analyses and a reasoning system for modeling and analyzing traffic scenarios. An overview of a specific solution for communication is presented in this paper. This solution proposes techniques for network organization and data dissemination that make use of contextual information. This allows the development of a communication system that is adaptable to the specifics of the traffic situation. © 2007 IEEE.

  • 68.
    Chisalita, Ioan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Performance evaluation of safety communication for vehicles2006Ingår i: 3rd International Symposium on Wireless Information Systems,2006, Valencia, Spain: ISWCS/ IEEE , 2006Konferensbidrag (Refereegranskat)
  • 69.
    Christin, Delphine
    et al.
    Technical University of Darmstadt, Germany .
    Rosskopf, Christian
    Technical University of Darmstadt, Germany .
    Hollick, Matthias
    Technical University of Darmstadt, Germany .
    Martucci, Leonardo
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Kanhere, Salil S.
    University of New S Wales, Australia .
    IncogniSense: An anonymity-preserving reputation framework for participatory sensing applications2013Ingår i: 2012 IEEE International Conference on Pervasive Computing and Communications (PerCom), Elsevier , 2013, Vol. 9, nr 3, s. 353-371Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reputation systems are fundamental for assessing the quality of user contributions in participatory sensing. However, naively associating reputation scores to contributions allows adversaries to establish links between multiple contributions and thus de-anonymize users. We present the IncogniSense framework as a panacea to these privacy threats. IncogniSense utilizes periodic pseudonyms generated using blind signature and relies on reputation transfer between these pseudonyms. Simulations are used to analyze various reputation cloaking schemes that address the inherent trade-off between anonymity protection and loss in reputation. Our threat analysis confirms the robustness of IncogniSense and a prototype demonstrates that associated overheads are minimal.

  • 70.
    Cuenca Grau, Bernardo
    et al.
    University of Oxford, UK.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eckert, Kai
    University of Mannheim, Germany.
    Euzenat, Jerome
    INRIA, France.
    Ferrara, Alfio
    Universita degli studi di Milano, Italy.
    Granada, Roger
    Pontifıcia Universidade Catolica do Rio Grande do Sul, Porto Alegre, Brazil.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Jimenez-Ruiz, Ernesto
    University of Oxford, UK.
    Kempf, Oscar Alexander
    Leibniz Institute for the Social Sciences, Cologne, Germany.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Nikolov, Andriy
    Fluid operations, Walldorf, Germany.
    Paulheim, Heiko
    University of Mannheim, Germany.
    Ritze, Dominique
    University of Mannheim, Germany.
    Scharffe, Francois
    LIRMM, Montpellier, France.
    Shvaiko, Pavel
    Informatica Trentina, Trento, Italy.
    Trojahn, Cassia
    Universite Toulouse II, Toulouse, France.
    Zamazal, Ondrej
    University of Economics, Prague, Czech Republic.
    Results of the Ontology Alignment Evaluation Initiative 20132013Ingår i: International Workshop on Ontology Matching, 2013, s. 61-100Konferensbidrag (Refereegranskat)
  • 71.
    Dahlberg, Tobias
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Distributed Storage and Processing of Image Data2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Systems operating in a medical environment need to maintain high standards regarding availability and performance. Large amounts of images are stored and studied to determine what is wrong with a patient. This puts hard requirements on the storage of the images. In this thesis, ways of incorporating distributed storage into a medical system are explored. Products, inspired by the success of Google, Amazon and others, are experimented with and compared to the current storage solutions. Several “non-relational databases” (NoSQL) are investigated for storing medically relevant metadata of images, while a set of distributed file systems are considered for storing the actual images. Distributed processing of the stored data is investigated by using Hadoop MapReduce to generate a useful model of the images' metadata.

  • 72.
    Dan, Gyorgy
    et al.
    KTH Royal Institute of Technology, Stockholm.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Centralized and Distributed Protocols for Tracker-based Dynamic Swarm Management2013Ingår i: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 21, nr 1, s. 297-310Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With BitTorrent, efficient peer upload utilization is achieved by splitting contents into many small pieces, each of which may be downloaded from different peers within the same swarm. Unfortunately, piece and bandwidth availability may cause the file-sharing efficiency to degrade in small swarms with few participating peers. Using extensive measurements, we identified hundreds of thousands of torrents with several small swarms for which reallocating peers among swarms and/or modifying the peer behavior could significantly improve the system performance. Motivated by this observation, we propose a centralized and a distributed protocol for dynamic swarm management. The centralized protocol (CSM) manages the swarms of peers at minimal tracker overhead. The distributed protocol (DSM) manages the swarms of peers while ensuring load fairness among the trackers. Both protocols achieve their performance improvements by identifying and merging small swarms and allow load sharing for large torrents. Our evaluations are based on measurement data collected during eight days from over 700 trackers worldwide, which collectively maintain state information about 2.8 million unique torrents. We find that CSM and DSM can achieve most of the performance gains of dynamic swarm management. These gains are estimated to be up to 40% on average for small torrents.

  • 73.
    Dan, Gyorgy
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Chatzidrossos, Illias
    Royal Institute of Technology, Stockholm, Sweden.
    Efficient and Highly Available Peer Discovery: A Case for Independent Trackers and Gossiping2011Ingår i: 2011 IEEE International Conference on Peer-to-Peer Computing (P2P), IEEE , 2011, s. 290-299Konferensbidrag (Refereegranskat)
    Abstract [en]

    Tracker-based peer-discovery is used in most commercial peer-to-peer content distribution systems, as it provides performance benefits compared to distributed solutions, and facilitates the control and monitoring of the overlay. But a tracker is a central point of failure, and its deployment and maintenance incur costs; hence an important question is how high tracker availability can be achieved at low cost. We investigate highly available, low overhead peer discovery, using independent trackers and a simple gossip protocol. This work is a step towards understanding the trade-off between the overhead and the achievable peer connectivity in highly available distributed overlay-management systems for peer-to-peer content distribution. We propose two protocols that connect peers in different swarms efficiently with a constant, but tunable, overhead. The two protocols, Random Peer Migration (RPM) and Random Multi-Tracking (RMT), employ a small fraction of peers in a torrent to virtually increase the size of swarms. We develop analytical models of the protocols based on renewal theory, and validate the models using both extensive simulations and controlled experiments. We illustrate the potential value of the protocols using large-scale measurement data that contains hundreds of thousands of public torrents with several small swarms, with limited peer connectivity. We estimate the achievable gains to be up to 40% on average for small torrents.

  • 74.
    Dan, György
    et al.
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dynamic Content Allocation for Cloud-assisted Service of Periodic Workloads2014Ingår i: INFOCOM 2014, IEEE , 2014, s. 853-861Konferensbidrag (Refereegranskat)
    Abstract [en]

    Motivated by improved models for content workload prediction, in this paper we consider the problem of dynamic content allocation for a hybrid content delivery system that combines cloud-based storage with low cost dedicated servers that have limited storage and unmetered upload bandwidth. We formulate the problem of allocating contents to the dedicated storage as a finite horizon dynamic decision problem, and show that a discrete time decision problem is a good approximation for piecewise stationary workloads. We provide an exact solution to the discrete time decision problem in the form of a mixed integerlinear programming problem, propose computationally feasible approximations, and give bounds on their approximation ratios.Finally, we evaluate the algorithms using synthetic and measuredtraces from a commercial music on-demand service and give insight into their performance as a function of the workload characteristics.

  • 75.
    Dawelbait, Gihan
    et al.
    Technische Universität Dresden, Germany.
    Doms, Andreas
    Technische Universität Dresden, Germany.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Royer, Loic
    Technische Universität Dresden, Germany.
    Schroeder, Michael
    Technische Universität Dresden, Germany.
    Bioinformatics Demonstrators2006Rapport (Övrigt vetenskapligt)
  • 76.
    de Leng, Daniel
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerade datorsystem. Linköpings universitet, Tekniska fakulteten.
    Tiger, Mattias
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerade datorsystem. Linköpings universitet, Tekniska fakulteten.
    Almquist, Mathias
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Almquist, Viktor
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Second Screen Journey to the Cup: Twitter Dynamics during the Stanley Cup Playoffs2018Ingår i: Proceedings of the 2nd Network Traffic Measurement and Analysis Conference (TMA), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    With Twitter and other microblogging services, users can easily express their opinion and ideas in short text messages. A recent trend is that users use the real-time property of these services to share their opinions and thoughts as events unfold on TV or in the real world. In the context of TV broadcasts, Twitter (over a mobile device, for example) is referred to as a second screen. This paper presents the first characterization of the second screen usage over the playoffs of a major sports league. We present both temporal and spatial analysis of the Twitter usage during the end of the National Hockey League (NHL) regular season and the 2015 Stanley Cup playoffs. Our analysis provides insights into the usage patterns over the full 72-day period and with regards to in-game events such as goals, but also with regards to geographic biases. Quantifying these biases and the significance of specific events, we then discuss and provide insights into how the playoff dynamics may impact advertisers and third-party developers that try to provide increased personalization.

  • 77.
    Doms, Andreas
    et al.
    Technische Universität Dresden, Germany.
    Jakoniené, Vaida
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Schroeder, Michael
    Technische Universität Dresden, Germany.
    Wächter, Thomas
    Technische Universität Dresden, Germany.
    Ontologies and Text Mining as a Basis for a Semantic Web for the Life Sciences2006Ingår i: Reasoning Web, Second International Summer School: Summer School 2006, Lisbon, Portugal, September 4-8, 2006, Tutorial Lectures / [ed] Pedro BarahonaFrançois Bry, Enrico Franconi, Nicola Henze et, Springer Berlin/Heidelberg, 2006, s. 164-183Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This book presents thoroughly arranged tutorial papers corresponding to lectures given by leading researchers at the Second International Summer School on Reasoning Web in Lisbon, Portugal, in September 2006. Building on the predessor school held in 2005 and published as LNCS 3564, the ten tutorial lectures presented provide competent coverage of current topics in semantic Web research and development.

  • 78.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Completing the Is-a Structure in Description Logics Ontologies2014Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The World Wide Web contains large amounts of data and in most cases this data is without any explicit structure. The lack of structure makes it difficult for automated agents to understand and use such data. A step towards a more structured World Wide Web is the idea of the Semantic Web which aims at introducing semantics to data on the World Wide Web. One of the key technologies in this endeavour are ontologies which provide means for modeling a domain of interest.

    Developing and maintaining ontologies is not an easy task and it is often the case that defects are introduced into ontologies. This can be a problem for semantically-enabled applications such as ontology-based querying. Defects in ontologies directly influence the quality of the results of such applications as correct results can be missed and wrong results can be returned.

    This thesis considers one type of defects in ontologies, namely the problem of completing the is-a structure in ontologies represented in description logics. We focus on two variants of description logics, the EL family and ALC, which are often used in practice.

    The contributions of this thesis are as follows. First, we formalize the problem of completing the is-a structure as a generalized TBox abduction problem (GTAP) which is a new type of abduction problem in description logics. Next, we provide algorithms for solving GTAP in the EL family and ALC description logics. Finally, we describe two implemented systems based on the introduced algorithms. The systems were evaluated in two experiments which have shown the usefulness of our approach. For example, in one experiment using ontologies from the Ontology Alignment Evaluation Initiative 58 and 94 detected missing is-a relations were repaired by adding 54 and 101 is-a relations, respectively, introducing new knowledge to the ontologies.

  • 79.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Completion of Ontologies and Ontology Networks2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The World Wide Web contains large amounts of data, and in most cases this data has no explicit structure. The lack of structure makes it difficult for automated agents to understand and use such data. A step towards a more structured World Wide Web is the Semantic Web, which aims at introducing semantics to data on the World Wide Web. One of the key technologies in this endeavour are ontologies, which provide a means for modeling a domain of interest and are used for search and integration of data.

    In recent years many ontologies have been developed. To be able to use multiple ontologies it is necessary to align them, i.e., find inter-ontology relationships. However, developing and aligning ontologies is not an easy task and it is often the case that ontologies and their alignments are incorrect and incomplete. This can be a problem for semantically-enabled applications. Incorrect and incomplete ontologies and alignments directly influence the quality of the results of such applications, as wrong results can be returned and correct results can be missed. This thesis focuses on the problem of completing ontologies and ontology networks.

    The contributions of the thesis are threefold. First, we address the issue of completing the is-a structure and alignment in ontologies and ontology networks. We have formalized the problem of completing the is-a structure in ontologies as an abductive reasoning problem and developed algorithms as well as systems for dealing with the problem. With respect to the completion of alignments, we have studied system performance in the Ontology Alignment Evaluation Initiative, a yearly evaluation campaign for ontology alignment systems. We have also addressed the scalability of ontology matching, which is one of the current challenges, by developing an approach for reducing the search space when generating the alignment.Second, high quality completion requires user involvement. As users' time and effort are a limited resource we address the issue of limiting and facilitating user interaction in the completion process. We have conducted a broad study of state-of-the-art ontology alignment systems and identified different issues related to the process. We have also conducted experiments to assess the impact of user errors in the completion process.

    While the completion of ontologies and ontology networks can be done at any point in the life-cycle of ontologies and ontology networks, some of the issues can be addressed already in the development phase. The third contribution of the thesis addresses this by introducing ontology completion and ontology alignment into an existing ontology development methodology.

    Delarbeten
    1. Completing the is-a structure in light-weight ontologies
    Öppna denna publikation i ny flik eller fönster >>Completing the is-a structure in light-weight ontologies
    2015 (Engelska)Ingår i: Journal of Biomedical Semantics, ISSN 2041-1480, E-ISSN 2041-1480, Vol. 6, artikel-id 12Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

     Background: With the increasing presence of biomedical data sources on the Internet more and more research effort is put into finding possible ways for integrating and searching such often heterogeneous sources. Ontologies are a key technology in this effort. However, developing ontologies is not an easy task and often the resulting ontologies are not complete. In addition to being problematic for the correct modelling of a domain, such incomplete ontologies, when used in semantically-enabled applications, can lead to valid conclusions being missed.

    Results: We consider the problem of repairing missing is-a relations in ontologies. We formalize the problem as a generalized TBox abduction problem. Based on this abduction framework, we present complexity results for the existence, relevance and necessity decision problems for the generalized TBox abduction problem with and without some specific preference relations for ontologies that can be represented using a member of the EL family of description logics. Further, we present algorithms for finding solutions, a system as well as experiments.

    Conclusions: Semantically-enabled applications need high quality ontologies and one key aspect is their completeness. We have introduced a framework and system that provides an environment for supporting domain experts to complete the is-a structure of ontologies. We have shown the usefulness of the approach in different experiments. For the two Anatomy ontologies from the Ontology Alignment Evaluation Initiative, we repaired 94 and 58 initial given missing is-a relations, respectively, and detected and repaired additionally, 47 and 10 missing is-a relations. In an experiment with BioTop without given missing is-a relations, we detected and repaired 40 new missing is-a relations.

    Nationell ämneskategori
    Datavetenskap (datalogi) Bioinformatik (beräkningsbiologi)
    Identifikatorer
    urn:nbn:se:liu:diva-116628 (URN)10.1186/s13326-015-0002-8 (DOI)000353197200001 ()25883780 (PubMedID)
    Forskningsfinansiär
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)
    Tillgänglig från: 2015-03-29 Skapad: 2015-03-29 Senast uppdaterad: 2018-01-11
    2. Get my pizza right: Repairing missing is-a relations in ALC ontologies
    Öppna denna publikation i ny flik eller fönster >>Get my pizza right: Repairing missing is-a relations in ALC ontologies
    2012 (Engelska)Ingår i: Second Joint International Semantic Technology Conference, Springer Berlin/Heidelberg, 2012, s. 17-32Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    With the increased use of ontologies in semantically-enabled applications, the issue of debugging defects in ontologies has become increasingly important. These defects can lead to wrong or incomplete results for the applications. Debugging consists of the phases of detection and repairing. In this paper we focus on the repairing phase of a particular kind of defects, i.e. the missing relations in the is-a hierarchy. Previous work has dealt with the case of taxonomies. In this work we extend the scope to deal with ALC ontologies that can be represented using acyclic terminologies. We present algorithms and discuss a system.

    Ort, förlag, år, upplaga, sidor
    Springer Berlin/Heidelberg, 2012
    Serie
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 7774
    Nyckelord
    ontologies, ontology engineering, ontology debugging, knowledge representation
    Nationell ämneskategori
    Datavetenskap (datalogi)
    Identifikatorer
    urn:nbn:se:liu:diva-91435 (URN)10.1007/978-3-642-37996-3_2 (DOI)978-3-642-37995-6 (ISBN)978-3-642-37996-3 (ISBN)
    Konferens
    Joint International Semantic Technology Conference
    Forskningsfinansiär
    Swedish e‐Science Research CenterVetenskapsrådet, 2010-4759CUGS (National Graduate School in Computer Science)
    Tillgänglig från: 2013-04-24 Skapad: 2013-04-24 Senast uppdaterad: 2018-07-17
    3. Reducing the search space in ontology alignment using clustering techniques and topic identification
    Öppna denna publikation i ny flik eller fönster >>Reducing the search space in ontology alignment using clustering techniques and topic identification
    2015 (Engelska)Ingår i: Proceedings of the 8th International Conference on Knowledge Capture, New York: ACM Digital Library, 2015, s. 21-Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    One of the current challenges in ontology alignment is scalability and one technique to deal with this issue is to reduce the search space for the generation of mapping suggestions. In this paper we develop a method to prune that search space by using clustering techniques and topic identification. Further, we provide experiments showing that we are able to generate partitions that allow for high quality alignments with a highly reduced effort for computation and validation of mapping suggestions for the parts of the ontologies in the partition. Other techniques will still be needed for finding mappings that are not in the partition.

    Ort, förlag, år, upplaga, sidor
    New York: ACM Digital Library, 2015
    Nyckelord
    Knowledge representation, data mining, ontology alignment
    Nationell ämneskategori
    Datavetenskap (datalogi)
    Identifikatorer
    urn:nbn:se:liu:diva-121838 (URN)10.1145/2815833.2816959 (DOI)978-1-4503-3849-3 (ISBN)
    Konferens
    8th International Conference on Knowledge Capture
    Forskningsfinansiär
    CUGS (National Graduate School in Computer Science)Swedish e‐Science Research CenterEU, FP7, Sjunde ramprogrammet, FP7-IP-608142
    Tillgänglig från: 2015-10-09 Skapad: 2015-10-09 Senast uppdaterad: 2018-01-11
    4. Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative
    Öppna denna publikation i ny flik eller fönster >>Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative
    2017 (Engelska)Ingår i: Journal of Biomedical Semantics, ISSN 2041-1480, E-ISSN 2041-1480, Vol. 8, artikel-id 56Artikel, forskningsöversikt (Refereegranskat) Published
    Abstract [en]

    Background: One of the longest running tracks in the Ontology Alignment Evaluation Initiative is the Anatomy track which focuses on aligning two anatomy ontologies. The Anatomy track was started in 2005. In 2005 and 2006 the task in this track was to align the Foundational Model of Anatomy and the OpenGalen Anatomy Model. Since 2007 the ontologies used in the track are the Adult Mouse Anatomy and a part of the NCI Thesaurus. Since 2015 the data in the Anatomy track is also used in the Interactive track of the Ontology Alignment Evaluation Initiative.

    Results: In this paper we focus on the Anatomy track in the years 2007-2016 and the Anatomy part of the Interactive track in 2015-2016. We describe the data set and the changes it went through during the years. Further, we give an overview of all systems that participated in the track and the techniques they have used. We discuss the performance results of the systems and summarize the general trends.

    Conclusions: About 50 systems have participated in the Anatomy track. Many different techniques were used. The most popular matching techniques are string-based strategies and structure-based techniques. Many systems also use auxiliary information. The quality of the alignment has increased for the best performing systems since the beginning of the track and more and more systems check the coherence of the proposed alignment and implement a repair strategy.Further, interacting with an oracle is beneficial.

    Ort, förlag, år, upplaga, sidor
    BioMed Central, 2017
    Nyckelord
    ontologies, ontology matching, OAEI, anatomy
    Nationell ämneskategori
    Datavetenskap (datalogi)
    Identifikatorer
    urn:nbn:se:liu:diva-139775 (URN)10.1186/s13326-017-0166-5 (DOI)000416915300001 ()29202830 (PubMedID)
    Forskningsfinansiär
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)EU, FP7, Sjunde ramprogrammet, FP7-IP-608142
    Anmärkning

    Funding agencies: Swedish e-Science Research Centre (SeRC); Swedish national graduate school in computer science (CUGS); EU project VALCRI [FP7-IP-608142]

    Tillgänglig från: 2017-08-21 Skapad: 2017-08-21 Senast uppdaterad: 2018-01-13
    5. User validation in ontology alignment
    Öppna denna publikation i ny flik eller fönster >>User validation in ontology alignment
    Visa övriga...
    2016 (Engelska)Ingår i: The Semantic Web - ISWC 2016: 15th International Semantic Web Conference, Kobe, Japan, October 17–21, 2016, Proceedings, Part I / [ed] Paul Groth, Elena Simperl, Alasdair Gray, Marta Sabou, Markus Krötzsch, Freddy Lecue, Fabian Flöck and Yolanda Gil, Cham, Switzerland: Springer Publishing Company, 2016, s. 200-217Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    User validation is one of the challenges facing the ontology alignment community, as there are limits to the quality of automated alignment algorithms. In this paper we present a broad study on user validation of ontology alignments that encompasses three distinct but interrelated aspects: the profile of the user, the services of the alignment system, and its user interface. We discuss key issues pertaining to the alignment validation process under each of these aspects, and provide an overview of how current systems address them. Finally, we use experiments from the Interactive Matching track of the Ontology Alignment Evaluation Initiative (OAEI) 2015 to assess the impact of errors in alignment validation, and how systems cope with them as function of their services.

    Ort, förlag, år, upplaga, sidor
    Cham, Switzerland: Springer Publishing Company, 2016
    Serie
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 9981
    Nyckelord
    knowledge representation, user interfaces, ontology engineering, ontology alignment
    Nationell ämneskategori
    Datavetenskap (datalogi)
    Identifikatorer
    urn:nbn:se:liu:diva-131806 (URN)10.1007/978-3-319-46523-4_13 (DOI)000389086500013 ()9783319465227 (ISBN)9783319465234 (ISBN)
    Konferens
    International Semantic Web Conference
    Forskningsfinansiär
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)EU, FP7, Sjunde ramprogrammet, FP7-IP-608142
    Tillgänglig från: 2016-10-07 Skapad: 2016-10-07 Senast uppdaterad: 2018-07-17Bibliografiskt granskad
    6. Integrating Ontology Debugging and Matching into the eXtreme Design Methodology
    Öppna denna publikation i ny flik eller fönster >>Integrating Ontology Debugging and Matching into the eXtreme Design Methodology
    2015 (Engelska)Ingår i: Proceedings of the 6th Workshop on Ontology and Semantic Web Patterns (WOP 2015) / [ed] Eva Blomqvist; Pascal Hitzler; Adila Krisnadhi; Tom Narock; Monika Solanki, Rheinisch-Westfaelische Technische Hochschule Aachen University , 2015Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Ontology design patterns (ODPs) and related ontology development methodologies were designed as ways of sharing and reusing best practices in ontology engineering. However, while the use of these reduces the number of issues in the resulting ontologies defects can still be introduced into the ontology due to improper use or misinterpretation of the patterns. Thus, the quality of the developed ontologies is still a major concern. In this paper we address this issue by describing how ontology debugging and matching can be integrated in a state-of-the-art ontology development methodology based on ontology design patterns- the eXtreme Design methodology, and show the advantages in a case study based on a real world ontology.

    Ort, förlag, år, upplaga, sidor
    Rheinisch-Westfaelische Technische Hochschule Aachen University, 2015
    Serie
    CEUR Workshop Proceedings, ISSN 1613-0073 ; 1461
    Nationell ämneskategori
    Medieteknik
    Identifikatorer
    urn:nbn:se:liu:diva-121794 (URN)
    Konferens
    6th Workshop on Ontology and Semantic Web Patterns (WOP 2015), Bethlehem, Pensylvania, USA, October 11, 2015
    Forskningsfinansiär
    EU, FP7, Sjunde ramprogrammet, FP7-IP-608142CUGS (National Graduate School in Computer Science)Swedish e‐Science Research Center
    Tillgänglig från: 2015-10-06 Skapad: 2015-10-06 Senast uppdaterad: 2018-01-11Bibliografiskt granskad
  • 80.
    Dragisic, Zlatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eckert, Kai
    University of Mannheim, Mannheim, Germany.
    Euzenat, Jerome
    INRIA, France; University of Grenoble-Alpes, Grenoble, France.
    Faria, Daniel
    Universidade de Lisboa, Portugal.
    Ferrara, Alfio
    Universita degli studi di Milano, Italy.
    Granada, Roger
    Pontifıcia Universidade Catolica do Rio Grande do Sul, Porto Alegre, Brazil; IRIT & Universite Toulouse II, Toulouse, France.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Jimenez-Ruiz, Ernesto
    University of Oxford, UK.
    Kempf, Andreas
    Leibniz Institute for the Social Sciences, Cologne, Germany.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Montanelli, Stefano
    Universita degli studi di Milano, Italy.
    Paulheim, Heiko
    University of Mannheim, Mannheim, Germany.
    Ritze, Dominique
    University of Mannheim, Mannheim, Germany.
    Shvaiko, Pavel
    Informatica Trentina, Trento, Italy.
    Solimando, Alessandro
    University of Genova, Italy.
    Trojahn, Cassia
    IRIT, France; Universite Toulouse II, Toulouse, France.
    Zamazal, Ondrej
    University of Economics, Prague, Czech Republic.
    Cuenca Grau, Bernardo
    University of Oxford, UK.
    Results of the Ontology Alignment Evaluation Initiative 20142014Ingår i: International Workshop on Ontology Matching, 2014, s. 61-104Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ontology matching consists of finding correspondences between se-mantically related entities of two ontologies. OAEI campaigns aim at comparingontology matching systems on precisely defined test cases. These test cases canuse ontologies of different nature (from simple thesauri to expressive OWL on-tologies) and use different modalities, e.g., blind evaluation, open evaluation andconsensus. OAEI 2014 offered 7 tracks with 9 test cases followed by 14 partici-pants. Since 2010, the campaign has been using a new evaluation modality which provides more automation to the evaluation. This paper is an overall presentationof the OAEI 2014 campaign.

  • 81.
    Dragisic, Zlatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Faria, Daniel
    Gulbenkian Science Institute, Oeiras, Portugal.
    Jimenez-Ruiz, Ernesto
    University of Oxford, Oxford, UK.
    Pesquita, Catia
    LaSIGE, Faculdade de Ciencias, Universidade de Lisboa, Lisboa, Portugal.
    User validation in ontology alignment2016Ingår i: The Semantic Web - ISWC 2016: 15th International Semantic Web Conference, Kobe, Japan, October 17–21, 2016, Proceedings, Part I / [ed] Paul Groth, Elena Simperl, Alasdair Gray, Marta Sabou, Markus Krötzsch, Freddy Lecue, Fabian Flöck and Yolanda Gil, Cham, Switzerland: Springer Publishing Company, 2016, s. 200-217Konferensbidrag (Refereegranskat)
    Abstract [en]

    User validation is one of the challenges facing the ontology alignment community, as there are limits to the quality of automated alignment algorithms. In this paper we present a broad study on user validation of ontology alignments that encompasses three distinct but interrelated aspects: the profile of the user, the services of the alignment system, and its user interface. We discuss key issues pertaining to the alignment validation process under each of these aspects, and provide an overview of how current systems address them. Finally, we use experiments from the Interactive Matching track of the Ontology Alignment Evaluation Initiative (OAEI) 2015 to assess the impact of errors in alignment validation, and how systems cope with them as function of their services.

  • 82.
    Dragisic, Zlatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Li, Huanyu
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative2017Ingår i: Journal of Biomedical Semantics, ISSN 2041-1480, E-ISSN 2041-1480, Vol. 8, artikel-id 56Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Background: One of the longest running tracks in the Ontology Alignment Evaluation Initiative is the Anatomy track which focuses on aligning two anatomy ontologies. The Anatomy track was started in 2005. In 2005 and 2006 the task in this track was to align the Foundational Model of Anatomy and the OpenGalen Anatomy Model. Since 2007 the ontologies used in the track are the Adult Mouse Anatomy and a part of the NCI Thesaurus. Since 2015 the data in the Anatomy track is also used in the Interactive track of the Ontology Alignment Evaluation Initiative.

    Results: In this paper we focus on the Anatomy track in the years 2007-2016 and the Anatomy part of the Interactive track in 2015-2016. We describe the data set and the changes it went through during the years. Further, we give an overview of all systems that participated in the track and the techniques they have used. We discuss the performance results of the systems and summarize the general trends.

    Conclusions: About 50 systems have participated in the Anatomy track. Many different techniques were used. The most popular matching techniques are string-based strategies and structure-based techniques. Many systems also use auxiliary information. The quality of the alignment has increased for the best performing systems since the beginning of the track and more and more systems check the coherence of the proposed alignment and implement a repair strategy.Further, interacting with an oracle is beneficial.

  • 83.
    Dragisic, Zlatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Blomqvist, Eva
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten.
    Integrating Ontology Debugging and Matching into the eXtreme Design Methodology2015Ingår i: Proceedings of the 6th Workshop on Ontology and Semantic Web Patterns (WOP 2015) / [ed] Eva Blomqvist; Pascal Hitzler; Adila Krisnadhi; Tom Narock; Monika Solanki, Rheinisch-Westfaelische Technische Hochschule Aachen University , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ontology design patterns (ODPs) and related ontology development methodologies were designed as ways of sharing and reusing best practices in ontology engineering. However, while the use of these reduces the number of issues in the resulting ontologies defects can still be introduced into the ontology due to improper use or misinterpretation of the patterns. Thus, the quality of the developed ontologies is still a major concern. In this paper we address this issue by describing how ontology debugging and matching can be integrated in a state-of-the-art ontology development methodology based on ontology design patterns- the eXtreme Design methodology, and show the advantages in a case study based on a real world ontology.

  • 84.
    Dragisic, Zlatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Wei-Kleiner, Fang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A System for Debugging Missing Is-a Structure in EL Ontologies2014Ingår i: Proceedings of the Third International Workshop on Debugging Ontologies and Ontology Mappings - WoDOOM14, 2014, s. 51-58Konferensbidrag (Refereegranskat)
  • 85.
    Dragisic, Zlatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Wei-Kleiner, Fang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Completing the is-a structure of biomedical ontologies2014Ingår i: Data Integration in the Life Sciences 10th International Conference, DILS 2014, Lisbon, Portugal, July 17-18, 2014. Proceedings / [ed] Helena Galhardas, Erhard Rahm, Berlin: Springer Science+Business Media B.V., 2014, s. 66-80Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ontologies in the biomedical domain are becoming a key element for data integration and search. The usefulness of the applications which use ontologies is often directly influenced by the quality of ontologies, as incorrect or incomplete ontologies might lead to wrong or incomplete results for the applications. Therefore, there is an increasing need for repairing defects in ontologies. In this paper we focus on completing ontologies. We provide an algorithm for completing the is-a structure in TeX ontologies which covers many biomedical ontologies. Further, we present an implemented system based on the algorithm as well as an evaluation using three biomedical ontologies.

  • 86.
    Duma, Claudiu
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Herzog, Almut
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Privacy in the Semantic Web: What Policy Languages Have to Offer2007Ingår i: IEEE Workshop on Policies for Distributed Systems and Networks,2007, Bologna, Italy: IEEE , 2007, s. 109-Konferensbidrag (Refereegranskat)
  • 87.
    Duma, Claudiu
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Karresand, Martin
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan. IDA Linköpings universitet.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Caronni, Germano
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    A Trust-Aware, P2P-Based Overlay for Intrusion Detection2006Ingår i: International Workshop on Database and Expert Systems Applications DEXA06,2006, IEEE , 2006, s. 692-Konferensbidrag (Refereegranskat)
  • 88.
    Duma, Claudiu
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A flexible category-based collusion-resistant key management scheme for multicast2003Ingår i: Security and privacy in the age of uncertainty: IFIP TC11 18th International Conference on Information Security (SEC2003) May 26-28, 2003, Athens, Greece / [ed] Dimitris Gritzalis; Sabrina De Capitani di Vimercati; Pierangela Samarati; Sokratis Katsikas, Kluwer Academic Publishers, 2003, s. 133-144Konferensbidrag (Refereegranskat)
    Abstract [en]

    Current key management schemes for multicast provide either no resistance to collusion or perfect resistance to collusion. However, resistance to collusion is achieved at the expense of efficiency in terms of the number of transmissions and the number of keys that are used. We argue that applications may have certain assumptions regarding the users and their access to the multicast channel that may be used to provide a broader range of choices for balancing efficiency against resistance to collusion.

    We formalize the collusion requirement based upon the users' access to the multicast channel. Different user categorizations give different degrees of collusion resistance and we show that the existing work has focused on special cases of user categorizations. Further, we go on to propose and evaluate a flexible key management strategy for the general case where the accessibility relation defines the order of exclusion of the categories. The theoretical and experimental results show that our scheme has good performance regarding transmissions and keys per controller.

  • 89.
    Duma, Claudiu
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A hybrid key tree scheme for multicast to balance security and efficiency requirement2003Ingår i: Proceedings of the Twelfth IEEE International Workshops on Enabling Technologies: Infrastructure for Collaborative Enterprises (WET ICE '03), Institute of Electrical and Electronics Engineers (IEEE), 2003, s. 208-213Konferensbidrag (Refereegranskat)
    Abstract [en]

    Security and efficiency of rekeying are crucial requirements for multicast key management. However, the two requirements pull in different directions and balancing them to meet the application needs is still an open issue. In this paper we introduce a hybrid key tree scheme to balance security, namely the resistance to collusion, and the efficiency. The resistance to collusion is measured by an integer parameter. The communication and the storage requirements for the controller depend on this parameter too, and they decrease as the resistance to collusion is relaxed. We analytically evaluate the efficiency of our scheme and compare with the previous work. The results show that our scheme allows a fine-tuning of security requirements versus efficiency requirements at run-time, which is not possible with the previous key management schemes.

  • 90.
    Duma, Claudiu
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Efficient storage for category-based group key management2004Ingår i: Proceedings of the 5th Conference on Computer Science and Systems Engineering in Linköping, 2004, s. 139-146Konferensbidrag (Refereegranskat)
    Abstract [en]

    In multicast group communication, efficiency- and security are competing requirements and balancing them is an acknowledged challenge. In particular, the collusion resistance has an impact on the efficiency of any scheme. In this context, the category-based group key management (category-based GKM) scheme balances the collusion resistance constraints against the communication cost and the group controller storage. However, this scheme increases the storage requirements for users. In this paper we address this problem by introducing a novel technique based on spanning hash key tree (SKT). In the worst case, using our t echnique, the storage requirement remains the same as in the original category-based GKM scheme. However, the experimentalresults show that, in general, the SKT technique greatly reduces the key storage for the users as well as for the controller.

  • 91.
    Ekendahl, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ada code generation support for Google Protocol Buffers2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    We now live in an information society where increasingly large volumes of data are exchanged between networked nodes in distributed systems. Recent years have seen a multitude of dierent serialization frameworks released to efficiently handle all this information while minimizing developer effort. One such format is Google Protocol Buers, which has gained additional code generation support for a wide variety of programming languages from third-party developers.

    Ada is a widely used programming language in safety-critical systems today. However, it lacks support for Protocol Buffers. This limits the use of Protocol Buffers at companies like Saab, where Ada is the language of choice for many systems. To amend this situation Ada code generation support for Protocol Buffers has been developed. The developed solution supports a majority of Protocol Buffers' language constructs, extensions being a notable exception.

    To evaluate the developed solution, an artificial benchmark was constructed and a comparison was made with GNATColl.JSON. Although the benchmark was artificial, data used by the benchmark followed the same format as an existing radar system. The benchmark showed that if serialization performance is a limiting factor for the radar system, it could potentially receive a significant speed boost from a substitution of serialization framework. Results from the benchmark reveal that Protocol Buffers is about 6 to 8 times faster in a combined serialization/deserialization performance comparison. In addition, the change of serialization format has the added benefit of reducing size of serialized objects by approximately 45%.

  • 92.
    Ellkvist, Tommy
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Koop, David
    University of Utah.
    Freire, Juliana
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan. University of Utah.
    Silvia, Claudiu
    University of Utah.
    Strömbäck, Lena
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Using Mediation to Achieve Provenance Interoperability2009Ingår i: 2009 Congress on Services - I, IEEE Press, 2009, s. 291-298Konferensbidrag (Refereegranskat)
    Abstract [en]

    Provenance is essential in scientific experiments. It contains information that is key to preserving the data, to determining their quality and authorship, and to reproduce as well as validate the results. In complex experiments and analyses, where multiple tools are used to derive data products, provenance captured by these tools must be combined in order to determine the complete lineage of the derived products. In this paper we describe a mediator-based architecture for integrating provenance information from multiple sources. This architecture contains two key components: a global mediated schema that is general and capable of representing provenance information represented in different model; and describe a new system-independent query API that is general and able to express complex queries over provenance information from different sources. We also present a case study where we show how this model was applied to integrate provenance from three provenance-enabled systems and discuss the issues involved in this integration process.

  • 93.
    Ellkvist, Tommy
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Strömbäck, Lena
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Didier Linz, Lauro
    University of Utah.
    Freire, Juliana
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan. University of Utah.
    A First Study on Strategies for Generating Workflow Snippets2009Ingår i: The first International Workshop on Keyword Search ob structured data KEYS 2009, Collocated with ACM SIGMOD/PODS, Association for Computing Machinery (ACM), 2009, s. 15-20Konferensbidrag (Refereegranskat)
    Abstract [en]

    Workflows are increasingly being used to specify computational tasks, from simulations and data analysis to the creation of Web mashups. Recently, a number of public workflow repositories have become available, for example, myExperiment for scientific workflows, and Yahoo! Pipes. Workflow collections are also commonplace in many scientific projects. Having such collections opens up new opportunities for knowledge sharing and re-use. But for this to become a reality, mechanisms are needed that help users explore these collections and locate useful workflows. Although there has been work on querying workflows, not much attention has been given to presenting query results. In this paper, we take a first look at the requirements for workflow snippets and study alternative techniques for deriving concise, yet informative snippets.

  • 94.
    Ellqvist, Tommy
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Koop, David
    CS University of Utah.
    Anderson, Erik W.
    SCI University of Utah.
    Freire, Juliana
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan. University of Utah.
    Silva, Claudio
    SCI University of Utah.
    Using Provenance to Support Real-Time Collaborative Design of Workflows2008Ingår i: Second International Provenance and Annotation Workshop,2008, New York: Springer , 2008, Vol. 5272, s. 266-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Because designing workflows is a notoriously difficult task, it often requires multiple users to collaborate. In such scenarios, sharing workflow evolution provenance in a timely manner is critical. We present an environment where collaborating users can see each other’s changes in real-time. The synchronization of workflow evolution provenance is automatic, immediate, and unobtrusive, allowing users to see collaborators’ changes as they are made. This enables a richer and fuller method of collaboration. We present the interface and algorithm for the synchronization and discuss common scenarios where this mechanism has been utilized.

  • 95.
    Ellqvist, Tommy
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Koop, David
    University of Utah, USA.
    Freire, Juliana
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan. University of Utah.
    Silva, Claudio
    University of Utah, USA.
    Strömbäck, Lena
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Using Mediation to Achieve Provenance Interoperability2008Ingår i: 2009 World Conference on Services - I, IEEE , 2008, s. 398-399Konferensbidrag (Refereegranskat)
    Abstract [en]

    Provenance is essential in scientific experiments. It contains information that is key to preserving the data and to determine its quality and uthorship. In complex experiments and analyses, where multiple tools are used to derive data products, provenance captured by these tools must be combined in order to determine the complete lineage of the derived products. We propose a mediator-based architecture to integrate provenance information from multiple sources, which contains two key components: a global mediated schema that is general and capable of representing provenance information represented in different models; and an expressive query interface that supports complex queries over provenance information spread over multiple different sources. We also present a case study where we show how this model was applied to integrate provenance from three provenance-enabled systems.

  • 96.
    Elo, Hans-Filip
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Opera Software.
    Exploring web protocols for use on cellular networks: QUIC on poor network links2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    New developments in web transport such as HTTP/2 and first and foremost QUIC promise fewer connections to track as well as shorter connection setup times. These protocols have proven themselves on modern reliable connections with a high bandwidth-delay-product, but how do they perform over cellular connections in rural or crowded areas where the connections are much more unreliable? A lot of new users of the web in todays mobile-first usage scenarios are located on poor connections.

    A testbench was designed that allowed for web browsing over limited network links in a con- trolled environment. We have compared the network load time of page loading over the protocols QUIC, HTTP/2 and HTTP/1.1 using a variety of different network conditions. We then used these measurements as a basis for suggesting which protocol to use during different conditions.

    The results show that newer is not always better. QUIC in general works reasonably well under all conditions, while HTTP/1.1 and HTTP/2 trade blows depending on connection conditions, with HTTP/1.1 sometimes outperforming both of the newer protocols.

  • 97.
    Engvall, Christoffer
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Security in Wireless Sensor Networks for Open Controller2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this thesis we develop, evaluate and implement a security solution for Open Controllers wireless sensor network platform. A scenario is used to describe an exemplar application showing how our system is supposed to function. The security of the platform is analyzed using a well-established threat modeling process and attack trees which result in the identification of a number of risks, which could be security weaknesses. These attack trees visualize the security weaknesses in an easy to access way even for individuals without special security expertise. We develop a security solution to counter these identified risks. The developed security solution consists of three different security levels together with a number of new security policies. Each additional level applies different security mechanisms to provide increasingly improved security for the platform. The new security policies ensure that the security solution is continuously secure during its operating time. We implement part of the security solution in the Contiki operating system to assess its function in practice. Finally we evaluate the developed security solution by looking back to the previously identified weaknesses and the implementation proving that the security solution mitigates the risks.

  • 98.
    Ericsson, Joakim
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Object Migration in a Distributed, Heterogeneous SQL Database Network2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    There are many different database management systems (DBMSs) on the market today. They all have different strengths and weaknesses. What if all of these different DBMSs could be used together in a heterogeneous network? The purpose of this thesis is to explore ways of connecting the many different DBMSs together. This thesis will explore suitable architectures, features, and performance of such a network. This is all done in the context of Ericsson’s wireless communication network. This has not been done in this context before, and a big part of the thesis is exploring if it is even possible. The result of this thesis shows that it is not possible to find a solution that can fulfill the requirements of such a network in this context

  • 99.
    Eriksson, Jesper
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Hakim, Amir
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Format Conversions and Query Rewriting for RDF* and SPARQL*2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Resource Description Framework (RDF) is a modern graph database model which has a proposed extension called RDF*. However, currently there are no tools available that allow for transitions between RDF and RDF*. In this thesis tools were developed that allow for conversions between these two formats. A conversion tool for transforming RDF’s associated query language SPARQL into SPARQL* was also made. Furthermore, tools for converting between RDF* and another graph database model called Property Graph were developed. Measurements of the memory usage and conversion times for the developed conversion tools were made. Where possible, tests were also performed to control that there was no data loss in the conversions. The results showed varying memory usage and conversion times for the different conversions and that some conversions were very difficult to check for data corruption. Complex testing tools would be required to make sure all conversions are made correctly.

  • 100.
    Eriksson, Oskar
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A web-based tool for managing intellectual property laws2013Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Ipendo Systems AB är ett företag som tillhandahåller en webbaserad tjänst, Ipendo Platform, för administration av immateriella rättigheter. De lagar och regler som reglerar hur immateriella rättigheterna hanteras skiljer sig från varje land och tjänsten måste då innehålla information om alla dessa. Dessa lagar eller regler, hädanefter regler, hålls uppdaterade utanför tjänsten i ett Exceldokument, därefter importeras de till Ipendo Platform manuellt. Innan det görs måste de valideras enligt förutbestämda restriktioner, detta för att de dels ska vara i rätt format för Ipendo Platform eller någonting annat som måste vara i rätt format.

    Syftet och motivationen till detta examensarbete är att man vill ersätta denna process med ett enklare webbaserat adminstrationsverktyg som låter back-office hantera och uppdatera reglerna och sedan själva utföra validering och importering. Detta gör att tid sparas och de personer som jobbar med att uppdatera regler får feedback direkt från valideringen istället för att man ska vänta på att en annan avdelning gör valideringen. Min uppgift var att undersöka hur man skulle kunna utveckla ett sådant här verktyg och framställa en prototyp som visar på hur det skulle kunna se ut och fungera. I prototypen ville man ha möjlighet för användaren att redigera reglerna i ett rutnät, i stort sett på samma sätt som i Excel, men även automatisk validering och versionshantering av regler, man skulle alltså kunna ha flera temporära versioner av samma regler.

    Redan från början visste man att det fanns ett utvecklingsverktyg som hade de grundläggande förutsättningarna att kunna utveckla ett sådant verktyg, det var Visual Studio LightSwitch. Det är ett ramverk till Visual Studio som förenklar utveckling av dataintensiva affärsapplikationer för webben samt som en vanlig skrivbordsapplikation. Examensarbetets syfte skulle sedan bli att utveckla en prototyp för administrationsverktyget med hjälp av LightSwitch, utvärdera den och sedan dra en slutsats om huruvida man borde vidareutveckla prototypen eller se sig om efter en annan utvecklingsmetod. Slutsatsen som kunde dras i slutet av examensarbetet var att prototypen utvecklad i LightSwitch fungerar bra och är användarvänlig, men det finns vissa begränsningar i utvecklingsmetoden som man bör ta ställning till om de går att förbise eller lösa. Om de inte går att lösa eller förbise bör LightSwitch eventuellt inte användas som utvecklingsmetod till den slutgiltiga utvecklingen av administrationsverktyget.

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