Roman Vitenberg

• Tabatabaei, Mohammad Hossein; Garrett, Thiago & Vitenberg, Roman (2026). Transactional feature analysis and synthetic workload generator for UTXO-based DLTs. Future Generation Computer Systems. ISSN 0167-739X. 182. doi: 10.1016/j.future.2026.108472. Fulltekst i vitenarkiv
• Manimaran, Praveensankar; Garrett, Thiago; Jehl, Leander Nikolaus & Vitenberg, Roman (2025). Decentralization trends in identity management: From federated to Self-Sovereign Identity Management Systems. Computer Science Review. ISSN 1574-0137. 58. doi: 10.1016/j.cosrev.2025.100776. Fulltekst i vitenarkiv Vis sammendrag

  Identity Management Systems (IMSs) are fundamental elements in a myriad of digital services across different industries. Traditionally, electronic IMSs have been centralized, similar to historical paper-based IMSs: there is a single authority responsible for issuing, storing, and sharing identity-related information on behalf of the identified subjects (people or devices). Over the last decade, we have been witnessing a decentralization trend in IMSs due to a number of reasons such as an attempt to bridge disconnected identity silos and the strive to involve the user in identity management to a larger degree. Federated and Self-Sovereign IMSs are the two most prominent approaches in the decentralization trend. Despite significant progress in this area, Federated and Self-Sovereign IMSs have not been studied from a conceptual point of view and the fundamental differences between different decentralization approaches have not been analyzed. It is important to understand the implications of different approaches when designing future IMSs that may affect millions of users daily. In this work, we conduct a conceptual study of these two IMS classes. First, we propose a generic model consisting of a set of functionalities and a set of operations and use it as a comparison framework. Using the generic model, we analyze three representatives from Federated and Self-Sovereign IMSs, namely, IOTA Identity, Hyperledger Indy, and eIDAS. Based on the analysis, we propose a new multi-dimensional taxonomy to capture the key differences between these systems. Furthermore, we discuss SSI principles and decentralization approaches followed in IMSs. Finally, we present research gaps in Self-Sovereign IMSs along with solution directions.

• Garrett, Thiago; Song, Weijia; Vitenberg, Roman & Birman, Ken (2025). Keep Your Friends Close: Leveraging Affinity Groups to Accelerate AI Inference Workflows. I Bhatotia, Pramod & Ravindran, Binoy (Red.), SYSTOR '25: The 18th ACM International Systems and Storage Conference. Association for Computing Machinery (ACM). ISSN 9798400721199. doi: 10.1145/3757347.3759129. Fulltekst i vitenarkiv
• Raikwar, Mayank; Garrett, Thiago & Vitenberg, Roman (2025). Deconstruction of Knowledge-Building in DAG-Based DLTs. Distributed Ledger Technologies: Research and Practice (DLT). 5(2). doi: 10.1145/3746647. Fulltekst i vitenarkiv Vis sammendrag

  As Distributed Ledger Technologies (DLTs) mature, the inherent performance and scalability shortcomings of linearly structured blockchain designs become better understood. Protocols based on Directed Acyclic Graphs (DAGs) have been proposed to address such shortcomings. DAG-based protocols differ from traditional DLTs in the way they build and represent knowledge about transactions and relations between them. While traditional DLTs have straightforward homogeneous semantic attached to blocks and links between blocks, the semantic of vertices and edges in DAG-based protocols is nuanced and varied. In this work, we identify almost a dozen of knowledge-building dimensions in DAG-based DLTs, none of which have been studied before. Knowledge-building is important in DAG-based DLTs because of its significant impact on the size of the DAG, the pace at which new transactions are added, the finality of transactions, and so on. We analyze 40 DAG-based DLTs from this perspective, summarize our results in a taxonomy, and identify a number of research gaps.

• Tabatabaei, Mohammad Hossein; Vitenberg, Roman & Veeraragavan, Narasimha Raghavan (2023). Understanding blockchain: Definitions, architecture, design, and system comparison. Computer Science Review. ISSN 1574-0137. 50. doi: 10.1016/j.cosrev.2023.100575. Fulltekst i vitenarkiv
• Arbabi, Mohammad Salar; Conceiçao, Arlindo Flavio Da; Garrett, Thiago; Nygård, Jan Franz & Vitenberg, Roman (2023). Tracking Decisions about Granting Access to Health Data: Application Analysis and Requirements, 2023 IEEE International Conference on Decentralized Applications and Infrastructures (DAPPS). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9798350335354. s. 1–6. doi: 10.1109/DAPPS57946.2023.00010. Fulltekst i vitenarkiv Vis sammendrag

  Medical research often requires access to sensitive personal health data. According to GDPR, such access is only possible under certain legal bases, such as consent. Verifiable and secure management of health data access is thus essential for promoting public trust in organizations that manage sensitive health data, for ensuring legal compliance, as well as for motivating patients to participate in research projects and allow access to their health data. In this work, we advocate a blockchain-based approach for verifiable management of sensitive health data access for medical research. We present the life cycle of a medical research project w.r.t. health data access, by identifying the involved entities and their interactions. Important requirements for verifiable management of health data access are also identified. We believe that the advocated approach will contribute to satisfying the identified requirements in the context of the defined life cycle.

• Zhu, Xiaojie; Ayday, Erman & Vitenberg, Roman (2023). A Privacy-Preserving Framework for Conducting Genome-Wide Association Studies Over Outsourced Patient Data. IEEE Transactions on Dependable and Secure Computing. ISSN 1545-5971. 20(3), s. 2390–2405. doi: 10.1109/TDSC.2022.3182944. Fulltekst i vitenarkiv
• Song, Weijia; Yang, Yuting; Liu, Thompson; Merlina, Andrea; Garrett, Thiago & Vitenberg, Roman [Vis alle 10 forfattere av denne artikkelen] (2022). Cascade: An Edge Computing Platform for Real-time Machine Intelligence, ApPLIED '22: Proceedings of the 2022 Workshop on Advanced tools, programming languages, and PLatforms for Implementing and Evaluating algorithms for Distributed systems. Association for Computing Machinery (ACM). ISSN 9781450392808. s. 2–6. doi: 10.1145/3524053.3542741. Fulltekst i vitenarkiv Vis sammendrag

  Intelligent IoT is a prerequisite for societal priorities such as a smart power grid, smart urban infrastructures and smart highways. These applications bring requirements such as real-time guarantees, data and action consistency, fault-tolerance, high availability, temporal data indexing, scalability, and even self-organization and self-stabilization. Existing platforms are oriented towards asynchronous, out of band upload of data to the cloud: Important functionality, but not enough to address the need. Cornell's Cascade project seeks to close the gap by creating a new platform for hosting ML and AI, optimized to achieve sharply lower delay and substantially higher bandwidth than in any existing platform. At the same time, Cascade introduces much stronger guarantees - a mix that we believe will be particularly appealing in applications where events should trigger a quick and trustworthy response. This short paper is intended as a brief overview of the effort, with details to be published elsewhere.

• Merlina, Andrea; Vitenberg, Roman & Setty, Vinay (2022). A General and Configurable Framework for Blockchain-based Marketplaces. I Hong, Jiman; Bures, Miroslav; Park, Juw Won & Cerny, Tomas (Red.), SAC '22: Proceedings of the 37th ACM/SIGAPP Symposium on Applied Computing. Association for Computing Machinery (ACM). ISSN 9781450387132. s. 216–225. doi: 10.1145/3477314.3507039. Fulltekst i vitenarkiv
• Arbabi, Mohammad Salar; Lal, Chhagan; Veeraragavan, Narasimha Raghavan; Marijan, Dusica; Nygård, Jan Franz & Vitenberg, Roman (2022). A Survey on Blockchain for Healthcare: Challenges, Benefits, and Future Directions. IEEE Communications Surveys and Tutorials. 25(1), s. 386–424. doi: 10.1109/COMST.2022.3224644. Fulltekst i vitenarkiv
• Chen, Chen; Vitenberg, Roman & Jacobsen, Hans-Arno (2021). Building Fault-Tolerant Overlays with Low Node Degrees for Topic-based Publish/Subscribe. IEEE Transactions on Dependable and Secure Computing. ISSN 1545-5971. 19(5), s. 3011–3023. doi: 10.1109/TDSC.2021.3080281. Fulltekst i vitenarkiv
• Zhu, Xiaojie; Ayday, Erman; Vitenberg, Roman & Veeraragavan, Narasimha Raghavan (2021). Privacy-Preserving Search for a Similar Genomic Makeup in the Cloud. IEEE Transactions on Dependable and Secure Computing. ISSN 1545-5971. 19(4), s. 2771–2788. doi: 10.1109/TDSC.2021.3074327. Fulltekst i vitenarkiv
• Zhu, Xiaojie; Erman, Ayday & Vitenberg, Roman (2019). A privacy-preserving framework for outsourcing location-based services to the cloud. IEEE Transactions on Dependable and Secure Computing. ISSN 1545-5971. 18(1), s. 384–399. doi: 10.1109/TDSC.2019.2892150. Fulltekst i vitenarkiv Vis sammendrag

  Thanks to the popularity of mobile devices numerous location-based services (LBS) have emerged. While several privacy-preserving solutions for LBS have been proposed, most of these solutions do not consider the fact that LBS are typically cloud-based nowadays. Outsourcing data and computation to the cloud raises a number of significant challenges related to data confidentiality, user identity and query privacy, fine-grained access control, and query expressiveness. In this work, we propose a privacy-preserving framework for outsourcing LBS to the cloud. The framework supports multi-location queries with fine-grained access control, and search by location attributes, while providing semantic security. In particular, the framework implements a new model that allows the user to govern the trade-off between precision and privacy on a dynamic per-query basis.We also provide a security analysis to show that the proposed scheme preserves privacy in the presence of different threats. We also show the viability of our proposed solution and scalability with the number of locations through an experimental evaluation, using a real-life OpenStreetMap dataset.

• Zhang, Kaiwen; Vitenberg, Roman & Jacobsen, Hans Arno (2018). Deconstructing Blockchains: Concepts, Systems, and Insights. I Hinze, Annika & Eyers, David (Red.), Proceedings of the 12th ACM International Conference on Distributed and Event-based Systems. Association for Computing Machinery (ACM). ISSN 9781450357821. s. 187–190. doi: 10.1145/3210284.3219502. Fulltekst i vitenarkiv
• Provensi, Lucas Luiz; Singh, Abhishek; Eliassen, Frank & Vitenberg, Roman (2018). Maelstream: Self-organizing media streaming for many-to-many interaction. IEEE Transactions on Parallel and Distributed Systems. ISSN 1045-9219. 29(6), s. 1342–1356. doi: 10.1109/TPDS.2018.2791599. Fulltekst i vitenarkiv
• Provensi, Lucas Luiz; Eliassen, Frank & Vitenberg, Roman (2017). A Cloud-Assisted Tree-Based P2P System for Low Latency Streaming. I Hariri, Salim (Red.), 2017 International Conference on Cloud and Autonomic Computing. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781538619391. s. 172–183. doi: 10.1109/ICCAC.2017.24. Fulltekst i vitenarkiv Vis sammendrag

  Live media streaming applications are increasingly popular, with services such as Twitch.tv and YouNow being used by millions of people. Deploying such services on the cloud can be very expensive, as the cost is proportional to the amount of data transferred to the users. However, adopting a much less costly peer-to-peer (P2P) solution may reduce the overall quality-of-service (QoS) experienced by users, since there are no guarantees regarding resource availability. Therefore, hybrid P2P/Cloud solutions have been proposed to reduce the cost of using a cloud infrastructure while still providing QoS guarantees. Most existing P2P/cloud streaming solutions apply a pull-based data dissemination mechanism, and use the cloud to ensure that all users receive the data before playback deadline. Although push-based streaming trees can reduce the overall dissemination latency, they have been overlooked in these settings since they are less robust to user churn. In this paper we present a cloud-assisted P2P solution that is self-organizing, robust to user churn and leverages streaming trees to push data to users with low latency. We show through extensive simulations that the proposed solution can reduce playback latency considerably when compared to an alternative pull-based system, without compromising QoS or increasing the cost. © 2017 Institute of Electrical and Electronics Engineers (IEEE)

• Chen, Chen; Jacobsen, Hans-Arno & Vitenberg, Roman (2016). Algorithms based on divide and conquer for topic-based publish/subscribe overlay design. IEEE/ACM Transactions on Networking. ISSN 1063-6692. 24(1), s. 422–436. doi: 10.1109/TNET.2014.2369346. Fulltekst i vitenarkiv
• Veeraragavan, Narasimha Raghavan; Montecchi, Leonardo; Nostro, Nicola; Vitenberg, Roman; Meling, Hein & Bondavalli, Andrea (2016). Modeling QoE in dependable tele-immersive applications: a case study of world opera. IEEE Transactions on Parallel and Distributed Systems. ISSN 1045-9219. 27(9), s. 2667–2681. doi: 10.1109/TPDS.2015.2503291. Fulltekst i vitenarkiv
• Karpenko, Dmytro; Vitenberg, Roman & Read, Alexander Lincoln (2015). ATLAS grid workload on NDGF resources: Analysis, modeling, and workload generation. Future Generation Computer Systems. ISSN 0167-739X. 47, s. 31–47. doi: 10.1016/j.future.2014.12.005. Fulltekst i vitenarkiv
• Jehl, Leander; Vitenberg, Roman & Meling, Hein (2015). SmartMerge: A New Approach to Reconfiguration for Atomic Storage. I Moses, Yoram (Red.), Distributed Computing - 29th International Symposium, DISC 2015. Springer. ISSN 9783642336508. s. 154–169. doi: 10.1007/978-3-662-48653-5_11. Fulltekst i vitenarkiv
• Chen, Chen; Tock, Yoav; Jacobsen, Hans Arno & Vitenberg, Roman (2015). Weighted Overlay Design for Topic-Based Publish/Subscribe Systems on Geo-Distributed Data Centers. I Abdelzaher, Tarek (Red.), 35th IEEE International Conference on Distributed Computing Systems, ICDCS 2015. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781467372145. s. 474–485. doi: 10.1109/ICDCS.2015.55. Fulltekst i vitenarkiv
• Rao, Weixiong; Vitenberg, Roman; Chen, Lei & Tarkoma, Sasu (2015). MTAF: An Adaptive Design for Keyword-based Content Dissemination on DHT Networks. IEEE Transactions on Parallel and Distributed Systems. ISSN 1045-9219. 26(4), s. 1071–1084. doi: 10.1109/TPDS.2014.5. Fulltekst i vitenarkiv
• Pandey, Navneet Kumar; Zhang, Kaiwen; Weiss, Stéphane Rene Emile; Jacobsen, Hans Arno & Vitenberg, Roman (2015). Minimizing the Communication Cost of Aggregation in Publish/Subscribe Systems. I Abdelzaher, Tarek (Red.), 35th IEEE International Conference on Distributed Computing Systems, ICDCS 2015. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781467372145. s. 462–473. doi: 10.1109/ICDCS.2015.54. Fulltekst i vitenarkiv
• Chen, Chen; Jacobsen, Hans Arno & Vitenberg, Roman (2014). Algorithms Based on Divide and Conquer for Topic-Based Publish/Subscribe Overlay Design. IEEE/ACM Transactions on Networking. ISSN 1063-6692. doi: 10.1109/tnet.2014.2369346. Fulltekst i vitenarkiv
• Korsveien, Nils Peder; Setty, Vinay Jayarama & Vitenberg, Roman (2014). VizPub: visualizing the performance of overlay-based pub/sub systems. I Bellur, Umesh & Kothari, Ravi (Red.), Proceedings of the 8th ACM International Conference on Distributed Event-Based Systems: DEBS '14 The 8th ACM International Conference on Distributed Event-Based Systems. Association for Computing Machinery (ACM). ISSN 9781450327374. s. 326–329. doi: 10.1145/2611286.2611312. Fulltekst i vitenarkiv
• Pandey, Navneet Kumar; Zhang, Kaiwen; Weiss, Stéphane Rene Emile; Jacobsen, Hans-Arno & Vitenberg, Roman (2014). Distributed event aggregation for content-based publish/subscribe systems. I Bellur, Umesh & Kothari, Ravi (Red.), Proceedings of the 8th ACM International Conference on Distributed Event-Based Systems: DEBS '14 The 8th ACM International Conference on Distributed Event-Based Systems. Association for Computing Machinery (ACM). ISSN 9781450327374. doi: 10.1145/2611286.2611302. Fulltekst i vitenarkiv
• Setty, Vinay Jayarama; Vitenberg, Roman; Kreitz, Gunnar; Urdaneta, Guido & Steen, Maarten van (2014). Cost-Effective Resource Allocation for Deploying Pub/Sub on Cloud. I Jimenez, Ricardo (Red.), IEEE 34th International Conference on Distributed Computing Systems. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781479951680. s. 555–566. doi: 10.1109/ICDCS.2014.63. Fulltekst i vitenarkiv
• Setty, Vinay Jayarama; Kreitz, Gunnar; Urdaneta, Guido; Vitenberg, Roman & Steen, Maarten van (2014). Maximizing the number of satisfied subscribers in pub/sub systems under capacity constraints. I Leon-Garcia, Alberto (Red.), INFOCOM, 2014 Proceedings. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781479933600. s. 2580–2588. doi: 10.1109/INFOCOM.2014.6848205. Fulltekst i vitenarkiv
• Chen, Chen; Vitenberg, Roman & Jacobsen, Arno (2013). Constructing fault-tolerant overlay networks for topic-based publish/subscribe. I Fatourou, Panagiota & Taubenfeld, Gadi (Red.), Proceedings of the 2013 ACM symposium on Principles of distributed computing. Association for Computing Machinery (ACM). ISSN 9781450320658. s. 184–186. doi: 10.1145/2484239.2484282. Fulltekst i vitenarkiv
• Provensi, Lucas Luiz; Eliassen, Frank; Vitenberg, Roman & Rouvoy, Romain (2013). Using Fuzzy Policies to Improve Context Interpretation in Adaptive Systems. ACM SIGAPP Applied Computing Review. ISSN 1559-6915. 13(3), s. 26–37. doi: 10.1145/2537728.2537731. Fulltekst i vitenarkiv
• Provensi, Lucas Luiz; Eliassen, Frank; Vitenberg, Roman & Rouvoy, Romain (2013). Improving context interpretation by using fuzzy policies: the case of adaptive video streaming. I Y., Shin Sung & Carlos, Maldonado José (Red.), Proceedings of the 28th Annual ACM Symposium on Applied Computing. Association for Computing Machinery (ACM). ISSN 9781450316569. s. 415–422. doi: 10.1145/2480362.2480447. Fulltekst i vitenarkiv Vis sammendrag

  Adaptation is an increasingly important requirement for software systems executing in large-scale, heterogeneous, and dynamic environments. A central aspect of the adaptation methodology is management of contextual information needed to support the adaptation process. A major design challenge of managing contextual data lies in the fact that the information is partial, uncertain, and inherently suitable for diverging interpretations. While existing adaptation solutions focus on techniques, methods, and tools, the challenge of managing and interpreting ambiguous contextual information remains largely unresolved. In this paper, we present a new adaptation approach that aims to overcome these issues by applying fuzzy set theory and approximate reasoning. It proposes a knowledge management scheme to interpret imprecise information and effectively integrate this information into the adaptation feedback control loop. To test and evaluate our solution, we implemented it in an adaptation engine to perform rate control for media streaming applications. The evaluation results show the benefits of our approach in terms of flexibility and performance when compared to more traditional methods, such as TCP-friendly rate control.

• Setty, Vinay Jayarama; Kreitz, Gunnar; Vitenberg, Roman; Steen, Maarten van; Urdaneta, Guido & Gimåker, Staffan (2013). The hidden pub/sub of spotify. I Pietzuch, Peter & Rundensteiner, Elka A. (Red.), The 7th ACM International Conference on Distributed Event-Based Systems. Association for Computing Machinery (ACM). ISSN 9781450317580. s. 231–240. doi: 10.1145/2488222.2488273. Fulltekst i vitenarkiv
• Veeraragavan, Narasimha Raghavan; Meling, Hein & Vitenberg, Roman (2013). QoE Estimation Models for Tele-immersive Applications, Proceedings of IEEE Eurocon 2013. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781467322300. s. 154–161. doi: 10.1109/EUROCON.2013.6624980. Fulltekst i vitenarkiv
• Veeraragavan, Narasimha Raghavan; Bondavalli, Andrea; Montecchi, Leonardo; Vitenberg, Roman; Nostro, Nicola & Meling, Hein (2013). Understanding the quality of experience in modern distributed interactive multimedia applications in presence of failures: metrics and analysis. I Y., Shin Sung & Carlos, Maldonado José (Red.), Proceedings of the 28th Annual ACM Symposium on Applied Computing. Association for Computing Machinery (ACM). ISSN 9781450316569. s. 439–446. doi: 10.1145/2480362.2480450. Fulltekst i vitenarkiv
• Singh, Abhishek; Paredes, Guido Alonso Urdaneta; Steen, Maarten van & Vitenberg, Roman (2012). On leveraging social relationships for decentralized privacy-preserving group communication. I Yoneki, Eiko; Frey, Davide & Brown, Ian (Red.), Proceedings of the Fifth Workshop on Social Network Systems (SNS '12). Association for Computing Machinery (ACM). ISSN 9781450311649. doi: 10.1145/2181176.2181181. Fulltekst i vitenarkiv
• Karpenko, Dmytro; Vitenberg, Roman & Read, Alexander Lincoln (2012). ATLAS Grid Workload on NDGF resources: analysis, modeling, and workload generation. International Conference for High Performance Computing, Networking, Storage and Analysis. ISSN 2167-4329. doi: 10.1109/SC.2012.21. Fulltekst i vitenarkiv
• Karpenko, Dmytro; Vitenberg, Roman & Read, Alexander Lincoln (2012). ATLAS grid workload on NDGF resources: analysis, modeling, and workload generation. I Hollingsworth, Jeffrey K. (Red.), SC '12: Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781467308069. s. 79:1–79:11. Fulltekst i vitenarkiv
• Setty, Vinay Jayarama; Steen, Maarten van; Vitenberg, Roman & Voulgaris, Spyros (2012). PolderCast: Fast, Robust, and Scalable Architecture for P2P Topic-Based Pub/Sub. I Triantafillou, Peter (Red.), Middleware 2012. Springer. ISSN 9783642351709. s. 271–291. doi: 10.1007/978-3-642-35170-9_14. Fulltekst i vitenarkiv
• Singh, Abhishek; Paredes, Guido Alonso Urdaneta; Steen, Maarten van & Vitenberg, Roman (2012). Robust overlays for privacy-preserving data dissemination over a social graph. Distributed Computing Systems. ISSN 1063-6927. s. 234–244. doi: 10.1109/ICDCS.2012.57. Fulltekst i vitenarkiv
• Veeraragavan, Narasimha Raghavan; Vitenberg, Roman & Meling, Hein (2012). Reliability Modeling and Analysis of Modern Distributed Interactive Multimedia Applications: A Case Study of a Distributed Opera Performance. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 7272, s. 185–193. doi: 10.1007/978-3-642-30823-9_16. Fulltekst i vitenarkiv
• Chen, Chen; Vitenberg, Roman & Jacobsen, Arno (2012). A Generalized Algorithm for Publish/Subscribe Overlay Design and Its Fast Implementation. I Aguilera, Marcos (Red.), Distributed Computing : 26th International Symposium, DISC 2012, Salvador, Brazil, October 16-18, 2012. Springer. ISSN 9783642336508. s. 76–90. doi: 10.1007/978-3-642-33651-5_6. Fulltekst i vitenarkiv
• Raghavan, Narasimha & Vitenberg, Roman (2011). Balancing the Communication Load of State Transfer in Replicated Systems. Symposium on Reliable Distributed Systems. Proceedings. ISSN 1060-9857. s. 41–50. doi: 10.1109/SRDS.2011.14. Fulltekst i vitenarkiv
• Vitenberg, Roman; Zinenko, Dimitry; Kvilekval, Kristian & Singh, Ambuj (2011). Analyzing Performance of Lease-Based Schemes Under Failures. Symposium on Reliable Distributed Systems. Proceedings. ISSN 1060-9857. s. 193–202. doi: 10.1109/SRDS.2011.31. Fulltekst i vitenarkiv
• Vitenberg, Roman; Zinenko, Dmitry; Kvilekval, Kristian & Singh, Ambuj (2011). Analyzing Performance of Lease-Based Schemes under Failures. I Casimiro, Antonio (Red.), Proceedings of 2011 30th IEEE Symposium on Reliable Distributed Systems. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781457713491. doi: 10.1109/srds.2011.31. Fulltekst i vitenarkiv
• Rao, Weixiong; Vitenberg, Roman & Tarkoma, Sasu (2011). Towards optimal keyword-based content dissemination in DHT-based P2P networks. I Asami, Tohru & Higashino, Teruo (Red.), IEEE International Conference on Peer-to-Peer Computing (P2P). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781457701504. s. 102–111. doi: 10.1109/p2p.2011.6038667. Fulltekst i vitenarkiv
• Chen, Chen; Vitenberg, Roman & Jacobsen, Arno (2011). Scaling Construction of Low Fan-out Overlays for Topic-Based Publish/Subscribe Systems. I Du, David Hung-Chang (Red.), 31st International Conference on Distributed Computing Systems (ICDCS). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781612843841. s. 225–236. doi: 10.1109/icdcs.2011.68. Fulltekst i vitenarkiv
• Veeraragavan, Narasimha Raghavan & Vitenberg, Roman (2011). Balancing the Communication Load of State Transfer in Replicated Systems. I Casimiro, Antonio (Red.), Proceedings of 2011 30th IEEE Symposium on Reliable Distributed Systems. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781457713491. s. 41–50. doi: 10.1109/srds.2011.14. Fulltekst i vitenarkiv
• Dar, Kashif Sana; Taherkordi, Amirhosein; Vitenberg, Roman; Rouvoy, Romain & Eliassen, Frank (2011). Adaptable Service Composition for Very-Large-Scale Internet of Things Systems. I Mokhtar, Sonia Ben (Red.), Middleware 2011: Proceedings of the Workshop on Posters and Demos Track. ACM Publications. ISSN 9781450310734. Fulltekst i vitenarkiv
• Chen, Chen; Jacobsen, Arno & Vitenberg, Roman (2010). Divide and Conquer Algorithms for Publish/Subscribe Overlay Design. I Davoli, Franco (Red.), ICDCS - International Conference on Distributed Computing Systems. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9780769540597. Fulltekst i vitenarkiv
• Vitenberg, Roman & Jimenez-Peris, Ricardo (2008). Maximizing Quorum Availability in Multi-Clustered Systems. I Patt-Shamir, Boaz (Red.), Proceedings of the 27th Annual ACM Symposium on Principles of Distributed Computing. Association for Computing Machinery (ACM). ISSN 9781595939890. Fulltekst i vitenarkiv
• Rouvoy, Romain; Vitenberg, Roman & Eliassen, Frank (2008). Enhancing Planning-Based Adaptation Middleware with Support for Dependability: a Case Study. Electronic Communications of the EASST. 11. Fulltekst i vitenarkiv
• Shraer, Alexander; Chokler, Gregory; Keidar, Idit; Melamed, Roie; Tock, Yoav & Vitenberg, Roman (2007). Local On-Line Maintenance of Scalable Pub/Sub Infrastructure. I Nakamura, Hiroshi (Red.), Proceedings of the 37th Annual IEEE/IFIP International Conference on Dependable Systems and Networks. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9780769528557. Fulltekst i vitenarkiv
• Chokler, Gregory; Melamed, Roie; Tock, Yoav & Vitenberg, Roman (2007). SpiderCast: A Scalable Interest-Aware Overlay for Topic-Based Pub/Sub Communication. I Jacobsen, Hans-Arno (Red.), Proceedings of the 2007 inaugural international conference on Distributed event-based systems. Association for Computing Machinery (ACM). ISSN 9781595936653. Fulltekst i vitenarkiv
• Chokler, Gregory; Melamed, Roie; Tock, Yoav & Vitenberg, Roman (2007). Constructing Scalable Overlays for Pub-Sub with Many Topics: Problems, Algorithms, and Evaluation. I Wattenhofer, Roger (Red.), Proceedings of the Twenty-Sixth Annual ACM Symposium on Principles of Distributed Computing, PODC 2007. Association for Computing Machinery (ACM). ISSN 9781595936165. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Zhang, Kaiwen; Sadoghi, Mohammad; Vitenberg, Roman; Kalogeraki, Vana & Renesse, Robbert Van (2019). Proceedings of the 20th International ACM/USENIX Middleware conference. Association for Computing Machinery (ACM). ISBN 9781450370097. 333 s. Fulltekst i vitenarkiv
• Eliassen, Frank; Meling, Hein & Vitenberg, Roman (2015). Proceedings of the 9th ACM International Conference on Distributed Event-Based Systems, DEBS '15. Association for Computing Machinery (ACM). ISBN 9781450332866. 371 s. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Vitenberg, Roman (2022). Norway Blockchain: Secure Sharing of Medical Records. Fulltekst i vitenarkiv
• Bjørkeng, Per Kristian & Vitenberg, Roman (2021). Betaler for kryptokunst uten å motta verket. [Journal]. Aftenposten. Fulltekst i vitenarkiv
• Salas-Gulliksen, Camilla & Vitenberg, Roman (2021). Nysgjerrig på kryptovaluta? Slik kommer du i gang. [Journal]. VG. Fulltekst i vitenarkiv
• Vitenberg, Roman (2021). Course in distributed systems - recording of lectures. Fulltekst i vitenarkiv
• Finsveen, Jesper Nordahl & Vitenberg, Roman (2020). Derfor er krypto-sporing «umulig». [Journal]. Dagbladet. Fulltekst i vitenarkiv
• Ramezanifarkhani, Toktam & Vitenberg, Roman (2020). Preparation for Academic Jobs After PhD. Fulltekst i vitenarkiv
• Vitenberg, Roman; Zhang, Kaiwen; Jacobsen, Hans Arno; Tabatabaei, Mohammad Hossein & Sadoghi, Mohammad (2019). Deconstructing Blockchains: Concepts, Systems, and Insights. Fulltekst i vitenarkiv
• Tabatabaei, Mohammad Hossein & Vitenberg, Roman (2019). Blockchain Tutorial on Smart Contracts. Fulltekst i vitenarkiv
• Merlina, Andrea; Vitenberg, Roman & Setty, Vinay Jayarama (2019). Towards Useful Proof of Work: combining Blockchain and Machine Learning. Fulltekst i vitenarkiv
• Tabatabaei, Mohammad Hossein; Vitenberg, Roman & Meling, Hein (2019). Understanding Blockchain: Definitions, Properties, Architecture, and Comparisons. Fulltekst i vitenarkiv
• Danielsen, Dag Inge & Vitenberg, Roman (2019). Blockchain er faget der studentene er lærere. [Internet]. Universitetet i Oslo. Fulltekst i vitenarkiv
• Tabatabaei, Mohammad Hossein & Vitenberg, Roman (2018). A hands-on Tutorial: Blockchain and Smart Contract Deployment. Fulltekst i vitenarkiv
• Vitenberg, Roman; Meling, Hein & Grønli, Kristin Straumsheim (2015). Gjør det mørke nettet enda mørkere. [Internet]. Forskningsrådet. Fulltekst i vitenarkiv
• Pandey, Navneet Kumar; Zhang, Kaiwen; Weiss, Stéphane Rene Emile; Jacobsen, Hans Arno & Vitenberg, Roman (2014). Distributed event aggregation for content-based publish/subscribe systems. Fulltekst i vitenarkiv
• Vitenberg, Roman (2008). Maximizing Quorum Availability in Multi-Clustered Systems. Fulltekst i vitenarkiv
• Shraer, Alexander; Bercovici, Sivan; Chokler, Gregory; Keidar, Idit; Melamed, Roie & Tock, Yoav [Vis alle 7 forfattere av denne artikkelen] (2007). Local Building Blocks for a Scalable Pub/Sub Infrastructure. Fulltekst i vitenarkiv
• Rouvoy, Romain; Vitenberg, Roman & Eliassen, Frank (2007). Middleware for Dependable Adaptation. Fulltekst i vitenarkiv
• Chokler, Gregory; Melamed, Roie; Tock, Yoav & Vitenberg, Roman (2007). Constructing Scalable Overlays for Pub-Sub with Many Topics: Problems, Algorithms, and Evaluation. Fulltekst i vitenarkiv
• Shraer, Alexander; Chokler, Gregory; Keidar, Idit; Melamed, Roie; Tock, Yoav & Vitenberg, Roman (2007). Local On-Line Maintenance of Scalable Pub/Sub Infrastructure. Fulltekst i vitenarkiv
• Tabatabaei, Mohammad Hossein; Vitenberg, Roman & Raghavan, Narasimha (2022). Understanding blockchain: definitions, architecture, design, and system comparison. Universitetet i Oslo. Fulltekst i vitenarkiv
• Zhu, Xiaojie; Ayday, Erman & Vitenberg, Roman (2021). Privacy-Preserving Identification of Target Patients from Outsourced Patient Data. Universitetet i Oslo. Fulltekst i vitenarkiv
• Zhu, Xiaojie; Ayday, Erman & Vitenberg, Roman (2019). A privacy-preserving framework for outsourcing location-based services to the cloud. IEEE (Institute of Electrical and Electronics Engineers). ISSN 9788273684431. Fulltekst i vitenarkiv Vis sammendrag

  Thanks to the popularity of mobile devices a large number of location-based services (LBS) have emerged. While a large number of privacy-preserving solutions for LBS have been proposed, most of these solutions do not consider the fact that LBS are typically cloud-based nowadays. Outsourcing data and computation to the cloud raises a number of significant challenges related to data confidentiality, user identity and query privacy, fine-grain access control, and query expressiveness. In this work, to the best of our knowledge, we propose the first privacy-preserving outsourced LBS system supporting continuous access control, multi-location queries, and per-query privacy limit. The proposed framework also supports search by location attributes in addition to locations themselves. We provide a security analysis to show that the proposed scheme preserves privacy in the presence of different threats. We also show the viability of our proposed solution and scalability with the number of locations through an experimental evaluation, using a real-life OpenStreetMap dataset.

• Provensi, Lucas Luiz; Singh, Abhishek Kumar; Eliassen, Frank & Vitenberg, Roman (2017). Self-Organizing Media Streaming for Many-to-many Interaction. Universitetet i Oslo. ISSN 9788273684332. Fulltekst i vitenarkiv Vis sammendrag

  In this research report we propose a self-organizing media streaming solution that supports multiple interacting participants as well as a large number of observers. This solution is aimed at a number of emerging multimedia applications over the Internet, such as distributed discussion panels, that require users to interact by exchanging live media content. Keeping the end-to-end latency as low as possible while not violating the bandwidth constraints of all participants is one of the most important requirements for this type of application. While there exists some solutions to the above problem for applications such as multi-party video streaming, they rely on dedicated infrastructures which may be expensive and not available to all users. On the other hand, decentralized P2P solutions have been focusing on single source media streaming applications, such as video-on-demand, which does not consider multiple interactive participants. We present a preliminary evaluation of our solution with simulations implemented using Peersim peer-to-peer simulator and also ns-3 network simulator. The evaluation results show that the system can achieve low end-to-end latencies and scales well with the number of streams.

• Setty, Vinay Jayarama; Vitenberg, Roman & Steen, Maarten van (2015). Publish/Subscribe for Large-Scale Social Interaction: Design, Analysis and Resource Provisioning. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Publish/subscribe (pub/sub) is a popular communication paradigm in the design of large-scale distributed systems. We are witnessing an increasingly widespread use of pub/sub for a wide array of applications both in industry and academia. For instance, the pub/sub paradigm is used for RSS feed notifications, financial data dissemination and business process management. Pub/sub has also been used in social interaction message notifications such as in Spotify. Social network interactions have grown exponentially in recent years to the order of billions of notifications generated by millions of users every day. However, there are a number of critical challenges yet to be addressed to design a pub/sub system that can scale massively. Pub/sub systems are generally deployed in centralized datacenters or using federated organizations of cooperatively managed servers. However, an increasingly higher number of pub/sub applications are being deployed in P2P environments due to their ability to provide scalable and robust decentralized solutions. The design of a system with a goal to support notifications at massive scale from social interactions has several challenges. For one, such a large-scale system has to possess a distinctively high number of desirable characteristics all at once in order to be a viable practical solution. However, we show that the existing state-of-the-art solutions provide only a subset of these characteristics. In this thesis, we propose PolderCast, a P2P topic-based pub/sub system that is fault-tolerant, robust, scalable and fast in terms of dissemination latency while attaining a low communication overhead. We do an extensive experimental analysis of PolderCast using Twitter and Facebook traces and show that PolderCast performs well under realistic churn compared to the widely used pub/sub system Scribe. Understanding the challenges faced by a real pub/sub system and getting insights from the workload it drives are critical to design a pub/sub system. Yet there is a serious lack of detailed study of a large-scale pub/sub system and its workload. In this thesis, we present an overview of a pub/sub system used to drive social interaction at Spotify. We then present a detailed analysis of traces from a real deployment of Spotify pub/sub. We further analyze the Twitter traces we collected via public APIs provided by Twitter. The analysis of these traces provides several interesting observations and conclusions which can benefit pub/sub designers. Inspired by the peer-assisted solution used by Spotify to stream music, we explore a similar solution to provide a scalable dissemination of notification events to the users. The task of distributing the workload among user peers and datacenter servers prompts a fundamental problem: How to select a subset of the pub/sub workload to be served by datacenter servers in a manner to maximize satisfaction requirements of users under resource constraints? In this thesis we provide, to the best of our knowledge, the first formal treatment of the above problem by introducing two metrics that capture subscriber satisfaction in the presence of limited resources. This allows us to formulate the problem as two new flavors of maximum coverage optimization problems. Unfortunately, both variants of the problem prove to be NP-hard. By subsequently providing formal approximation bounds and heuristics, we show however, that efficient approximations can be attained. We validate our approach using real-world traces from Spotify and show that our solutions can be executed periodically in real- time in order to adapt to workload variations. One of the fundamental challenges which remains to be addressed in deploying pub/sub systems on a datacenter or a cloud infrastructure is efficient and cost- effective resource allocation that would allow delivery of notifications to all subscribers. Specifically, the challenge is to answer the following three fundamental questions: Given a pub/sub workload, (1) what is the minimum amount of resources needed to meet satisfaction requirements of all the subscribers, (2) what is a cost-effective way to allocate resources for the given workload, and (3) what is the cost of hosting it on a public Infrastructure-as-a-Service (IaaS) provider like Amazon EC2. We formulate the problem to address these questions and provide an efficient solution. We do an extensive evaluation of the solution using real traces from Twitter and Spotify. With evidence from the empirical results we show that our solution can be used as a tool to allocate resources on datacenters and cloud so as to minimize infrastructure costs.

• Setty, Vinay; Vitenberg, Roman; Kreitz, Gunnar; Urdaneta, Guido & Steen, Maarten van (2014). Cost-Effective Resource Allocation for Deploying Pub/Sub on Cloud. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Publish/subscribe (pub/sub) is a popular communication paradigm in the design of largescale distributed systems. A fundamental challenge in deploying pub/sub systems on a data center or a cloud infrastructure is efficient and cost-effective resource allocation that would allow delivery of notifications to all subscribers. In this paper, we provide answers to the following three fundamental questions: Given a pub/sub workload, (1) what is the minimum amount of resources needed to satisfy all the subscribers, (2) what is a cost-effective way to allocate resources for the given workload, and (3) what is the cost of hosting it on a public Infrastructure-as-a-Service (IaaS) provider like Amazon EC2. To answer these questions, we formulate a problem coined Minimum Cost Subscriber Satisfaction (MCSS).We prove MCSS to be NP-hard and provide an efficient heuristic solution based on a combination of optimizations.We evaluate the solution experimentally using real traces from Spotify and Twitter along with a pricing model from Amazon. We show the impact of each optimization using a naive solution as the baseline. Using a variety of practical scenarios for each dataset, we also show that our solution scales well for millions of subscribers and runs fast.

• Setty, Vinay; Kreitz, Gunnar; Urdaneta, Guido; Vitenberg, Roman & Steen, Maarten van (2013). Maximizing the Number of Satisfied Subscribers in Pub/Sub Systems Under Capacity Constraints. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Publish/subscribe (pub/sub) is a popular communication paradigm in the design of largescale distributed systems. A provider of a pub/sub service (whether centralized, peer-assisted, or based on a federated organization of cooperatively managed servers) commonly faces a fundamental challenge: given limited resources, how to maximize the satisfaction of subscribers? We provide, to the best of our knowledge, the first formal treatment of this problem by introducing two metrics that capture subscriber satisfaction in the presence of limited resources. This allows us to formulate matters as two new flavors of maximum coverage optimization problems. Unfortunately, both variants of the problem prove to be NP-hard. By subsequently providing formal approximation bounds and heuristics, we show, however, that efficient approximations can be attained. We validate our approach using real-world traces from Spotify and show that our solutions can be executed periodically in real-time in order to adapt to workload variations.

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