Distributed Systems

Distributed systems consist of multiple independent components that are connected by a network and provide a common service. Depending on the particular use case, this includes deployments in which a collection of small data sets is distributed among a few nodes, as well as architectures for the massively parallelized processing of large workloads in the context of cloud applications. While on the one hand the distribution of a system offers new opportunities, for example the improvement of fault-tolerance properties through replication of data and computations, on the other hand it also creates additional challenges such as the need for an efficient implementation of services when several geographic sites are involved. A key goal of this group's research activities is the development of concepts and techniques that enable systems to leverage the advantages associated with distribution and at the same time use the available resources as efficiently as possible.

Projects:

BALu: Blockchain applications in aviation

Term: 1. September 2022 - 31. August 2024
Funding source: Bundesministerium für Wirtschaft und Energie (BMWE)
Acronym: BALu
Project leader: Rüdiger Kapitza

Prof. Dr.-Ing. Rüdiger Kapitza

• LinkedIn: Seite von Rüdiger Kapitza

Das Konzept von Distributed Ledger Systemen (Blockchain) ist eine grundlegend neue Basistechnologie, welche in der öffentlichen Wahrnehmung derzeit verstärkt im Fokus steht und welche erhöhtes Potential zur Lösung von Problemstellungen in einer Vielzahl von Anwendungsbereichen verspricht.Daneben wandelt sich die Luftverkehrslandschaft absehbar mit einer massiven Zunahme an Luftverkehrsteilnehmern und weiteren Luftverkehrsarten wie autonomen Kleinstsystemen. Des Weiteren besteht ein Bedarf bei de…

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BFT2Chain: Design and validation of scalable, Byzantine fault tolerant consensus algorithms for blockchains

Term: 1. September 2022 - 30. September 2026
Funding source: Deutsche Forschungsgemeinschaft (DFG)
Acronym: BFT2Chain
Project leader: Rüdiger Kapitza

Prof. Dr.-Ing. Rüdiger Kapitza

• LinkedIn: Seite von Rüdiger Kapitza

Distributed Ledger Technologies (DLTs), often referred to as blockchains, enable the realisation of reliable and attack-resilient services without a central infrastructure. However, the widely used proof-of-work mechanisms for DLTs suffer from high latencies of operations and enormous energy costs. Byzantine fault-tolerant (BFT) consensus protocols prove to be a potentially energy-efficient alternative to proof-of-work. However, current BFT protocols also present challenges that still limit thei…

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Contact Persons:

• Rüdiger Kapitza
• Christian Berger

Participating Scientists:

• Rüdiger Kapitza
• Harald Böhm
• Thomas Preisner
• Maxim Ritter von Onciul
• Signe Schwarz-Rüsch
• Tobias Distler
• Christian Berger
• Paul Bergmann

Publications:

• Messadi I., Gerber ME., Distler T., Kapitza R.:
  TEE-Assisted Recovery and Upgrades for Long-Running BFT Services
  20th International Conference on Availability, Reliability and Security (ARES '25) (Ghent, 11. August 2025 - 14. August 2025)
  In: Proceedings of the 20th International Conference on Availability, Reliability and Security (ARES '25) 2025
  URL: https://sys.cs.fau.de/publications/2025/messadi_25_ares.pdf
• Avelãs D., Heydari H., Alchieri E., Distler T., Bessani A.:
  Probabilistic Byzantine Fault Tolerance
  43rd Symposium on Principles of Distributed Computing (PODC 2024) (Nantes, 17. June 2024 - 21. June 2024)
  In: Proceedings of the 43rd Symposium on Principles of Distributed Computing (PODC 2024) 2024
• Böhm H., Distler T., Wägemann P.:
  TinyBFT: Byzantine Fault-Tolerant Replication for Highly Resource-Constrained Embedded Systems
  30th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS 2024) (Hong Kong, China, 13. May 2024 - 16. May 2024)
  In: Proceedings of the 30th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS 2024) 2024
  DOI: 10.1109/RTAS61025.2024.00026
  URL: https://sys.cs.fau.de/publications/2024/boehm_24_rtas.pdf
• Eischer M., Distler T.:
  Spider: A BFT Architecture for Geo-Replicated Cloud Services
  (2024)
  DOI: 10.48550/arXiv.2407.07899
• Lawniczak L., Distler T.:
  Tough on the Outside, Reliable on the Inside: Utilizing System Composition for Improved Resilience
  1st Workshop on Resilient Operations – Byzantine Fault Tolerance and State-Machine Replication (ROBUST '24) (Erlangen, 13. March 2024 - 14. March 2024)
  Open Access: https://robust2024.github.io/robust24/assets/abstracts/Utilizing_System_Composition_for_Improved_Resilience.pdf
• Böhm H., Distler T.:
  Memory-Efficient Byzantine Fault-Tolerant Replication for Highly Resource-Constrained Systems
  1st Workshop on Resilient Operations – Byzantine Fault Tolerance and State-Machine Replication (ROBUST '24) (Erlangen, 13. March 2024 - 14. March 2024)
  Open Access: https://robust2024.github.io/robust24/assets/abstracts/memory-efficient-bft.pdf
• Eischer M.:
  Geo-Replicated Byzantine Fault-Tolerant State-Machine Replication with Low Latency (Dissertation, 2024)
  DOI: 10.25593/open-fau-545
• Distler T., Eischer M., Lawniczak L.:
  Micro Replication
  53rd Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN '23) (Porto, Portugal, 27. June 2023 - 30. June 2023)
  In: Proceedings of the 53rd Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN '23) 2023
  DOI: 10.1109/DSN58367.2023.00024
• Berger C., Schwarz-Rüsch S., Vogel A., Bleeke K., Jehl L., Reiser HP., Kapitza R.:
  SoK: Scalability Techniques for BFT Consensus
  IEEE International Conference on Blockchain and Cryptocurrency (Dubai, United Arab Emirates, 1. May 2023 - 5. May 2023)
  In: Proceedings of the 5th IEEE International Conference on Blockchain and Cryptocurrency 2023
  DOI: 10.48550/arXiv.2303.11045
  URL: https://arxiv.org/pdf/2303.11045.pdf
• Bessani A., Correia M., Distler T., Kapitza R., Esteves-Veríssimo P., Yu J.:
  Vivisecting the Dissection: On the Role of Trusted Components in BFT Protocols
  (2023)
  DOI: 10.48550/arXiv.2312.05714
• Lawniczak L., Ammon M., Distler T.:
  Generic Checkpointing Support for Stream-based State-Machine Replication
  Proceedings of the 10th Workshop on Principles and Practice of Consistency for Distributed Data (PaPoC '23) (Rome, 8. May 2023 - 8. May 2023)
  DOI: 10.1145/3578358.3591329
  URL: https://sys.cs.fau.de/publications/2023/lawniczak_23_papoc.pdf
• Schwarz-Rüsch S., Bleeke K., Messadi I., Schmidt S., Krampf A., Olze K., Stahnke S., Schmid R., Pirl L., Kittel R., Polze A., Franz M., Müller M., Jehl L., Kapitza R.:
  ZugChain: Blockchain-Based Juridical Data Recording in Railway Systems
  Conference on Dependable Systems and Networks (Baltimore, Maryland, USA, 27. June 2022 - 30. June 2022)
  In: Proceedings of the 52nd International Conference on Dependable Systems and Networks 2022
  DOI: 10.1109/DSN53405.2022.00019
  URL: https://www.ibr.cs.tu-bs.de/users/ruesch/papers/ruesch-dsn22.pdf
• Schwarz-Rüsch S., Behlendorf M., Becker MH., Kudlek R., Mohamed HHE., Schoenitz F., Jehl L., Kapitza R.:
  EventChain: A Blockchain Framework for Secure, Privacy-Preserving Event Verification
  23rd ACM/IFIP International Middleware Conference (Quebec, QC, 7. November 2022 - 11. November 2022)
  DOI: 10.1145/3528535.3565243
  URL: https://dl.acm.org/doi/10.1145/3528535.3565243
• Messadi I., Becker MH., Bleeke K., Jehl L., Mokhtar SB., Kapitza R.:
  SplitBFT: Improving Byzantine Fault Tolerance Safety Using Trusted Compartments
  23rd ACM/IFIP International Middleware Conference, Middleware 2022 (Quebec, QC, 7. November 2022 - 11. November 2022)
  In: Middleware 2022 - Proceedings of the 23rd ACM/IFIP International Middleware Conference 2022
  DOI: 10.1145/3528535.3531516
• Distler T.:
  Byzantine Fault-Tolerant State-machine Replication from a Systems Perspective
  In: ACM Computing Surveys 54 (2021), Article No.: 24
  ISSN: 0360-0300
  DOI: 10.1145/3436728
• Eischer M., Distler T.:
  Egalitarian Byzantine Fault Tolerance
  2021 IEEE 26th Pacific Rim International Symposium on Dependable Computing (PRDC) (Perth, 1. December 2021 - 3. December 2021)
  DOI: 10.1109/PRDC53464.2021.00019
  URL: https://www4.cs.fau.de/Publications/2021/eischer_21_prdc.pdf
• Lawniczak L., Distler T.:
  Stream-based State Machine Replication
  In: Proceedings of the 17th European Dependable Computing Conference (EDCC '21) 2021
  DOI: 10.1109/edcc53658.2021.00024
  URL: https://arxiv.org/pdf/2106.13019
• Eischer M., Distler T.:
  Resilient Cloud-based Replication with Low Latency
  21st International Middleware Conference, Middleware 2020 (, 7. December 2020 - 11. December 2020)
  In: Middleware 2020 - Proceedings of the 2020 21st International Middleware Conference 2020
  DOI: 10.1145/3423211.3425689
  URL: https://www4.cs.fau.de/Publications/2020/eischer_20_middleware.pdf
• Eischer M., Straßner B., Distler T.:
  Low-Latency Geo-Replicated State Machines with Guaranteed Writes
  7th Workshop on Principles and Practice of Consistency for Distributed Data, PaPoC 2020 (Heraklion, 27. April 2020 - 27. April 2020)
  In: Proceedings of the 7th Workshop on Principles and Practice of Consistency for Distributed Data, PaPoC 2020 2020
  DOI: 10.1145/3380787.3393686
  URL: https://www4.cs.fau.de/Publications/2020/eischer_20_papoc.pdf
• Eischer M., Büttner M., Distler T.:
  Deterministic Fuzzy Checkpoints
  International Symposium on Reliable Distributed Systems (SRDS '19) (Lyon, 1. October 2019 - 4. October 2019)
  In: Proceedings of the 38th International Symposium on Reliable Distributed Systems (SRDS '19) 2019
  DOI: 10.1109/SRDS47363.2019.00026
  URL: https://www4.cs.fau.de/Publications/2019/eischer_19_srds.pdf
• Deyerl C., Distler T.:
  In Search of a Scalable Raft-based Replication Architecture
  6th Workshop on Principles and Practice of Consistency for Distributed Data, PaPoC 2019 (Dresden, 25. March 2019)
  In: Proceedings of the 6th Workshop on Principles and Practice of Consistency for Distributed Data, PaPoC 2019 2019
  DOI: 10.1145/3301419.3323968
• Li B., Weichbrodt N., Behl J., Aublin PL., Distler T., Kapitza R.:
  Troxy: Transparent Access to Byzantine Fault-Tolerant Systems
  48th International Conference on Dependable Systems and Networks (DSN '18) (Luxembourg City, Luxembourg, 25. June 2018 - 28. June 2018)
  In: Proceedings of the 48th International Conference on Dependable Systems and Networks (DSN '18) 2018
  DOI: 10.1109/DSN.2018.00019
  URL: https://www4.cs.fau.de/Publications/2018/li_18_dsn.pdf
• Eibel C., Gulden C., Schröder-Preikschat W., Distler T.:
  Strome: Energy-Aware Data-Stream Processing
  Distributed Applications and Interoperable Systems (Madrid, 18. June 2018 - 21. June 2018)
  In: Proceedings of the 18th International Conference on Distributed Applications and Interoperable Systems (DAIS '18) 2018
  DOI: 10.1007/978-3-319-93767-0_4
• Eischer M., Distler T.:
  Scalable Byzantine Fault-tolerant State-Machine Replication on Heterogeneous Servers
  In: Computing (2018), p. 1-22
  ISSN: 0010-485X
  DOI: 10.1007/s00607-018-0652-3
  URL: https://www4.cs.fau.de/Publications/2018/eischer_18_computing.pdf
• Eischer M., Distler T.:
  Latency-Aware Leader Selection for Geo-Replicated Byzantine Fault-Tolerant Systems
  1st Workshop on Byzantine Consensus and Resilient Blockchains (BCRB '18) (Luxembourg City, 25. June 2018 - 28. June 2018)
  In: Proceedings of the 48th International Conference on Dependable Systems and Networks Workshops (DSN-W '18) 2018
  DOI: 10.1109/DSN-W.2018.00053
  URL: https://www4.cs.fau.de/Publications/2018/eischer_18_bcrb.pdf
• Behl J., Distler T., Kapitza R.:
  Hybrids on Steroids: SGX-based High Performance BFT
  EuroSys 2017 (Belgrade)
  In: Proceedings of the 12th European Conference on Computer Systems (EuroSys '17) 2017
  URL: https://www4.cs.fau.de/Publications/2017/behl_17_eurosys.pdf
• Behl J., Distler T., Kapitza R.:
  Hybster - A Highly Parallelizable Protocol for Hybrid Fault-Tolerant Service Replication
  (2017)
  DOI: 10.24355/dbbs.084-201703031341
• Distler T., Cachin C., Kapitza R.:
  Resource-efficient Byzantine Fault Tolerance
  In: IEEE Transactions on Computers, Washington, DC, USA: IEEE Computer Society, 2016, p. 2807-2819 (IEEE Transactions on Computers, Vol.65(9))
  DOI: 10.1109/TC.2015.2495213
  URL: https://www4.cs.fau.de/Publications/2015/distler_15_ieeetc.pdf
• Li B., Xu W., Abid MZ., Distler T., Kapitza R.:
  SAREK: Optimistic Parallel Ordering in Byzantine Fault Tolerance
  EDCC 2016 (Gothenburg)
  In: Proceedings of the 12th European Dependable Computing Conference (EDCC '16) 2016
• Behl J., Distler T., Kapitza R.:
  Consensus-Oriented Parallelization: How to Earn Your First Million
  Middleware 2015 (Vancouver)
  In: Proceedings of the 16th Middleware Conference (Middleware '15) 2015
  DOI: 10.1145/2814576.2814800
  URL: https://www4.cs.fau.de/Publications/2015/behl_15_mw.pdf
• Eibel C., Distler T.:
  Towards Energy-Proportional State-Machine Replication
  14th Workshop on Adaptive and Reflective Middleware (Vancouver)
  In: Proceedings of the 14th Workshop on Adaptive and Reflective Middleware (ARM '15) 2015
  DOI: 10.1145/2834965.2834969
  URL: https://www4.cs.fau.de/Publications/2015/eibel_15_arm.pdf
• Behl J., Distler T., Kapitza R.:
  Scalable BFT for Multi-Cores: Actor-based Decomposition and Consensus-oriented Parallelization
  HotDep 2014 (Broomfield)
  In: Proceedings of the 10th Workshop on Hot Topics in System Dependability (HotDep '14) 2014
• Kapitza R., Behl J., Cachin C., Distler T., Kuhnle S., Mohammadi SV., Schröder-Preikschat W., Stengel K.:
  CheapBFT: Resource-efficient Byzantine Fault Tolerance
  EuroSys 2012 (Bern, 10. April 2012 - 13. April 2012)
  In: Proceedings of the EuroSys 2012 Conference (EuroSys '12) 2012
  DOI: 10.1145/2168836.2168866
  URL: http://www4.cs.fau.de/Publications/2012/kapitza_12_eurosys.pdf
• Distler T., Kapitza R.:
  Increasing Performance in Byzantine Fault-Tolerant Systems with On-Demand Replica Consistency
  EuroSys 2011 (Salzburg, 10. April 2011 - 13. April 2011)
  In: Proceedings of the EuroSys 2011 Conference (EuroSys '11) 2011
  DOI: 10.1145/1966445.1966455
  URL: http://eurosys2011.cs.uni-salzburg.at/pdf/eurosys2011-distler.pdf
• Distler T., Kapitza R., Popov I., Reiser H., Schröder-Preikschat W.:
  SPARE: Replicas on Hold
  18th Network and Distributed System Security Symposium (NDSS '11) (San Diego)
  In: Proceedings of the 18th Network and Distributed System Security Symposium (NDSS '11) 2011
  URL: http://www.isoc.org/isoc/conferences/ndss/11/pdf/8_1.pdf
• Distler T., Kapitza R., Reiser HP.:
  State Transfer for Hypervisor-Based Proactive Recovery of Heterogeneous Replicated Services
  SICHERHEIT '10 (Berlin, 5. October 2010 - 7. October 2010)
  In: Proceedings of the 5th "Sicherheit, Schutz und Zuverlässigkeit" Conference (SICHERHEIT '10) 2010
  URL: http://www4.informatik.uni-erlangen.de/~distler/publications/distler10state.pdf
• Reiser HP., Distler T., Kapitza R.:
  Functional Decomposition and Interactions in Hybrid Intrusion-tolerant Systems
  In: Proceedings of the 3rd Workshop on Middleware-Application Interaction (MAI '09) 2009
• Distler T., Kapitza R., Reiser HP.:
  Efficient State Transfer for Hypervisor-Based Proactive Recovery
  In: Proceedings of the 2nd Workshop on Recent Advances on Intrusion-Tolerant Systems (WRAITS '08) 2008
• Bessani Alysson, Reiser Hans P. , Sousa Paulo, Gashi Ilir, Stankovic Vladimir, Distler Tobias, Kapitza Rüdiger, Daidone Alessandro , Obelheiro Rafael:
  FOREVER: Fault/intrusiOn REmoVal through Evolution & Recovery
  ACM/IFIP/USENIX Middleware '08 (Leuven, Belgium)
  In: Companion '08: Proceedings of the ACM/IFIP/USENIX Middleware '08 Conference Companion 2008
  DOI: 10.1145/1462735.1462763
• Lawniczak L., Distler T.:
  Targeting Tail Latency in Replicated Systems with Proactive Rejection
  25th Middleware Conference (Middleware '24) (Hong Kong, 2. December 2024 - 6. December 2024)
  In: Proceedings of the 25th Middleware Conference (Middleware '24) 2024
  DOI: 10.1145/3652892.3700775
  URL: https://sys.cs.fau.de/publications/2024/lawniczak_24_middleware.pdf
• Distler T.:
  Vision trifft auf Wirklichkeit: Ergebnisse und Erkenntnisse langjähriger Forschung im Bereich replizierter Systeme
  (2020)
  URL: https://www4.cs.fau.de/~distler/publications/distler20vision.pdf
• Böhm H., Distler T., Kapitza R.:
  Towards a Blockchain-based Data Recorder for Small Drones
  2nd Workshop on Resilient Operations – Byzantine Fault Tolerance and State-Machine Replication (ROBUST '25) (Karlsruhe, 17. March 2025 - 18. March 2025)
  Open Access: https://gi-robust.github.io/robust25/assets/abstracts/7-Blockchain-Data-Recorder-for-Drones.pdf
• Lawniczak L., Distler T.:
  Hard Shell, Reliable Core: Improving Resilience in Replicated Systems with Selective Hybridization
  44th International Symposium on Reliable Distributed Systems (SRDS '25) (Porto, 29. September 2025 - 2. October 2025)
  In: Proceedings of the 44th International Symposium on Reliable Distributed Systems (SRDS '25) 2025
  URL: https://sys.cs.fau.de/publications/2025/lawniczak_25_srds.pdf
• Gogada H., Berger C., Jehl L., Reiser HP., Meling H.:
  OptiLog: Assigning Roles in Byzantine Consensus
  EuroSys 2026 (Edinburgh, 27. April 2026 - 30. April 2026)
  In: ACM (ed.): EUROSYS ’26 2026
• Bessani ., Correia M., Distler T., Kapitza R., Esteves-Verissimo P., Yu J.:
  Vivisecting the Dissection: On the Role of Trusted Components in BFT Protocols
  In: IEEE Transactions on Computers (2026), p. 1-8
  ISSN: 0018-9340
  DOI: 10.1109/TC.2026.3715788