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:

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

Prof. Dr.-Ing. 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…

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

Prof. Dr.-Ing. 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 their practical use in production systems. This research project addresses these challenges by (1) improving the scalability of BFT consensus protocols without reducing their resilience, (2) applying modelling approaches for making the expected performance and timing behaviour of these protocols more predictable, even under attacks, taking into consideration environmental conditions, and (3) supporting the design process for valid, automated testable BFT systems from specification to deployment in a blockchain infrastructure. The topic of scalability aims at finding practical solutions that take into account challenges such as recovery from major outages or upgrades, as well as reconfigurations at runtime. We also want to design a resilient communication layer that decouples the choice of a suitable communication topology from the actual BFT consensus protocol and thus reduces its complexity.This should be supported by the use of trusted hardware components. In addition, we want to investigate combinations of these concepts with suitable cryptographic primitives to further improve scalability. Using systematic modelling techniques, we want to be able to analyse the efficiency of scalable, complex BFT protocols (for example, in terms of throughput and latency of operations), already before deploying them in a real environment, based on knowledge of system size, computational power of nodes, and basic characteristics of the communication links. We also want to investigate robust countermeasures that help defending against targeted attacks in large-scale blockchain systems. The third objective is to support the systematic and valid implementation in a practical system, structured into a constructive, modular approach, in which a validatable BFT protocol is assembled based on smaller, validatable building blocks; the incorporation of automated test procedures based on a heuristic algorithm which makes the complex search space of misbehaviour in BFT systems more manageable; and a tool for automated deployment with accompanying benchmarking and stress testing in large-scale DLTs.

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