The Institute of Distributed Systems is actively researching scalability, reliability, security and privacy, self-organization, and complexity management issues in distributed systems. We apply our research to a wide range of practical use cases, including cloud computing and vehicular communication networks.


Moreover, we offer lectures and projects related to our research, including computer networks, distributed systems, and security and privacy. Open theses and projects can be found on the corresponding web pages. For exams, please refer to corresponding details.

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Our Most Recent Publications

Volpert, S., Erb, B., Eisenhart, G., Seybold, D., Wesner, S. and Domaschka, J. 2023. A Methodology and Framework to Determine the Isolation Capabilities of Virtualisation Technologies. Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering (Coimbra, Portugal, Apr. 2023), 149–160.
The capability to isolate system resources is an essential characteristic of virtualisation technologies and is therefore important for research and industry alike. It allows the co-location of experiments and workloads, the partitioning of system resources and enables multi-tenant business models such as cloud computing. Poor isolation among tenants bears the risk of noisy-neighbour and contention effects which negatively impacts all of those use-cases. These effects describe the negative impact of one tenant onto another by utilising shared resources. Both industry and research provide many different concepts and technologies to realise isolation. Yet, the isolation capabilities of all these different approaches are not well understood; nor is there an established way to measure the quality of their isolation capabilities. Such an understanding, however, is of uttermost importance in practice to elaborately decide on a suited implementation. Hence, in this work, we present a novel methodology to measure the isolation capabilities of virtualisation technologies for system resources, that fulfils all requirements to benchmarking including reliability. It relies on an immutable approach, based on Experiment-as-Code. The complete process holistically includes everything from bare metal resource provisioning to the actual experiment enactment.The results determined by this methodology help in the decision for a virtualisation technology regarding its capability to isolate given resources. Such results are presented here as a closing example in order to validate the proposed methodology.
Köstler, J., Reiser, H.P., Hauck, F.J. and Habiger, G. 2023. Fluidity: location-awareness in replicated state machines. 38th ACM/SIGAPP Symp. on Appl. Comp. – SAC (Mar. 2023).
In planetary-scale replication systems, the overall response delay is greatly influenced by the geographical distances between client and server nodes. Current systems define the replica locations statically during startup time. However, the selected locations might be suboptimal for the clients, and the client request origin distribution may change over time, so a different replica placement may provide lower overall request latencies. In this work, we propose a locationaware replicated state machine that is able to adapt the geographic location of its replicas dynamically during runtime to locations geographically closer to client request origins. Our prototype is able to observe emerging optimization potentials and to reduce the overall request latency for the majority of clients by adapting its replica locations to the time-dependent optimum placement during real-world use case evaluations, whereby the absolute performance gain is dependent on the respective usage scenario.
Schillings, C., Meißner, D., Erb, B., Schultchen, D., Bendig, E. and Pollatos, O. 2023. A chatbot-based intervention with ELME to improve stress and health-related parameters in a stressed sample: Study protocol of a randomised controlled trial. Frontiers in Digital Health. 5, (Mar. 2023), 14.
Background: Stress levels in the general population had already been increasing in recent years, and have subsequently been exacerbated by the global pandemic. One approach for innovative online-based interventions are “chatbots” – computer programs that can simulate a text-based interaction with human users via a conversational interface. Research on the efficacy of chatbot-based interventions in the context of mental health is sparse. The present study is designed to investigate the effects of a three-week chatbot-based intervention with the chatbot ELME, aiming to reduce stress and to improve various health-related parameters in a stressed sample. Methods: In this multicenter, two-armed randomised controlled trial with a parallel design, a three-week chatbot-based intervention group including two daily interactive intervention sessions via smartphone (á 10-20 min.) is compared to a treatment-as-usual control group. A total of 130 adult participants with a medium to high stress levels will be recruited in Germany. Assessments will take place pre-intervention, post-intervention (after three weeks), and follow-up (after six weeks). The primary outcome is perceived stress. Secondary outcomes include self-reported interoceptive accuracy, mindfulness, anxiety, depression, personality, emotion regulation, psychological well-being, stress mindset, intervention credibility and expectancies, affinity for technology, and attitudes towards artificial intelligence. During the intervention, participants undergo ecological momentary assessments. Furthermore, satisfaction with the intervention, the usability of the chatbot, potential negative effects of the intervention, adherence, potential dropout reasons, and open feedback questions regarding the chatbot are assessed post-intervention. Discussion: To the best of our knowledge, this is the first chatbot-based intervention addressing interoception, as well as in the context with the target variables stress and mindfulness. The design of the present study and the usability of the chatbot were successfully tested in a previous feasibility study. To counteract a low adherence of the chatbot-based intervention, a high guidance by the chatbot, short sessions, individual and flexible time points of the intervention units and the ecological momentary assessments, reminder messages, and the opportunity to postpone single units were implemented.
Heß, A. and Hauck, F.J. 2023. Towards a Cloud Service for State-Machine Replication. Tagungsband des FG-BS Frühjahrstreffens 2023 (Bonn - Germany, 2023).
State-machine replication (SMR) is a well-known technique to achieve fault tolerance for services that require high availability and fast recovery times. While the concept of SMR has been extensively investigated, there are still missing building blocks to provide a generic offer, which automatically serves applications with SMR technology in the cloud. In this work, we introduce a cloud service architecture that enables automatic deployment of service applications based on customer-friendly service parameters, which are mapped onto an internal configuration that comprises the number of replicas, tolerable failures, and the consensus algorithm, amongst other aspects. The deployed service configuration is masked to large extent with the use of threshold signatures. As a consequence, a reconfiguration in the cloud deployment does not affect the client-side code. We conclude the paper by discussing open engineering questions that need to be addressed in order to provide a productive cloud offer.
Pampel, B., Standl, B., Hildebrand, C., Hauck, F.J., Ulbrich, M. and Paech, B. 2023. Neue Einblicke in den Berufswahlprozess von Informatiklehrkräften. Informatikunterricht zwischen Aktualität und Zeitlosigkeit – INFOS (2023). [accepted for publication]
Mit der Einführung bzw. dem Ausbau des seit Jahren geforderten Pflichtfaches Informatik entsteht noch mehr Bedarf an qualifizierten Lehrkräften. Auch wenn Maßnahmen zur Nachqualifizierung von bestehenden Lehrkräften einen wichtigen Beitrag zur Deckung des Bedarfs leisten, muss gleichzeitig die Anzahl der Absolvent:innen aus lehramtsbezogenen Informatik-Studiengängen gesteigert werden. Allerdings zeigen die Zahlen, dass es noch immer zu wenig Studienanfänger:innen und noch weniger Absolvent:innen im Lehramt Informatik gibt. Um Maßnahmen zur Stärkung der Lehramtsausbildung im Fach Informatik gezielt auszurichten, muss der Berufswahlprozess erneut in den Blick genommen werden. Die wenigen bisher dazu durchgeführten Untersuchungen haben hier verschiedene Fragen offengelassen bzw. aufgrund der noch nicht ausreichenden Datenlage teils nur mit Vermutungen beantworten können. Der vorliegende Artikel widmet sich der Auswertung einer landesweit in Baden-Württemberg durchgeführten Umfrage unter aktiven Lehramtsstudierenden der Informatik mit erfreulich hoher Rücklaufquote. Es werden neue Erkenntnisse zur Reihenfolge von Teilentscheidungen für das Lehramtsstudium bzw. für die Fächer vorgestellt und der Anteil an Fachwechsler:innen betrachtet. Es wird unterschieden zwischen Studierenden, die während der Schulzeit keinen, einen als nicht gut bewerteten oder als gut bewerteten Informatikunterricht hatten. Darüber hinaus werden Motive der Berufs- bzw. Studiengangswahl in den Blick genommen und der Frage nach Unterschieden zwischen männlichen und weiblichen Studierenden nachgegangen.

Click here for an overview of all our publications.

Old news can be found in the archive.


Secretary's Office

Marion Köhler
Phone: +49 731 50-24140
available in the morning
Fax: +49 731 50-24142

Postal Address

Institute of Distributed Systems
Ulm University
Albert-Einstein-Allee 11
89081 Ulm

Visiting Address

Gebäude O27, Raum 349
89081 Ulm
manned in the morning Monday to Thursday