“Causality-aware Log Pruning in Distributed event-sourced Systems,” individual lab project VS-P21-2019, B. Erb and D. Meißner (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2019 – Completed.
“Bringing Height to the Chronograph Platform,” individual lab project VS-R08-2018, B. Erb and D. Meißner (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2018 – Completed.
“Event-Sourced Graph Processing in Internet of Things Scenarios,” Master's thesis VS-M03-2018, B. Erb and D. Meißner (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2018 – Completed.
“Online Text Processing for Chatting Applications,” Bachelor's thesis VS-B19-2018, D. Meißner and B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2018 – Completed.
“Revisited: A platform architecture for retroactive programming using event sourcing,” individual lab project VS-R07-2018, B. Erb and D. Meißner (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2018 – Completed.
D. Meißner, “A Methodology for Performance Analysis and Performance Engineering of Distributed Event-sourced Systems,” Master's thesis VS-M22-2017, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2017 –
Completed.
Distributed event-sourced systems adopt a fairly new architectural style for data-intensive applications that maintain the complete history of the application state. However, the performance implications of such systems is not yet well explored, let alone how the performance of these systems can be improved. A central issue is the lack of systematic performance engineering approaches that incorporate the specific properties of distributed event-sourced systems, such as messaging and event persistence. To address this problem, we developed a methodology for performance engineering and performance analysis of distributed event-sourced systems as part of a software engineering process. This approach helps developers to identify bottlenecks and resolve performance issues based on specific micro benchmarks and subsequent targeted optimizations. To show the practicality of our methology, we applied it to the \cg platform to improve the overall performance of its current research prototype. Using our structured approach, we improved the performance of the prototype system and made it more than twice as fast for certain workloads.
“A platform architecture for retroactive programming using event sourcing,” individual lab project VS-R23-2017, B. Erb and D. Meißner (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2017 – Completed.
“Asynchrones latentes Snapshotting von dynamischen event-sourced Systemen,” Bachelor's thesis VS-B05-2017, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2017 – Completed.
“Design and Implementation of an Web-based API and Interactive Dashboard,” Bachelor's thesis VS-B07-2017, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2017 – Completed.
“Querying and Processing Event-sourced Graphs,” Master's thesis VS-M06-2017, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2017 – Completed.
“A Persistence Layer for Distributed Event-Sourced Architectures,” Master's thesis VS-M09-2016, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2016 –
Completed.
Due to the increasingly large amount of data which is collected and processed each day, enabling fast, reliable, and scalable distributed computing on very large datasets has become more important than ever. Unfortunately, distributed computation on large inhomogeneous datasets is still time-consuming and it is very difficult to make evaluations and predictions. To address these issues, event sourcing and graph computing are relevant topics. While event sourcing provides techniques to save data in a particular way, which enables evaluations and makes predictions possible, graph computing provides a way to distribute the computation on large datasets. Although there is a conceptual idea which addresses these issues, no practical experience how such a concept can be implemented in case of persistence and communication is available. As a result, a prototype system to measure and evaluate different persistence and communication implementations for distributed event-sourced architectures using event sourcing and graph computing needs to be created. Such a system can be used to find a way how to persist and work on large distributed inhomogeneous datasets efficiently.
“Enabling Retroactive Computing Through Event Sourcing,” Master's thesis VS-M01-2016, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2016 –
Completed.
Event sourcing is a style of software architecture wherein state altering operations to an application are captured as immutable events. Each event is appended to an event log, with the current state of a system derived from this series of events. This thesis addresses the utilization of retroactive capabilities in event-sourced systems: computing alternate application states, post hoc bug fixes, or the support of algorithms which have access to their own history, for example. The possibility of retroactively accessing and modifying this event log is a potential capability of an event-sourced system, but a detailed exploration how these operations can be facilitated and supported has not yet been conducted. We examine how retroaction can be applied to event-sourced systems and discuss conceptual considerations. Furthermore, we demonstrate how different architectures can be used to provide retroaction and describe the prototypical implementation of an appropriate programming model. These findings are applied in the Chronograph research project, in order to utilize potential temporal aspects of this platform.
“Performance Engineering in verteilten, polyglotten Berechnungsplattformen,” Master's thesis VS-M08-2016, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2016 – Completed.
“Vergleich und Evaluierung von Time Series Databases,” Bachelor's thesis VS-B07-2016, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2016 – Completed.
“An Evaluation of Distributed Approaches to Large-Scale Graph Computing,” Bachelor's thesis VS-B09-2015, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 –
Completed.
This thesis takes a look at several considerations for developers and users of distributed graph computing platforms. Two popular computing platforms, Apache Giraph on Hadoop and the GraphX library in Apache Spark, are analyzed and tested through a benchmarking process. We examine a basic PageRank and ConnectedComponents algorithm for a variety of input graphs and cluster sizes. We hereby discover how immensely different parameters of distributed graph computations, such as graph sizes and topology properties, impact the execution time. Concluding, we carve out the application fields, for which both platforms are practical and where trade-offs have to be made.
“Communication Patterns for Concurrent and Distributed Computations,” Bachelor's thesis VS-B04-2015, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 –
Completed.
This bachelor thesis presents a catalog of communication patterns for concurrent and distributed computations. We compose this catalog by reviewing the inter-process communication in common concurrency models and surveying existing pattern resources, such as professional books and weblogs. In addition to the selection and composition of patterns, we determine our own pattern template structure and an appropriate visualization, specifically matching the requirements of communication patterns. The catalog itself consists of a variety of patterns, intended for the reader to get a grasp of proven solutions for recurring problems in the field of concurrent programming. We provide simplified examples for every solution by the means of message-passing.
D. Meißner, “Designing a Disaster Area Network for First Responders in Disastrous and Emergency Scenarios,” Bachelor's thesis VS-B18-2015, B. Erb and R. van der Heijden (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 –
Completed.
Man-made disasters, earthquakes, floods, and other natural disasters come with a great number of casualties, which have to be treated as quickly as possible by emergency services to minimize fatalities. Due to the large number of casualties and aid workers, it is difficult to maintain an accurate overview of the situation. To improve the clarity of the situation, a comprehensive support system can be used for the forces on-site, which supports them in information gathering and distribution to all involved parties. Previous work has failed to implement independency of public infrastructure (e.g. power grid, cellular network) or suffer data loss due to single node failures. To solve this problem, we propose a fault-tolerant design that fully distributes information to all devices in a mobile ad hoc network, while allowing offline work outside of it. We present a proof-of-concept prototype for the proposed design and show that its data distribution component behaves as designed using a series of trials. To the best of our knowledge, there is currently no DAN system that uses multi master replication to fully distribute data, where every node has an individual copy of every piece of information.
“Design und Implementierung eines interaktiven Explorers für räumlich-zeitliche Trace-Daten,” individual lab project VS-R12-2015, R. van der Heijden and B. Erb (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2015 –
Completed.
Räumlich-zeitliche Trace-Daten speichern Bewegungsmuster von Entitäten in einem zeitlichen Verlauf. Die Exploration von solchen räumlich-zeitlichen Daten ist für verschiedenste Einsatzzwecke interessant, unter anderem auch für die Visualisierung von Fahrplandaten im öffentlichen Nahverkehr sowie für die Analyse von durchgeführten VANET-Simulationsläufen. Im Rahmen der Arbeit soll eine performante webbasierte Client/Server-Anwendung enstehen. Der Server soll Tracefiles aus verschiedenen Quellen importieren und effizient speicheren, die dann in interaktiven Explorationssessions von Clients abgespielt werden können.
G. Habiger, “Distributed Versioning and Snapshot Mechanisms on Event-Sourced Graphs,” Master's thesis VS-M13-2015, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 –
Completed.
Two interesting approaches to tackle many of today's problems in large scale data processing and live query resolution on big graph datasets have emerged in recent years. Firstly, after Google's presentation of its graph computing platform Pregel in 2010, an influx of more or less similar platforms could be observed. These platforms all share the goal of providing highly performant data mining and analysis capabilities to users, enabling a wide variety of today's technologies like ranking web pages in the the web graph of the WWW or analysing user interactions in social networks. Secondly, the old concept of message logging for failure recovery was rediscovered and combined with event based computing in the early 2000s and is now known as event sourcing. This approach to system design keeps persistent logs of every single change of all entities in a computation, providing highly interesting options like state restoration by replaying old events, retroactive event modifications, phenomenal debugging capabilities and many more. A recently published paper suggests the merging of those two approaches to create a hybrid event-sourced graph computing platform. This platform would show unique characteristics compared to other known solutions. For example, computations on temporal data can yield information about the evolution of a graph and not only its current state. Furthermore, for backups or to enable offline analysis on large compute clusters, snapshot extraction – i.e. reproducing any consistent global state the graph has ever been in – from the event logs produced by event-sourced graph computations is possible. This thesis provides one of the first major works related to this proposed hybrid platform and provides background knowledge related to these aforementioned topics. It presents a thorough overview over the current state-of-the-art in graph computing platforms and causality tracking in distributed systems and finally develops an efficient mechanism for extracting arbitrary, consistent global snapshots from a distributed event log produced by an event-sourced graph computation.
“Ereignisorientierte, diskrete Netzwerksimulation mit Pregel,” Bachelor's thesis VS-B05-2015, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 –
Completed.
Diese Arbeit verfolgt das Ziel festzustellen, ob sich die Architektur von Pregel - ein Framework für verteilte Berechnungen auf großen Graphen - eignet, um eine ereignisorientiert-diskrete Netzwerksimulation zu implementieren. Dazu wurde ein Simulator entworfen, der das Verhalten eines Transportprotokolls innerhalb eines Computernetzwerks darstellt. In der Entwurfsphase hat es sich ergeben, dass die Konzepte, die eine ereignisorientiert-diskrete Simulation ausmachen, in Pregel umgesetzt werden können. Dieser Entwurf wurde praktisch umgesetzt, um innerhalb einer Evaluierung zu ermitteln, wie sich die Simulation verhält, je größer die Eingabe-Netzwerkgraphen werden.
“Verhalten von TCP-Varianten in Hochgeschwindigkeitsnetzwerken,” Bachelor's thesis VS-B08-2015, B. Erb and T. Lukaseder (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 – Completed.
“Verwendung von CRDTs in mobilen verteilten Anwendungen,” Bachelor's thesis VS-B07-2015, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2015 –
Completed.
Einen Ansatz für asynchrone Datenhaltung in verteilten Systemen bieten Conflict-free Replicated Data Types (CRDT). Sie stellen Verfügbarkeit über strikte Konsistenz, trotzdem konvergieren die Zustände der Datentypen zu einem späteren Zeitpunkt mit Hilfe einfacher mathematischer Annahmen wie Kommutativität oder den Eigenschaften eines Halbverbandes. Diese Arbeit erklärt die Grundsätze, Unterscheidungsmöglichkeiten, Funktionsweisen, Anwendungsfälle und Probleme dieser CRDTs und überträgt deren Konzepte anschließend in den mobilen Kontext. Dabei werden auf theoretischer Basis zunächst geeignete Anwendungsszenarien unter verschiedenen Kriterien untersucht und anschließend ein Framework entwickelt, mit dem Entwickler mobiler Anwendungen CRDT-Instanzen verschiedener Datentypen verwenden können, die automatisiert über mehrere Geräte repliziert werden.
“A Collection of Privacy Patterns,” Bachelor's thesis VS-B06-2014, B. Erb and H. Kopp (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2014 –
Completed.
In dieser Arbeit wurde die Dokumentation von Patterns im Kontext von Privacy untersucht. Es wurden Anforderungen an die Struktur von Privacy Patterns diskutiert sowie die Kategorisierung von Privacy Patterns in einem Katalog betrachtet. Auf Basis einer eigenen Pattern-Struktur wurde dann anhand von exemplarischen Privacy Patterns ein kleiner, beispielhafter Katalog von Privacy Patterns vorgestellt.
“Design und Implementierung eines skalierenden Database-as-a-Service Systems,” Master's thesis VS-M05-2014, J. Domaschka and B. Erb (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2014 –
Completed.
Datenbanksysteme stellen in Anwendungen die zentrale Komponente zur Persistierung von Daten dar. Die Speicherung der Daten kann über verschieden Datenmodelle, welche die Literatur in die Kategorien relational und NoSQL einteilt, realisiert werden. Die Datenmodelle bieten unterschiedliche Funktionalitäten in Bereichen wie Konsistenz, Verteilung und Skalierbarkeit. Skalierbarkeit stellt besonders für Datenbanken innerhalb Webanwendungen eine wichtige Anforderungen dar, da zum einen die Nutzeranzahl von Webanwendungen immer weiter steigt und zum anderen die Webanwendungen starke Lastschwankungen bewältigen müssen. Um diese Lastschwankungen verarbeiten zu können, werden flexible Ressourcen benötigt, die das Cloud-Computing verspricht. Diese Arbeit betrachtet die Cloud-Computing-Architektur des DBaaS, welche Datenbanken als abstrakte Ressource bereitstellt. Der Schwerpunkt liegt hierbei auf skalierenden DBaaS-Systemen. Das Ziel dieser Arbeit besteht aus dem Design und der Implementierung eines DBaaS-Dienstes, der eine automatisierte Skalierung bietet und auf frei verfügbarer Software basiert. Hierfür werden die Anforderungen eines solchen DBaaS-Dienstes anhand eines Anwendungsfalls herausgearbeitet und die Skalierbarkeit existierender Datenbanken auf Basis von Benchmarks untersucht. Aus diesen Ergebnissen wird ein prototypisches DBaaS-System umgesetzt.
“Design und Implementierung eines zuverlässigen und verfügbaren (NoSQL) Datenbanksystems,” Master's thesis OMI-2014-M-02, J. Domaschka and B. Erb (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2014 –
Completed.
Datenbanken bilden das Rückgrat vieler Anwendungen. Wegen dieser zentralen Rolle sind Zuverlässigkeit und Ausfallsicherheit für sie essentiell. In dieser Arbeit sollen existierende Ansätze zur Fehlertoleranz bestehender relationaler und nicht-relationer Datenbanken zunächst untersucht und verglichen werden. Aufbauend darauf soll ein System mit Hilfe des Virtual Nodes Frameworks nachimplementiert werden.
“Distributed Architecture using Event Sourcing & Command Query Responsibility Segregation,” Bachelor's thesis VS-B04-2014, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2014 –
Completed.
In a common software system we occasionally want to know how we got to the current application state without making the system more complicated. Mostly, this question can not be answered because the software just saves the newest application state. Even if the software architects implement their own history support later, it can not tell anything about the previous changes. This is where Event Sourcing and Command Query Responsibility Segregation come into play. Event Sourcing saves every change as an event and Command Query Responsibility Segregation helps to handle the increased complexity. Therefore, we can build a system which provides a history support and which is still maintainable. If we use Event Sourcing and Command Query Responsibility Segregation, we just have to make small changes to a traditional architecture in order to fix that problem. By saving all changes as events we can evaluate everything we want.
“Entwurf & Implementierung einer kollaborativen Web-Plattform zur Dokumentation von Design Patterns,” Bachelor's thesis VS-B07-2014, B. Erb (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2014 –
Completed.
In dieser Arbeit wurde eine Plattform zur kollaborativen Dokumentation von Patterns entworfen und prototypisch implementiert. Hierfür wurden die Anforderungen für eine generische Plattform gesammelt und Konzepte für die kollaborative Nutzung erörtert. Die Implementierung verwendet verschiedene Konzepte des Web 2.0 zur Kollaboration und zeigt prototypisch den Funktionsumfang einer Plattform für Patterns verschiedener Anwendungsgebiete.
“Evaluation von Distributed Event Processing Frameworks für Zeitreihenanalysen,” Bachelor's thesis VS-B03-2014, B. Erb (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2014 – Completed.
“Intrusion Detection in Software Defined Networks,” Bachelor's thesis VS-B02-2014, R. van der Heijden and B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2014 –
Completed.
Intrusion detection systems are valuable tools to improve security in a network. Due to growing network bandwidths not all packets can be investigated because of resource limitations. Special traffic filters can be used to forward only traffic that is suspected of containing intrusions. Software defined network is an architecture which allows to interact with a network in a programmable way. With OpenFlow a switch can be programmed reactive, were flows are created dynamically and proactive, were flows are created statically. This work evaluates the impact of filtering traffic proactive and reactive. Evaluated was the number of alerts the SNORT IDS generated. An emulated SDN testbed was used for the evaluation. Compared to forwarding without filtering, the traffic can be reduced by more than a half.The results show that supporting an IDS is possible with OpenFlow, either in a reactive or a proactive way.
“Sicherheitsanalyse von NoSQL-Datenbanken,” Bachelor's thesis VS-B15-2014, R. van der Heijden and B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2014 –
Completed.
NoSQL-Datenbanken werden immer häufiger produktiv eingesetzt, um die steigenden Datenmengen bewältigen zu können. Derzeit ist allerdings noch nicht klar, ob diese die notwendigen Sicherheitsanforderungen erfüllen. Zu diesem Zweck stellt die vorliegende Arbeit eine Methodik zur Sicherheitsanalyse von NoSQL-Datenbanken vor. Hierzu werden die wichtigsten Sicherheitsrisiken identifiziert und es wird aufgezeigt, wie eine NoSQL-Datenbank auf diese überprüft werden kann. Die Methodik wird auf die NoSQL-Vertreter Neo4j und CouchDB angewendet. Es zeigt sich hierbei, dass beide Datenbanken schwerwiegende Sicherheitsdefizite aufweisen. Deshalb werden Empfehlungen zur Steigerung der Informationssicherheit gegeben, die bei Beachtung die ermittelten Schwachstellen beheben.
“Comparison of Concurrency Frameworks for the JVM,” Bachelor's thesis VS-B13-2013, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2013 –
Completed.
Aufgrund von Multi-Core-CPUs wird Nebenläufigkeit ein zunehmend wichtigerer Teil bei der Programmierung von performanten und skalierbaren Anwendungen. Für Java existieren diverse Frameworks, die höhere Abstraktionen für Nebenläufigkeit anbieten und somit nebenläufige Programmierung vereinfachen. Im Rahmen dieser Bachelor-Arbeit wurden wichtigte Frameworks vorgestellt und miteinander verglichen. Ebenso wurde aufgezeigt, welche Frameworks sich für welche Einsatzzwecke besonders eignen.
F. Engelmann, “Content-Inspection in Hochgeschwindigkeitsnetzen,” Bachelor's thesis VS-B17-2013, R. van der Heijden and B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2013 –
Completed.
Computational power for content filtering in high-speed networks reaches a limit, but many applications as intrusion detection systems rely on such processes. Especially signature based methods need extraction of header fields. Hence we created an parallel protocol-stack parser module on the NetFPGA 10G architecture with a framework for simple adaption to custom protocols. Our measurements prove that the appliance operates at 9.5 Gb/s with a delay in order of any active hop. The work provides the foundation to use for application specific projects in the NetFPGA context.
“Design & Durchführung einer Benutzerstudie zur Nutzung von Netzwerksimulatoren,” Bachelor's thesis VS-B06-2013, B. Erb (Supervisor), F. Kargl (Examiner), Inst. f. Vert. Sys., Univ. Ulm, 2013 –
Completed.
Im Rahmen dieser Arbeit wurde eine Benutzerstudie durchgeführt, die sich mit Fragen der Benutzerbarkeit und Komplexität von Netzwerksimulatoren befasst und offene Problemstellungen für Anwender von Netzwerksimulatoren identifizierte.
“Evaluation von existierenden Lösungen zur Simulation von Netzwerken,” Bachelor's thesis VS-B05-2013, B. Erb (Supervisor), F. Kargl (Examiner), Inst. of Distr. Sys., Ulm Univ., 2013 –
Completed.
Gegenstand dieser Arbeit ist die Erstellung eines aktuellen Surveys von bestehenden Netzwerksimulatoren, insbesondere für VANET-Simulationen.
