Institut für Mobile und Verteilte Systeme
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Publikation A space- and time-efficient Implementation of the Merkle Tree Traversal Algorithm(12/2013) Knecht, Markus; Nicola, Carlo U.We have developed an algorithm for the Merkle tree traversal problem which combines the efficient spacetime trade-off from the fractal Merkle-trees and the space efficiency from the improved log space-time Merkle-trees traversal. We further programmed a low storage space and a low time overhead version of the algorithm in Java and measured its performance with respect to two different implementations.01B - Beitrag in Magazin oder ZeitungPublikation Active Data logger(12/2011) Krebs, Matthias Christian; Stamm, ChristophIn the project „Active Data Logger“ we investigate the design of embedded data acquisition systems when focusing on mobility, efficiency and coverage of as many use cases as possible. Mobile data acquisition systems are needed in many fields of research and productive environments that require mobility, and they have different requirements than non-mobile data acquisition systems. After all, data collection and analysis is a very important task, as it provides a basis for gaining knowledge and taking decisions based on the results. The feasibility of a universal mobile data acquisition system is demonstrated with a proof of concept design and implementation which covers multiple use cases.01B - Beitrag in Magazin oder ZeitungPublikation Agile Practices, Collaboration and Experience: An Empirical Study About the Effect of Experience in Agile Software Development(Springer, 2016) Kropp, Martin; Meier, Andreas; Biddle, Robert; Abrahamsson, Pekka; Jedlitschka, Andreas04B - Beitrag KonferenzschriftPublikation Agile Software Development: Practices, Self-Organization, and Satisfaction(Springer, 2021) Biddle, Robert; Kropp, Martin; Meier, Andreas; Anslow, Craig; Pfeiffer, Sabine; Nicklich, Manuel; Sauer, Stefan04A - Beitrag SammelbandPublikation Aktorenmodel am Beispiel Erlang(12/2010) Gruntz, DominikUm die Leistung von Mehrprozessorkernen nutzen zu können, müssen Programme so geschrieben sein, dass die verfügbaren Prozessoren auch beschäftigt werden. Die Entwicklung solcher Programme ist jedoch eine grosse Herausforderung. Erleichterung versprechen Konzepte wie das Aktorenmodell. In diesem Artikel wird das Aktorenmodell im Kontext der Programmiersprache Erlang vorgestellt und es wird aufgezeigt, dass auch dieses Modell seine Tücken hat.01B - Beitrag in Magazin oder ZeitungPublikation Am Rande des Weltalls(12/2012) Hudritsch, Marcus; Schindler, Martin; Krebs, Matthias ChristianBis vor einigen Jahren war es alleine den Raumfahrtorganisationen wie der NASA vorbehalten, Bilder der Erde aus dem Weltall zu erstellen. Heutzutage stehen aber immer mehr moderne Technologien wie Mobilfunk, GPS und hochauflösende Kameras jedermann zur Verfügung und dies zu erschwinglichen Preisen. Deshalb sind nun auch ambitionierte Hobby-Weltraumforscher in der Lage, mit geringem finanziellem Aufwand erstaunliche Bilder der Erde aus der Stratosphäre zu produzieren und Messdaten zu sammeln.01B - Beitrag in Magazin oder ZeitungPublikation Android API Levels(12/2011) Gruntz, DominikMit jeder neuen Android Version werden auch immer neue Features unterstützt. Mit Android 2.0 (Eclair) wurde Multi-Touch eingeführt, seit Android 2.3 (Gingerbread) ist neu die Kommunikation über NFC (Near Field Communication) möglich und Android 3.0 (Honeycomb) kennt neben Activities auch Fragments, um die UI-Möglichkeiten von Tablets besser unterstützen zu können. Der Programmierer muss bei jeder Applikation entscheiden, auf welcher Version er seine Programme entwickelt, und dabei Vorwärts- und Rückwärtskompatibilität beachten. Wir diskutieren dies in diesem Artikel am Beispiel einer Applikation, welche (optional) für den Austausch von Daten auch NFC verwenden soll.01B - Beitrag in Magazin oder ZeitungPublikation Android Best Practices to Improve Battery Efficiency(12/2014) Yereaztian, Chris; Luthiger, JürgMulti-core CPUs, motion sensors and multiple wireless radios all draw a significant amount of power which make a regular battery recharge a necessity. Applications, which extensively use the available hardware, reduce the battery runtime severely. Continuous motion sensor recording excessively stress a smartphone’s CPU preventing it from entering a deep sleep state. Android 4.4 introduces a new batchmode for sensors data to keep the CPU asleep for longer periods of time by delaying the reporting of new data from the sensors. The same technique is applied when writing to flash memory. When using a content provider to store data write amplification occurs, which affects writing performance negatively. The longer write times due to the reduced writing speed decrease the battery efficiency even more. A similar batch-oriented strategy reduces the occurrence of write amplification. In return, the reduced writing time improves the battery efficiency.01B - Beitrag in Magazin oder ZeitungPublikation Annular Barcodes(12/2015) Stamm, ChristophIn this publication1 we present a generic design for a novel annular barcode. On round media, circular or annular barcodes are more natural and preferable instead of traditional rectangular barcodes. Especially on round media with a distinctly convex or concave conic surface, an annular barcode is even more preferable than a full circle, because printing the barcode in the center of the media might be much more complicated or imprecise. Our generic annular barcode design supports different barcode and module sizes and therefore different data sizes. It includes different marker, synchronization, and data areas. For improved data robustness a data protocol and error correcting codes similar to them in QR codes are suggested. The feasibility of the design is shown by an implementation of an efficient and effective barcode decoder in C++ and a series of tests with distorted and noisy pictures of our annular barcodes.01B - Beitrag in Magazin oder ZeitungPublikation Automated acceptance test refactoring(ACM, 2011) Kropp, Martin; Borg, Rodrick04B - Beitrag KonferenzschriftPublikation Automated Testing in the Internet of Things(12/2016) Dobler, Thomas; Khatchatourov, Artem; Stamm, Christoph; Weck, WolfgangThis article presents a novel approach to testing distributed systems. Our automated test environment (ATE) is created to validate the BACnet/IT building automation protocol and is easily adaptable to other domains. During development of the new BACnet/IT reference implementation, we had to face several testing challenges. Based on that, we derived requirements for the ATE. The result is a flexible and lightweight test environment, which consists of only a few interacting components. Our ATE is able to simulate real-life situations like a power outage or a replacement of a BACnet/IT device. Further, it allows manipulating the behavior of BACnet/IT components during runtime. With such a test environment it is possible to automate tests in a straightforward and efficient way.01B - Beitrag in Magazin oder ZeitungPublikation Automatisierung von Systemtests im industriellen Umfeld(12/2011) Kellner, Anja; Kropp, MartinContinuous Integration Umgebungen werden in der Regel im Software-Entwicklungszyklus für die kontinuierliche Integration der Software eingesetzt. In diesem Artikel zeigen wir, dass sich solche Systeme auch hervorragend für die Realisierung von automatisierten Testinfrastrukturen im industriellen Umfeld eignen. Im vorliegenden Anwendungsfall wird damit eine fast vollständig automatisierte System- und Akzeptanztestumgebung von Softwareprodukten zur Überwachung und Steuerung von Messtechnik-Sensoren erreicht.01B - Beitrag in Magazin oder ZeitungPublikation aWall: A Socio-Cognitive Tool for Agile Team Collaboration using Large Multi-Touch Wall Systems(ACM, 2015) Kropp, Martin; Mateescu, Magdalena; Burkhard, Roger; Zahn, Carmen; Vischi, DarioAgile methods emphasize highly interactive and close collaboration within teams and among stakeholders. Due to still missing adequate digital tools, agile teams use mostly physical artefacts like wallboards and story cards. In this paper, we present aWall, an agile team collaboration tool for large multi-touch wall systems. aWall was designed based on empirical user research using new interaction and visualization concepts to support and foster the highly collaborative and communicative agile work style. The application is based on web technology and can be used in both co-located and distributed setting. The implemented prototypes were validated with end-users in a user workshop.04B - Beitrag KonferenzschriftPublikation aWall: A Socio-Cognitive Tool for Agile Team Collaboration using Large Multi-Touch Wall Systems(ACM, 2015) Kropp, Martin; Mateescu, Magdalena; Burkhard, Roger; Zahn, Carmen; Vischi, DarioAgile methods emphasize highly interactive and close collaboration within teams and among stakeholders. Due to still missing adequate digital tools, agile teams use mostly physical artefacts like wallboards and story cards. In this paper, we present aWall, an agile team collaboration tool for large multi-touch wall systems. aWall was designed based on empirical user research using new interaction and visualization concepts to support and foster the highly collaborative and communicative agile work style. The application is based on web technology and can be used in both co-located and distributed setting. The implemented prototypes were validated with end-users in a user workshop. In the demo, users can experience the interaction and visualization concepts hands-on.04B - Beitrag KonferenzschriftPublikation aWall: Agile Collaboration using Large Digital Multi-Touch Cardwalls(12/2016) Anslow, Craig; Burkhard, Roger; Kropp, Martin; Mateescu, Magdalena; Vischi, Dario; Zahn, CarmenDespite the availability of many digital agile board tools, most co-located agile software teams still use physical cardboards for their daily standup meetings. This is due to the fact that existing digital agile boards lacks supporting a collaborative workspace, direct interaction for the whole team in meetings, or making project information directly visible. In this paper we present aWall, a digital agile cardwall designed for the highly collaborative agile work style using large multi-touch wall displays. The effectiveness of aWall was evaluated in a user study with eleven software practitioners. Our findings indicate that aWall enables and encourages team work due to the large size of the wall, accessibility and visibility of large amounts of information, and possibility of customization of the interface. Based on this work, we suggest that augmenting digital cardwalls with large interactive touch technology and new interaction concepts is a useful way to support effective collaborative agile software development processes.01B - Beitrag in Magazin oder ZeitungPublikation BACnet/IT – Gebäudeautomation in Zeiten des Internets(03/2018) Weck, WolfgangÜber die letzten Jahrzehnte hat Datenkommunikation in verschiedenen Anwendungsbereichen Einzug gehalten und zu jeweils eigenen Lösungen geführt. So haben die Gebäudeautomations-Ingenieure für ihre Zwecke verschiedene Datennetzwerkstandards entwickelt, die sich in der Industrie und in bestehenden Gebäuden etabliert haben. Zugleich hat sich aus verschiedenen Anwendungen wie der Datenverarbeitung und der Büroinformation die bekannte Internet-Technologie entwickelt. Diese ist mittlerweile so verbreitet, dass eine Sogwirkung einsetzt: Dank hoher Stückzahlen, Marktmacht, Bekanntheit usw. wird es immer interessanter die Internet-Standards anstelle eigener, anwendungsspezifischer zu nutzen. Wie man zwei etablierte Standards – BACnet aus der Gebäudeautomation und die IT-Netze der Gebäude-Nutzer – zusammenbringen kann, ohne dass sich eine der beiden Welten komplett der anderen unterwirft, haben wir in einem KTI-geförderten Projekt zur Konvergenz der Gebäudeautomation und IT-Welt untersucht.01B - Beitrag in Magazin oder ZeitungPublikation Badminton-Smash Geschwindigkeitsmessung(12/2012) Stamm, ChristophIm Gegensatz zu internationalen Tennisturnieren, wo die Ballgeschwindigkeitsmessung bei Aufschlägen seit vielen Jahren zum Standard gehört, gibt es bei entsprechenden Badmintonturnieren keine vergleichbaren Messungen. Solche Geschwindigkeitsmessungen sind primär als Bereicherung für die Zuschauer gedacht, können darüber hinaus aber auch den Spielern, Trainern und Ausrüstern wichtige Informationen liefern. Wir beschreiben in diesem Artikel unseren Ansatz zur Geschwindigkeitsmessung von Schmetterbällen in Badminton und berichten über erste Erfahrungen mit unserem Messsystem an den Badminton Swiss Open 2012 in Basel.01B - Beitrag in Magazin oder ZeitungPublikation Benefits of card walls in agile software development. A systematic literature review(Springer, 2022) Sallin, Marc; Kropp, Martin; Stray, Viktoria; Stol, Klaas-Jan; Paasivaara, Maria; Kruchten, PhilippeCard walls are often used to visualize various aspects of the software development process. They are an essential and widespread agile practice. Despite the drawback of physical card walls, its digital version is often not considered a sufficient alternative. This paper aims to find the reason for this and suggests how to evolve digital card walls into a viable alternative. We conducted a systematic literature review and analyzed twenty-two studies. We identified which desirable effects agile teams get from card wall usage and derived a set of properties a card wall needs to achieve those effects. Furthermore, we suggested a typology of card walls to compare the benefits and challenges among them.04B - Beitrag KonferenzschriftPublikation Beyond REST: GraphQL with Java(17.10.2019) Gruntz, DominikRESTful Web services are well established for accessing data from the backend, but REST interfaces have their disadvantages and constraints. That’s why Facebook developed GraphQL as an alternative. In this talk the goals and principles of GraphQL are presented. We will look at GraphQL's Schema Language and its Query Language and play around with the GraphQL API of github. Using an example application we will show how Java can be used to build a GraphQL server which supports queries, mutations and notifications.06 - PräsentationPublikation Collaboration and human factors in software development: Teaching agile methodologies based on industrial insight(IEEE, 2016) Kropp, Martin; Meier, Andreas; Al Hammadi, Hussain04B - Beitrag Konferenzschrift