@book{MeinelGalbasHageboelling2023, author = {Meinel, Christoph and Galbas, Michael and Hageb{\"o}lling, David}, title = {Digitale Souver{\"a}nit{\"a}t: Erkenntnisse aus dem deutschen Bildungssektor}, number = {156}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-560-6}, issn = {1613-5652}, doi = {10.25932/publishup-59513}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-595138}, publisher = {Universit{\"a}t Potsdam}, pages = {1 -- 29}, year = {2023}, abstract = {Digitale Technologien bieten erhebliche politische, wirtschaftliche und gesellschaftliche Chancen. Zugleich ist der Begriff digitale Souver{\"a}nit{\"a}t zu einem Leitmotiv im deutschen Diskurs {\"u}ber digitale Technologien geworden: das heißt, die F{\"a}higkeit des Staates, seine Verantwortung wahrzunehmen und die Bef{\"a}higung der Gesellschaft - und des Einzelnen - sicherzustellen, die digitale Transformation selbstbestimmt zu gestalten. Exemplarisch f{\"u}r die Herausforderung in Deutschland und Europa, die Vorteile digitaler Technologien zu nutzen und gleichzeitig Souver{\"a}nit{\"a}tsbedenken zu ber{\"u}cksichtigen, steht der Bildungssektor. Er umfasst Bildung als zentrales {\"o}ffentliches Gut, ein schnell aufkommendes Gesch{\"a}ftsfeld und wachsende Best{\"a}nde an hochsensiblen personenbezogenen Daten. Davon ausgehend beschreibt der Bericht Wege zur Entsch{\"a}rfung des Spannungsverh{\"a}ltnisses zwischen Digitalisierung und Souver{\"a}nit{\"a}t auf drei verschiedenen Ebenen - Staat, Wirtschaft und Individuum - anhand konkreter technischer Projekte im Bildungsbereich: die HPI Schul-Cloud (staatliche Souver{\"a}nit{\"a}t), die MERLOT-Datenr{\"a}ume (wirtschaftliche Souver{\"a}nit{\"a}t) und die openHPI-Plattform (individuelle Souver{\"a}nit{\"a}t).}, language = {de} } @book{MeinelGalbasHageboelling2023, author = {Meinel, Christoph and Galbas, Michael and Hageb{\"o}lling, David}, title = {Digital sovereignty: insights from Germany's education sector}, number = {157}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-561-3}, issn = {1613-5652}, doi = {10.25932/publishup-59772}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-597723}, publisher = {Universit{\"a}t Potsdam}, pages = {1 -- 27}, year = {2023}, abstract = {Digital technology offers significant political, economic, and societal opportunities. At the same time, the notion of digital sovereignty has become a leitmotif in German discourse: the state's capacity to assume its responsibilities and safeguard society's - and individuals' - ability to shape the digital transformation in a self-determined way. The education sector is exemplary for the challenge faced by Germany, and indeed Europe, of harnessing the benefits of digital technology while navigating concerns around sovereignty. It encompasses education as a core public good, a rapidly growing field of business, and growing pools of highly sensitive personal data. The report describes pathways to mitigating the tension between digitalization and sovereignty at three different levels - state, economy, and individual - through the lens of concrete technical projects in the education sector: the HPI Schul-Cloud (state sovereignty), the MERLOT data spaces (economic sovereignty), and the openHPI platform (individual sovereignty).}, language = {en} } @book{MeinelGayvoronskayaSchnjakin2018, author = {Meinel, Christoph and Gayvoronskaya, Tatiana and Schnjakin, Maxim}, title = {Blockchain}, number = {124}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-441-8}, issn = {1613-5652}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-414525}, publisher = {Universit{\"a}t Potsdam}, pages = {102}, year = {2018}, abstract = {The term blockchain has recently become a buzzword, but only few know what exactly lies behind this approach. According to a survey, issued in the first quarter of 2017, the term is only known by 35 percent of German medium-sized enterprise representatives. However, the blockchain technology is very interesting for the mass media because of its rapid development and global capturing of different markets. For example, many see blockchain technology either as an all-purpose weapon— which only a few have access to—or as a hacker technology for secret deals in the darknet. The innovation of blockchain technology is found in its successful combination of already existing approaches: such as decentralized networks, cryptography, and consensus models. This innovative concept makes it possible to exchange values in a decentralized system. At the same time, there is no requirement for trust between its nodes (e.g. users). With this study the Hasso Plattner Institute would like to help readers form their own opinion about blockchain technology, and to distinguish between truly innovative properties and hype. The authors of the present study analyze the positive and negative properties of the blockchain architecture and suggest possible solutions, which can contribute to the efficient use of the technology. We recommend that every company define a clear target for the intended application, which is achievable with a reasonable cost-benefit ration, before deciding on this technology. Both the possibilities and the limitations of blockchain technology need to be considered. The relevant steps that must be taken in this respect are summarized /summed up for the reader in this study. Furthermore, this study elaborates on urgent problems such as the scalability of the blockchain, appropriate consensus algorithm and security, including various types of possible attacks and their countermeasures. New blockchains, for example, run the risk of reducing security, as changes to existing technology can lead to lacks in the security and failures. After discussing the innovative properties and problems of the blockchain technology, its implementation is discussed. There are a lot of implementation opportunities for companies available who are interested in the blockchain realization. The numerous applications have either their own blockchain as a basis or use existing and widespread blockchain systems. Various consortia and projects offer "blockchain-as-a-service{\"a}nd help other companies to develop, test and deploy their own applications. This study gives a detailed overview of diverse relevant applications and projects in the field of blockchain technology. As this technology is still a relatively young and fast developing approach, it still lacks uniform standards to allow the cooperation of different systems and to which all developers can adhere. Currently, developers are orienting themselves to Bitcoin, Ethereum and Hyperledger systems, which serve as the basis for many other blockchain applications. The goal is to give readers a clear and comprehensive overview of blockchain technology and its capabilities.}, language = {en} } @book{MeinelJohnWollowski2022, author = {Meinel, Christoph and John, Catrina and Wollowski, Tobias}, title = {Die HPI Schul-Cloud - Von der Vision zur digitale Infrastruktur f{\"u}r deutsche Schulen}, number = {144}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-526-2}, issn = {1613-5652}, doi = {10.25932/publishup-53586}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-535860}, publisher = {Universit{\"a}t Potsdam}, pages = {v, 77}, year = {2022}, abstract = {Digitale Medien sind aus unserem Alltag kaum noch wegzudenken. Einer der zentralsten Bereiche f{\"u}r unsere Gesellschaft, die schulische Bildung, darf hier nicht hintanstehen. Wann immer der Einsatz digital unterst{\"u}tzter Tools p{\"a}dagogisch sinnvoll ist, muss dieser in einem sicheren Rahmen erm{\"o}glicht werden k{\"o}nnen. Die HPI Schul-Cloud ist dieser Vision gefolgt, die vom Nationalen IT-Gipfel 2016 angestoßen wurde und dem Bericht vorangestellt ist - gefolgt. Sie hat sich in den vergangenen f{\"u}nf Jahren vom Pilotprojekt zur unverzichtbaren IT-Infrastruktur f{\"u}r zahlreiche Schulen entwickelt. W{\"a}hrend der Corona-Pandemie hat sie f{\"u}r viele Tausend Schulen wichtige Unterst{\"u}tzung bei der Umsetzung ihres Bildungsauftrags geboten. Das Ziel, eine zukunftssichere und datenschutzkonforme Infrastruktur zur digitalen Unterst{\"u}tzung des Unterrichts zur Verf{\"u}gung zu stellen, hat sie damit mehr als erreicht. Aktuell greifen rund 1,4 Millionen Lehrkr{\"a}fte und Sch{\"u}lerinnen und Sch{\"u}ler bundesweit und an den deutschen Auslandsschulen auf die HPI Schul-Cloud zu.}, language = {de} } @book{MeinelRenzLuderichetal.2019, author = {Meinel, Christoph and Renz, Jan and Luderich, Matthias and Malyska, Vivien and Kaiser, Konstantin and Oberl{\"a}nder, Arne}, title = {Die HPI Schul-Cloud}, number = {125}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-453-1}, issn = {1613-5652}, doi = {10.25932/publishup-42306}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423062}, publisher = {Universit{\"a}t Potsdam}, pages = {57}, year = {2019}, abstract = {Die digitale Transformation durchdringt alle gesellschaftlichen Ebenen und Felder, nicht zuletzt auch das Bildungssystem. Dieses ist auf die Ver{\"a}nderungen kaum vorbereitet und begegnet ihnen vor allem auf Basis des Eigenengagements seiner Lehrer*innen. Strukturelle Reaktionen auf den Mangel an qualitativ hochwertigen Fortbildungen, auf schlecht ausgestattete Unterrichtsr{\"a}ume und nicht professionell gewartete Computersysteme gibt es erst seit kurzem. Doch auch wenn Beharrungskr{\"a}fte unter P{\"a}dagog*innen verbreitet sind, erfordert die Transformation des Systems Schule auch eine neue Mentalit{\"a}t und neue Arbeits- und Kooperationsformen. Zeitgem{\"a}ßer Unterricht ben{\"o}tigt moderne Technologie und zeitgem{\"a}ße IT-Architekturen. Nur Systeme, die f{\"u}r Lehrer*innen und Sch{\"u}ler*innen problemlos verf{\"u}gbar, benutzerfreundlich zu bedienen und didaktisch flexibel einsetzbar sind, finden in Schulen Akzeptanz. Hierf{\"u}r haben wir die HPI Schul-Cloud entwickelt. Sie erm{\"o}glicht den einfachen Zugang zu neuesten, professionell gewarteten Anwendungen, verschiedensten digitalen Medien, die Vernetzung verschiedener Lernorte und den rechtssicheren Einsatz von Kommunikations- und Kollaborationstools. Die Entwicklung der HPI Schul-Cloud ist umso notwendiger, als dass rechtliche Anforderungen - insbesondere aus der Datenschutzgrundverordnung der EU herr{\"u}hrend - den Einsatz von Cloud-Anwendungen, die in der Arbeitswelt verbreitet sind, in Schulen unm{\"o}glich machen. Im Bildungsbereich verbreitete Anwendungen sind gr{\"o}ßtenteils technisch veraltet und nicht benutzerfreundlich. Dies n{\"o}tigt die Bundesl{\"a}nder zu kostspieligen Eigenentwicklungen mit Aufw{\"a}nden im zweistelligen Millionenbereich - Projekte die teilweise gescheitert sind. Dank der modularen Micro-Service-Architektur k{\"o}nnen die Bundesl{\"a}nder zuk{\"u}nftig auf die HPI Schul-Cloud als technische Grundlage f{\"u}r ihre Eigen- oder Gemeinschaftsprojekte zur{\"u}ckgreifen. Hierf{\"u}r gilt es, eine nachhaltige Struktur f{\"u}r die Weiterentwicklung der Open-Source-Software HPI Schul-Cloud zu schaffen. Dieser Bericht beschreibt den Entwicklungsstand und die weiteren Perspektiven des Projekts HPI Schul-Cloud im Januar 2019. 96 Schulen deutschlandweit nutzen die HPI Schul-Cloud, bereitgestellt durch das Hasso-Plattner-Institut. Weitere 45 Schulen und Studienseminare nutzen die Nieders{\"a}chsische Bildungscloud, die technisch auf der HPI Schul-Cloud basiert. Das vom Bundesministerium f{\"u}r Bildung und Forschung gef{\"o}rderte Projekt l{\"a}uft in der gegenw{\"a}rtigen Roll-Out-Phase bis zum 31. Juli 2021. Gemeinsam mit unserem Kooperationspartner MINT-EC streben wir an, die HPI Schul-Cloud m{\"o}glichst an allen Schulen des Netzwerks einzusetzen.}, language = {de} } @book{MeinelWillemsStaubitzetal.2022, author = {Meinel, Christoph and Willems, Christian and Staubitz, Thomas and Sauer, Dominic and Hagedorn, Christiane}, title = {openHPI}, number = {148}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-544-6}, issn = {1613-5652}, doi = {10.25932/publishup-56020}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-560208}, publisher = {Universit{\"a}t Potsdam}, pages = {125}, year = {2022}, abstract = {On the occasion of the 10th openHPI anniversary, this technical report provides information about the HPI MOOC platform, including its core features, technology, and architecture. In an introduction, the platform family with all partner platforms is presented; these now amount to nine platforms, including openHPI. This section introduces openHPI as an advisor and research partner in various projects. In the second chapter, the functionalities and common course formats of the platform are presented. The functionalities are divided into learner and admin features. The learner features section provides detailed information about performance records, courses, and the learning materials of which a course is composed: videos, texts, and quizzes. In addition, the learning materials can be enriched by adding external exercise tools that communicate with the HPI MOOC platform via the Learning Tools Interoperability (LTI) standard. Furthermore, the concept of peer assessments completed the possible learning materials. The section then proceeds with further information on the discussion forum, a fundamental concept of MOOCs compared to traditional e-learning offers. The section is concluded with a description of the quiz recap, learning objectives, mobile applications, gameful learning, and the help desk. The next part of this chapter deals with the admin features. The described functionality is restricted to describing the news and announcements, dashboards and statistics, reporting capabilities, research options with A/B testing, the course feed, and the TransPipe tool to support the process of creating automated or manual subtitles. The platform supports a large variety of additional features, but a detailed description of these features goes beyond the scope of this report. The chapter then elaborates on common course formats and openHPI teaching activities at the HPI. The chapter concludes with some best practices for course design and delivery. The third chapter provides insights into the technology and architecture behind openHPI. A special characteristic of the openHPI project is the conscious decision to operate the complete application from bare metal to platform development. Hence, the chapter starts with a section about the openHPI Cloud, including detailed information about the data center and devices, the used cloud software OpenStack and Ceph, as well as the openHPI Cloud Service provided for the HPI. Afterward, a section on the application technology stack and development tooling describes the application infrastructure components, the used automation, the deployment pipeline, and the tools used for monitoring and alerting. The chapter is concluded with detailed information about the technology stack and concrete platform implementation details. The section describes the service-oriented Ruby on Rails application, inter-service communication, and public APIs. It also provides more information on the design system and components used in the application. The section concludes with a discussion of the original microservice architecture, where we share our insights and reasoning for migrating back to a monolithic application. The last chapter provides a summary and an outlook on the future of digital education.}, language = {en} } @book{MeinelWillemsStaubitzetal.2022, author = {Meinel, Christoph and Willems, Christian and Staubitz, Thomas and Sauer, Dominic and Hagedorn, Christiane}, title = {openHPI}, number = {150}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-546-0}, issn = {1613-5652}, doi = {10.25932/publishup-56179}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-561792}, publisher = {Universit{\"a}t Potsdam}, pages = {86}, year = {2022}, abstract = {Anl{\"a}sslich des 10-j{\"a}hrigen Jubil{\"a}ums von openHPI informiert dieser technische Bericht {\"u}ber die HPI-MOOC-Plattform einschließlich ihrer Kernfunktionen, Technologie und Architektur. In einer Einleitung wird die Plattformfamilie mit allen Partnerplattformen vorgestellt; diese belaufen sich inklusive openHPI aktuell auf neun Plattformen. In diesem Abschnitt wird außerdem gezeigt, wie openHPI als Berater und Forschungspartner in verschiedenen Projekten fungiert. Im zweiten Kapitel werden die Funktionalit{\"a}ten und g{\"a}ngigen Kursformate der Plattform pr{\"a}sentiert. Die Funktionalit{\"a}ten sind in Lerner- und Admin-Funktionen unterteilt. Der Bereich Lernerfunktionen bietet detaillierte Informationen zu Leistungsnachweisen, Kursen und den Lernmaterialien, aus denen sich ein Kurs zusammensetzt: Videos, Texte und Quiz. Dar{\"u}ber hinaus k{\"o}nnen die Lernmaterialien durch externe {\"U}bungstools angereichert werden, die {\"u}ber den Standard Learning Tools Interoperability (LTI) mit der HPI MOOC-Plattform kommunizieren. Das Konzept der Peer-Assessments rundet die m{\"o}glichen Lernmaterialien ab. Der Abschnitt geht dann weiter auf das Diskussionsforum ein, das einen grundlegenden Unterschied von MOOCs im Vergleich zu traditionellen E-Learning-Angeboten darstellt. Zum Abschluss des Abschnitts folgen eine Beschreibung von Quiz-Recap, Lernzielen, mobilen Anwendungen, spielerischen Lernens und dem Helpdesk. Der n{\"a}chste Teil dieses Kapitels besch{\"a}ftigt sich mit den Admin-Funktionen. Die Funktionalit{\"a}tsbeschreibung beschr{\"a}nkt sich Neuigkeiten und Ank{\"u}ndigungen, Dashboards und Statistiken, Berichtsfunktionen, Forschungsoptionen mit A/B-Tests, den Kurs-Feed und das TransPipe-Tool zur Unterst{\"u}tzung beim Erstellen von automatischen oder manuellen Untertiteln. Die Plattform unterst{\"u}tzt außerdem eine Vielzahl zus{\"a}tzlicher Funktionen, doch eine detaillierte Beschreibung dieser Funktionen w{\"u}rde den Rahmen des Berichts sprengen. Das Kapitel geht dann auf g{\"a}ngige Kursformate und openHPI-Lehrveranstaltungen am HPI ein, bevor es mit einigen Best Practices f{\"u}r die Gestaltung und Durchf{\"u}hrung von Kursen schließt. Zum Abschluss des technischen Berichts gibt das letzte Kapitel eine Zusammenfassung und einen Ausblick auf die Zukunft der digitalen Bildung. Ein besonderes Merkmal des openHPI-Projekts ist die bewusste Entscheidung, die komplette Anwendung von den physischen Netzwerkkomponenten bis zur Plattformentwicklung eigenst{\"a}ndig zu betreiben. Bei der vorliegenden deutschen Variante handelt es sich um eine gek{\"u}rzte {\"U}bersetzung des technischen Berichts 148, bei der kein Einblick in die Technologien und Architektur von openHPI gegeben wird. Interessierte Leser:innen k{\"o}nnen im technischen Bericht 148 (vollst{\"a}ndige englische Version) detaillierte Informationen zum Rechenzentrum und den Ger{\"a}ten, der Cloud-Software und dem openHPI Cloud Service aber auch zu Infrastruktur-Anwendungskomponenten wie Entwicklungstools, Automatisierung, Deployment-Pipeline und Monitoring erhalten. Außerdem finden sich dort weitere Informationen {\"u}ber den Technologiestack und konkrete Implementierungsdetails der Plattform inklusive der serviceorientierten Ruby on Rails-Anwendung, die Kommunikation zwischen den Diensten, {\"o}ffentliche APIs, sowie Designsystem und -komponenten. Der Abschnitt schließt mit einer Diskussion {\"u}ber die urspr{\"u}ngliche Microservice-Architektur und die Migration zu einer monolithischen Anwendung.}, language = {de} } @book{NiephausFelgentreffHirschfeld2017, author = {Niephaus, Fabio and Felgentreff, Tim and Hirschfeld, Robert}, title = {Squimera}, number = {120}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-422-7}, doi = {10.25932/publishup-40338}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-403387}, publisher = {Universit{\"a}t Potsdam}, pages = {92}, year = {2017}, abstract = {Programmierwerkzeuge, die verschiedene Programmiersprachen unterst{\"u}tzen und sich konsistent bedienen lassen, sind hilfreich f{\"u}r Softwareentwickler, weil diese sich nicht erst mit neuen Werkzeugen vertraut machen m{\"u}ssen, wenn sie in einer neuen Sprache entwickeln wollen. Außerdem ist es n{\"u}tzlich, verschiedene Programmiersprachen in einer Anwendung kombinieren zu k{\"o}nnen, da Entwickler dann Softwareframeworks und -bibliotheken nicht in der jeweiligen Sprache nachbauen m{\"u}ssen und stattdessen bestehende Software wiederverwenden k{\"o}nnen. Dennoch haben Entwickler eine sehr große Auswahl, wenn sie nach Werkzeugen suchen, die teilweise zudem speziell nur f{\"u}r eine Sprache ausgelegt sind. Einige integrierte Entwicklungsumgebungen unterst{\"u}tzen verschiedene Programmiersprachen, k{\"o}nnen aber h{\"a}ufig keine konsistente Bedienung ihrer Werkzeuge gew{\"a}hrleisten, da die jeweiligen Ausf{\"u}hrungsumgebungen der Sprachen zu verschieden sind. Dar{\"u}ber hinaus gibt es bereits Mechansimen, die es erlauben, Programme aus anderen Sprachen in einem Programm wiederzuverwenden. Dazu werden h{\"a}ufig das Betriebssystem oder eine Netzwerkverbindung verwendet. Programmierwerkzeuge unterst{\"u}tzen jedoch h{\"a}ufig eine solche Indirektion nicht und sind deshalb nur eingeschr{\"a}nkt nutzbar bei beispielsweise Debugging Szenarien. In dieser Arbeit stellen wir einen neuartigen Ansatz vor, der das Programmiererlebnis in Bezug auf das Arbeiten mit mehreren dynamischen Programmiersprachen verbessern soll. Dazu verwenden wir die Werkzeuge einer Smalltalk Programmierumgebung wieder und entwickeln eine virtuelle Ausf{\"u}hrungsumgebung, die verschiedene Sprachen gleichermaßen unterst{\"u}tzt. Der auf unserem Ansatz basierende Prototyp Squimera demonstriert, dass es m{\"o}glich ist, Programmierwerkzeuge in der Art wiederzuverwenden, sodass sie sich f{\"u}r verschiedene Programmiersprachen gleich verhalten und somit die Arbeit f{\"u}r Entwickler vereinfachen. Außerdem erm{\"o}glicht Squimera einfaches Wiederverwenden und dar{\"u}ber hinaus das Verschmischen von in unterschiedlichen Sprachen geschriebenen Softwarebibliotheken und -frameworks und erlaubt dabei zus{\"a}tzlich Debugging {\"u}ber mehrere Sprachen hinweg.}, language = {en} } @book{RanaMohapatraSidorovaetal.2022, author = {Rana, Kaushik and Mohapatra, Durga Prasad and Sidorova, Julia and Lundberg, Lars and Sk{\"o}ld, Lars and Lopes Grim, Lu{\´i}s Fernando and Sampaio Gradvohl, Andr{\´e} Leon and Cremerius, Jonas and Siegert, Simon and Weltzien, Anton von and Baldi, Annika and Klessascheck, Finn and Kalancha, Svitlana and Lichtenstein, Tom and Shaabani, Nuhad and Meinel, Christoph and Friedrich, Tobias and Lenzner, Pascal and Schumann, David and Wiese, Ingmar and Sarna, Nicole and Wiese, Lena and Tashkandi, Araek Sami and van der Walt, Est{\´e}e and Eloff, Jan H. P. and Schmidt, Christopher and H{\"u}gle, Johannes and Horschig, Siegfried and Uflacker, Matthias and Najafi, Pejman and Sapegin, Andrey and Cheng, Feng and Stojanovic, Dragan and Stojnev Ilić, Aleksandra and Djordjevic, Igor and Stojanovic, Natalija and Predic, Bratislav and Gonz{\´a}lez-Jim{\´e}nez, Mario and de Lara, Juan and Mischkewitz, Sven and Kainz, Bernhard and van Hoorn, Andr{\´e} and Ferme, Vincenzo and Schulz, Henning and Knigge, Marlene and Hecht, Sonja and Prifti, Loina and Krcmar, Helmut and Fabian, Benjamin and Ermakova, Tatiana and Kelkel, Stefan and Baumann, Annika and Morgenstern, Laura and Plauth, Max and Eberhard, Felix and Wolff, Felix and Polze, Andreas and Cech, Tim and Danz, Noel and Noack, Nele Sina and Pirl, Lukas and Beilharz, Jossekin Jakob and De Oliveira, Roberto C. L. and Soares, F{\´a}bio Mendes and Juiz, Carlos and Bermejo, Belen and M{\"u}hle, Alexander and Gr{\"u}ner, Andreas and Saxena, Vageesh and Gayvoronskaya, Tatiana and Weyand, Christopher and Krause, Mirko and Frank, Markus and Bischoff, Sebastian and Behrens, Freya and R{\"u}ckin, Julius and Ziegler, Adrian and Vogel, Thomas and Tran, Chinh and Moser, Irene and Grunske, Lars and Sz{\´a}rnyas, G{\´a}bor and Marton, J{\´o}zsef and Maginecz, J{\´a}nos and Varr{\´o}, D{\´a}niel and Antal, J{\´a}nos Benjamin}, title = {HPI Future SOC Lab - Proceedings 2018}, number = {151}, editor = {Meinel, Christoph and Polze, Andreas and Beins, Karsten and Strotmann, Rolf and Seibold, Ulrich and R{\"o}dszus, Kurt and M{\"u}ller, J{\"u}rgen}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-547-7}, issn = {1613-5652}, doi = {10.25932/publishup-56371}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-563712}, publisher = {Universit{\"a}t Potsdam}, pages = {x, 277}, year = {2022}, abstract = {The "HPI Future SOC Lab" is a cooperation of the Hasso Plattner Institute (HPI) and industry partners. Its mission is to enable and promote exchange and interaction between the research community and the industry partners. The HPI Future SOC Lab provides researchers with free of charge access to a complete infrastructure of state of the art hard and software. This infrastructure includes components, which might be too expensive for an ordinary research environment, such as servers with up to 64 cores and 2 TB main memory. The offerings address researchers particularly from but not limited to the areas of computer science and business information systems. Main areas of research include cloud computing, parallelization, and In-Memory technologies. This technical report presents results of research projects executed in 2018. Selected projects have presented their results on April 17th and November 14th 2017 at the Future SOC Lab Day events.}, language = {en} } @book{ReschkeTaeumelPapeetal.2018, author = {Reschke, Jakob and Taeumel, Marcel and Pape, Tobias and Niephaus, Fabio and Hirschfeld, Robert}, title = {Towards version control in object-based systems}, volume = {121}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-430-2}, issn = {1613-5652}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410812}, publisher = {Universit{\"a}t Potsdam}, pages = {100}, year = {2018}, abstract = {Version control is a widely used practice among software developers. It reduces the risk of changing their software and allows them to manage different configurations and to collaborate with others more efficiently. This is amplified by code sharing platforms such as GitHub or Bitbucket. Most version control systems track files (e.g., Git, Mercurial, and Subversion do), but some programming environments do not operate on files, but on objects instead (many Smalltalk implementations do). Users of such environments want to use version control for their objects anyway. Specialized version control systems, such as the ones available for Smalltalk systems (e.g., ENVY/Developer and Monticello), focus on a small subset of objects that can be versioned. Most of these systems concentrate on the tracking of methods, classes, and configurations of these. Other user-defined and user-built objects are either not eligible for version control at all, tracking them involves complicated workarounds, or a fixed, domain-unspecific serialization format is used that does not equally suit all kinds of objects. Moreover, these version control systems that are specific to a programming environment require their own code sharing platforms; popular, well-established platforms for file-based version control systems cannot be used or adapter solutions need to be implemented and maintained. To improve the situation for version control of arbitrary objects, a framework for tracking, converting, and storing of objects is presented in this report. It allows editions of objects to be stored in an exchangeable, existing backend version control system. The platforms of the backend version control system can thus be reused. Users and objects have control over how objects are captured for the purpose of version control. Domain-specific requirements can be implemented. The storage format (i.e. the file format, when file-based backend version control systems are used) can also vary from one object to another. Different editions of objects can be compared and sets of changes can be applied to graphs of objects. A generic way for capturing and restoring that supports most kinds of objects is described. It models each object as a collection of slots. Thus, users can begin to track their objects without first having to implement version control supplements for their own kinds of objects. The proposed architecture is evaluated using a prototype implementation that can be used to track objects in Squeak/Smalltalk with Git. The prototype improves the suboptimal standing of user objects with respect to version control described above and also simplifies some version control tasks for classes and methods as well. It also raises new problems, which are discussed in this report as well.}, language = {en} } @book{Scheer2019, author = {Scheer, August-Wilhelm}, title = {Was macht das Hasso-Plattner-Institut f{\"u}r Digital Engineering zu einer Besonderheit?}, number = {131}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-481-4}, issn = {1613-5652}, doi = {10.25932/publishup-43923}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439232}, publisher = {Universit{\"a}t Potsdam}, pages = {17}, year = {2019}, language = {de} } @book{SchneiderLambersOrejas2019, author = {Schneider, Sven and Lambers, Leen and Orejas, Fernando}, title = {A logic-based incremental approach to graph repair}, number = {126}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-462-3}, issn = {1613-5652}, doi = {10.25932/publishup-42751}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427517}, publisher = {Universit{\"a}t Potsdam}, pages = {34}, year = {2019}, abstract = {Graph repair, restoring consistency of a graph, plays a prominent role in several areas of computer science and beyond: For example, in model-driven engineering, the abstract syntax of models is usually encoded using graphs. Flexible edit operations temporarily create inconsistent graphs not representing a valid model, thus requiring graph repair. Similarly, in graph databases—managing the storage and manipulation of graph data—updates may cause that a given database does not satisfy some integrity constraints, requiring also graph repair. We present a logic-based incremental approach to graph repair, generating a sound and complete (upon termination) overview of least-changing repairs. In our context, we formalize consistency by so-called graph conditions being equivalent to first-order logic on graphs. We present two kind of repair algorithms: State-based repair restores consistency independent of the graph update history, whereas deltabased (or incremental) repair takes this history explicitly into account. Technically, our algorithms rely on an existing model generation algorithm for graph conditions implemented in AutoGraph. Moreover, the delta-based approach uses the new concept of satisfaction (ST) trees for encoding if and how a graph satisfies a graph condition. We then demonstrate how to manipulate these STs incrementally with respect to a graph update.}, language = {en} } @book{SchneiderMaximovaGiese2022, author = {Schneider, Sven and Maximova, Maria and Giese, Holger}, title = {Invariant Analysis for Multi-Agent Graph Transformation Systems using k-Induction}, number = {143}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-531-6}, issn = {1613-5652}, doi = {10.25932/publishup-54585}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-545851}, publisher = {Universit{\"a}t Potsdam}, pages = {37}, year = {2022}, abstract = {The analysis of behavioral models such as Graph Transformation Systems (GTSs) is of central importance in model-driven engineering. However, GTSs often result in intractably large or even infinite state spaces and may be equipped with multiple or even infinitely many start graphs. To mitigate these problems, static analysis techniques based on finite symbolic representations of sets of states or paths thereof have been devised. We focus on the technique of k-induction for establishing invariants specified using graph conditions. To this end, k-induction generates symbolic paths backwards from a symbolic state representing a violation of a candidate invariant to gather information on how that violation could have been reached possibly obtaining contradictions to assumed invariants. However, GTSs where multiple agents regularly perform actions independently from each other cannot be analyzed using this technique as of now as the independence among backward steps may prevent the gathering of relevant knowledge altogether. In this paper, we extend k-induction to GTSs with multiple agents thereby supporting a wide range of additional GTSs. As a running example, we consider an unbounded number of shuttles driving on a large-scale track topology, which adjust their velocity to speed limits to avoid derailing. As central contribution, we develop pruning techniques based on causality and independence among backward steps and verify that k-induction remains sound under this adaptation as well as terminates in cases where it did not terminate before.}, language = {en} } @book{SchneiderMaximovaGiese2022, author = {Schneider, Sven and Maximova, Maria and Giese, Holger}, title = {Probabilistic metric temporal graph logic}, number = {146}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-532-3}, issn = {1613-5652}, doi = {10.25932/publishup-54586}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-545867}, publisher = {Universit{\"a}t Potsdam}, pages = {34}, year = {2022}, abstract = {Cyber-physical systems often encompass complex concurrent behavior with timing constraints and probabilistic failures on demand. The analysis whether such systems with probabilistic timed behavior adhere to a given specification is essential. When the states of the system can be represented by graphs, the rule-based formalism of Probabilistic Timed Graph Transformation Systems (PTGTSs) can be used to suitably capture structure dynamics as well as probabilistic and timed behavior of the system. The model checking support for PTGTSs w.r.t. properties specified using Probabilistic Timed Computation Tree Logic (PTCTL) has been already presented. Moreover, for timed graph-based runtime monitoring, Metric Temporal Graph Logic (MTGL) has been developed for stating metric temporal properties on identified subgraphs and their structural changes over time. In this paper, we (a) extend MTGL to the Probabilistic Metric Temporal Graph Logic (PMTGL) by allowing for the specification of probabilistic properties, (b) adapt our MTGL satisfaction checking approach to PTGTSs, and (c) combine the approaches for PTCTL model checking and MTGL satisfaction checking to obtain a Bounded Model Checking (BMC) approach for PMTGL. In our evaluation, we apply an implementation of our BMC approach in AutoGraph to a running example.}, language = {en} } @book{SchneiderMaximovaGiese2021, author = {Schneider, Sven and Maximova, Maria and Giese, Holger}, title = {Probabilistic metric temporal graph logic}, number = {140}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-517-0}, issn = {1613-5652}, doi = {10.25932/publishup-51506}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-515066}, publisher = {Universit{\"a}t Potsdam}, pages = {40}, year = {2021}, abstract = {Cyber-physical systems often encompass complex concurrent behavior with timing constraints and probabilistic failures on demand. The analysis whether such systems with probabilistic timed behavior adhere to a given specification is essential. When the states of the system can be represented by graphs, the rule-based formalism of Probabilistic Timed Graph Transformation Systems (PTGTSs) can be used to suitably capture structure dynamics as well as probabilistic and timed behavior of the system. The model checking support for PTGTSs w.r.t. properties specified using Probabilistic Timed Computation Tree Logic (PTCTL) has been already presented. Moreover, for timed graph-based runtime monitoring, Metric Temporal Graph Logic (MTGL) has been developed for stating metric temporal properties on identified subgraphs and their structural changes over time. In this paper, we (a) extend MTGL to the Probabilistic Metric Temporal Graph Logic (PMTGL) by allowing for the specification of probabilistic properties, (b) adapt our MTGL satisfaction checking approach to PTGTSs, and (c) combine the approaches for PTCTL model checking and MTGL satisfaction checking to obtain a Bounded Model Checking (BMC) approach for PMTGL. In our evaluation, we apply an implementation of our BMC approach in AutoGraph to a running example.}, language = {en} } @book{SchwarzerWeissSaoumiKitteletal.2023, author = {Schwarzer, Ingo and Weiß-Saoumi, Said and Kittel, Roland and Friedrich, Tobias and Kaynak, Koraltan and Durak, Cemil and Isbarn, Andreas and Diestel, J{\"o}rg and Knittel, Jens and Franz, Marquart and Morra, Carlos and Stahnke, Susanne and Braband, Jens and Dittmann, Johannes and Griebel, Stephan and Krampf, Andreas and Link, Martin and M{\"u}ller, Matthias and Radestock, Jens and Strub, Leo and Bleeke, Kai and Jehl, Leander and Kapitza, R{\"u}diger and Messadi, Ines and Schmidt, Stefan and Schwarz-R{\"u}sch, Signe and Pirl, Lukas and Schmid, Robert and Friedenberger, Dirk and Beilharz, Jossekin Jakob and Boockmeyer, Arne and Polze, Andreas and R{\"o}hrig, Ralf and Sch{\"a}be, Hendrik and Thiermann, Ricky}, title = {RailChain}, number = {152}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-550-7}, issn = {1613-5652}, doi = {10.25932/publishup-57740}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-577409}, publisher = {Universit{\"a}t Potsdam}, pages = {140}, year = {2023}, abstract = {The RailChain project designed, implemented, and experimentally evaluated a juridical recorder that is based on a distributed consensus protocol. That juridical blockchain recorder has been realized as distributed ledger on board the advanced TrainLab (ICE-TD 605 017) of Deutsche Bahn. For the project, a consortium consisting of DB Systel, Siemens, Siemens Mobility, the Hasso Plattner Institute for Digital Engineering, Technische Universit{\"a}t Braunschweig, T{\"U}V Rheinland InterTraffic, and Spherity has been formed. These partners not only concentrated competencies in railway operation, computer science, regulation, and approval, but also combined experiences from industry, research from academia, and enthusiasm from startups. Distributed ledger technologies (DLTs) define distributed databases and express a digital protocol for transactions between business partners without the need for a trusted intermediary. The implementation of a blockchain with real-time requirements for the local network of a railway system (e.g., interlocking or train) allows to log data in the distributed system verifiably in real-time. For this, railway-specific assumptions can be leveraged to make modifications to standard blockchains protocols. EULYNX and OCORA (Open CCS On-board Reference Architecture) are parts of a future European reference architecture for control command and signalling (CCS, Reference CCS Architecture - RCA). Both architectural concepts outline heterogeneous IT systems with components from multiple manufacturers. Such systems introduce novel challenges for the approved and safety-relevant CCS of railways which were considered neither for road-side nor for on-board systems so far. Logging implementations, such as the common juridical recorder on vehicles, can no longer be realized as a central component of a single manufacturer. All centralized approaches are in question. The research project RailChain is funded by the mFUND program and gives practical evidence that distributed consensus protocols are a proper means to immutably (for legal purposes) store state information of many system components from multiple manufacturers. The results of RailChain have been published, prototypically implemented, and experimentally evaluated in large-scale field tests on the advanced TrainLab. At the same time, the project showed how RailChain can be integrated into the road-side and on-board architecture given by OCORA and EULYNX. Logged data can now be analysed sooner and also their trustworthiness is being increased. This enables, e.g., auditable predictive maintenance, because it is ensured that data is authentic and unmodified at any point in time.}, language = {en} } @book{SeitzLinckeReinetal.2021, author = {Seitz, Klara and Lincke, Jens and Rein, Patrick and Hirschfeld, Robert}, title = {Language and tool support for 3D crochet patterns}, number = {137}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-505-7}, issn = {1613-5652}, doi = {10.25932/publishup-49253}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-492530}, publisher = {Universit{\"a}t Potsdam}, pages = {vii, 94}, year = {2021}, abstract = {Crochet is a popular handcraft all over the world. While other techniques such as knitting or weaving have received technical support over the years through machines, crochet is still a purely manual craft. Not just the act of crochet itself is manual but also the process of creating instructions for new crochet patterns, which is barely supported by domain specific digital solutions. This leads to unstructured and often also ambiguous and erroneous pattern instructions. In this report, we propose a concept to digitally represent crochet patterns. This format incorporates crochet techniques which allows domain specific support for crochet pattern designers during the pattern creation and instruction writing process. As contributions, we present a thorough domain analysis, the concept of a graph structure used as domain specific language to specify crochet patterns and a prototype of a projectional editor using the graph as representation format of patterns and a diagramming system to visualize them in 2D and 3D. By analyzing the domain, we learned about crochet techniques and pain points of designers in their pattern creation workflow. These insights are the basis on which we defined the pattern representation. In order to evaluate our concept, we built a prototype by which the feasibility of the concept is shown and we tested the software with professional crochet designers who approved of the concept.}, language = {en} } @book{vanderWaltOdunAyoBastianetal.2018, author = {van der Walt, Estee and Odun-Ayo, Isaac and Bastian, Matthias and Eldin Elsaid, Mohamed Esam}, title = {Proceedings of the Fifth HPI Cloud Symposium "Operating the Cloud" 2017}, number = {122}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-432-6}, issn = {1613-5652}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-411330}, publisher = {Universit{\"a}t Potsdam}, pages = {70}, year = {2018}, abstract = {Every year, the Hasso Plattner Institute (HPI) invites guests from industry and academia to a collaborative scientific workshop on the topic Operating the Cloud. Our goal is to provide a forum for the exchange of knowledge and experience between industry and academia. Co-located with the event is the HPI's Future SOC Lab day, which offers an additional attractive and conducive environment for scientific and industry related discussions. Operating the Cloud aims to be a platform for productive interactions of innovative ideas, visions, and upcoming technologies in the field of cloud operation and administration. In these proceedings, the results of the fifth HPI cloud symposium Operating the Cloud 2017 are published. We thank the authors for exciting presentations and insights into their current work and research. Moreover, we look forward to more interesting submissions for the upcoming symposium in 2018.}, language = {en} } @book{Weber2023, author = {Weber, Benedikt}, title = {Human pose estimation for decubitus prophylaxis}, number = {153}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-551-4}, issn = {1613-5652}, doi = {10.25932/publishup-56719}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-567196}, publisher = {Universit{\"a}t Potsdam}, pages = {73}, year = {2023}, abstract = {Decubitus is one of the most relevant diseases in nursing and the most expensive to treat. It is caused by sustained pressure on tissue, so it particularly affects bed-bound patients. This work lays a foundation for pressure mattress-based decubitus prophylaxis by implementing a solution to the single-frame 2D Human Pose Estimation problem. For this, methods of Deep Learning are employed. Two approaches are examined, a coarse-to-fine Convolutional Neural Network for direct regression of joint coordinates and a U-Net for the derivation of probability distribution heatmaps. We conclude that training our models on a combined dataset of the publicly available Bodies at Rest and SLP data yields the best results. Furthermore, various preprocessing techniques are investigated, and a hyperparameter optimization is performed to discover an improved model architecture. Another finding indicates that the heatmap-based approach outperforms direct regression. This model achieves a mean per-joint position error of 9.11 cm for the Bodies at Rest data and 7.43 cm for the SLP data. We find that it generalizes well on data from mattresses other than those seen during training but has difficulties detecting the arms correctly. Additionally, we give a brief overview of the medical data annotation tool annoto we developed in the bachelor project and furthermore conclude that the Scrum framework and agile practices enhanced our development workflow.}, language = {en} } @book{ZhangPlauthEberhardtetal.2020, author = {Zhang, Shuhao and Plauth, Max and Eberhardt, Felix and Polze, Andreas and Lehmann, Jens and Sejdiu, Gezim and Jabeen, Hajira and Servadei, Lorenzo and M{\"o}stl, Christian and B{\"a}r, Florian and Netzeband, Andr{\´e} and Schmidt, Rainer and Knigge, Marlene and Hecht, Sonja and Prifti, Loina and Krcmar, Helmut and Sapegin, Andrey and Jaeger, David and Cheng, Feng and Meinel, Christoph and Friedrich, Tobias and Rothenberger, Ralf and Sutton, Andrew M. and Sidorova, Julia A. and Lundberg, Lars and Rosander, Oliver and Sk{\"o}ld, Lars and Di Varano, Igor and van der Walt, Est{\´e}e and Eloff, Jan H. P. and Fabian, Benjamin and Baumann, Annika and Ermakova, Tatiana and Kelkel, Stefan and Choudhary, Yash and Cooray, Thilini and Rodr{\´i}guez, Jorge and Medina-P{\´e}rez, Miguel Angel and Trejo, Luis A. and Barrera-Animas, Ari Yair and Monroy-Borja, Ra{\´u}l and L{\´o}pez-Cuevas, Armando and Ram{\´i}rez-M{\´a}rquez, Jos{\´e} Emmanuel and Grohmann, Maria and Niederleithinger, Ernst and Podapati, Sasidhar and Schmidt, Christopher and Huegle, Johannes and de Oliveira, Roberto C. L. and Soares, F{\´a}bio Mendes and van Hoorn, Andr{\´e} and Neumer, Tamas and Willnecker, Felix and Wilhelm, Mathias and Kuster, Bernhard}, title = {HPI Future SOC Lab - Proceedings 2017}, number = {130}, editor = {Meinel, Christoph and Polze, Andreas and Beins, Karsten and Strotmann, Rolf and Seibold, Ulrich and R{\"o}dszus, Kurt and M{\"u}ller, J{\"u}rgen}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-475-3}, issn = {1613-5652}, doi = {10.25932/publishup-43310}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-433100}, publisher = {Universit{\"a}t Potsdam}, pages = {ix, 235}, year = {2020}, abstract = {The "HPI Future SOC Lab" is a cooperation of the Hasso Plattner Institute (HPI) and industry partners. Its mission is to enable and promote exchange and interaction between the research community and the industry partners. The HPI Future SOC Lab provides researchers with free of charge access to a complete infrastructure of state of the art hard and software. This infrastructure includes components, which might be too expensive for an ordinary research environment, such as servers with up to 64 cores and 2 TB main memory. The offerings address researchers particularly from but not limited to the areas of computer science and business information systems. Main areas of research include cloud computing, parallelization, and In-Memory technologies. This technical report presents results of research projects executed in 2017. Selected projects have presented their results on April 25th and November 15th 2017 at the Future SOC Lab Day events.}, language = {en} }