004 Datenverarbeitung; Informatik
Refine
Year of publication
Document Type
- Monograph/Edited Volume (166) (remove)
Language
- English (124)
- German (40)
- Multiple languages (2)
Keywords
- Hasso-Plattner-Institut (10)
- Hasso Plattner Institute (9)
- cloud computing (9)
- Cloud Computing (8)
- Forschungskolleg (8)
- Klausurtagung (8)
- Service-oriented Systems Engineering (8)
- Forschungsprojekte (7)
- Future SOC Lab (7)
- In-Memory Technologie (7)
- Multicore Architekturen (7)
- openHPI (7)
- multicore architectures (6)
- research projects (6)
- Identitätsmanagement (5)
- Ph.D. retreat (5)
- cloud (5)
- cyber-physical systems (5)
- quantitative analysis (5)
- service-oriented systems engineering (5)
- Modellierung (4)
- Research School (4)
- Smalltalk (4)
- Virtualisierung (4)
- digital education (4)
- digitale Bildung (4)
- identity management (4)
- in-memory technology (4)
- machine learning (4)
- maschinelles Lernen (4)
- nested graph conditions (4)
- probabilistic timed systems (4)
- qualitative Analyse (4)
- qualitative analysis (4)
- quantitative Analyse (4)
- research school (4)
- Cloud (3)
- Computer Networks (3)
- Computernetzwerke (3)
- Datenintegration (3)
- Datenschutz (3)
- Design Thinking (3)
- Digitalisierung (3)
- E-Learning (3)
- Graphtransformationen (3)
- IPv4 (3)
- IPv6 (3)
- In-Memory technology (3)
- Infrastructure (3)
- Infrastruktur (3)
- Innovation (3)
- Internet Protocol (3)
- Lively Kernel (3)
- MOOCs (3)
- Model Synchronisation (3)
- Model Transformation (3)
- Network Politics (3)
- Netzpolitik (3)
- Online-Lernen (3)
- Onlinekurs (3)
- Ph.D. Retreat (3)
- Privacy (3)
- Sicherheit (3)
- Tele-Lab (3)
- Tele-Teaching (3)
- Tripel-Graph-Grammatik (3)
- Verifikation (3)
- Werkzeuge (3)
- artifical intelligence (3)
- conference (3)
- digitalization (3)
- graph transformation (3)
- graph transformation systems (3)
- privacy (3)
- security (3)
- tele-TASK (3)
- verification (3)
- virtual machines (3)
- virtualization (3)
- ACINQ (2)
- ASIC (2)
- AUTOSAR (2)
- Australian securities exchange (2)
- BCCC (2)
- BPM (2)
- BPMN (2)
- BTC (2)
- Betriebssysteme (2)
- BitShares (2)
- Bitcoin Core (2)
- Blockchain Auth (2)
- Blockchain-Konsortium R3 (2)
- Blockkette (2)
- Blockstack (2)
- Blockstack ID (2)
- Blumix-Plattform (2)
- Blöcke (2)
- Bounded Model Checking (2)
- Byzantine Agreement (2)
- Cloud-Sicherheit (2)
- Cloud-Speicher (2)
- Colored Coins (2)
- DAO (2)
- DPoS (2)
- Data Integration (2)
- Delegated Proof-of-Stake (2)
- Distributed Proof-of-Research (2)
- E-Wallet (2)
- ECDSA (2)
- Eris (2)
- Ether (2)
- Ethereum (2)
- European Union (2)
- Europäische Union (2)
- Federated Byzantine Agreement (2)
- Fehlertoleranz (2)
- FollowMyVote (2)
- Fork (2)
- Formale Verifikation (2)
- Graphentransformationssysteme (2)
- Graphtransformationssysteme (2)
- Gridcoin (2)
- HPI Schul-Cloud (2)
- Hard Fork (2)
- Hashed Timelock Contracts (2)
- Hauptspeicherdatenbank (2)
- IT-Infrastruktur (2)
- IT-infrastructure (2)
- Internet (2)
- Internet Service Provider (2)
- Internet der Dinge (2)
- Internet of Things (2)
- IoT (2)
- Japanese Blockchain Consortium (2)
- Japanisches Blockchain-Konsortium (2)
- Java (2)
- Kette (2)
- Konferenz (2)
- Konsensalgorithmus (2)
- Konsensprotokoll (2)
- Lightning Network (2)
- Live-Programmierung (2)
- Lock-Time-Parameter (2)
- MERLOT (2)
- MOOC (2)
- Micropayment-Kanäle (2)
- Microsoft Azur (2)
- Model Synchronization (2)
- Model-Driven Engineering (2)
- Modeling (2)
- Modellprüfung (2)
- NASDAQ (2)
- NameID (2)
- Namecoin (2)
- Off-Chain-Transaktionen (2)
- Onename (2)
- Online Course (2)
- Online-Learning (2)
- OpenBazaar (2)
- Oracles (2)
- Orphan Block (2)
- P2P (2)
- Peer-to-Peer Netz (2)
- Peercoin (2)
- PoB (2)
- PoS (2)
- PoW (2)
- Process Modeling (2)
- Proof-of-Burn (2)
- Proof-of-Stake (2)
- Proof-of-Work (2)
- Prozessmodellierung (2)
- Python (2)
- Ressourcenoptimierung (2)
- Ripple (2)
- SCP (2)
- SHA (2)
- SPV (2)
- Schule (2)
- Schwierigkeitsgrad (2)
- Simplified Payment Verification (2)
- Skalierbarkeit der Blockchain (2)
- Slock.it (2)
- Soft Fork (2)
- Steemit (2)
- Stellar Consensus Protocol (2)
- Storj (2)
- Studie (2)
- SysML (2)
- The Bitfury Group (2)
- The DAO (2)
- Timed Automata (2)
- Transaktion (2)
- Two-Way-Peg (2)
- Unspent Transaction Output (2)
- Verlässlichkeit (2)
- Versionsverwaltung (2)
- Verträge (2)
- Virtuelle Maschinen (2)
- Visualisierung (2)
- Watson IoT (2)
- Zielvorgabe (2)
- Zookos Dreieck (2)
- Zookos triangle (2)
- altchain (2)
- alternative chain (2)
- atomic swap (2)
- batch processing (2)
- bidirectional payment channels (2)
- bitcoins (2)
- blockchain (2)
- blockchain consortium (2)
- blockchain-übergreifend (2)
- blocks (2)
- blumix platform (2)
- bounded model checking (2)
- chain (2)
- confirmation period (2)
- consensus algorithm (2)
- consensus protocol (2)
- contest period (2)
- continuous integration (2)
- contracts (2)
- cross-chain (2)
- cyber-physische Systeme (2)
- data profiling (2)
- debugging (2)
- decentralized autonomous organization (2)
- dependability (2)
- dezentrale autonome Organisation (2)
- difficulty (2)
- difficulty target (2)
- digital enlightenment (2)
- digital learning platform (2)
- digital sovereignty (2)
- digitale Aufklärung (2)
- digitale Lernplattform (2)
- digitale Souveränität (2)
- doppelter Hashwert (2)
- double hashing (2)
- fault tolerance (2)
- federated voting (2)
- graph constraints (2)
- hashrate (2)
- incremental graph pattern matching (2)
- innovation (2)
- intelligente Verträge (2)
- inter-chain (2)
- k-inductive invariant checking (2)
- kontinuierliche Integration (2)
- künstliche Intelligenz (2)
- lebenslanges Lernen (2)
- ledger assets (2)
- lifelong learning (2)
- live programming (2)
- merged mining (2)
- merkle root (2)
- micropayment (2)
- micropayment channels (2)
- miner (2)
- mining (2)
- mining hardware (2)
- minting (2)
- model checking (2)
- modeling (2)
- modellgetriebene Entwicklung (2)
- nonce (2)
- off-chain transaction (2)
- operating systems (2)
- peer-to-peer network (2)
- pegged sidechains (2)
- probabilistische gezeitete Systeme (2)
- probabilistische zeitgesteuerte Systeme (2)
- programming (2)
- quorum slices (2)
- real-time systems (2)
- rootstock (2)
- scalability of blockchain (2)
- scarce tokens (2)
- sidechain (2)
- smalltalk (2)
- smart contracts (2)
- timed automata (2)
- tools (2)
- transaction (2)
- triple graph grammars (2)
- typed attributed graphs (2)
- verschachtelte Graphbedingungen (2)
- version control (2)
- virtuelle Maschinen (2)
- visualization (2)
- Abhängigkeiten (1)
- Abstraktion von Geschäftsprozessmodellen (1)
- Agile (1)
- Agilität (1)
- Aktivitäten (1)
- Algorithmen (1)
- Ambiguity (1)
- Ambiguität (1)
- Analog-zu-Digital-Konvertierung (1)
- Anfragesprache (1)
- Angriffe (1)
- Anwendungsvirtualisierung (1)
- Apriori (1)
- Architektur (1)
- Artem Erkomaishvili (1)
- Aspect-oriented Programming (1)
- Aspektorientierte Softwareentwicklung (1)
- Association Rule Mining (1)
- Assoziationsregeln (1)
- Asynchrone Schaltung (1)
- Asynchronous circuit (1)
- Attribut-Merge-Prozess (1)
- Attribute Merge Process (1)
- Ausführung von Modellen (1)
- Auswirkungen (1)
- Authentifizierung (1)
- Bahnwesen (1)
- Basic Storage Anbieter (1)
- Batchprozesse (1)
- Batchverarbeitung (1)
- Bayes'sche Netze (1)
- Bayesian networks (1)
- Bedingte Inklusionsabhängigkeiten (1)
- Behavior change (1)
- Benutzerinteraktion (1)
- Beschränkungen und Abhängigkeiten (1)
- Biometrie (1)
- Bisimulation (1)
- Bitcoin (1)
- Blockchain (1)
- Blockheizkraftwerke (1)
- Bounded Backward Model Checking (1)
- CEP (1)
- CSC (1)
- CSCW (1)
- Change Management (1)
- Conditional Inclusion Dependency (1)
- Conformance Überprüfung (1)
- Constraints (1)
- Context-oriented Programming (1)
- Contracts (1)
- Controller-Resynthese (1)
- Creative (1)
- Cyber-Physical Systems (1)
- Cyber-Physical-Systeme (1)
- Cyber-physical-systems (1)
- Cyber-physikalische Systeme (1)
- Data Dependency (1)
- Data Modeling (1)
- Data Profiling (1)
- Data Quality (1)
- Data Warehouse (1)
- Database Cost Model (1)
- Datenabhängigkeiten (1)
- Datenanalyse (1)
- Datenbank (1)
- Datenbank-Kostenmodell (1)
- Datenflusskorrektheit (1)
- Datenmodellierung (1)
- Datenqualität (1)
- Datensatz (1)
- Datenschutz-sicherer Einsatz in der Schule (1)
- Datensicht (1)
- Datenvertraulichkeit (1)
- Datenvisualisierung (1)
- Deadline-Verbreitung (1)
- Debugging (1)
- Dekubitus (1)
- Denkweise (1)
- Differential Privacy (1)
- Digital Engineering (1)
- Discrimination Networks (1)
- Distributed-Ledger-Technologie (DLT) (1)
- Duplicate Detection (1)
- Duplikaterkennung (1)
- Dynamic Type System (1)
- Dynamische Typ Systeme (1)
- EHR (1)
- EPA (1)
- Echtzeit (1)
- Echtzeitsysteme (1)
- Effizienz (1)
- Eingebettete Systeme (1)
- Elektronische Patientenakte (1)
- Energiesparen (1)
- Entwurfsmuster (1)
- Ereignisse (1)
- Erfüllbarkeitsanalyse (1)
- Erkennen von Meta-Daten (1)
- Evolution (1)
- Evolution in MDE (1)
- Extract-Transform-Load (ETL) (1)
- FIDO (1)
- FRP (1)
- Fallstudie (1)
- Feedback Loops (1)
- Fehlerinjektion (1)
- Fehlersuche (1)
- Functional Lenses (1)
- Generalized Discrimination Networks (1)
- Georgian chant (1)
- Georgische liturgische Gesänge (1)
- German schools (1)
- Geschäftsanwendungen (1)
- Geschäftsprozesse (1)
- Geschäftsprozessmanagement (1)
- Gesetze (1)
- GitHub (1)
- Graph-Constraints (1)
- Graph-basierte Suche (1)
- Graphbedingungen (1)
- Graphdatenbanken (1)
- Graphreparatur (1)
- Graphtransformation (1)
- Gruppierung von Prozessinstanzen (1)
- HENSHIN (1)
- HPI Forschung (1)
- HPI research (1)
- Hasso-Plattner-Institute (1)
- Heuristiken (1)
- Homomorphe Verschlüsselung (1)
- Häkeln (1)
- Ideation (1)
- Ideenfindung (1)
- Identity Management (1)
- Identität (1)
- Impact (1)
- Implementation in Organizations (1)
- Implementierung in Organisationen (1)
- In-Memory (1)
- In-Memory Database (1)
- In-Memory Datenbank (1)
- In-Memory-Datenbank (1)
- Individuen (1)
- Infinite State (1)
- Informatik (1)
- Informatikdidaktik (1)
- Informatiksystem (1)
- Informatikunterricht (1)
- Information Extraction (1)
- Information Systems (1)
- Informationsextraktion (1)
- Informationssysteme (1)
- Inkrementelle Graphmustersuche (1)
- Innovationsmanagement (1)
- Innovationsmethode (1)
- Interdisciplinary Teams (1)
- Interpreter (1)
- Interval Timed Automata (1)
- Invariant-Checking (1)
- Invarianten (1)
- Invariants (1)
- JCop (1)
- Kausalität (1)
- Kollaborationen (1)
- Kompetenz (1)
- Konsensprotokolle (1)
- Konsistenzrestauration (1)
- Kreativität (1)
- Kunstanalyse (1)
- Künstliche Intelligenz (1)
- Laufzeitanalyse (1)
- Laufzeitmodelle (1)
- Leadership (1)
- Leistungsmodelle von virtuellen Maschinen (1)
- Lernsoftware (1)
- Link Discovery (1)
- Link-Entdeckung (1)
- Linked Data (1)
- Linked Open Data (1)
- Liveness (1)
- Lösungsraum (1)
- MDE Ansatz (1)
- MDE settings (1)
- Management (1)
- Marktübersicht (1)
- Measurement (1)
- Megamodell (1)
- Megamodels (1)
- Mehr-Faktor-Authentifizierung (1)
- Mehrfamilienhäuser (1)
- Mehrkernsysteme (1)
- Messung (1)
- Metadata Discovery (1)
- Metadatenentdeckung (1)
- Metadatenqualität (1)
- Middleware (1)
- Mindset (1)
- Mobile Application Development (1)
- Model Execution (1)
- Model-driven SOA Security (1)
- Modeling Languages (1)
- Modell-getriebene SOA-Sicherheit (1)
- Modell-getriebene Softwareentwicklung (1)
- Modelle mit mehreren Versionen (1)
- Modellerzeugung (1)
- Modellgetriebene Softwareentwicklung (1)
- Modellierungssprachen (1)
- Modellreparatur (1)
- Modelltransformationen (1)
- Models at Runtime (1)
- Morphic (1)
- Multi-Instanzen (1)
- Multicore architectures (1)
- Multidisciplinary Teams (1)
- Muster (1)
- Musterabgleich (1)
- Nebenläufigkeit (1)
- Nested Graph Conditions (1)
- Netzneutralität (1)
- Netzwerkprotokolle (1)
- Newspeak (1)
- OAuth (1)
- Object Constraint Programming (1)
- Object-Oriented Programming (1)
- Objekt-Constraint Programmierung (1)
- Objekt-Orientiertes Programmieren (1)
- Objekt-orientiertes Programmieren mit Constraints (1)
- Objektlebenszyklus-Synchronisation (1)
- OpenID Connect (1)
- Optimierungen (1)
- Organisationsveränderung (1)
- PRISM Modell-Checker (1)
- PRISM model checker (1)
- PTCTL (1)
- Pattern Matching (1)
- Patterns (1)
- Petri net Mapping (1)
- Petri net mapping (1)
- Petrinetz (1)
- Posenabschätzung (1)
- Privatsphäre (1)
- Problem Solving (1)
- Problemlösung (1)
- Process (1)
- Process Enactment (1)
- Process Mining (1)
- Prognosen (1)
- Programmieren (1)
- Programmiererlebnis (1)
- Programmierkonzepte (1)
- Programmierung (1)
- Programming Languages (1)
- Propagation von Aktivitätsinstanzzuständen (1)
- Prototyping (1)
- Prozess (1)
- Prozessausführung (1)
- Prozesserhebung (1)
- Prozessinstanz (1)
- Prozessoren (1)
- Quanten-Computing (1)
- Quantitative Analysen (1)
- Realzeitsysteme (1)
- Regressionstests (1)
- Research Projects (1)
- Reverse Engineering (1)
- Ruby (1)
- Runtime Binding (1)
- Runtime-monitoring (1)
- SOA Security (1)
- SOA Sicherheit (1)
- SQL (1)
- STG decomposition (1)
- STG-Dekomposition (1)
- Sammlungsdatentypen (1)
- Savanne (1)
- Schemaentdeckung (1)
- Schlüsselentdeckung (1)
- Schriftartgestaltung (1)
- Schriftrendering (1)
- Scrollytelling (1)
- Secure Digital Identities (1)
- Secure Enterprise SOA (1)
- Self-Adaptive Software (1)
- Sequenzeigenschaften (1)
- Sequenzen von s/t-Pattern (1)
- Serialisierung (1)
- Service Provider (1)
- Service-Oriented Architecture (1)
- Service-Orientierte Architekturen (1)
- Service-orientierte Systme (1)
- Sichere Digitale Identitäten (1)
- Signalflankengraph (SFG oder STG) (1)
- Simulation (1)
- Single-Sign-On (1)
- Skript-Entwicklungsumgebungen (1)
- SoaML (1)
- Software-Testen (1)
- Software/Hardware Co-Design (1)
- Softwarearchitektur (1)
- Softwareproduktlinien (1)
- Softwaretests (1)
- Solution Space (1)
- Sozialen Medien (1)
- Spaltenlayout (1)
- Speicheroptimierungen (1)
- Spezifikation von gezeiteten Graph Transformationen (1)
- Sprachspezifikation (1)
- Squeak (1)
- Standardisierung (1)
- Standards (1)
- Synchronisation (1)
- System of Systems (1)
- Systemsoftware (1)
- Tableaumethode (1)
- Telemedizin (1)
- Temporallogik (1)
- Testergebnisse (1)
- Testpriorisierungs (1)
- Threshold Cryptography (1)
- Tools (1)
- Trajektorien (1)
- Transaktionen (1)
- Transformationsebene (1)
- Transformationssequenzen (1)
- Travis CI (1)
- Tripel-Graph-Grammatiken (1)
- Triple Graph Grammar (1)
- Triple Graph Grammars (1)
- Triple-Graph-Grammatiken (1)
- Trust Management (1)
- Unbegrenzter Zustandsraum (1)
- Unterricht mit digitalen Medien (1)
- Unveränderlichkeit (1)
- VUCA-World (1)
- Verbindungsnetzwerke (1)
- Verhaltensabstraktion (1)
- Verhaltensbewahrung (1)
- Verhaltensverfeinerung (1)
- Verhaltensänderung (1)
- Verhaltensäquivalenz (1)
- Verification (1)
- Verteilungsalgorithmen (1)
- Verteilungsalgorithmus (1)
- Verzögerungs-Verbreitung (1)
- Virtual Desktop Infrastructure (1)
- Virtual machines (1)
- Visualisierungskonzept-Exploration (1)
- Wartung von Graphdatenbanksichten (1)
- Web applications (1)
- Web-Anwendungen (1)
- Wicked Problems (1)
- Wikipedia (1)
- Wüstenbildung (1)
- Zugriffskontrolle (1)
- access control (1)
- activity instance state propagation (1)
- adaptive Systeme (1)
- adaptive systems (1)
- adoption (1)
- agil (1)
- algorithms (1)
- analog-to-digital conversion (1)
- application virtualization (1)
- apriori (1)
- architecture (1)
- art analysis (1)
- asset management (1)
- ausführbare Semantiken (1)
- authentication (1)
- basic cloud storage services (1)
- behavior preservation (1)
- behavioral abstraction (1)
- behavioral equivalenc (1)
- behavioral refinement (1)
- benutzergenerierte Inhalte (1)
- beschreibende Feldstudie (1)
- big data services (1)
- biometrics (1)
- bisimulation (1)
- bitcoin (1)
- bounded backward model checking (1)
- business process management (1)
- business process model abstraction (1)
- business process modeling (1)
- business processes (1)
- case study (1)
- causality (1)
- change management (1)
- cloud security (1)
- cloud storage (1)
- cogeneration units (1)
- collaboration (1)
- collection types (1)
- compositional analysis (1)
- computational ethnomusicology (1)
- computer vision (1)
- computer-aided design (1)
- computergestützte Musikethnologie (1)
- confidentiality (1)
- conformance checking (1)
- consensus protocols (1)
- consistency restoration (1)
- continuous testing (1)
- control resynthesis (1)
- controlled experiment (1)
- convolutional neural networks (1)
- crochet (1)
- cultural heritage (1)
- cyber-physikalische Systeme (1)
- data center management (1)
- data flow correctness (1)
- data in business processes (1)
- data integration (1)
- data modeling (1)
- data security (1)
- data set (1)
- data view (1)
- data visualization (1)
- deadline propagation (1)
- decentral identities (1)
- decubitus (1)
- deep learning (1)
- delay propagation (1)
- demografische Informationen (1)
- demographic information (1)
- dependable computing (1)
- dependencies (1)
- desertification (1)
- design thinking (1)
- dezentrale Identitäten (1)
- differential privacy (1)
- diffusion (1)
- digital picture archive (1)
- digital unterstützter Unterricht (1)
- digitale Infrastruktur für den Schulunterricht (1)
- digitales Bildarchiv (1)
- direct manipulation (1)
- direkte Manipulation (1)
- discrete-event model (1)
- discrimination networks (1)
- diskretes Ereignismodell (1)
- distributed performance monitoring (1)
- distribution algorithm (1)
- dynamic typing (1)
- dynamic programming languages (1)
- dynamic systems (1)
- dynamische Programmiersprachen (1)
- dynamische Sprachen (1)
- dynamische Systeme (1)
- e-learning (1)
- efficiency (1)
- eindeutig (1)
- electronic health record (1)
- embedded-systems (1)
- energy savings (1)
- erfahrbare Medien (1)
- events (1)
- evolution in MDE (1)
- executable semantics (1)
- exploratives Programmieren (1)
- exploratory programming (1)
- fault injection (1)
- feedback loops (1)
- fehlende Daten (1)
- font engineering (1)
- font rendering (1)
- forecasts (1)
- formal verification (1)
- formal verification methods (1)
- formale Verifikation (1)
- functional dependency (1)
- functional lenses (1)
- functional programming (1)
- funktionale Abhängigkeit (1)
- funktionale Programmierung (1)
- future SOC lab (1)
- gefaltete neuronale Netze (1)
- generalized discrimination networks (1)
- getypte Attributierte Graphen (1)
- global model management (1)
- globales Modellmanagement (1)
- graph databases (1)
- graph queries (1)
- graph repair (1)
- graph transformations (1)
- heuristics (1)
- homomorphic encryption (1)
- human-centered (1)
- hybrid graph-transformation-systems (1)
- hybride Graph-Transformations-Systeme (1)
- identity (1)
- immutable values (1)
- in-memory database (1)
- individuals (1)
- inductive invariant checking (1)
- induktives Invariant Checking (1)
- inkrementelles Graph Pattern Matching (1)
- innovation capabilities (1)
- innovation management (1)
- integrated development environments (1)
- integrierte Entwicklungsumgebungen (1)
- interactive media (1)
- interaktive Medien (1)
- interconnect (1)
- interdisziplinäre Teams (1)
- interpreters (1)
- interval probabilistic timed systems (1)
- interval probabilistische zeitgesteuerte Systeme (1)
- interval timed automata (1)
- intuitive Benutzeroberflächen (1)
- intuitive interfaces (1)
- invariant checking (1)
- juridical recording (1)
- k-Induktion (1)
- k-induction (1)
- k-inductive invariants (1)
- k-induktive Invarianten (1)
- k-induktive Invariantenprüfung (1)
- k-induktives Invariant-Checking (1)
- key discovery (1)
- kompositionale Analyse (1)
- kontinuierliches Testen (1)
- kontrolliertes Experiment (1)
- kulturelles Erbe (1)
- language specification (1)
- law (1)
- leadership (1)
- lebenszentriert (1)
- left recursion (1)
- life-centered (1)
- lively kernel (1)
- liveness (1)
- location-based (1)
- management (1)
- many-core (1)
- market study (1)
- maschinelles Sehen (1)
- mehrdimensionale Belangtrennung (1)
- mehrsprachige Ausführungsumgebungen (1)
- memory optimization (1)
- menschenzentriert (1)
- metadata discovery (1)
- metadata quality (1)
- metric temporal logic (1)
- metric termporal graph logic (1)
- metrisch temporale Graph Logic (1)
- metrische Temporallogik (1)
- middleware (1)
- missing data (1)
- model generation (1)
- model repair (1)
- model transformation (1)
- model-driven engineering (1)
- monitoring (1)
- morphic (1)
- multi factor authentication (1)
- multi-core (1)
- multi-dimensional separation of concerns (1)
- multi-instances (1)
- multi-version models (1)
- multi-family residential buildings (1)
- multidisziplinäre Teams (1)
- musical scales (1)
- musikalische Tonleitern (1)
- nested application conditions (1)
- network protocols (1)
- object life cycle synchronization (1)
- object-constraint programming (1)
- object-oriented programming (1)
- objektorientiertes Programmieren (1)
- online course (1)
- online-learning (1)
- optimizations (1)
- organizational change (1)
- orts-basiert (1)
- packrat parsing (1)
- parallel and sequential independence (1)
- parallel computing (1)
- parallele und Sequentielle Unabhängigkeit (1)
- paralleles Rechnen (1)
- parsing expression grammars (1)
- partial application conditions (1)
- partielle Anwendungsbedingungen (1)
- performance models of virtual machines (1)
- periodic tasks (1)
- periodische Aufgaben (1)
- petri net (1)
- polyglot execution environments (1)
- pose estimation (1)
- probabilistic timed automata (1)
- probabilistische zeitbehaftete Automaten (1)
- process elicitation (1)
- process instance (1)
- process instance grouping (1)
- process mining (1)
- process modeling languages (1)
- processor hardware (1)
- profiling (1)
- programming experience (1)
- prototyping (1)
- public cloud storage services (1)
- qualitative model (1)
- qualitatives Modell (1)
- quantum computing (1)
- railways (1)
- reactive (1)
- reaktive Programmierung (1)
- real-time (1)
- rechnerunterstütztes Konstruieren (1)
- regression testing (1)
- relational model transformation (1)
- relationale Modelltransformationen (1)
- resource optimization (1)
- reverse engineering (1)
- runtime adaptations (1)
- runtime monitoring (1)
- s/t-pattern sequences (1)
- satisfiabilitiy solving (1)
- savanna (1)
- schema discovery (1)
- school (1)
- scripting environments (1)
- scrollytelling (1)
- selbstbestimmte Identitäten (1)
- self-sovereign identity (1)
- semantics preservation (1)
- sequence properties (1)
- serialization (1)
- service-oriented systems (1)
- signal transition graph (1)
- simulation (1)
- small talk (1)
- smartphone (1)
- software architecture (1)
- software product lines (1)
- software testing (1)
- software tests (1)
- software/hardware co-design (1)
- specification of timed graph transformations (1)
- speed independent (1)
- squeak (1)
- standardization (1)
- standards (1)
- static analysis (1)
- static source-code analysis (1)
- statische Analyse (1)
- statische Quellcodeanalyse (1)
- stochastic Petri nets (1)
- stochastische Petri Netze (1)
- study (1)
- symbolic analysis (1)
- symbolic graphs (1)
- symbolische Analyse (1)
- symbolische Graphen (1)
- synchronization (1)
- system of systems (1)
- systems software (1)
- t.BPM (1)
- tableau method (1)
- tangible media (1)
- tele-lab (1)
- tele-teaching (1)
- telemedicine (1)
- temporal logic (1)
- test case prioritization (1)
- test results (1)
- threshold cryptography (1)
- tiefes Lernen (1)
- traditional Georgian music (1)
- traditionelle Georgische Musik (1)
- trajectories (1)
- transformation level (1)
- transformation sequences (1)
- typed graph transformation systems (1)
- typisierte attributierte Graphen (1)
- unique (1)
- user interaction (1)
- user-generated content (1)
- verifiable credentials (1)
- verschachtelte Anwednungsbedingungen (1)
- verschachtelte Anwendungsbedingungen (1)
- verteilte Leistungsüberwachung (1)
- verzwickte Probleme (1)
- view maintenance (1)
- virtual desktop infrastructure (1)
- visual language (1)
- visual languages (1)
- visualization concept exploration (1)
- visuelle Sprache (1)
- visuelle Sprachen (1)
- wearables (1)
- web-applications (1)
- web-based development (1)
- web-based development environment (1)
- web-basierte Entwicklungsumgebung (1)
- webbasierte Entwicklung (1)
- zuverlässige Datenverarbeitung (1)
- zuverlässigen Datenverarbeitung (1)
- Überwachung (1)
- öffentliche Cloud Speicherdienste (1)
- überprüfbare Nachweise (1)
Institute
- Hasso-Plattner-Institut für Digital Engineering gGmbH (119)
- Hasso-Plattner-Institut für Digital Engineering GmbH (40)
- Extern (7)
- Institut für Informatik und Computational Science (3)
- Institut für Geowissenschaften (1)
- Kommunalwissenschaftliches Institut (1)
- Lehreinheit für Wirtschafts-Arbeit-Technik (1)
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 2019. Selected projects have presented their results on April 9th and November 12th 2019 at the Future SOC Lab Day events.
This technical report presents the results of student projects which were prepared during the lecture “Operating Systems II” offered by the “Operating Systems and Middleware” group at HPI in the Summer term of 2020. The lecture covered ad- vanced aspects of operating system implementation and architecture on topics such as Virtualization, File Systems and Input/Output Systems. In addition to attending the lecture, the participating students were encouraged to gather practical experience by completing a project on a closely related topic over the course of the semester. The results of 10 selected exceptional projects are covered in this report.
The students have completed hands-on projects on the topics of Operating System Design Concepts and Implementation, Hardware/Software Co-Design, Reverse Engineering, Quantum Computing, Static Source-Code Analysis, Operating Systems History, Application Binary Formats and more. It should be recognized that over the course of the semester all of these projects have achieved outstanding results which went far beyond the scope and the expec- tations of the lecture, and we would like to thank all participating students for their commitment and their effort in completing their respective projects, as well as their work on compiling this report.
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).
Digitale Technologien bieten erhebliche politische, wirtschaftliche und gesellschaftliche Chancen. Zugleich ist der Begriff digitale Souveränität zu einem Leitmotiv im deutschen Diskurs über digitale Technologien geworden: das heißt, die Fähigkeit des Staates, seine Verantwortung wahrzunehmen und die Befähigung der Gesellschaft – und des Einzelnen – sicherzustellen, die digitale Transformation selbstbestimmt zu gestalten. Exemplarisch für die Herausforderung in Deutschland und Europa, die Vorteile digitaler Technologien zu nutzen und gleichzeitig Souveränitätsbedenken zu berücksichtigen, steht der Bildungssektor. Er umfasst Bildung als zentrales öffentliches Gut, ein schnell aufkommendes Geschäftsfeld und wachsende Bestände an hochsensiblen personenbezogenen Daten. Davon ausgehend beschreibt der Bericht Wege zur Entschärfung des Spannungsverhältnisses zwischen Digitalisierung und Souveränität auf drei verschiedenen Ebenen – Staat, Wirtschaft und Individuum – anhand konkreter technischer Projekte im Bildungsbereich: die HPI Schul-Cloud (staatliche Souveränität), die MERLOT-Datenräume (wirtschaftliche Souveränität) und die openHPI-Plattform (individuelle Souveränität).
Proceedings of the HPI Research School on Service-oriented Systems Engineering 2020 Fall Retreat
(2021)
Design and Implementation of service-oriented architectures imposes a huge number of research questions from the fields of software engineering, system analysis and modeling, adaptability, and application integration. Component orientation and web services are two approaches for design and realization of complex web-based system. Both approaches allow for dynamic application adaptation as well as integration of enterprise application.
Service-Oriented Systems Engineering represents a symbiosis of best practices in object-orientation, component-based development, distributed computing, and business process management. It provides integration of business and IT concerns.
The annual Ph.D. Retreat of the Research School provides each member the opportunity to present his/her current state of their research and to give an outline of a prospective Ph.D. thesis. Due to the interdisciplinary structure of the research school, this technical report covers a wide range of topics. These include but are not limited to: Human Computer Interaction and Computer Vision as Service; Service-oriented Geovisualization Systems; Algorithm Engineering for Service-oriented Systems; Modeling and Verification of Self-adaptive Service-oriented Systems; Tools and Methods for Software Engineering in Service-oriented Systems; Security Engineering of Service-based IT Systems; Service-oriented Information Systems; Evolutionary Transition of Enterprise Applications to Service Orientation; Operating System Abstractions for Service-oriented Computing; and Services Specification, Composition, and Enactment.
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.
RailChain
(2023)
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 Universität Braunschweig, TÜV 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.
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.
Pictures are a medium that helps make the past tangible and preserve memories. Without context, they are not able to do so. Pictures are brought to life by their associated stories. However, the older pictures become, the fewer contemporary witnesses can tell these stories.
Especially for large, analog picture archives, knowledge and memories are spread over many people. This creates several challenges: First, the pictures must be digitized to save them from decaying and make them available to the public. Since a simple listing of all the pictures is confusing, the pictures should be structured accessibly. Second, known information that makes the stories vivid needs to be added to the pictures. Users should get the opportunity to contribute their knowledge and memories. To make this usable for all interested parties, even for older, less technophile generations, the interface should be intuitive and error-tolerant.
The resulting requirements are not covered in their entirety by any existing software solution without losing the intuitive interface or the scalability of the system.
Therefore, we have developed our digital picture archive within the scope of a bachelor project in cooperation with the Bad Harzburg-Stiftung. For the implementation of this web application, we use the UI framework React in the frontend, which communicates via a GraphQL interface with the Content Management System Strapi in the backend. The use of this system enables our project partner to create an efficient process from scanning analog pictures to presenting them to visitors in an organized and annotated way. To customize the solution for both picture delivery and information contribution for our target group, we designed prototypes and evaluated them with people from Bad Harzburg. This helped us gain valuable insights into our system’s usability and future challenges as well as requirements.
Our web application is already being used daily by our project partner. During the project, we still came up with numerous ideas for additional features to further support the exchange of knowledge.
Like conventional software projects, projects in model-driven software engineering require adequate management of multiple versions of development artifacts, importantly allowing living with temporary inconsistencies. In the case of model-driven software engineering, employed versioning approaches also have to handle situations where different artifacts, that is, different models, are linked via automatic model transformations.
In this report, we propose a technique for jointly handling the transformation of multiple versions of a source model into corresponding versions of a target model, which enables the use of a more compact representation that may afford improved execution time of both the transformation and further analysis operations. Our approach is based on the well-known formalism of triple graph grammars and a previously introduced encoding of model version histories called multi-version models. In addition to showing the correctness of our approach with respect to the standard semantics of triple graph grammars, we conduct an empirical evaluation that demonstrates the potential benefit regarding execution time performance.
Modular and incremental global model management with extended generalized discrimination networks
(2023)
Complex projects developed under the model-driven engineering paradigm nowadays often involve several interrelated models, which are automatically processed via a multitude of model operations. Modular and incremental construction and execution of such networks of models and model operations are required to accommodate efficient development with potentially large-scale models. The underlying problem is also called Global Model Management.
In this report, we propose an approach to modular and incremental Global Model Management via an extension to the existing technique of Generalized Discrimination Networks (GDNs). In addition to further generalizing the notion of query operations employed in GDNs, we adapt the previously query-only mechanism to operations with side effects to integrate model transformation and model synchronization. We provide incremental algorithms for the execution of the resulting extended Generalized Discrimination Networks (eGDNs), as well as a prototypical implementation for a number of example eGDN operations.
Based on this prototypical implementation, we experiment with an application scenario from the software development domain to empirically evaluate our approach with respect to scalability and conceptually demonstrate its applicability in a typical scenario. Initial results confirm that the presented approach can indeed be employed to realize efficient Global Model Management in the considered scenario.
Learning from failure
(2022)
Regression testing is a widespread practice in today's software industry to ensure software product quality. Developers derive a set of test cases, and execute them frequently to ensure that their change did not adversely affect existing functionality. As the software product and its test suite grow, the time to feedback during regression test sessions increases, and impedes programmer productivity: developers wait longer for tests to complete, and delays in fault detection render fault removal increasingly difficult.
Test case prioritization addresses the problem of long feedback loops by reordering test cases, such that test cases of high failure probability run first, and test case failures become actionable early in the testing process. We ask, given test execution schedules reconstructed from publicly available data, to which extent can their fault detection efficiency improved, and which technique yields the most efficient test schedules with respect to APFD?
To this end, we recover regression 6200 test sessions from the build log files of Travis CI, a popular continuous integration service, and gather 62000 accompanying changelists. We evaluate the efficiency of current test schedules, and examine the prioritization results of state-of-the-art lightweight, history-based heuristics. We propose and evaluate a novel set of prioritization algorithms, which connect software changes and test failures in a matrix-like data structure.
Our studies indicate that the optimization potential is substantial, because the existing test plans score only 30% APFD. The predictive power of past test failures proves to be outstanding: simple heuristics, such as repeating tests with failures in recent sessions, result in efficiency scores of 95% APFD. The best-performing matrix-based heuristic achieves a similar score of 92.5% APFD. In contrast to prior approaches, we argue that matrix-based techniques are useful beyond the scope of effective prioritization, and enable a number of use cases involving software maintenance.
We validate our findings from continuous integration processes by extending a continuous testing tool within development environments with means of test prioritization, and pose further research questions. We think that our findings are suited to propel adoption of (continuous) testing practices, and that programmers' toolboxes should contain test prioritization as an existential productivity tool.
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.
Modeling and Formal Analysis of Meta-Ecosystems with Dynamic Structure using Graph Transformation
(2022)
The dynamics of ecosystems is of crucial importance. Various model-based approaches exist to understand and analyze their internal effects. In this paper, we model the space structure dynamics and ecological dynamics of meta-ecosystems using the formal technique of Graph Transformation (short GT). We build GT models to describe how a meta-ecosystem (modeled as a graph) can evolve over time (modeled by GT rules) and to analyze these GT models with respect to qualitative properties such as the existence of structural stabilities. As a case study, we build three GT models describing the space structure dynamics and ecological dynamics of three different savanna meta-ecosystems. The first GT model considers a savanna meta-ecosystem that is limited in space to two ecosystem patches, whereas the other two GT models consider two savanna meta-ecosystems that are unlimited in the number of ecosystem patches and only differ in one GT rule describing how the space structure of the meta-ecosystem grows. In the first two GT models, the space structure dynamics and ecological dynamics of the meta-ecosystem shows two main structural stabilities: the first one based on grassland-savanna-woodland transitions and the second one based on grassland-desert transitions. The transition between these two structural stabilities is driven by high-intensity fires affecting the tree components. In the third GT model, the GT rule for savanna regeneration induces desertification and therefore a collapse of the meta-ecosystem. We believe that GT models provide a complementary avenue to that of existing approaches to rigorously study ecological phenomena.
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.
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.
openHPI
(2022)
Anlässlich des 10-jährigen Jubiläums von openHPI informiert dieser technische Bericht über 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 Funktionalitäten und gängigen Kursformate der Plattform präsentiert. Die Funktionalitäten 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. Darüber hinaus können die Lernmaterialien durch externe Übungstools angereichert werden, die über den Standard Learning Tools Interoperability (LTI) mit der HPI MOOC-Plattform kommunizieren. Das Konzept der Peer-Assessments rundet die möglichen 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 nächste Teil dieses Kapitels beschäftigt sich mit den Admin-Funktionen. Die Funktionalitätsbeschreibung beschränkt sich Neuigkeiten und Ankündigungen, Dashboards und Statistiken, Berichtsfunktionen, Forschungsoptionen mit A/B-Tests, den Kurs-Feed und das TransPipe-Tool zur Unterstützung beim Erstellen von automatischen oder manuellen Untertiteln. Die Plattform unterstützt außerdem eine Vielzahl zusätzlicher Funktionen, doch eine detaillierte Beschreibung dieser Funktionen würde den Rahmen des Berichts sprengen.
Das Kapitel geht dann auf gängige Kursformate und openHPI-Lehrveranstaltungen am HPI ein, bevor es mit einigen Best Practices für die Gestaltung und Durchführung 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 eigenständig zu betreiben. Bei der vorliegenden deutschen Variante handelt es sich um eine gekürzte Übersetzung des technischen Berichts 148, bei der kein Einblick in die Technologien und Architektur von openHPI gegeben wird. Interessierte Leser:innen können im technischen Bericht 148 (vollständige englische Version) detaillierte Informationen zum Rechenzentrum und den Geräten, 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 über den Technologiestack und konkrete Implementierungsdetails der Plattform inklusive der serviceorientierten Ruby on Rails-Anwendung, die Kommunikation zwischen den Diensten, öffentliche APIs, sowie Designsystem und -komponenten. Der Abschnitt schließt mit einer Diskussion über die ursprüngliche Microservice-Architektur und die Migration zu einer monolithischen Anwendung.
openHPI
(2022)
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.
Scrollytellings are an innovative form of web content. Combining the benefits of books, images, movies, and video games, they are a tool to tell compelling stories and provide excellent learning opportunities. Due to their multi-modality, creating high-quality scrollytellings is not an easy task. Different professions, such as content designers, graphics designers, and developers, need to collaborate to get the best out of the possibilities the scrollytelling format provides. Collaboration unlocks great potential. However, content designers cannot create scrollytellings directly and always need to consult with developers to implement their vision. This can result in misunderstandings. Often, the resulting scrollytelling will not match the designer’s vision sufficiently, causing unnecessary iterations. Our project partner Typeshift specializes in the creation of individualized scrollytellings for their clients. Examined existing solutions for authoring interactive content are not optimally suited for creating highly customized scrollytellings while still being able to manipulate all their elements programmatically. Based on their experience and expertise, we developed an editor to author scrollytellings in the lively.next live-programming environment. In this environment, a graphical user interface for content design is combined with powerful possibilities for programming behavior with the morphic system. The editor allows content designers to take on large parts of the creation process of scrollytellings on their own, such as creating the visible elements, animating content, and fine-tuning the scrollytelling. Hence, developers can focus on interactive elements such as simulations and games. Together with Typeshift, we evaluated the tool by recreating an existing scrollytelling and identified possible future enhancements. Our editor streamlines the creation process of scrollytellings. Content designers and developers can now both work on the same scrollytelling. Due to the editor inside of the lively.next environment, they can both work with a set of tools familiar to them and their traits. Thus, we mitigate unnecessary iterations and misunderstandings by enabling content designers to realize large parts of their vision of a scrollytelling on their own. Developers can add advanced and individual behavior. Thus, developers and content designers benefit from a clearer distribution of tasks while keeping the benefits of collaboration.
Language developers who design domain-specific languages or new language features need a way to make fast changes to language definitions. Those fast changes require immediate feedback. Also, it should be possible to parse the developed languages quickly to handle extensive sets of code.
Parsing expression grammars provides an easy to understand method for language definitions. Packrat parsing is a method to parse grammars of this kind, but this method is unable to handle left-recursion properly. Existing solutions either partially rewrite left-recursive rules and partly forbid them, or use complex extensions to packrat parsing that are hard to understand and cost-intensive. We investigated methods to make parsing as fast as possible, using easy to follow algorithms while not losing the ability to make fast changes to grammars.
We focused our efforts on two approaches.
One is to start from an existing technique for limited left-recursion rewriting and enhance it to work for general left-recursive grammars. The second approach is to design a grammar compilation process to find left-recursion before parsing, and in this way, reduce computational costs wherever possible and generate ready to use parser classes.
Rewriting parsing expression grammars is a task that, if done in a general way, unveils a large number of cases such that any rewriting algorithm surpasses the complexity of other left-recursive parsing algorithms. Lookahead operators introduce this complexity. However, most languages have only little portions that are left-recursive and in virtually all cases, have no indirect or hidden left-recursion. This means that the distinction of left-recursive parts of grammars from components that are non-left-recursive holds great improvement potential for existing parsers.
In this report, we list all the required steps for grammar rewriting to handle left-recursion, including grammar analysis, grammar rewriting itself, and syntax tree restructuring. Also, we describe the implementation of a parsing expression grammar framework in Squeak/Smalltalk and the possible interactions with the already existing parser Ohm/S. We quantitatively benchmarked this framework directing our focus on parsing time and the ability to use it in a live programming context. Compared with Ohm, we achieved massive parsing time improvements while preserving the ability to use our parser it as a live programming tool.
The work is essential because, for one, we outlined the difficulties and complexity that come with grammar rewriting. Also, we removed the existing limitations that came with left-recursion by eliminating them before parsing.
These days design thinking is no longer a “new approach”. Among practitioners, as well as academics, interest in the topic has gathered pace over the last two decades. However, opinions are divided over the longevity of the phenomenon: whether design thinking is merely “old wine in new bottles,” a passing trend, or still evolving as it is being spread to an increasing number of organizations and industries. Despite its growing relevance and the diffusion of design thinking, knowledge on the actual status quo in organizations remains scarce. With a new study, the research team of Prof. Uebernickel and Stefanie Gerken investigates temporal developments and changes in design thinking practices in organizations over the past six years comparing the results of the 2015 “Parts without a whole” study with current practices and future developments. Companies of all sizes and from different parts of the world participated in the survey. The findings from qualitative interviews with experts, i.e., people who have years of knowledge with design thinking, were cross-checked with the results from an exploratory analysis of the survey data. This analysis uncovers significant variances and similarities in how design thinking is interpreted and applied in businesses.
Digitale Medien sind aus unserem Alltag kaum noch wegzudenken. Einer der zentralsten Bereiche für unsere Gesellschaft, die schulische Bildung, darf hier nicht hintanstehen. Wann immer der Einsatz digital unterstützter Tools pädagogisch sinnvoll ist, muss dieser in einem sicheren Rahmen ermöglicht werden können. 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 fünf Jahren vom Pilotprojekt zur unverzichtbaren IT-Infrastruktur für zahlreiche Schulen entwickelt. Während der Corona-Pandemie hat sie für viele Tausend Schulen wichtige Unterstützung bei der Umsetzung ihres Bildungsauftrags geboten. Das Ziel, eine zukunftssichere und datenschutzkonforme Infrastruktur zur digitalen Unterstützung des Unterrichts zur Verfügung zu stellen, hat sie damit mehr als erreicht. Aktuell greifen rund 1,4 Millionen Lehrkräfte und Schülerinnen und Schüler bundesweit und an den deutschen Auslandsschulen auf die HPI Schul-Cloud zu.
The analysis of behavioral models is of high importance for cyber-physical systems, as the systems often encompass complex behavior based on e.g. concurrent components with mutual exclusion or probabilistic failures on demand. The rule-based formalism of probabilistic timed graph transformation systems is a suitable choice when the models representing states of the system can be understood as graphs and timed and probabilistic behavior is important. However, model checking PTGTSs is limited to systems with rather small state spaces.
We present an approach for the analysis of large scale systems modeled as probabilistic timed graph transformation systems by systematically decomposing their state spaces into manageable fragments. To obtain qualitative and quantitative analysis results for a large scale system, we verify that results obtained for its fragments serve as overapproximations for the corresponding results of the large scale system. Hence, our approach allows for the detection of violations of qualitative and quantitative safety properties for the large scale system under analysis. We consider a running example in which we model shuttles driving on tracks of a large scale topology and for which we verify that shuttles never collide and are unlikely to execute emergency brakes. In our evaluation, we apply an implementation of our approach to the running example.
The formal modeling and analysis is of crucial importance for software development processes following the model based approach. We present the formalism of Interval Probabilistic Timed Graph Transformation Systems (IPTGTSs) as a high-level modeling language. This language supports structure dynamics (based on graph transformation), timed behavior (based on clocks, guards, resets, and invariants as in Timed Automata (TA)), and interval probabilistic behavior (based on Discrete Interval Probability Distributions). That is, for the probabilistic behavior, the modeler using IPTGTSs does not need to provide precise probabilities, which are often impossible to obtain, but rather provides a probability range instead from which a precise probability is chosen nondeterministically. In fact, this feature on capturing probabilistic behavior distinguishes IPTGTSs from Probabilistic Timed Graph Transformation Systems (PTGTSs) presented earlier.
Following earlier work on Interval Probabilistic Timed Automata (IPTA) and PTGTSs, we also provide an analysis tool chain for IPTGTSs based on inter-formalism transformations. In particular, we provide in our tool AutoGraph a translation of IPTGTSs to IPTA and rely on a mapping of IPTA to Probabilistic Timed Automata (PTA) to allow for the usage of the Prism model checker. The tool Prism can then be used to analyze the resulting PTA w.r.t. probabilistic real-time queries asking for worst-case and best-case probabilities to reach a certain set of target states in a given amount of time.
In recent years, computer vision algorithms based on machine learning have seen rapid development. In the past, research mostly focused on solving computer vision problems such as image classification or object detection on images displaying natural scenes. Nowadays other fields such as the field of cultural heritage, where an abundance of data is available, also get into the focus of research. In the line of current research endeavours, we collaborated with the Getty Research Institute which provided us with a challenging dataset, containing images of paintings and drawings. In this technical report, we present the results of the seminar "Deep Learning for Computer Vision". In this seminar, students of the Hasso Plattner Institute evaluated state-of-the-art approaches for image classification, object detection and image recognition on the dataset of the Getty Research Institute. The main challenge when applying modern computer vision methods to the available data is the availability of annotated training data, as the dataset provided by the Getty Research Institute does not contain a sufficient amount of annotated samples for the training of deep neural networks. However, throughout the report we show that it is possible to achieve satisfying to very good results, when using further publicly available datasets, such as the WikiArt dataset, for the training of machine learning models.
The noble way to substantiate decisions that affect many people is to ask these people for their opinions. For governments that run whole countries, this means asking all citizens for their views to consider their situations and needs.
Organizations such as Africa's Voices Foundation, who want to facilitate communication between decision-makers and citizens of a country, have difficulty mediating between these groups. To enable understanding, statements need to be summarized and visualized. Accomplishing these goals in a way that does justice to the citizens' voices and situations proves challenging. Standard charts do not help this cause as they fail to create empathy for the people behind their graphical abstractions. Furthermore, these charts do not create trust in the data they are representing as there is no way to see or navigate back to the underlying code and the original data. To fulfill these functions, visualizations would highly benefit from interactions to explore the displayed data, which standard charts often only limitedly provide.
To help improve the understanding of people's voices, we developed and categorized 80 ideas for new visualizations, new interactions, and better connections between different charts, which we present in this report. From those ideas, we implemented 10 prototypes and two systems that integrate different visualizations. We show that this integration allows consistent appearance and behavior of visualizations. The visualizations all share the same main concept: representing each individual with a single dot. To realize this idea, we discuss technologies that efficiently allow the rendering of a large number of these dots. With these visualizations, direct interactions with representations of individuals are achievable by clicking on them or by dragging a selection around them. This direct interaction is only possible with a bidirectional connection from the visualization to the data it displays. We discuss different strategies for bidirectional mappings and the trade-offs involved. Having unified behavior across visualizations enhances exploration. For our prototypes, that includes grouping, filtering, highlighting, and coloring of dots. Our prototyping work was enabled by the development environment Lively4. We explain which parts of Lively4 facilitated our prototyping process. Finally, we evaluate our approach to domain problems and our developed visualization concepts.
Our work provides inspiration and a starting point for visualization development in this domain. Our visualizations can improve communication between citizens and their government and motivate empathetic decisions. Our approach, combining low-level entities to create visualizations, provides value to an explorative and empathetic workflow. We show that the design space for visualizing this kind of data has a lot of potential and that it is possible to combine qualitative and quantitative approaches to data analysis.
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.
In this study we examine the tonal organization of a series of recordings of liturgical chants, sung in 1966 by the Georgian master singer Artem Erkomaishvili. This dataset is the oldest corpus of Georgian chants from which the time synchronous F0-trajectories for all three voices have been reliably determined (Müller et al. 2017). It is therefore of outstanding importance for the understanding of the tuning principles of traditional Georgian vocal music.
The aim of the present study is to use various computational methods to analyze what these recordings can contribute to the ongoing scientific dispute about traditional Georgian tuning systems. Starting point for the present analysis is the re-release of the original audio data together with estimated fundamental frequency (F0) trajectories for each of the three voices, beat annotations, and digital scores (Rosenzweig et al. 2020). We present synoptic models for the pitch and the harmonic interval distributions, which are the first of such models for which the complete Erkomaishvili dataset was used. We show that these distributions can be very compactly be expressed as Gaussian mixture models, anchored on discrete sets of pitch or interval values for the pitch and interval distributions, respectively. As part of our study we demonstrate that these pitch values, which we refer to as scale pitches, and which are determined as the mean values of the Gaussian mixture elements, define the scale degrees of the melodic sound scales which build the skeleton of Artem Erkomaishvili’s intonation. The observation of consistent pitch bending of notes in melodic phrases, which appear in identical form in a group of chants, as well as the observation of harmonically driven intonation adjustments, which are clearly documented for all pure harmonic intervals, demonstrate that Artem Erkomaishvili intentionally deviates from the scale pitch skeleton quite freely. As a central result of our study, we proof that this melodic freedom is always constrained by the attracting influence of the scale pitches. Deviations of the F0-values of individual note events from the scale pitches at one instance of time are compensated for in the subsequent melodic steps. This suggests a deviation-compensation mechanism at the core of Artem Erkomaishvili’s melody generation, which clearly honors the scales but still allows for a large degree of melodic flexibility. This model, which summarizes all partial aspects of our analysis, is consistent with the melodic scale models derived from the observed pitch distributions, as well as with the melodic and harmonic interval distributions. In addition to the tangible results of our work, we believe that our work has general implications for the determination of tuning models from audio data, in particular for non-tempered music.
Technical report
(2019)
Design and Implementation of service-oriented architectures imposes a huge number of research questions from the fields of software engineering, system analysis and modeling, adaptability, and application integration. Component orientation and web services are two approaches for design and realization of complex web-based system. Both approaches allow for dynamic application adaptation as well as integration of enterprise application.
Commonly used technologies, such as J2EE and .NET, form de facto standards for the realization of complex distributed systems. Evolution of component systems has lead to web services and service-based architectures. This has been manifested in a multitude of industry standards and initiatives such as XML, WSDL UDDI, SOAP, etc. All these achievements lead to a new and promising paradigm in IT systems engineering which proposes to design complex software solutions as collaboration of contractually defined software services.
Service-Oriented Systems Engineering represents a symbiosis of best practices in object-orientation, component-based development, distributed computing, and business process management. It provides integration of business and IT concerns.
The annual Ph.D. Retreat of the Research School provides each member the opportunity to present his/her current state of their research and to give an outline of a prospective Ph.D. thesis. Due to the interdisciplinary structure of the research school, this technical report covers a wide range of topics. These include but are not limited to: Human Computer Interaction and Computer Vision as Service; Service-oriented Geovisualization Systems; Algorithm Engineering for Service-oriented Systems; Modeling and Verification of Self-adaptive Service-oriented Systems; Tools and Methods for Software Engineering in Service-oriented Systems; Security Engineering of Service-based IT Systems; Service-oriented Information Systems; Evolutionary Transition of Enterprise Applications to Service Orientation; Operating System Abstractions for Service-oriented Computing; and Services Specification, Composition, and Enactment.
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.
SandBlocks
(2020)
Visuelle Programmiersprachen werden heutzutage zugunsten textueller Programmiersprachen nahezu nicht verwendet, obwohl visuelle Programmiersprachen einige Vorteile bieten. Diese reichen von der Vermeidung von Syntaxfehlern, über die Nutzung konkreter domänenspezifischer Notation bis hin zu besserer Lesbarkeit und Wartbarkeit des Programms. Trotzdem greifen professionelle Softwareentwickler nahezu ausschließlich auf textuelle Programmiersprachen zurück.
Damit Entwickler diese Vorteile visueller Programmiersprachen nutzen können, aber trotzdem nicht auf die ihnen bekannten textuellen Programmiersprachen verzichten müssen, gibt es die Idee, textuelle und visuelle Programmelemente gemeinsam in einer Programmiersprache nutzbar zu machen. Damit ist dem Entwickler überlassen wann und wie er visuelle Elemente in seinem Programmcode verwendet.
Diese Arbeit stellt das SandBlocks-Framework vor, das diese gemeinsame Nutzung visueller und textueller Programmelemente ermöglicht. Neben einer Auswertung visueller Programmiersprachen, zeigt es die technische Integration visueller Programmelemente in das Squeak/Smalltalk-System auf, gibt Einblicke in die Umsetzung und Verwendung in Live-Programmiersystemen und diskutiert ihre Verwendung in unterschiedlichen Domänen.
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.
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.
Creating fonts is a complex task that requires expert knowledge in a variety of domains. Often, this knowledge is not held by a single person, but spread across a number of domain experts. A central concept needed for designing fonts is the glyph, an elemental symbol representing a readable character. Required domains include designing glyph shapes, engineering rules to combine glyphs for complex scripts and checking legibility. This process is most often iterative and requires communication in all directions. This report outlines a platform that aims to enhance the means of communication, describes our prototyping process, discusses complex font rendering and editing in a live environment and an approach to generate code based on a user’s live-edits.
Squimera
(2017)
Software development tools that work and behave consistently across different programming languages are helpful for developers, because they do not have to familiarize themselves with new tooling whenever they decide to use a new language. Also, being able to combine multiple programming languages in a program increases reusability, as developers do not have to recreate software frameworks and libraries in the language they develop in and can reuse existing software instead.
However, developers often have a broad choice with regard to tools, some of which are designed for only one specific programming language. Various Integrated Development Environments have support for multiple languages, but are usually unable to provide a consistent programming experience due to different features of language runtimes. Furthermore, common mechanisms that allow reuse of software written in other languages usually use the operating system or a network connection as the abstract layer. Tools, however, often cannot support such indirections well and are therefore less useful in debugging scenarios for example.
In this report, we present a novel approach that aims to improve the programming experience with regard to working with multiple high-level programming languages. As part of this approach, we reuse the tools of a Smalltalk programming environment for other languages and build a multi-language virtual execution environment which is able to provide the same runtime capabilities for all languages.
The prototype system Squimera is an implementation of our approach and demonstrates that it is possible to reuse development tools, so that they behave in the same way across all supported programming languages. In addition, it provides convenient means to reuse and even mix software libraries and frameworks written in different languages without breaking the debugging experience.
Die HPI Schul-Cloud
(2019)
Die digitale Transformation durchdringt alle gesellschaftlichen Ebenen und Felder, nicht zuletzt auch das Bildungssystem. Dieses ist auf die Veränderungen 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 Unterrichtsräume und nicht professionell gewartete Computersysteme gibt es erst seit kurzem. Doch auch wenn Beharrungskräfte unter Pädagog*innen verbreitet sind, erfordert die Transformation des Systems Schule auch eine neue Mentalität und neue Arbeits- und Kooperationsformen.
Zeitgemäßer Unterricht benötigt moderne Technologie und zeitgemäße IT-Architekturen. Nur Systeme, die für Lehrer*innen und Schüler*innen problemlos verfügbar, benutzerfreundlich zu bedienen und didaktisch flexibel einsetzbar sind, finden in Schulen Akzeptanz. Hierfür haben wir die HPI Schul-Cloud entwickelt. Sie ermöglicht 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 herrührend - den Einsatz von Cloud-Anwendungen, die in der Arbeitswelt verbreitet sind, in Schulen unmöglich machen. Im Bildungsbereich verbreitete Anwendungen sind größtenteils technisch veraltet und nicht benutzerfreundlich.
Dies nötigt die Bundesländer zu kostspieligen Eigenentwicklungen mit Aufwänden im zweistelligen Millionenbereich - Projekte die teilweise gescheitert sind. Dank der modularen Micro-Service-Architektur können die Bundesländer zukünftig auf die HPI Schul-Cloud als technische Grundlage für ihre Eigen- oder Gemeinschaftsprojekte zurückgreifen. Hierfür gilt es, eine nachhaltige Struktur für 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 Niedersächsische Bildungscloud, die technisch auf der HPI Schul-Cloud basiert. Das vom Bundesministerium für Bildung und Forschung geförderte Projekt läuft in der gegenwärtigen Roll-Out-Phase bis zum 31. Juli 2021. Gemeinsam mit unserem Kooperationspartner MINT-EC streben wir an, die HPI Schul-Cloud möglichst an allen Schulen des Netzwerks einzusetzen.
Blockchain
(2018)
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-serviceänd 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.
Various kinds of typed attributed graphs are used to represent states of systems from a broad range of domains. For dynamic systems, established formalisms such as graph transformations provide a formal model for defining state sequences. We consider the extended case where time elapses between states and introduce a logic to reason about these sequences. With this logic we express properties on the structure and attributes of states as well as on the temporal occurrence of states that are related by their inner structure, which no formal logic over graphs accomplishes concisely so far. Firstly, we introduce graphs with history by equipping every graph element with the timestamp of its creation and, if applicable, its deletion. Secondly, we define a logic on graphs by integrating the temporal operator until into the well-established logic of nested graph conditions. Thirdly, we prove that our logic is equally expressive to nested graph conditions by providing a suitable reduction. Finally, the implementation of this reduction allows for the tool-based analysis of metric temporal properties for state sequences.
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.
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.
Blockchain
(2018)
Der Begriff Blockchain ist in letzter Zeit zu einem Schlagwort geworden, aber nur wenige wissen, was sich genau dahinter verbirgt. Laut einer Umfrage, die im ersten Quartal 2017 veröffentlicht wurde, ist der Begriff nur bei 35 Prozent der deutschen Mittelständler bekannt. Dabei ist die Blockchain-Technologie durch ihre rasante Entwicklung und die globale Eroberung unterschiedlicher Märkte für Massenmedien sehr interessant.
So sehen viele die Blockchain-Technologie entweder als eine Allzweckwaffe, zu der aber nur wenige einen Zugang haben, oder als eine Hacker-Technologie für geheime Geschäfte im Darknet. Dabei liegt die Innovation der Blockchain-Technologie in ihrer erfolgreichen Zusammensetzung bereits vorhandener Ansätze: dezentrale Netzwerke, Kryptographie, Konsensfindungsmodelle. Durch das innovative Konzept wird ein Werte-Austausch in einem dezentralen System möglich. Dabei wird kein Vertrauen zwischen dessen Knoten (z.B. Nutzer) vorausgesetzt.
Mit dieser Studie möchte das Hasso-Plattner-Institut den Lesern helfen, ihren eigenen Standpunkt zur Blockchain-Technologie zu finden und dabei dazwischen unterscheiden zu können, welche Eigenschaften wirklich innovativ und welche nichts weiter als ein Hype sind.
Die Autoren der vorliegenden Arbeit analysieren positive und negative Eigenschaften, welche die Blockchain-Architektur prägen, und stellen mögliche Anpassungs- und Lösungsvorschläge vor, die zu einem effizienten Einsatz der Technologie beitragen können. Jedem Unternehmen, bevor es sich für diese Technologie entscheidet, wird dabei empfohlen, für den geplanten Anwendungszweck zunächst ein klares Ziel zu definieren, das mit einem angemessenen Kosten-Nutzen-Verhältnis angestrebt werden kann. Dabei sind sowohl die Möglichkeiten als auch die Grenzen der Blockchain-Technologie zu beachten. Die relevanten Schritte, die es in diesem Zusammenhang zu beachten gilt, fasst die Studie für die Leser übersichtlich zusammen.
Es wird ebenso auf akute Fragestellungen wie Skalierbarkeit der Blockchain, geeigneter Konsensalgorithmus und Sicherheit eingegangen, darunter verschiedene Arten möglicher Angriffe und die entsprechenden Gegenmaßnahmen zu deren Abwehr. Neue Blockchains etwa laufen Gefahr, geringere Sicherheit zu bieten, da Änderungen an der bereits bestehenden Technologie zu Schutzlücken und Mängeln führen können.
Nach Diskussion der innovativen Eigenschaften und Probleme der Blockchain-Technologie wird auf ihre Umsetzung eingegangen. Interessierten Unternehmen stehen viele Umsetzungsmöglichkeiten zur Verfügung. Die zahlreichen Anwendungen haben entweder eine eigene Blockchain als Grundlage oder nutzen bereits bestehende und weitverbreitete Blockchain-Systeme. Zahlreiche Konsortien und Projekte bieten „Blockchain-as-a-Service“ an und unterstützen andere Unternehmen beim Entwickeln, Testen und Bereitstellen von Anwendungen.
Die Studie gibt einen detaillierten Überblick über zahlreiche relevante Einsatzbereiche und Projekte im Bereich der Blockchain-Technologie. Dadurch, dass sie noch relativ jung ist und sich schnell entwickelt, fehlen ihr noch einheitliche Standards, die Zusammenarbeit der verschiedenen Systeme erlauben und an die sich alle Entwickler halten können. Aktuell orientieren sich Entwickler an Bitcoin-, Ethereum- und Hyperledger-Systeme, diese dienen als Grundlage für viele weitere Blockchain-Anwendungen.
Ziel ist, den Lesern einen klaren und umfassenden Überblick über die Blockchain-Technologie und deren Möglichkeiten zu vermitteln.
Design and Implementation of service-oriented architectures imposes a huge number of research questions from the fields of software engineering, system analysis and modeling, adaptability, and application integration. Component orientation and web services are two approaches for design and realization of complex web-based system. Both approaches allow for dynamic application adaptation as well as integration of enterprise application.
Commonly used technologies, such as J2EE and .NET, form de facto standards for the realization of complex distributed systems. Evolution of component systems has lead to web services and service-based architectures. This has been manifested in a multitude of industry standards and initiatives such as XML, WSDL UDDI, SOAP, etc. All these achievements lead to a new and promising paradigm in IT systems engineering which proposes to design complex software solutions as collaboration of contractually defined software services.
Service-Oriented Systems Engineering represents a symbiosis of best practices in object-orientation, component-based development, distributed computing, and business process management. It provides integration of business and IT concerns.
The annual Ph.D. Retreat of the Research School provides each member the opportunity to present his/her current state of their research and to give an outline of a prospective Ph.D. thesis. Due to the interdisciplinary structure of the research school, this technical report covers a wide range of topics. These include but are not limited to: Human Computer Interaction and Computer Vision as Service; Service-oriented Geovisualization Systems; Algorithm Engineering for Service-oriented Systems; Modeling and Verification of Self-adaptive Service-oriented Systems; Tools and Methods for Software Engineering in Service-oriented Systems; Security Engineering of Service-based IT Systems; Service-oriented Information Systems; Evolutionary Transition of Enterprise Applications to Service Orientation; Operating System Abstractions for Service-oriented Computing; and Services Specification, Composition, and Enactment.
Today, software has become an intrinsic part of complex distributed embedded real-time systems. The next generation of embedded real-time systems will interconnect the today unconnected systems via complex software parts and the service-oriented paradigm. Therefore besides timed behavior and probabilistic behaviour also structure dynamics, where the architecture can be subject to changes at run-time, e.g. when dynamic binding of service end-points is employed or complex collaborations are established dynamically, is required. However, a modeling and analysis approach that combines all these necessary aspects does not exist so far.
To fill the identified gap, we propose Probabilistic Timed Graph Transformation Systems (PTGTSs) as a high-level description language that supports all the necessary aspects of structure dynamics, timed behavior, and probabilistic behavior. We introduce the formal model of PTGTSs in this paper and present a mapping of models with finite state spaces to probabilistic timed automata (PTA) that allows to use the PRISM model checker to analyze PTGTS models with respect to PTCTL properties.
Every year, the Hasso Plattner Institute (HPI) invites guests from industry and academia to a collaborative scientific workshop on the topic 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.
On the occasion of this symposium we called for submissions of research papers and practitioner's reports. A compilation of the research papers realized during the fourth HPI cloud symposium "Operating the Cloud" 2016 are published in this proceedings. 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 later in the year. 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.
While offering significant expressive power, graph transformation systems often come with rather limited capabilities for automated analysis, particularly if systems with many possible initial graphs and large or infinite state spaces are concerned. One approach that tries to overcome these limitations is inductive invariant checking. However, the verification of inductive invariants often requires extensive knowledge about the system in question and faces the approach-inherent challenges of locality and lack of context.
To address that, this report discusses k-inductive invariant checking for graph transformation systems as a generalization of inductive invariants. The additional context acquired by taking multiple (k) steps into account is the key difference to inductive invariant checking and is often enough to establish the desired invariants without requiring the iterative development of additional properties.
To analyze possibly infinite systems in a finite fashion, we introduce a symbolic encoding for transformation traces using a restricted form of nested application conditions. As its central contribution, this report then presents a formal approach and algorithm to verify graph constraints as k-inductive invariants. We prove the approach's correctness and demonstrate its applicability by means of several examples evaluated with a prototypical implementation of our algorithm.
Graphs are ubiquitous in Computer Science. For this reason, in many areas, it is very important to have the means to express and reason about graph properties. In particular, we want to be able to check automatically if a given graph property is satisfiable. Actually, in most application scenarios it is desirable to be able to explore graphs satisfying the graph property if they exist or even to get a complete and compact overview of the graphs satisfying the graph property.
We show that the tableau-based reasoning method for graph properties as introduced by Lambers and Orejas paves the way for a symbolic model generation algorithm for graph properties. Graph properties are formulated in a dedicated logic making use of graphs and graph morphisms, which is equivalent to firstorder logic on graphs as introduced by Courcelle. Our parallelizable algorithm gradually generates a finite set of so-called symbolic models, where each symbolic model describes a set of finite graphs (i.e., finite models) satisfying the graph property. The set of symbolic models jointly describes all finite models for the graph property (complete) and does not describe any finite graph violating the graph property (sound). Moreover, no symbolic model is already covered by another one (compact). Finally, the algorithm is able to generate from each symbolic model a minimal finite model immediately and allows for an exploration of further finite models. The algorithm is implemented in the new tool AutoGraph.
Seit Jahren ist der Mangel an Informatiklehrkräften bekannt und wird fachdidaktisch und politisch diskutiert. Aufgrund der geringen Anzahl von Studierenden mit dem Berufsziel Informatiklehrkraft ist eine Vergrößerung des Mangels vorhersehbar. Es stellt sich die Frage, warum so wenige Studierende sich für das Studienziel Lehramt Informatik entscheiden.
Das Ziel der vorliegenden Arbeit ist es, die Berufswahl von Informatiklehrkräften aus der individuellen, biographischen Perspektive der Beteiligten zu erforschen und dabei Faktoren zu identifizieren, die die Berufswahl Informatiklehrkraft positiv oder negativ beeinflussen. Der Forschungsschwerpunkt liegt auf der qualitativen empirischen Untersuchung des Berufswahlprozesses, während eine quantitative Befragung aktiver Informatiklehrkräfte zu berufswahlrelevanten Aspekten des Berufsbildes diese ergänzt. Das Forschungskonzept der qualitativen Untersuchung orientiert sich an der Grounded Theory. Es wurden angehende Informatiklehrkräfte zu ihrem Berufswahlprozess befragt, wobei die Daten durch mündliche Interviews, Gruppendiskussionen und schriftliche Berufswahlbiographien erhoben wurden. Die Datenauswertung orientiert sich zudem methodisch an der dokumentarischen Methode nach Ralf Bohnsack.
Die Ergebnisse der Untersuchung zeigen, dass der Berufswahlprozess von angehenden Informatiklehrkräften häufig mit Umwegen in Form von Studienzielwechseln verbunden ist. Neben dem eigenen Bild der Informatik und dem Informatikselbstkonzept kommt dem Informatikunterricht der eigenen Schulzeit eine wichtige Rolle in diesem Prozess zu. Von der Lehrerforschung werden die Unterrichtserfahrungen während der eigenen Schulzeit im später studierten Fach als entscheidend für die Fachwahl identifiziert. Dies bestätigt sich in den Berufswahlbiographien derjenigen angehenden Informatiklehrkräfte, die den Informatikunterricht ihrer eigenen Schulzeit positiv erinnern. Diese streben meist direkt in ihrem ersten Studium das Berufsziel Informatiklehrkraft an. Sie hatten zur Schulzeit ein positives Bild der Informatik und ein hohes Informatikselbstkonzept. Der Informatiklehrkraft ihrer Schulzeit bescheinigen sie oft eine berufliche Vorbildfunktion. Allerdings hatten die meisten der befragten angehenden Informatiklehrkräfte selbst keinen Informatikunterricht oder erinnern diesen negativ. Der Weg zum Studium Informatiklehrkraft führt bei diesen Befragten häufig über den Umweg von zunächst anderen Studienentscheidungen, meistens über ein Lehramtsstudium mit anderen Fächern oder ein Informatikstudium. Die Informatikstudierenden haben zum Zeitpunkt ihrer ersten Studienwahl ein positives Bild der Informatik und ein hohes Informatikselbstkonzept aber kein positives Berufsbild Informatiklehrkraft. Ihr Wechsel von einem Informatikstudium zum Studium mit dem Berufsziel Informatiklehrkraft wird in der Regel durch den Wunsch nach einer stärkeren sozialen Komponente im späteren Berufsalltag ausgelöst. Bei den Lehramtsstudierenden, die häufig zunächst ein niedriges Informatikselbstkonzept und/oder ein negatives Bild der Informatik haben, kann es zu einer Umorientierung hin zum Studienziel Informatiklehrkraft kommen, wenn diese Vorstellungen sich während des ersten Studiums – z. B. durch den Besuch von universitären Lehrveranstaltungen zu informatischen Inhalten – ändern. Die letztliche Entscheidung für den Beruf Informatiklehrkraft wird von denjenigen, die ihr Studienziel wechselten, mit Recht als durch Zufälle bestimmt empfunden.
The correctness of model transformations is a crucial element for model-driven engineering of high quality software. In particular, behavior preservation is the most important correctness property avoiding the introduction of semantic errors during the model-driven engineering process. Behavior preservation verification techniques either show that specific properties are preserved, or more generally and complex, they show some kind of behavioral equivalence or refinement between source and target model of the transformation. Both kinds of behavior preservation verification goals have been presented with automatic tool support for the instance level, i.e. for a given source and target model specified by the model transformation. However, up until now there is no automatic verification approach available at the transformation level, i.e. for all source and target models specified by the model transformation.
In this report, we extend our results presented in [27] and outline a new sophisticated approach for the automatic verification of behavior preservation captured by bisimulation resp. simulation for model transformations specified by triple graph grammars and semantic definitions given by graph transformation rules. In particular, we show that the behavior preservation problem can be reduced to invariant checking for graph transformation and that the resulting checking problem can be addressed by our own invariant checker even for a complex example where a sequence chart is transformed into communicating automata. We further discuss today's limitations of invariant checking for graph transformation and motivate further lines of future work in this direction.
Um den zunehmenden Diebstahl digitaler Identitäten zu bekämpfen, gibt es bereits mehr als ein Dutzend Technologien. Sie sind, vor allem bei der Authentifizierung per Passwort, mit spezifischen Nachteilen behaftet, haben andererseits aber auch jeweils besondere Vorteile. Wie solche Kommunikationsstandards und -Protokolle wirkungsvoll miteinander kombiniert werden können, um dadurch mehr Sicherheit zu erreichen, haben die Autoren dieser Studie analysiert. Sie sprechen sich für neuartige Identitätsmanagement-Systeme aus, die sich flexibel auf verschiedene Rollen eines einzelnen Nutzers einstellen können und bequemer zu nutzen sind als bisherige Verfahren. Als ersten Schritt auf dem Weg hin zu einer solchen Identitätsmanagement-Plattform beschreiben sie die Möglichkeiten einer Analyse, die sich auf das individuelle Verhalten eines Nutzers oder einer Sache stützt.
Ausgewertet werden dabei Sensordaten mobiler Geräte, welche die Nutzer häufig bei sich tragen und umfassend einsetzen, also z.B. internetfähige Mobiltelefone, Fitness-Tracker und Smart Watches. Die Wissenschaftler beschreiben, wie solche Kleincomputer allein z.B. anhand der Analyse von Bewegungsmustern, Positionsund Netzverbindungsdaten kontinuierlich ein „Vertrauens-Niveau“ errechnen können. Mit diesem ermittelten „Trust Level“ kann jedes Gerät ständig die Wahrscheinlichkeit angeben, mit der sein aktueller Benutzer auch der tatsächliche Besitzer ist, dessen typische Verhaltensmuster es genauestens „kennt“.
Wenn der aktuelle Wert des Vertrauens-Niveaus (nicht aber die biometrischen Einzeldaten) an eine externe Instanz wie einen Identitätsprovider übermittelt wird, kann dieser das Trust Level allen Diensten bereitstellen, welche der Anwender nutzt und darüber informieren will. Jeder Dienst ist in der Lage, selbst festzulegen, von welchem Vertrauens-Niveau an er einen Nutzer als authentifiziert ansieht. Erfährt er von einem unter das Limit gesunkenen Trust Level, kann der Identitätsprovider seine Nutzung und die anderer Services verweigern.
Die besonderen Vorteile dieses Identitätsmanagement-Ansatzes liegen darin, dass er keine spezifische und teure Hardware benötigt, um spezifische Daten auszuwerten, sondern lediglich Smartphones und so genannte Wearables. Selbst Dinge wie Maschinen, die Daten über ihr eigenes Verhalten per Sensor-Chip ins Internet funken, können einbezogen werden. Die Daten werden kontinuierlich im Hintergrund erhoben, ohne dass sich jemand darum kümmern muss. Sie sind nur für die Berechnung eines Wahrscheinlichkeits-Messwerts von Belang und verlassen niemals das Gerät. Meldet sich ein Internetnutzer bei einem Dienst an, muss er sich nicht zunächst an ein vorher festgelegtes Geheimnis – z.B. ein Passwort – erinnern, sondern braucht nur die Weitergabe seines aktuellen Vertrauens-Wertes mit einem „OK“ freizugeben.
Ändert sich das Nutzungsverhalten – etwa durch andere Bewegungen oder andere Orte des Einloggens ins Internet als die üblichen – wird dies schnell erkannt. Unbefugten kann dann sofort der Zugang zum Smartphone oder zu Internetdiensten gesperrt werden. Künftig kann die Auswertung von Verhaltens-Faktoren noch erweitert werden, indem z.B. Routinen an Werktagen, an Wochenenden oder im Urlaub erfasst werden. Der Vergleich mit den live erhobenen Daten zeigt dann an, ob das Verhalten in das übliche Muster passt, der Benutzer also mit höchster Wahrscheinlichkeit auch der ausgewiesene Besitzer des Geräts ist.
Über die Techniken des Managements digitaler Identitäten und die damit verbundenen Herausforderungen gibt diese Studie einen umfassenden Überblick. Sie beschreibt zunächst, welche Arten von Angriffen es gibt, durch die digitale Identitäten gestohlen werden können. Sodann werden die unterschiedlichen Verfahren von Identitätsnachweisen vorgestellt. Schließlich liefert die Studie noch eine zusammenfassende Übersicht über die 15 wichtigsten Protokolle und technischen Standards für die Kommunikation zwischen den drei beteiligten Akteuren: Service Provider/Dienstanbieter, Identitätsprovider und Nutzer. Abschließend wird aktuelle Forschung des Hasso-Plattner-Instituts zum Identitätsmanagement vorgestellt.