TY - JOUR A1 - Chujfi-La-Roche, Salim A1 - Meinel, Christoph T1 - Matching cognitively sympathetic individual styles to develop collective intelligence in digital communities JF - AI & society : the journal of human-centred systems and machine intelligence N2 - Creation, collection and retention of knowledge in digital communities is an activity that currently requires being explicitly targeted as a secure method of keeping intellectual capital growing in the digital era. In particular, we consider it relevant to analyze and evaluate the empathetic cognitive personalities and behaviors that individuals now have with the change from face-to-face communication (F2F) to computer-mediated communication (CMC) online. This document proposes a cyber-humanistic approach to enhance the traditional SECI knowledge management model. A cognitive perception is added to its cyclical process following design thinking interaction, exemplary for improvement of the method in which knowledge is continuously created, converted and shared. In building a cognitive-centered model, we specifically focus on the effective identification and response to cognitive stimulation of individuals, as they are the intellectual generators and multiplicators of knowledge in the online environment. Our target is to identify how geographically distributed-digital-organizations should align the individual's cognitive abilities to promote iteration and improve interaction as a reliable stimulant of collective intelligence. The new model focuses on analyzing the four different stages of knowledge processing, where individuals with sympathetic cognitive personalities can significantly boost knowledge creation in a virtual social system. For organizations, this means that multidisciplinary individuals can maximize their extensive potential, by externalizing their knowledge in the correct stage of the knowledge creation process, and by collaborating with their appropriate sympathetically cognitive remote peers. KW - argumentation research KW - cyber humanistic KW - cognition KW - collaboration KW - knowledge building KW - knowledge management KW - teamwork KW - virtual groups Y1 - 2017 U6 - https://doi.org/10.1007/s00146-017-0780-x SN - 0951-5666 SN - 1435-5655 VL - 35 IS - 1 SP - 5 EP - 15 PB - Springer CY - New York ER - TY - GEN A1 - Alibabaie, Najmeh A1 - Ghasemzadeh, Mohammad A1 - Meinel, Christoph T1 - A variant of genetic algorithm for non-homogeneous population T2 - International Conference Applied Mathematics, Computational Science and Systems Engineering 2016 N2 - Selection of initial points, the number of clusters and finding proper clusters centers are still the main challenge in clustering processes. In this paper, we suggest genetic algorithm based method which searches several solution spaces simultaneously. The solution spaces are population groups consisting of elements with similar structure. Elements in a group have the same size, while elements in different groups are of different sizes. The proposed algorithm processes the population in groups of chromosomes with one gene, two genes to k genes. These genes hold corresponding information about the cluster centers. In the proposed method, the crossover and mutation operators can accept parents with different sizes; this can lead to versatility in population and information transfer among sub-populations. We implemented the proposed method and evaluated its performance against some random datasets and the Ruspini dataset as well. The experimental results show that the proposed method could effectively determine the appropriate number of clusters and recognize their centers. Overall this research implies that using heterogeneous population in the genetic algorithm can lead to better results. Y1 - 2017 U6 - https://doi.org/10.1051/itmconf/20170902001 SN - 2271-2097 VL - 9 PB - EDP Sciences CY - Les Ulis ER - TY - GEN A1 - Lorenz, Claas A1 - Kiekheben, Sebastian A1 - Schnor, Bettina T1 - FaVe: Modeling IPv6 firewalls for fast formal verification T2 - International Conference on Networked Systems (NetSys) 2017 N2 - As virtualization drives the automation of networking, the validation of security properties becomes more and more challenging eventually ruling out manual inspections. While formal verification in Software Defined Networks is provided by comprehensive tools with high speed reverification capabilities like NetPlumber for instance, the presence of middlebox functionality like firewalls is not considered. Also, they lack the ability to handle dynamic protocol elements like IPv6 extension header chains. In this work, we provide suitable modeling abstractions to enable both - the inclusion of firewalls and dynamic protocol elements. We exemplarily model the Linux ip6tables/netfilter packet filter and also provide abstractions for an application layer gateway. Finally, we present a prototype of our formal verification system FaVe. Y1 - 2017 U6 - https://doi.org/10.1109/NetSys.2017.7903956 PB - IEEE CY - New York ER - TY - GEN A1 - Gawron, Marian A1 - Cheng, Feng A1 - Meinel, Christoph T1 - PVD: Passive Vulnerability Detection T2 - 8th International Conference on Information and Communication Systems (ICICS) N2 - The identification of vulnerabilities relies on detailed information about the target infrastructure. The gathering of the necessary information is a crucial step that requires an intensive scanning or mature expertise and knowledge about the system even though the information was already available in a different context. In this paper we propose a new method to detect vulnerabilities that reuses the existing information and eliminates the necessity of a comprehensive scan of the target system. Since our approach is able to identify vulnerabilities without the additional effort of a scan, we are able to increase the overall performance of the detection. Because of the reuse and the removal of the active testing procedures, our approach could be classified as a passive vulnerability detection. We will explain the approach and illustrate the additional possibility to increase the security awareness of users. Therefore, we applied the approach on an experimental setup and extracted security relevant information from web logs. Y1 - 2017 SN - 978-1-5090-4243-2 U6 - https://doi.org/10.1109/IACS.2017.7921992 SN - 2471-125X SP - 322 EP - 327 PB - IEEE CY - New York ER - TY - GEN A1 - Malchow, Martin A1 - Renz, Jan A1 - Bauer, Matthias A1 - Meinel, Christoph T1 - Embedded smart home BT - remote lab grading in a MOOC with over 6000 participants T2 - 11th Annual IEEE International Systems Conference (SysCon) N2 - The popularity of MOOCs has increased considerably in the last years. A typical MOOC course consists of video content, self tests after a video and homework, which is normally in multiple choice format. After solving this homeworks for every week of a MOOC, the final exam certificate can be issued when the student has reached a sufficient score. There are also some attempts to include practical tasks, such as programming, in MOOCs for grading. Nevertheless, until now there is no known possibility to teach embedded system programming in a MOOC course where the programming can be done in a remote lab and where grading of the tasks is additionally possible. This embedded programming includes communication over GPIO pins to control LEDs and measure sensor values. We started a MOOC course called "Embedded Smart Home" as a pilot to prove the concept to teach real hardware programming in a MOOC environment under real life MOOC conditions with over 6000 students. Furthermore, also students with real hardware have the possibility to program on their own real hardware and grade their results in the MOOC course. Finally, we evaluate our approach and analyze the student acceptance of this approach to offer a course on embedded programming. We also analyze the hardware usage and working time of students solving tasks to find out if real hardware programming is an advantage and motivating achievement to support students learning success. Y1 - 2017 SN - 978-1-5090-4623-2 U6 - https://doi.org/10.1109/SYSCON.2017.7934728 SN - 1944-7620 SP - 195 EP - 200 PB - IEEE CY - New York ER - TY - GEN A1 - Staubitz, Thomas A1 - Wilkins, Christian A1 - Hagedorn, Christiane A1 - Meinel, Christoph T1 - The Gamification of a MOOC Platform T2 - Proceedings of 2017 IEEE Global Engineering Education Conference (EDUCON) N2 - Massive Open Online Courses (MOOCs) have left their mark on the face of education during the recent years. At the Hasso Plattner Institute (HPI) in Potsdam, Germany, we are actively developing a MOOC platform, which provides our research with a plethora of e-learning topics, such as learning analytics, automated assessment, peer assessment, team-work, online proctoring, and gamification. We run several instances of this platform. On openHPI, we provide our own courses from within the HPI context. Further instances are openSAP, openWHO, and mooc.HOUSE, which is the smallest of these platforms, targeting customers with a less extensive course portfolio. In 2013, we started to work on the gamification of our platform. By now, we have implemented about two thirds of the features that we initially have evaluated as useful for our purposes. About a year ago we activated the implemented gamification features on mooc.HOUSE. Before activating the features on openHPI as well, we examined, and re-evaluated our initial considerations based on the data we collected so far and the changes in other contexts of our platforms. KW - MOOC KW - Gamification KW - e-learning KW - Massive Open Online Courses Y1 - 2017 SN - 978-1-5090-5467-1 U6 - https://doi.org/10.1109/EDUCON.2017.7942952 SN - 2165-9567 SP - 883 EP - 892 PB - IEEE CY - New York ER - TY - CHAP A1 - Schlosser, Rainer A1 - Boissier, Martin ED - Liberatore, Federico ED - Parlier, Greg H. ED - Demange, Marc T1 - Optimal price reaction strategies in the presence of active and passive competitors T2 - Proceedings of the 6th International Conference on Operations Research and Enterprise Systems - ICORES N2 - Many markets are characterized by pricing competition. Typically, competitors are involved that adjust their prices in response to other competitors with different frequencies. We analyze stochastic dynamic pricing models under competition for the sale of durable goods. Given a competitor’s pricing strategy, we show how to derive optimal response strategies that take the anticipated competitor’s price adjustments into account. We study resulting price cycles and the associated expected long-term profits. We show that reaction frequencies have a major impact on a strategy’s performance. In order not to act predictable our model also allows to include randomized reaction times. Additionally, we study to which extent optimal response strategies of active competitors are affected by additional passive competitors that use constant prices. It turns out that optimized feedback strategies effectively avoid a decline in price. They help to gain profits, especially, when aggressive competitor s are involved. KW - Dynamic Pricing KW - Competition KW - Optimal Control KW - Response Strategies KW - Reaction Time KW - Price Cycles Y1 - 2017 SN - 978-989-758-218-9 U6 - https://doi.org/10.5220/0006118200470056 SP - 47 EP - 56 PB - SCITEPRESS - Science and Technology Publications, Lda. CY - Setúbal ER - TY - GEN A1 - Plauth, Max A1 - Sterz, Christoph A1 - Eberhardt, Felix A1 - Feinbube, Frank A1 - Polze, Andreas T1 - Assessing NUMA performance based on hardware event counters T2 - IEEE International Parallel and Distributed Processing Symposium Workshops (IPDPSW) N2 - Cost models play an important role for the efficient implementation of software systems. These models can be embedded in operating systems and execution environments to optimize execution at run time. Even though non-uniform memory access (NUMA) architectures are dominating today's server landscape, there is still a lack of parallel cost models that represent NUMA system sufficiently. Therefore, the existing NUMA models are analyzed, and a two-step performance assessment strategy is proposed that incorporates low-level hardware counters as performance indicators. To support the two-step strategy, multiple tools are developed, all accumulating and enriching specific hardware event counter information, to explore, measure, and visualize these low-overhead performance indicators. The tools are showcased and discussed alongside specific experiments in the realm of performance assessment. KW - Parallel programming KW - Performance analysis KW - Memory management Y1 - 2017 SN - 978-0-7695-6149-3 U6 - https://doi.org/10.1109/IPDPSW.2017.51 SN - 2164-7062 SP - 904 EP - 913 PB - Institute of Electrical and Electronics Engineers CY - New York ER - TY - GEN A1 - Torkura, Kennedy A. A1 - Sukmana, Muhammad Ihsan Haikal A1 - Cheng, Feng A1 - Meinel, Christoph T1 - Leveraging cloud native design patterns for security-as-a-service applications T2 - IEEE International Conference on Smart Cloud (SmartCloud) N2 - This paper discusses a new approach for designing and deploying Security-as-a-Service (SecaaS) applications using cloud native design patterns. Current SecaaS approaches do not efficiently handle the increasing threats to computer systems and applications. For example, requests for security assessments drastically increase after a high-risk security vulnerability is disclosed. In such scenarios, SecaaS applications are unable to dynamically scale to serve requests. A root cause of this challenge is employment of architectures not specifically fitted to cloud environments. Cloud native design patterns resolve this challenge by enabling certain properties e.g. massive scalability and resiliency via the combination of microservice patterns and cloud-focused design patterns. However adopting these patterns is a complex process, during which several security issues are introduced. In this work, we investigate these security issues, we redesign and deploy a monolithic SecaaS application using cloud native design patterns while considering appropriate, layered security counter-measures i.e. at the application and cloud networking layer. Our prototype implementation out-performs traditional, monolithic applications with an average Scanner Time of 6 minutes, without compromising security. Our approach can be employed for designing secure, scalable and performant SecaaS applications that effectively handle unexpected increase in security assessment requests. KW - Cloud-Security KW - Security-as-a-Service KW - Vulnerability Assessment KW - Cloud Native Applications Y1 - 2017 SN - 978-1-5386-3684-8 U6 - https://doi.org/10.1109/SmartCloud.2017.21 SP - 90 EP - 97 PB - Institute of Electrical and Electronics Engineers CY - New York ER - TY - GEN A1 - Limberger, Daniel A1 - Scheibel, Willy A1 - Trapp, Matthias A1 - Döllner, Jürgen Roland Friedrich T1 - Mixed-projection treemaps BT - a novel approach mixing 2D and 2.5D treemaps T2 - 21st International Conference Information Visualisation (IV) N2 - This paper presents a novel technique for combining 2D and 2.5D treemaps using multi-perspective views to leverage the advantages of both treemap types. It enables a new form of overview+detail visualization for tree-structured data and contributes new concepts for real-time rendering of and interaction with treemaps. The technique operates by tilting the graphical elements representing inner nodes using affine transformations and animated state transitions. We explain how to mix orthogonal and perspective projections within a single treemap. Finally, we show application examples that benefit from the reduced interaction overhead. KW - Information Visualization KW - Overview plus Detail KW - Treemaps KW - 2.5D Treemaps KW - Multi-perspective Views Y1 - 2017 SN - 978-1-5386-0831-9 U6 - https://doi.org/10.1109/iV.2017.67 SN - 2375-0138 SP - 164 EP - 169 PB - Institute of Electrical and Electronics Engineers CY - Los Alamitos ER - TY - JOUR A1 - Hartig, Olaf A1 - Pirrò, Giuseppe T1 - SPARQL with property paths on the Web JF - Semantic web N2 - Linked Data on the Web represents an immense source of knowledge suitable to be automatically processed and queried. In this respect, there are different approaches for Linked Data querying that differ on the degree of centralization adopted. On one hand, the SPARQL query language, originally defined for querying single datasets, has been enhanced with features to query federations of datasets; however, this attempt is not sufficient to cope with the distributed nature of data sources available as Linked Data. On the other hand, extensions or variations of SPARQL aim to find trade-offs between centralized and fully distributed querying. The idea is to partially move the computational load from the servers to the clients. Despite the variety and the relative merits of these approaches, as of today, there is no standard language for querying Linked Data on theWeb. A specific requirement for such a language to capture the distributed, graph-like nature of Linked Data sources on the Web is a support of graph navigation. Recently, SPARQL has been extended with a navigational feature called property paths (PPs). However, the semantics of SPARQL restricts the scope of navigation via PPs to single RDF graphs. This restriction limits the applicability of PPs for querying distributed Linked Data sources on the Web. To fill this gap, in this paper we provide formal foundations for evaluating PPs on the Web, thus contributing to the definition of a query language for Linked Data. We first introduce a family of reachability-based query semantics for PPs that distinguish between navigation on the Web and navigation at the data level. Thereafter, we consider another, alternative query semantics that couples Web graph navigation and data level navigation; we call it context-based semantics. Given these semantics, we find that for some PP-based SPARQL queries a complete evaluation on the Web is not possible. To study this phenomenon we introduce a notion of Web-safeness of queries, and prove a decidable syntactic property that enables systems to identify queries that areWeb-safe. In addition to establishing these formal foundations, we conducted an experimental comparison of the context-based semantics and a reachability- based semantics. Our experiments show that when evaluating a PP-based query under the context-based semantics one experiences a significantly smaller number of dereferencing operations, but the computed query result may contain less solutions. KW - Property paths KW - Web navigational language KW - Web safeness KW - SPARQL Y1 - 2017 U6 - https://doi.org/10.3233/SW-160237 SN - 1570-0844 SN - 2210-4968 VL - 8 IS - 6 SP - 773 EP - 795 PB - IOS Press CY - Amsterdam ER - TY - GEN A1 - Giese, Holger ED - Kouchnarenko, Olga ED - Khosravi, Ramtin T1 - Formal models and analysis for self-adaptive cyber-physical systems BT - (extended abstract) T2 - Lecture notes in computer science N2 - In this extended abstract, we will analyze the current challenges for the envisioned Self-Adaptive CPS. In addition, we will outline our results to approach these challenges with SMARTSOS [10] a generic approach based on extensions of graph transformation systems employing open and adaptive collaborations and models at runtime for trustworthy self-adaptation, self-organization, and evolution of the individual systems and the system-of-systems level taking the independent development, operation, management, and evolution of these systems into account. Y1 - 2017 SN - 978-3-319-57666-4 SN - 978-3-319-57665-7 U6 - https://doi.org/10.1007/978-3-319-57666-4_1 SN - 0302-9743 SN - 1611-3349 VL - 10231 SP - 3 EP - 9 PB - Springer CY - Cham ER - TY - GEN A1 - Serth, Sebastian A1 - Podlesny, Nikolai A1 - Bornstein, Marvin A1 - Lindemann, Jan A1 - Latt, Johanna A1 - Selke, Jan A1 - Schlosser, Rainer A1 - Boissier, Martin A1 - Uflacker, Matthias T1 - An interactive platform to simulate dynamic pricing competition on online marketplaces T2 - 2017 IEEE 21st International Enterprise Distributed Object Computing Conference (EDOC) N2 - E-commerce marketplaces are highly dynamic with constant competition. While this competition is challenging for many merchants, it also provides plenty of opportunities, e.g., by allowing them to automatically adjust prices in order to react to changing market situations. For practitioners however, testing automated pricing strategies is time-consuming and potentially hazardously when done in production. Researchers, on the other side, struggle to study how pricing strategies interact under heavy competition. As a consequence, we built an open continuous time framework to simulate dynamic pricing competition called Price Wars. The microservice-based architecture provides a scalable platform for large competitions with dozens of merchants and a large random stream of consumers. Our platform stores each event in a distributed log. This allows to provide different performance measures enabling users to compare profit and revenue of various repricing strategies in real-time. For researchers, price trajectories are shown which ease evaluating mutual price reactions of competing strategies. Furthermore, merchants can access historical marketplace data and apply machine learning. By providing a set of customizable, artificial merchants, users can easily simulate both simple rule-based strategies as well as sophisticated data-driven strategies using demand learning to optimize their pricing strategies. Y1 - 2017 SN - 978-1-5090-3045-3 U6 - https://doi.org/10.1109/EDOC.2017.17 SN - 2325-6354 SP - 61 EP - 66 PB - Institute of Electrical and Electronics Engineers CY - New York ER - TY - JOUR A1 - Seiffert, Martin A1 - Holstein, Flavio A1 - Schlosser, Rainer A1 - Schiller, Jochen T1 - Next generation cooperative wearables BT - generalized activity assessment computed fully distributed with in a wireless body area network JF - IEEE access : practical research, open solutions N2 - Currently available wearables are usually based on a single sensor node with integrated capabilities for classifying different activities. The next generation of cooperative wearables could be able to identify not only activities, but also to evaluate them qualitatively using the data of several sensor nodes attached to the body, to provide detailed feedback for the improvement of the execution. Especially within the application domains of sports and health-care, such immediate feedback to the execution of body movements is crucial for (re-) learning and improving motor skills. To enable such systems for a broad range of activities, generalized approaches for human motion assessment within sensor networks are required. In this paper, we present a generalized trainable activity assessment chain (AAC) for the online assessment of periodic human activity within a wireless body area network. AAC evaluates the execution of separate movements of a prior trained activity on a fine-grained quality scale. We connect qualitative assessment with human knowledge by projecting the AAC on the hierarchical decomposition of motion performed by the human body as well as establishing the assessment on a kinematic evaluation of biomechanically distinct motion fragments. We evaluate AAC in a real-world setting and show that AAC successfully delimits the movements of correctly performed activity from faulty executions and provides detailed reasons for the activity assessment. KW - Body sensor networks KW - distributed computing KW - motion analysis KW - physical activity assessment KW - biomechanics KW - multilevel systems Y1 - 2017 U6 - https://doi.org/10.1109/ACCESS.2017.2749005 SN - 2169-3536 VL - 5 SP - 16793 EP - 16807 PB - Institute of Electrical and Electronics Engineers CY - Piscataway ER - TY - JOUR A1 - Omotosho, Adebayo A1 - Emuoyibofarhe, Justice A1 - Meinel, Christoph T1 - Securing e-prescription from medical identity theft using steganography and antiphishing techniques JF - Journal of applied security research N2 - Drug prescription is among the health care process that usually makes references to the patients’ medical and insurance information among other personal data, because this information is very vital and delicate, it should be adequately protected from identity thieves. This article aims at securing Electronic Prescription (EP) in order to minimize patient’s data theft and foster patients’ trust of EP system. This paper presents a steganography and antiphishing technique for preventing medical identity theft in EP. The proposed EP system design focused on the security features in the prescriber and dispensers’ modules of EP by ensuring the prescriber sends the prescription of the patient in a safe manner and to the right dispenser without the interference of fake third parties. Hexadecimal steganography image system is used to cover and secure the sent prescription details. Malicious electronic dispensing system is prevented through an authentication technique where a dispenser uses a captcha together with a one-time password, and the web server encrypted token for prescriber’s device authentication. The steganography system is evaluated using Peak Signal to Noise Ratio (PSNR). The system implementation results showed that steganography and antiphishing techniques are capable of providing a secure EP systems. KW - Electronic prescription KW - one-time password KW - steganography KW - phishing KW - medical identity theft Y1 - 2017 U6 - https://doi.org/10.1080/19361610.2017.1315788 SN - 1936-1610 SN - 1936-1629 VL - 12 SP - 447 EP - 461 PB - Routledge, Taylor & Francis Group CY - Philadelphia ER - TY - JOUR A1 - Felgentreff, Tim A1 - Perscheid, Michael A1 - Hirschfeld, Robert T1 - Implementing record and refinement for debugging timing-dependent communication JF - Science of computer programming N2 - Distributed applications are hard to debug because timing-dependent network communication is a source of non-deterministic behavior. Current approaches to debug non deterministic failures include post-mortem debugging as well as record and replay. However, the first impairs system performance to gather data, whereas the latter requires developers to understand the timing-dependent communication at a lower level of abstraction than they develop at. Furthermore, both approaches require intrusive core library modifications to gather data from live systems. In this paper, we present the Peek-At-Talk debugger for investigating non-deterministic failures with low overhead in a systematic, top-down method, with a particular focus on tool-building issues in the following areas: First, we show how our debugging framework Path Tools guides developers from failures to their root causes and gathers run-time data with low overhead. Second, we present Peek-At-Talk, an extension to our Path Tools framework to record non-deterministic communication and refine behavioral data that connects source code with network events. Finally, we scope changes to the core library to record network communication without impacting other network applications. KW - Distributed debugging KW - Record and replay KW - Dynamic analysis KW - Record and refinement Y1 - 2016 U6 - https://doi.org/10.1016/j.scico.2015.11.006 SN - 0167-6423 SN - 1872-7964 VL - 134 SP - 4 EP - 18 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Sapegin, Andrey A1 - Jaeger, David A1 - Cheng, Feng A1 - Meinel, Christoph T1 - Towards a system for complex analysis of security events in large-scale networks JF - Computers & security : the international journal devoted to the study of the technical and managerial aspects of computer security N2 - After almost two decades of development, modern Security Information and Event Management (SIEM) systems still face issues with normalisation of heterogeneous data sources, high number of false positive alerts and long analysis times, especially in large-scale networks with high volumes of security events. In this paper, we present our own prototype of SIEM system, which is capable of dealing with these issues. For efficient data processing, our system employs in-memory data storage (SAP HANA) and our own technologies from the previous work, such as the Object Log Format (OLF) and high-speed event normalisation. We analyse normalised data using a combination of three different approaches for security analysis: misuse detection, query-based analytics, and anomaly detection. Compared to the previous work, we have significantly improved our unsupervised anomaly detection algorithms. Most importantly, we have developed a novel hybrid outlier detection algorithm that returns ranked clusters of anomalies. It lets an operator of a SIEM system to concentrate on the several top-ranked anomalies, instead of digging through an unsorted bundle of suspicious events. We propose to use anomaly detection in a combination with signatures and queries, applied on the same data, rather than as a full replacement for misuse detection. In this case, the majority of attacks will be captured with misuse detection, whereas anomaly detection will highlight previously unknown behaviour or attacks. We also propose that only the most suspicious event clusters need to be checked by an operator, whereas other anomalies, including false positive alerts, do not need to be explicitly checked if they have a lower ranking. We have proved our concepts and algorithms on a dataset of 160 million events from a network segment of a big multinational company and suggest that our approach and methods are highly relevant for modern SIEM systems. KW - Intrusion detection KW - SAP HANA KW - In-memory KW - Security KW - Machine learning KW - Anomaly detection KW - Outlier detection Y1 - 2017 U6 - https://doi.org/10.1016/j.cose.2017.02.001 SN - 0167-4048 SN - 1872-6208 VL - 67 SP - 16 EP - 34 PB - Elsevier Science CY - Oxford ER - TY - THES A1 - Beyhl, Thomas T1 - A framework for incremental view graph maintenance T1 - Ein Framework für die inkrementelle Wartung von Sichten auf Graphen N2 - Nowadays, graph data models are employed, when relationships between entities have to be stored and are in the scope of queries. For each entity, this graph data model locally stores relationships to adjacent entities. Users employ graph queries to query and modify these entities and relationships. These graph queries employ graph patterns to lookup all subgraphs in the graph data that satisfy certain graph structures. These subgraphs are called graph pattern matches. However, this graph pattern matching is NP-complete for subgraph isomorphism. Thus, graph queries can suffer a long response time, when the number of entities and relationships in the graph data or the graph patterns increases. One possibility to improve the graph query performance is to employ graph views that keep ready graph pattern matches for complex graph queries for later retrieval. However, these graph views must be maintained by means of an incremental graph pattern matching to keep them consistent with the graph data from which they are derived, when the graph data changes. This maintenance adds subgraphs that satisfy a graph pattern to the graph views and removes subgraphs that do not satisfy a graph pattern anymore from the graph views. Current approaches for incremental graph pattern matching employ Rete networks. Rete networks are discrimination networks that enumerate and maintain all graph pattern matches of certain graph queries by employing a network of condition tests, which implement partial graph patterns that together constitute the overall graph query. Each condition test stores all subgraphs that satisfy the partial graph pattern. Thus, Rete networks suffer high memory consumptions, because they store a large number of partial graph pattern matches. But, especially these partial graph pattern matches enable Rete networks to update the stored graph pattern matches efficiently, because the network maintenance exploits the already stored partial graph pattern matches to find new graph pattern matches. However, other kinds of discrimination networks exist that can perform better in time and space than Rete networks. Currently, these other kinds of networks are not used for incremental graph pattern matching. This thesis employs generalized discrimination networks for incremental graph pattern matching. These discrimination networks permit a generalized network structure of condition tests to enable users to steer the trade-off between memory consumption and execution time for the incremental graph pattern matching. For that purpose, this thesis contributes a modeling language for the effective definition of generalized discrimination networks. Furthermore, this thesis contributes an efficient and scalable incremental maintenance algorithm, which updates the (partial) graph pattern matches that are stored by each condition test. Moreover, this thesis provides a modeling evaluation, which shows that the proposed modeling language enables the effective modeling of generalized discrimination networks. Furthermore, this thesis provides a performance evaluation, which shows that a) the incremental maintenance algorithm scales, when the graph data becomes large, and b) the generalized discrimination network structures can outperform Rete network structures in time and space at the same time for incremental graph pattern matching. N2 - Heutzutage werden Graphdatenmodelle verwendet um Beziehungen zwischen Entitäten zu speichern und diese Beziehungen später abzufragen. Jede Entität im Graphdatenmodell speichert lokal die Beziehungen zu anderen verknüpften Entitäten. Benutzer stellen Suchanfragen um diese Entitäten und Beziehungen abzufragen und zu modifizieren. Dafür machen Suchanfragen Gebrauch von Graphmustern um alle Teilgraphen in den Graphdaten zu finden, die über bestimmte Graphstrukturen verfügen. Diese Teilgraphen werden Graphmusterübereinstimmung (Match) genannt. Allerdings ist diese Suche nach Matches NP-vollständig für Teilgraphisomorphie. Daher können Suchanfragen einer langen Antwortzeit unterliegen, wenn die Anzahl von Entitäten und Beziehungen in den Graphdaten oder -mustern ansteigt. Eine Möglichkeit die Antwortzeiten von Suchanfragen zu verbessern ist Matches für komplexe Suchanfragen in sogenannten Sichten über die Graphdaten für spätere Suchanfragen bereitzuhalten. Allerdings müssen diese Sichten mittels einer inkrementellen Suche nach Matches gewartete werden um sie konsistent zu den sich ändernden Graphdaten zu halten. Diese Wartung ergänzt Teilgraphen, die Graphmuster erfüllen, in den Sichten und entfernt Teilgraphen, die Graphmuster nicht mehr erfüllen, aus den Sichten. Aktuelle Ansätze für die inkrementelle Suche nach Matches verwenden Rete Netzwerke. Rete Netzwerke sind sogenannte Discrimination Networks, die alle Matches für bestimmte Suchanfragen aufzählen und warten, indem sie ein Netzwerk aus einzelnen Teilgraphmustern anwenden, die zusammen eine vollständige Suchanfrage ergeben. Das Netzwerk speichert für jedes Teilgraphmuster welche Teilgraphen das Teilgraphmuster erfüllen. Daher haben Rete Netzwerke einen hohen Speicherverbrauch, da sie alle Zwischenergebnisse speichern müssen. Jedoch sind es gerade diese gespeicherten Zwischenergebnisse, die es dem Rete Netzwerk ermöglichen die gespeicherten Zwischenergebnisse effizient zu warten, da diese Zwischenergebnisse für das Auffinden neuer Matches ausgenutzt werden. Allerdings existieren andere Arten von Discrimination Networks, die hinsichtlich Speicher- und Zeitverbrauch effizienter sind, aber derzeit nicht für die inkrementelle Suche nach Matches verwendet werden. Diese Doktorarbeit wendet eine verallgemeinerte Art von Discrimination Networks an. Diese verallgemeinerte Art ermöglicht es die Balance zwischen Speicher- und Zeitverbrauch für die inkrementelle Suche nach Matches zu steuern. Dafür stellt diese Arbeit eine Modellierungssprache vor, die es ermöglicht verallgemeinerte Arten von Discrimination Networks effektiv zu spezifizieren. Darauf aufbauend stellt diese Arbeit einen inkrementellen Algorithmus vor, der die gespeicherten Matches effizient und skalierbar wartet. Abschließend stellt diese Arbeit eine Evaluierung vor, die aufzeigt dass die Modellierungssprache eine effektive Spezifikation von verallgemeinerten Discrimination Networks erlaubt. Außerdem zeigt die Evaluierung, dass a) der inkrementelle Wartungsalgorithmus für große Graphdaten skaliert und b) die Netzwerkstrukturen von verallgemeinerten Discrimination Networks im Vergleich zu den Netzwerkstrukturen von Rete Netzwerken im Speicher- und Zeitverbrauch für die inkrementelle Suche nach Matches effizienter sein können. KW - incremental graph pattern matching KW - discrimination networks KW - Rete networks KW - Gator networks KW - model-driven software engineering KW - inkrementelle Graphmustersuche KW - Discrimination Networks KW - Rete Netzwerk KW - Gator Netzwerk KW - modellgetriebene Softwareentwicklung Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-405929 ER - TY - BOOK A1 - Maximova, Maria A1 - Giese, Holger A1 - Krause, Christian T1 - Probabilistic timed graph transformation systems T1 - Probabilistische zeitbehaftete Graphtransformationssysteme N2 - 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. N2 - Software gehört heutzutage zu einem wesentlichen Bestandteil von komplexen eingebetteten Echtzeitsystemen. Die nächste Generation von eingebetteten Echtzeitsystemen wird in der Zukunft die bisher nicht verbundenen Systeme durch komplexe Softwarelösungen unter der Verwendung des serviceorientierten Paradigmas verbinden. Deswegen wird neben der Beschreibung des zeitbehafteten und probabilistischen Verhaltens auch die Betrachtung der Strukturdynamik benötigt, um die Modellierung der Architekturänderungen während der Laufzeit zu ermöglichen, wie z. B. die dynamische Anbindung von den Endpunkten der Services oder die dynamische Erstellung der komplexen Kollaborationen. Allerdings gibt es noch keinen Ansatz für die Modellierung und Analyse, der all diese drei notwendigen Aspekte kombiniert. Um die identifizierte Lücke zu schließen, führen wir probabilistische zeitbehaftete Graphtransformationssysteme (kurz PTGTS) ein, die als abstrakte Beschreibungssprache dienen und die notwendigen Aspekte der Strukturdynamik, des zeitbehafteten Verhaltens und des probabilistischen Verhaltens unterstützen. Außerdem stellen wir den Formalismus der probabilistischen zeitbehafteten Graphtransformationssysteme vor und definieren eine Abbildung zwischen den Modellen mit endlichen Zustandsräumen und probabilistischen zeitbehafteten Automaten, die die Nutzung des PRISM Modell-Checkers für die Analyse der PTGTS Modelle in Bezug auf PTCTL Eigenschaften ermöglichen. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 118 KW - graph transformations KW - probabilistic timed automata KW - PTCTL KW - PRISM model checker KW - HENSHIN KW - Graphtransformationen KW - probabilistische zeitbehaftete Automaten KW - PTCTL KW - PRISM Modell-Checker KW - HENSHIN Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-397055 SN - 978-3-86956-405-0 SN - 1613-5652 SN - 2191-1665 IS - 118 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Klauck, Stefan A1 - Maschler, Fabian A1 - Tausche, Karsten T1 - Proceedings of the Fourth HPI Cloud Symposium "Operating the Cloud" 2016 N2 - 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. N2 - Jedes Jahr lädt das Hasso-Plattner-Institut (HPI) Gäste aus der Industrie und der Wissenschaft zu einem kooperativen und wissenschaftlichen Workshop zum Thema Cloud Computing ein. Unser Ziel ist es, ein Forum für den Austausch von Wissen und Erfahrungen zwischen der Industrie und der Wissenschaft zu bieten. Parallel zur Veranstaltung findet der HPI Future SOC Lab Tag statt, der eine zusätzliche attraktive Umgebung für wissenschaftliche und branchenbezogene Diskussionen bietet. Der Workshop zielt darauf ab, eine Plattform für produktive Interaktionen von innovativen Ideen, Visionen und aufkommenden Technologien im Bereich von Cloud Computing zu bitten. Anlässlich dieses Symposiums fordern wir die Einreichung von Forschungsarbeiten und Erfahrungsberichte. Eine Zusammenstellung der im Rahmen des vierten HPI-Cloud-Symposiums "Operating the Cloud" 2016 angenommenen Forschungspapiere wird veröffentlicht. Wir danken den Autoren für spannende Vorträge und Einblicke in ihre aktuelle Arbeit und Forschung. Darüber hinaus freuen wir uns auf weitere interessante Einreichungen für das kommende Symposium im Laufe des Jahres. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 117 KW - cloud security KW - cloud storage KW - dependable computing KW - resource optimization KW - in-memory database KW - distribution algorithm KW - virtualization KW - Cloud-Speicher KW - Cloud-Sicherheit KW - zuverlässige Datenverarbeitung KW - Ressourcenoptimierung KW - In-Memory Datenbank KW - Verteilungsalgorithmen KW - Virtualisierung Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-394513 SN - 978-3-86956-401-2 SN - 1613-5652 SN - 2191-1665 IS - 117 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Dyck, Johannes A1 - Giese, Holger T1 - k-Inductive invariant checking for graph transformation systems N2 - 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. N2 - Während Graphtransformationssysteme einerseits einen ausdrucksstarken Formalismus bereitstellen, existieren andererseits nur eingeschränkte Möglichkeiten für die automatische Analyse. Dies gilt insbesondere für die Analyse von Systemen mit einer Vielzahl an initialen Graphen oder mit großen oder unendlichen Zustandsräumen. Ein möglicher Ansatz, um diese Einschränkungen zu umgehen, sind induktive Invarianten. Allerdings erfordert die Verifkation induktiver Invarianten oft erweitertes Wissen über das zu verifizierende System; weiterhin muss diese Verifikationstechnik mit den spezifischen Problemen der Lokalität und des Mangels an Kontextwissen umgehen. Dieser Bericht betrachtet k-induktive Invarianten - eine Verallgemeinerung induktiver Invarienten - für Graphtransformationssysteme als einen möglichen Ansatz, um diese Probleme anzugehen. Zusätzliches Kontextwissen, das durch die Analyse mehrerer (k) Schritte gewonnen werden kann, macht den entscheidenden Unterschied zu induktiven Invarianten aus und genügt oft, um die gewünschten Invarianten ohne die iterative Entwicklung zusätzlicher Eigenschaften zu verifizieren. Um unendliche Systeme in endlicher Zeit zu analysieren, führen wir eine symbolische Kodierung von Transformationssequenzen ein, die auf verschachtelten Anwendungsbedingungen basiert. Unser zentraler Beitrag ist dann ein formaler Ansatz und Algorithmus zur Verifikation von Graphbedingungen als k-induktive Invarianten. Wir führen einen formalen Beweis, um die Korrektheit unseres Verfahrens nachzuweisen, und demonstrieren die Anwendbarkeit des Verfahrens an mehreren Beispielen, die mit einer prototypischen Implementierung verifiziert wurden. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 119 KW - formal verification KW - static analysis KW - graph transformation KW - typed graph transformation systems KW - graph constraints KW - nested application conditions KW - k-inductive invariants KW - k-induction KW - k-inductive invariant checking KW - transformation sequences KW - s/t-pattern sequences KW - formale Verifikation KW - statische Analyse KW - Graphtransformationen KW - Graphtransformationssysteme KW - Graphbedingungen KW - verschachtelte Anwednungsbedingungen KW - k-induktive Invarianten KW - k-Induktion KW - k-induktives Invariant-Checking KW - Transformationssequenzen KW - Sequenzen von s/t-Pattern Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-397044 SN - 978-3-86956-406-7 SN - 1613-5652 SN - 2191-1665 IS - 119 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Schneider, Sven A1 - Lambers, Leen A1 - Orejas, Fernando T1 - Symbolic model generation for graph properties N2 - 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. N2 - Graphen sind allgegenwärtig in der Informatik. Daher ist die Verfügbarkeit von Methoden zur Darstellung und Untersuchung von Grapheigenschaften in vielen Gebieten von großer Wichtigkeit. Insbesondere ist die vollautomatische Überprüfung von Grapheigenschaften auf Erfüllbarkeit von zentraler Bedeutung. Darüberhinaus ist es in vielen Anwendungsszenarien wünschenswert diejenigen Graphen geeignet aufzuzählen, die eine Grapheigenschaft erfüllen. Im Falle einer unendlich großen Anzahl von solchen Graphen ist ein kompletter und gleichzeitig kompakter Überblick über diese Graphen anzustreben. Wir zeigen, dass die Tableau-Methode für Grapheigenschaften von Lambers und Orejas den Weg für einen Algorithmus zur Generierung von symbolischen Modellen frei gemacht hat. Wir formulieren Grapheigenschaften hierbei in einer dedizierten Logik basierend auf Graphen und Graphmorphismen. Diese Logik ist äquivalent zu der First-Order Logic auf Graphen, wie sie von Courcelle eingeführt wurde. Unser parallelisierbarer Algorithmus bestimmt graduell eine endliche Menge von sogenannten symbolischen Modellen. Hierbei beschreibt jedes symbolische Modell eine Menge von endlichen Graphen, die die Grapheigenschaft erfüllen. Die symbolischen Modelle decken so gemeinsam alle endlichen Modelle ab, die die Grapheigenschaft erfüllen (Vollständigkeit) und beschreiben keine endlichen Graphen, die die Grapheigenschaft verletzen (Korrektheit). Außerdem wird kein symbolisches Modell von einem anderen abgedeckt (Kompaktheit). Letztlich ist der Algorithmus in der Lage aus jedem symbolischen Modell ein minimales endliches Modell zu extrahieren und weitere endliche Modelle abzuleiten. Der Algorithmus ist in dem neuen Werkzeug AutoGraph implementiert. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 115 KW - model generation KW - nested graph conditions KW - tableau method KW - graph transformation KW - satisfiabilitiy solving KW - Modellerzeugung KW - verschachtelte Graphbedingungen KW - Tableaumethode KW - Graphtransformation KW - Erfüllbarkeitsanalyse Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-103171 SN - 978-3-86956-396-1 SN - 1613-5652 SN - 2191-1665 IS - 115 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Dyck, Johannes A1 - Giese, Holger A1 - Lambers, Leen T1 - Automatic verification of behavior preservation at the transformation level for relational model transformation N2 - 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. N2 - Die Korrektheit von Modelltransformationen ist von zentraler Wichtigkeit bei der Anwendung modellgetriebener Softwareentwicklung für die Entwicklung hochqualitativer Software. Insbesondere verhindert Verhaltensbewahrung als wichtigste Korrektheitseigenschaft die Entstehung semantischer Fehler während des modellgetriebenen Entwicklungsprozesses. Techniken zur Verifikation von Verhaltensbewahrung zeigen, dass bestimmte spezifische Eigenschaften bewahrt bleiben oder, im allgemeineren und komplexeren Fall, dass eine Form von Verhaltensäquivalenz oder Verhaltensverfeinerung zwischen Quell- und Zielmodell der Transformation besteht. Für beide Ansätze existieren automatisierte Werkzeuge für die Verifikation auf der Instanzebene, also zur Überprüfung konkreter Paare aus Quell- und Zielmodellen der Transformation. Allerdings existiert kein automatischer Verifikationsansatz, der auf der Transformationsebene arbeitet, also Aussagen zu allen Quell- und Zielmodellen einer Modelltransformation treffen kann. Dieser Bericht erweitert unsere Vorarbeit und Ergebnisse aus [27] und stellt einen neuen Ansatz zur automatischen Verifikation von Verhaltensbewahrung vor, der auf Bisimulation bzw. Simulation basiert. Dabei werden Modelltransformationen durch Triple-Graph-Grammatiken und Verhaltensdefinitionen mittels Graphtransformationsregeln beschrieben. Insbesondere weisen wir nach, dass das Problem der Verhaltensbewahrung durch Bisimulation auf Invariant-Checking für Graphtransformationssysteme reduziert werden kann und dass das entstehende Invariant-Checking-Problem für ein komplexes Beispiel durch unser Werkzeug zur Verifikation induktiver Invarianten gelöst werden kann. Das Beispiel beschreibt die Transformation von Sequenzdiagrammen in Systeme kommunizierender Automaten. Darüber hinaus diskutieren wir bestehende Einschränkungen von Invariant-Checking für Graphtransformationssysteme und Ansätze für zukünftige Arbeiten in diesem Bereich. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 112 KW - model transformation KW - behavior preservation KW - semantics preservation KW - relational model transformation KW - bisimulation KW - simulation KW - invariant checking KW - transformation level KW - behavioral equivalenc KW - behavioral refinement KW - behavioral abstraction KW - graph transformation systems KW - graph constraints KW - triple graph grammars KW - Modelltransformationen KW - Verhaltensbewahrung KW - relationale Modelltransformationen KW - Bisimulation KW - Simulation KW - Invariant-Checking KW - Transformationsebene KW - Verhaltensäquivalenz KW - Verhaltensverfeinerung KW - Verhaltensabstraktion KW - Graphtransformationssysteme KW - Graph-Constraints KW - Triple-Graph-Grammatiken Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-100279 SN - 978-3-86956-391-6 SN - 1613-5652 SN - 2191-1665 IS - 112 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Weyand, Christopher A1 - Chromik, Jonas A1 - Wolf, Lennard A1 - Kötte, Steffen A1 - Haase, Konstantin A1 - Felgentreff, Tim A1 - Lincke, Jens A1 - Hirschfeld, Robert T1 - Improving hosted continuous integration services T1 - Verbesserung gehosteter Dienste für kontinuierliche Integration N2 - Developing large software projects is a complicated task and can be demanding for developers. Continuous integration is common practice for reducing complexity. By integrating and testing changes often, changesets are kept small and therefore easily comprehensible. Travis CI is a service that offers continuous integration and continuous deployment in the cloud. Software projects are build, tested, and deployed using the Travis CI infrastructure without interrupting the development process. This report describes how Travis CI works, presents how time-driven, periodic building is implemented as well as how CI data visualization can be done, and proposes a way of dealing with dependency problems. N2 - Große Softwareprojekte zu entwickeln, ist eine komplizierte Aufgabe und fordernd für Entwickler. Kontinuierliche Integration ist eine geläufige Praxis zur Komplexitätsreduktion. Durch häufiges Integrieren und Testen werden Änderungen klein gehalten und sind daher übersichtlich. Travis CI ist ein Dienst, der kontinuierliche Integration und kontinuierliche Bereitstellung in der Cloud anbietet. Softwareprojekte werden auf der Travis CI Infrastruktur gebaut, getestet und bereitgestellt, ohne dass der Entwicklungsprozess unterbrochen wird. Dieser Bericht beschreibt, die Travis CI funktioniert, zeigt wie zeitgesteuertes, periodisches Bauen implentiert wurde, wie CI-Daten visualisiert werden können und schlägt ein Verfahren vor mit dem Abhängigkeitsprobleme gelöst werden können. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 108 KW - Travis CI KW - continuous integration KW - continuous testing KW - software tests KW - software architecture KW - periodic tasks KW - dependencies KW - visualization KW - Travis CI KW - kontinuierliche Integration KW - kontinuierliches Testen KW - Softwaretests KW - Softwarearchitektur KW - periodische Aufgaben KW - Abhängigkeiten KW - Visualisierung Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-94251 SN - 978-3-86956-377-0 SN - 1613-5652 SN - 2191-1665 IS - 108 PB - Universitätsverlag Potsdam CY - Potsdam ER -