http://www.ronpub.com/publications/search.php?journal=ALL&author=Sven+Groppe&exactauthor=on&title=&abstract=&volume=&issue=&year1=&year2=&searchtype=advanced This feed contains the result of an user-defined search in RonPub publications en-us https://www.ronpub.com/ojsw/OJSW-v1i2n02_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194858 Increasingly data on the Web is stored in the form of Semantic Web data. Because of today's information overload, it becomes very important to store and query these big datasets in a scalable way and hence in a distributed fashion. Cloud Computing offers such a distributed environment with dynamic reallocation of computing and storing resources based on needs. In this work we introduce a scalable distributed Semantic Web database in the Cloud. In order to reduce the number of (unnecessary) intermediate results early, we apply bloom filters. Instead of computing bloom filters, a time-consuming task during query processing as it has been done traditionally, we precompute the bloom filters as much as possible and store them in the indices besides the data. The experimental results with data sets up to 1 billion triples show that our approach speeds up query processing significantly and sometimes even reduces the processing time to less than half. https://www.ronpub.com/ojcc/OJCC-v1i2n01_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194478 Clouds are dynamic networks of common, off-the-shell computers to build computation farms. The rapid growth of databases in the context of the semantic web requires efficient ways to store and process this data. Using cloud technology for storing and processing Semantic Web data is an obvious way to overcome difficulties in storing and processing the enormously large present and future datasets of the Semantic Web. This paper presents a new approach for storing Semantic Web data, such that operations for the evaluation of Semantic Web queries are more likely to be processed only on local data, instead of using costly distributed operations. An experimental evaluation demonstrates the performance improvements in comparison to a naive distribution of Semantic Web data. https://www.ronpub.com/ojwt/OJWT_2014v1i2n02_Kusserow.html http://nbn-resolving.de/urn:nbn:de:101:1-201705291343 Every author and publisher is interested in adding their publications to the widely used bibliographic databases freely accessible in the world wide web: This ensures the visibility of their publications and hence of the published research. However, the inclusion requirements of publications in the bibliographic databases are heterogeneous even on the technical side. This survey paper aims in shedding light on the various data formats, protocols and technical requirements of getting indexed by widely used bibliographic databases in the area of computer science and provides hints for maximal database inclusion. Furthermore, we point out the possibilities to utilize the data of bibliographic databases, and describes some personal and institutional research repository systems with special regard to the support of inclusion in bibliographic databases. https://www.ronpub.com/ojdb/OJDB_2015v2i1n03_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194627 External merge sort belongs to the most efficient and widely used algorithms to sort big data: As much data as fits inside is sorted in main memory and afterwards swapped to external storage as so called initial run. After sorting all the data in this way block-wise, the initial runs are merged in a merging phase in order to retrieve the final sorted run containing the completely sorted original data. Patricia tries are one of the most space-efficient ways to store strings especially those with common prefixes. Hence, we propose to use patricia tries for initial run generation in an external merge sort variant, such that initial runs can become large compared to traditional external merge sort using the same main memory size. Furthermore, we store the initial runs as patricia tries instead of lists of sorted strings. As we will show in this paper, patricia tries can be efficiently merged having a superior performance in comparison to merging runs of sorted strings. We complete our discussion with a complexity analysis as well as a comprehensive performance evaluation, where our new approach outperforms traditional external merge sort by a factor of 4 for sorting over 4 billion strings of real world data. https://www.ronpub.com/ojcc/OJCC_2015v2i2n01e_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201704229173 Cloud computing provides on-demand access to a shared pool of configurable and dynamically reallocated computing resources typically located in third-party data centers. Ubiquitous computing aims at providing computing resources anytime and everywhere by using any device, in any location, and in any format. This special issue, Advances in Cloud and Ubiquitous Computing (ACUC), aims at addressing the challenges and reporting the latest research findings in the fields of Cloud computing and Ubiquitous Computing respectively, and how new technologies of Cloud Computing and Ubiquitous Computing complete each other. https://www.ronpub.com/ojsw/OJSW_2015v2i1n04_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194910 Currently many SPARQL endpoints are freely available and accessible without any costs to users: Everyone can submit SPARQL queries to SPARQL endpoints via a standardized protocol, where the queries are processed on the datasets of the SPARQL endpoints and the query results are sent back to the user in a standardized format. As these distributed execution environments for semantic big data (as intersection of semantic data and big data) are freely accessible, the Semantic Web is an ideal playground for big data research. However, when utilizing these distributed execution environments, questions about the performance arise. Especially when several datasets (locally and those residing in SPARQL endpoints) need to be combined, distributed joins need to be computed. In this work we give an overview of the various possibilities of distributed join processing in SPARQL endpoints, which follow the SPARQL specification and hence are "W3C conform". We also introduce new distributed join approaches as variants of the Bitvector-Join and combination of the Semi- and Bitvector-Join. Finally we compare all the existing and newly proposed distributed join approaches for W3C conform SPARQL endpoints in an extensive experimental evaluation. https://www.ronpub.com/ojsw/OJSW_2015v2i1n01e_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194864 The Web is everywhere in daily life. Business is not possible any more without the fast communication through the web. The knowledge of the humans is reflected in the information accessible in the web. New challenges occur with the flood of information and electronic possibilities for the human being. The current World Wide Web enables an easy, instant access to a vast amount of online information. However, the content in the Web is typically for human consumption, and is not tailored to be machine-processed. The Semantic Web, which is intended to establish a machine-understandable web, thereby offers a promising and potential solution to mining and analyzing web content. The Semantic Web is currently changing from an emergent trend to a technology used in complex real-world applications. This part of the special issue "Semantic and Web" especially investigates how semantic technologies can help the human being to open the new possibilities of the web. The papers, which contribute more to Web technologies, are published in Open Journal of Web Technologies (OJWT). https://www.ronpub.com/ojwt/OJWT_2015v2i1n01e_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194864 One major aim of the Semantic Web is to enable a machine-processable Web of data. Hence, the Semantic Web community regards it as extension of the traditional web. On the other hand, the applications of the Semantic Web rely deeply on web technologies in order to work in a distributed fashion, world-wide. The goal of this special issue is to bring together contributions from these communities to address the challenges in Semantic Web and Web technologies in cooperation. The papers included in this special issue demonstrate how new technologies of the Web and Semantic Web complement each other and provide more contributions to the area of web technologies. The semantic part of this special issue, which contains substantial theoretical and empirical contributions to Semantic Web, is published in Open Journal of Semantic Web (OJSW). https://www.ronpub.com/ojdb/OJDB_2016v3i1n02_Werner.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194645 This paper presents the fully integrated hardware-accelerated query engine for large-scale datasets in the context of Semantic Web databases. As queries are typically unknown at design time, a static approach is not feasible and not flexible to cover a wide range of queries at system runtime. Therefore, we introduce a runtime reconfigurable accelerator based on a Field Programmable Gate Array (FPGA), which transparently incorporates with the freely available Semantic Web database LUPOSDATE. At system runtime, the proposed approach dynamically generates an optimized hardware accelerator in terms of an FPGA configuration for each individual query and transparently retrieves the query result to be displayed to the user. During hardware-accelerated execution the host supplies triple data to the FPGA and retrieves the results from the FPGA via PCIe interface. The benefits and limitations are evaluated on large-scale synthetic datasets with up to 260 million triples as well as the widely known Billion Triples Challenge. https://www.ronpub.com/ojbd/OJBD_2016v2i1n02_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194418 The Semantic Web community collects masses of valuable and publicly available RDF data in order to drive the success story of the Semantic Web. Efficient processing of these datasets requires their indexing. Semantic Web indices make use of the simple data model of RDF: The basic concept of RDF is the triple, which hence has only 6 different collation orders. On the one hand having 6 collation orders indexed fast merge joins (consuming the sorted input of the indices) can be applied as much as possible during query processing. On the other hand constructing the indices for 6 different collation orders is very time-consuming for large-scale datasets. Hence the focus of this paper is the efficient Semantic Web index construction for large-scale datasets on today's multi-core computers. We complete our discussion with a comprehensive performance evaluation, where our approach efficiently constructs the indices of over 1 billion triples of real world data. https://www.ronpub.com/ojwt/OJWT_2017v4i1n01_Oberesch.html http://nbn-resolving.de/urn:nbn:de:101:1-2017070914565 Comparing the output of scientists as objective as possible is an important factor for, e.g., the approval of research funds or the filling of open positions at universities. Numeric indices, which express the scientific output in the form of a concrete value, may not completely supersede an overall view of a researcher, but provide helpful indications for the assessment. This work introduces the most important citation-based indices, analyzes their advantages and disadvantages and provides an overview of the aspects considered by them. On this basis, we identify the criteria that an advanced index should fulfill, and develop a new index, the mf-index. The objective of the mf-index is to combine the benefits of the existing indices, while avoiding as far as possible their drawbacks and to consider additional aspects. Finally, an evaluation based on data of real publications and citations compares the mf-index with existing indices and verifies that its advantages in theory can also be determined in practice. https://www.ronpub.com/ojiot/OJIOT_2017v3i1n02e_VLIoT2017.html http://nbn-resolving.de/urn:nbn:de:101:1-2017080613397 This article is an editorial for the proceedings of the "Very Large Internet of Things (VLIoT 2017)" workshop in conjunction with the 43th International Conference on Very Large Data Bases (VLDB 2017), which takes place in Munich, Germany, from August 28th to September 1, 2017. The editorial of VLIoT@VLDB 2017 provides an overview over the aims and scope of the workshop, the review procedure, and the accepted papers. The proceedings of VLIoT@VLDB 2017 are published as special issue in the Open Journal of Internet of Things (OJIOT) (www.ronpub.com/ojiot), and the publisher of OJIOT is RonPub (www.ronpub.com). https://www.ronpub.com/ojis/OJIS_2017v4i1n02_Rosenthal.html http://nbn-resolving.de/urn:nbn:de:101:1-201711266882 Citation data contains the citations among scholarly publications. The data can be used to find relevant sources during research, identify emerging trends and research areas, compute metrics for comparing authors or journals, or for thematic clustering. Manual administration of citation data is limited due to the large number of publications. In this work, we hence lay the foundations for the automatic search for scientific citations. The unique characteristics are a purposeful search of citations for a specified set of publications (of e.g., an author or an institute). Therefore, search strategies will be developed and evaluated in this work in order to reduce the costs for the analysis of documents without citations to the given set of publications. In our experiments, for authors with more than 100 publications about 75 % of the citations were found. The purposeful strategy examined thereby only 1.5 % of the 120 million publications of the used data set. https://www.ronpub.com/ojiot/OJIOT_2018v4i1n01_VLIoT2018.html http://nbn-resolving.de/urn:nbn:de:101:1-2018080519324071729480 The 2nd "Very Large Internet of Things" (VLIoT) workshop in conjunction with the 44th International Conference on Very Large Data Bases (VLDB) taking place in Rio de Janeiro, Brazil in 2018 is a forum for all researchers in the area of Internet of Things especially interested in related data management issues. This editorial of a special issue containing the workshop's papers provides an overview over the aims and scope of the workshop and the review procedure. Furthermore, we determine and shortly analyze a statistics of the topics addressed by the accepted papers. https://www.ronpub.com/ojwt/OJWT_2018v5i1n03_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-2018093019301629565937 Whenever clients shop in the Internet, they provide identifying data of themselves to parties like the webshop, shipper and payment system. These identifying data merged with their shopping history might be misused for targeted advertisement up to possible manipulations of the clients. The data also contains credit card or bank account numbers, which may be used for unauthorized money transactions by the involved parties or by criminals hacking the parties' computing infrastructure. In order to minimize these risks, we propose an approach for anonymous shopping by separation of data. We argue for the feasibility of our approach by discussing important operations like simple reclamation cases and criminal investigations. https://www.ronpub.com/ojwt/OJWT_2018v5i1n06_Babayigit.html http://nbn-resolving.de/urn:nbn:de:101:1-2018093019303617104000 In order to attract many visitors to their own website, it is extremely important for website developers that their webpage is one of the best ranked webpages of search engines. As a rule, search engine operators do not disclose their exact ranking algorithm, so that website developers usually have only vague ideas about which measures have particularly positive influences on the webpage ranking. Conversely, we ask the question: "What are the properties of the best ranked webpages?" For this purpose, we perform a detailed analysis, in which we compare the properties of the best ranked webpages with the worse ranked webpages. Furthermore, we compare countryspecific differences. https://www.ronpub.com/ojwt/OJWT_2018v5i1n01e_WDRAR2018.html http://nbn-resolving.de/urn:nbn:de:101:1-2018110508370722588082 The first Web Data Processing & Reasoning (WDPAR) workshop in conjunction with the 41st German Conference on Artificial Intelligence (KI) taking place in Berlin, Germany in 2018 is a forum for all researchers especially interested in processing of and reasoning on web data. The proceedings of WDPAR@KI 2018 are published in the Open Journal of Web Technologies (OJWT) (www.ronpub.com/ojwt) as special issue and the publisher of OJWT is RonPub. This editorial provides an overview over the aims and scope of the workshop and the review procedure. Furthermore, we introduce the accepted papers and their topics in the editorial. https://www.ronpub.com/ojiot/OJIOT_2019v5i1n01e_VLIoT2019.html http://nbn-resolving.de/urn:nbn:de:101:1-2019092919330960165487 We are proud of presenting the outcome of this third edition of the "Very Large Internet of Things" (VLIoT) workshop, which was held in Los Angeles (USA) in August 2019, in conjunction with the 45th International Conference on Very Large Data Bases (VLDB). Following the success path of the two previous workshop editions - in Munich (2017) and in Rio de Janeiro (2018) - VLIoT 2019 kept its tradition to be a vivid and high-quality technical forum for researchers and practitioners working with Internet of Things to share their experiences, visions and latest findings, most of them regarding the design, implementation, deployment and management of IoT systems at very large and scale. This editorial of the special issue introduces and introduces all papers presented at the workshop. https://www.ronpub.com/ojis/OJIS_2019v6i1n01_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-2020011918334950197619 Software developers compose computer instructions following the rules defined in programming languages for the purpose of automatic information processing. However, different programming languages have different syntax and semantic rules, and support different programming paradigms and design patterns. Learning a programming language needs many efforts and much practicing in order to master the rules and apply the patterns. Leaning multiple programming languages at the same time, of course, needs more efforts. In this work we develop the concept of multi-game and an e-learning platform called "Multi-Game Platform for Code-Duels" for learning multiple programming languages easily and efficiently. A multi-game is a video game, which consists of several mini-games. Dividing a big game into mini-games reduces the development efforts and implementation complexity. "Builders" is a multi-game developed in our platform consisting of three mini-games. Each mini-game can be solved by implementing a program by learners using different languages. Using our multi-game platform, each mini-game of Builders can be developed easily and played independently of the other mini-games. Finally, a user evaluation over our multi-game platform is performed, where users rate our multi-game approach and platform for learning programming languages very positively. https://www.ronpub.com/ojcc/OJCC_2019v6i1n01_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-2020011918330924188531 Traditional clusters for cloud computing are quite hard to configure and setup, and the number of cluster nodes is limited by the available hardware in the cluster. We hence envision the concept of a Browser Cloud: One just has to visit with his/her web browser a certain webpage in order to connect his/her computer to the Browser Cloud. In this way the setup of the Browser Cloud is much easier than those of traditional clouds. Furthermore, the Browser Cloud has a much larger number of potential nodes, as any computer running a browser may connect to and be integrated in the Browser Cloud. New challenges arise when setting up a cloud by web browsers: Data is processed within the browser, which requires to use the technologies offered by the browser for this purpose. The typically used JavaScript runtime environment may be too slow, because JavaScript is an interpreted language. Hence we investigate the possibilities for computing the work-intensive part of the query processing inside a virtual machine of the web browser. The technology WebAssemby for virtual machines is recently supported by all major browsers and promises high speedups in comparison with JavaScript. Recent approaches to efficient Big Data processing generate code for the data processing steps of queries. To run the generated code in a WebAssembly virtual machine, an online compiler is needed to generate the WebAssembly bytecode from the generated code. Hence our main contribution is an online compiler to WebAssembly bytecode especially developed to run in the web browser and for Big Data processing based on code generation of the processing steps. In our experiments, the runtimes of Big Data processing using JavaScript is compared with running WebAssembly technologies in the major web browsers. https://www.ronpub.com/ojiot/OJIOT_2020v6i1n01e_VLIOT2020.html http://nbn-resolving.de/urn:nbn:de:101:1-2020080219331432369272 The Very Large Internet of Things (VLIoT) workshop aims at discussing the solutions of problems arising especially for large-scale configurations. After continuously monitoring the global COVID-19 pandemic this year, the workshop changes the format the first time to an online event in order to overcome problems like travel restrictions. Besides missing face-to-face meetings the online format also has chances like an increased number of participants, less travel burdens and saving budget. Hence we received many high-quality submissions, from which we accepted 9 to be introduced in this editorial. https://www.ronpub.com/ojcc/OJCC_2020v7i1n01_Bittner.html http://nbn-resolving.de/urn:nbn:de:101:1-2020112218332015343957 The isolation property of database theory guarantees to avoid problems of not synchronized parallel execution of several transactions. In this paper we propose an algorithm for an optimal transaction schedule for the different cores of a multi-core CPU with minimal execution time ensuring the isolation property. Optimizing the transaction schedule is a combinatorial problem, which is ideal to be solved by quantum annealers as special form of quantum computers. In our contribution we show how to transform an instance of the transaction schedule problem into a formula that is accepted by quantum annealers including a proof of validity and optimality of the obtained result. Furthermore, we analyze the number of required qubits and the preprocessing time, and introduce an approach for caching formulas as result of preprocessing for the purpose of reducing the preprocessing time. In an experimental evaluation, the runtime on a quantum annealer outperforms the runtime of traditional algorithms to solve combinatorial problems like simulated annealing already for small problem sizes. https://www.ronpub.com/ojis/OJIS_2021v8i1n01_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-2021050919330457300473 Citation graphs visualize citation relationships of publications. Hence citation graphs enable in-depth analysis about the impact of publications to research areas, such that citation graphs have great benefits for systematic reviews about a special field of research. In this contribution, we introduce a tool for automatically generating citation graphs from a set of paper documents, which runs stand-alone or integrated in a systematic reviews application. As systematic reviews often include many papers, we also propose several strategies to reduce the complexity of citation graphs and add additional information for in-depth analysis of the impact of single publications. In addition to citation graphs our tool also visualizes the publication selection process of systematic reviews. The generated graphs and developed strategies are evaluated using different instruments, including an user survey, in which they are rated positively. https://www.ronpub.com/ojiot/OJIOT_2021v7i1n02e_VLIoT2021.html http://nbn-resolving.de/urn:nbn:de:101:1-2021082919330413733202 The Very Large Internet of Things (VLIoT) workshop aims at discussing the solutions of problems arising especially for large-scale Internet-of-Things (IoT) configurations. After online conferences and workshops are becoming the normal mode for running scientific events, after continuously monitoring the global COVID-19 pandemic this year with falling incidence rates in the last times due to vaccination successes, the workshop changes the format the first time to a hybrid event. This ensures that still problems are overcome like travel restrictions, but offers face-to-face discussions among those going to the local event. A hybrid format has still chances like an increased number of participants, less travel burdens and saving budget, but offers the possibility for going to the local event already for a large portion of the participants. Hence we received many high-quality submissions, from which we accepted 9 to be introduced in this editorial. https://www.ronpub.com/ojsw/OJSW_2021v8i1n01_Groppe.html http://nbn-resolving.de/urn:nbn:de:101:1-2022011618330544843704 Databases process a lot of intermediate steps generating many intermediate results during data processing for answering queries. It is not easy to understand these complex tasks and algorithms for students, developers and all those interested in databases. For this purpose, an additional medium is sonification, which maps data to auditory dimensions and offers a new audible experience to their listeners. Hence, we propose a sonification of query processing paired with a corresponding visualization both integrated in a web application. In a demonstration of our approach and in an extensive user evaluation we show that listeners increase their understanding of the operators' functionality and sonification supports easy remembering of requirements like merge joins work on sorted input. Furthermore, new ways of analyzing query processing are possible with our proposed sonification approach.