Editorial of the 2019 Workshop on Very Large Internet of Things (VLIoT)

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

Advances in Cloud and Ubiquitous Computing

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

The mf-index: A Citation-Based Multiple Factor Index to Evaluate and Compare the Output of Scientists

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

Webpage Ranking Analysis of Various Search Engines with Special Focus on Country-Specific Search

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

Getting Indexed by Bibliographic Databases in the Area of Computer Science

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

Multi-Game Code-Duel for Learning Programming Languages

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

Purposeful Searching for Citations of Scholarly Publications

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

Code Generation for Big Data Processing in the Web using WebAssembly

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

Distributed Join Approaches for W3C-Conform SPARQL Endpoints

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

Semantic and Web: The Web Part

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)