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Alsubaiee S.,University of California at Irvine | Behm A.,Cloudera | Borkar V.,University of California at Irvine | Heilbron Z.,University of California at Irvine | And 4 more authors.
Proceedings of the VLDB Endowment | Year: 2014

Social networks, online communities, mobile devices, and instant messaging applications generate complex, unstructured data at a high rate, resulting in large volumes of data. This poses new challenges for data management systems that aim to ingest, store, index, and analyze such data efficiently. In response, we released the first public version of AsterixDB, an open-source Big Data Management System (BDMS), in June of 2013. This paper describes the storage management layer of AsterixDB, providing a detailed description of its ingestion-oriented approach to local storage and a set of initial measurements of its ingestion-related performance characteristics. In order to support high frequency insertions, AsterixDB has wholly adopted Log-Structured Merge-trees as the storage technology for all of its index structures. We describe how the AsterixDB software framework enables "LSM-ification" (conversion from an in-place update, disk-based data structure to a deferredupdate, append-only data structure) of any kind of index structure that supports certain primitive operations, enabling the index to ingest data efficiently. We also describe how AsterixDB ensures the ACID properties for operations involving multiple heterogeneous LSM-based indexes. Lastly, we highlight the challenges related to managing the resources of a system when many LSM indexes are used concurrently and present AsterixDB's initial solution. © 2014 VLDB Endowment.

Waitelonis J.,Hasso Plattner Institute Potsdam | Sack H.,Hasso Plattner Institute Potsdam
Multimedia Tools and Applications | Year: 2012

Keyword-based search in general is particularly applicable if the searcher really knows what she is looking for and how to find it, i.e. to know the appropriate keywords to obtain the desired results. But in many cases either the objectives of the searcher are intrinsically fuzzy or she is not aware of the appropriate keywords. One way to solve this problem is to navigate and explore the search space along guided routes. In this paper we show, how Linked Open Data can be adopted to facilitate an exploratory semantic search for video data. We present a prototype implementation of exploratory video search and show how traditional keyword-based search can be augmented by the use of Linked Open Data. © Springer Science+Business Media, LLC 2011.

Wenzel M.,Hasso Plattner Institute Potsdam | Meinel C.,Hasso Plattner Institute Potsdam
2015 International Conference on Collaboration Technologies and Systems, CTS 2015 | Year: 2015

In modern computer systems, multicore processors are prevalent, even on mobile devices. Since JavaScript WebWorkers provide execution parallelism in a web browser, they can help utilize multicore CPUs more effectively. However, WebWorker limitations include a lack of access to web browser's native XML processing capabilities and related Document Object Model (DOM). We present a JavaScript DOM and XML processing implementation that adds missing APIs to WebWorkers. This way, it is possible to use JavaScript code that relies on native APIs within WebWorkers. We show and evaluate the seamless integration of an external XMPP library to enable parallel network data and user input processing in a web based real-time remote collaboration system. Evaluation shows that our XML processing solution has the same linear execution time complexity as its native API counterparts. The proposed JavaScript solution is a general approach to enable parallel XML data processing within web browser-based applications. By implementing standards compliant DOM interfaces, our implementation is useful for existing libraries and applications to leverage the processing power of multicore systems. © 2015 IEEE.

Gericke L.,Hasso Plattner Institute Potsdam | Meinel C.,Hasso Plattner Institute Potsdam
Proceedings of the 2012 IEEE 13th International Conference on Information Reuse and Integration, IRI 2012 | Year: 2012

Asynchronous work settings demand for certain hand-over processes - often performed by documentation of the work. This task is challenging especially for creative work, because finding the right form of documentation - including decisions that have been made and explanations how people came to solutions - is non-trivial. Capturing the whole process and replay it afterwards to distributed team members could solve those problems, but is hardly realizable in terms of time consumption. Our approach uses the complete capturing of a session - exemplary implemented using a digital whiteboard system - in order to find out phases of work. This enables us to point out relations between different phases, which can tell us what part was more important than another. We found out that the definition of time slices consisting of certain parameters describing the process can be aggregated into segments. Those segments are classified using an SVM approach, which turns out to give promising results. The overall contribution is an approach, which can be generalized for a variety of captured parameters to allow a precise classification of segments related to the respective overall task. © 2012 IEEE.

Trumper J.,Hasso Plattner Institute Potsdam | Telea A.,University of Groningen | Dollner J.,Hasso Plattner Institute Potsdam
Theory and Practice of Computer Graphics 2012, TPCG 2012 - Eurographics UK Chapter Proceedings | Year: 2012

Visualization of data on structure and related temporal activity supports the analysis of correlations between the two types of data. This is typically done by linked views. This has shortcomings with respect to efficient space usage and makes mapping the effect of user input into one view into the other view difficult. We propose here a novel, space-efficient technique that 'fuses' the two information spaces - structure and activity - in one view. We base our technique on the idea that user interaction should be simple, yet easy to understand and follow. We apply our technique, implemented in a prototype tool, for the understanding of software engineering datasets, namely static structure and execution traces of the Chromium web browser. © The Eurographics Association 2012.

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