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Königin-Luise-Straße 24-26
14195 Berlin

Tel.: +49-30-838-75221
Fax: +49-30-838-75220

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DigiPolis project publication accepted at NaBIC2011 Congress

The DigiPolis project here at AG NBI is developing a Self-organized Semantic Storage Service (“S4″). A research paper written by NBI staff members Hannes Mühleisen, Tilman Walther and Prof. Robert Tolksdorf discussing self-optimization of the stored data was just accepted for the Third World Congress on Nature and Biologically Inspired Computing (NaBIC2011) in Salamanca, Spain.
The publication is titled “Data Location Optimization for a Self-Organized Distributed Storage System”, here the abstract:

Nature-inspired algorithms allow the creation of complex systems that are scalable in many dimensions, adaptable to changing conditions, and robust against failure. Our S4 system employs these algorithms to provide a distributed storage service based on swarm operations. Here, autonomous agents move on a virtual landscape of connected computers to store and retrieve data. However, these swarm-based approaches achieve their impressive performance by trading away correctness guarantees, occasionally leading to misplaced data items. In order to achieve consistent storage, there is a need for a constant optimization of the store’s data structure. In this paper, we describe a fully distributed and scalable heuristic for the optimization of the location of stored data items within a distributed storage system. We evaluate our heuristic using best- and worst-case test data


DigiPolis project publication accepted at Web-KR3 Workshop

The DigiPolis project here at AG NBI is developing a Self-organized Semantic Storage Service (“S4″). A research paper written by NBI staff members Hannes Mühleisen, Tilman Walther and Prof. Robert Tolksdorf discussing the web-scale evaluation of range queries to support geospatial applications within this system was accepted for the 2011 International Workshop on Web-scale Knowledge Representation, Retrieval, and Reasoning (Web-KR3 2011) co-located with the 2011 IEEE/WIC/ACM International Conferences on Web Intelligence and Intelligent Agent Technology in Lyon, France.
The publication is titled “Web-scale Range Queries in a Self-Organized Storage Service”, here the abstract:

Distributed solutions for the storage and retrieval of large amounts of data are necessary to handle the growing amounts of knowledge expected from future applications. The support for range queries provides much-needed expressivity, for example for queries on data annotated with location and time. We present a novel and scalable way for range query evaluation in our distributed storage system based on behaviour found in ants. Routing decisions in this system are taken on the basis of virtual pheromone paths leading from one node to another node, distinct for different data items. Range queries for single ranges can be evaluated by checking the pheromone paths for


DigiPolis project publication accepted at CEC2011 conference

The DigiPolis project at AG NBI is developing a Self-organized Semantic Storage Service („S4“). A research paper written by NBI staff members Hannes Mühleisen, Tilman Walther and Prof. Robert Tolksdorf discussing the handling of different index levels within this system was just accepted for the 2011 IEEE Congress on Evolutionary Computation (CEC2011) , New Orleans, USA.
The publication is titled „Multi-Level Indexing in a Distributed Self-Organized Storage System“, here the abstract:

In many systems providing storage and retrieval operations on data, indices are used to make these operations more efficient. Distributed storage systems provide means to distribute the burden of storing and retrieving data on multiple different computers. Routing indices can answer the central question in these systems: Where should one look for a specified data item? To be able to query for different columns in a relation or different entries in tuples, indexing for multiple dimensions is necessary. Our group applies a swarm-based approach to distributed storage leading to a new class of distributed systems, which are fully self-organized in their behavior and lack any shared global data structures. Here, we research whether multiple levels of routing indices can be maintained and used in such a


DigiPolis: Selbst-Organisierender Semantischer Speicherdienst (S4)

Im Rahmen des vom Bundesministerium für Bildung und Forschung geförderten Verbundprojekts „DigiPolis“ entwickelt die AG NBI einen verteilten selbst-organisierenden semantischen Speicherdienst (S4) auf der Basis von naturinspirierten Algorithmen und Schwarmintelligenz. Im Zuge dieser Entwicklung sind verschiedene, für Abschlussarbeiten passende Themen zu bearbeiten:

  • Erstellung einer vergleichenden Studie zwischen unterschiedlichen Organisationsprinzipien (Hash Tables, Lookup Trees,..) für verteilte Systeme mit dem Ziel, für S4 passende Einsatzszenarien zu identifizieren und zu beschreiben.
  • Entwurf, Implementierung und Analyse eines integrierten Evaluationswerkzeuges, mit dem S4 für verschiedene Konfigurationen und Datensets getestet werden kann. Wichtiger Punkt ist die Aufzeichnung von Testresultaten für nachgelagerte Untersuchungen.
  • Untersuchung und Umsetzung eines Verfahrens zur Vermeidung von Überlast auf den Netzwerkverbindungen zwischen den verschiedenen Knoten („Overpathing“) für S4.
  • Untersuchung, Erstellung und Implementierung von Heuristiken für die Einstellungen verschiedene Parameter des selbstorganisierenden Systems.
  • Untersuchung und Umsetzung eines Verfahrens zur Behandlung von Ausfällen und Wiedereingliederung einzelner Knoten des verteilten Systems.

Sollten Sie an einem dieser Themen Interesse haben, wenden Sie sich bitte an einen der unten genannten Betreuuer.

Wichtig: Wegen der begrenzten Projektlaufzeit können leider keine weiteren Master- oder Diplomarbeiten zu diesen Themen vergeben werden. Bacheloararbeiten müssen spätestens Ende August angemeldet werden.

Kenntnisse in Programmierung mit Java, Vorkenntnisse in Verteilten … [...Weiterlesen/more...]

Paper accepted at SAKS 2011

The paper „Towards Swarm-based Federated Web Knowledgebases“ by Philipp Obermeier, Anne Augustin and Robert Tolksdorf has been accepted at the Workshop on Self-Organising, Adaptive, Context-Sensitive Distributed Systems (SAKS). Its abstract is

Nowadays internet knowledgebases are more and more described using ontological vocabularies. However, efficient coherent solutions for both federated storage and reasoning upon widely distributed web repositories are rarely explored.
To this end we present a self-organized, distributed storage and reasoning approach based on swarm intelligence exploiting the strong applicability of swarm algorithms to distributed environments. Our concept comprises two layers of swarm algorithms – storage and reasoning layer – for information storage and inference of new statements, respectively. We present for the former our concepts with first evaluation results and give for the latter a general swarm-based concept for forward-chaining assertional reasoning in the description logic ALC.


DigiPolis project publication accepted at SSWS2010 workshop

The DigiPolis project at AG NBI is developing a Self-organized Semantic Storage Service („S4“). A research paper written by NBI staff members Hannes Mühleisen, Tilman Walther, Anne Augustin and Marko Harasic under the supervision of Prof. Robert Tolksdorf describing the impact of various configuration parameters on this system was just accepted for the The 6th International Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS2010) at the 9th International Semantic Web Conference (ISWC2010), Shanghai, China.
The publication is entitled „Configuring a Self-Organized Semantic Storage Service“, here the abstract:

Scalability requirements for semantic stores lead to distributed hardware-independent solutions to handle and analyze massive amounts of semantic data. We use a different approach by imitating the behaviour of swarm individuals to achieve this scalability. We have implemented our concept of a Self-organized Semantic Storage Service (S4) and present preliminary evaluation results in order to investigate to what extent the performance of a distributed and swarm-based storage system is dependent on its configuration.


NBI poster awarded at FIS 2010

The poster Robert Tolksdorf, Hannes Mühleisen, Kia Teymourian, Marko Harasic and Anne Augustin: Nature Inspired Self-Organizing Semantic Storage was selected as 2nd best poster at the Future Internet Symposium.… [...Weiterlesen/more...]

DigiPolis project publication accepted at iiWAS2010 conference

The DigiPolis project at AG NBI is developing a Self-organized Semantic Storage Service („S4“). A research paper written by NBI staff describing the swarm-based concepts behind this system was just accepted at the 12th International Conference on Information Integration and Web-based Applications & Services (iiWAS2010) in Paris, France.

The publication is titled „A Self-Organized Semantic Storage Service„, here just the abstract:

Traditional approaches for data storage and analysis are facing their limits when handling the enormous data amounts of today’s applications. We believe that a radical departure from contemporary architectures of stores is necessary to satisfy that central scalability requirement. One of the most promising new schools of thought in system design are swarm intelligent and swarm-based approaches for data distribution and organization. In this paper, we describe our current work on a swarm-based storage service for Semantic Web data. This storage service utilizes algorithms discovered in the behavior of ant colonies. We describe these algorithms and our enhancements to them as well as our evaluation of a prototypical implementation.

Ameisen beim Girls‘ Day 2010

Das Team des
DigiPolis Projekts der AG NBI hat beim Girls‘ Day 2010 zwei Workshops zum Thema
Was haben Ameisen mit Computern zu tun? angeboten.
Die Schülerinnen aus fünf Berliner Gymnasien zwischen 14 und 17 Jahren konnten nach einer Einführung in die Thematik der Schwarmintelligenz selbst herausfinden,
wie Informatiker aus einer Idee einen Algorithmus entwickeln.… [...Weiterlesen/more...]

AG Netzbasierte Informationssysteme,
Königin-Luise-Straße 24-26, 14195 Berlin, Tel.: +49-30-838-75221, Fax: +49-30-838-75220