remote sources at runtime. We thus propose a hybrid query approach that improves upon both paradigms, offering fresher results from a broader range of sources than Linked Data caches while offering faster results than live querying. Our hybrid query engine takes a cached and live query engine as black

changes of original data are not immediately reflected on ma-terialized data. The second approach provides accurate responses but it is notorious for long response times. A hybrid SPARQL query processor provides a middle ground between two specified extremes by splitting triple patterns of the SPARQL

and backchase

Hiermit versichere ich, die vorliegende Diplomarbeit selbstständig und unter ausschliesslicher Verwendung der angegebenen Quellen und Hilfsmittel angefertigt zu haben. Diese Arbeit hat in gleicher oder ähnlicher Form noch keiner Prüfungsbehörde vorgelegen. Darmstadt, 14. Februar 2006

of scalability and maintainability. Hence, different approaches are based on Peer-to-Peer (P2P) technology. In particular, fast-paced NVEs stress these systems and most likely cause high overlay maintenance overhead. This Master’s Thesis presents a novel approach to spatial Publish/Subscribe (Pub/Sub) in P2P

constraint satisfaction. Meta-data elicitation involves a large group of experts working simul-taneously, while global constraint satisfaction involves a smaller group that uses the meta-data to form sessions. We evaluated Frenzy with 48 people during a deployment at the CSCW 2014 program committee meeting

Abstract-In the recent years, with the acquaintance of internet, there has been large amount of data resides on the web. Therefore it becomes necessity for fast retrieval search engines that retrieve documents and images.This paper tries to provide a comprehensive review and characterize

constraint satisfaction. Meta-data elicitation involves a large group of experts working simul-taneously, while global constraint satisfaction involves a smaller group that uses the meta-data to form sessions. We evaluated Frenzy with 48 people during a deployment at the CSCW 2014 program committee meeting

ii iv vTo my parents vi vii Acknowledgements I would first and foremost extend my whole-hearted gratitude to my advisors, An-drea Arpaci-Dusseau and Remzi Arpaci-Dusseau. Andrea and Remzi are the reason that I had the opportunity for this exceptional Ph.D. journey. To this day, I still re-member the moment when they took me as their student and the joy and hope in my heart. Andrea and Remzi have showed me what systems research is like and how much fun and challenging it can be. Before this journey with them, I had always liked and believed in the beauty of mathematics and theory. My initial interest in systems research happened when I took Remzi’s Advanced Operating Systems

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