Web services and Grid computing are technologies with a great impact these days. Both technologie... more Web services and Grid computing are technologies with a great impact these days. Both technologies are taking a syntactical based approach to describe services, and therefore, limited support is provided for service related tasks like: discovery, composition, etc. Semantic Web services try to overcome the limitations of syntactical based approaches by adding semantics to services descriptions. One of the most salient initiatives in Semantic Web services area is the Web Service Modeling Ontology(WSMO). WSMO provides a conceptual model and languages to express semantic descriptions of services. We believe that WSMO, the conceptual model, and WSML, the associated family of languages, with some extensions and/or restrictions could be the solution for semantically describe services in Grid environment. In order support this statement, we provide a modeling example of a Grid service using WSMO/WSML.
... Stefan Decker, Michael Erdmann, Dieter Fensel and Rudi Studer University of Karlsruhe, Instit... more ... Stefan Decker, Michael Erdmann, Dieter Fensel and Rudi Studer University of Karlsruhe, Institute AIFB, D-76128 Karlsruhe, Germany ((decker, erdmann, fensel, studer)@aifb.uni-karlsruhe.de) http://www.aifb.uni-karlsruhe.de/WBS/broker Abstract. ...
Proceedings of the Sigchi Conference on Human Factors in Computing Systems, Apr 10, 2010
Abstract There have been many studies of computer based text reading. However, only a few have co... more Abstract There have been many studies of computer based text reading. However, only a few have considered text integrated with video and 3D graphics. This paper presents an investigation into the effects of varying (a) text drawing style (plain, billboard, Anti-Interference, shadow),(b) image polarity (positive and negative), and (c) background style (video and 3D) on text readability. Reading speed and accuracy were measured and subjective views of participants recorded.
Ever since computer networks have become popular libraries tend to join into federations. Each fe... more Ever since computer networks have become popular libraries tend to join into federations. Each federated digital library, apart from delivering discovery and navigation features within their own database allows users to search among other digital library systems. However the variety of users introduces various types of libraries and eventually types of federations of libraries. We present the current state of communication between digital libraries. We also present how Semantic Web technologies can help to overcome the problems with creating heterogeneous networks of digital libraries. We finally exemplify possible solutions with existing tools.
We present a system that improves on current documentcentric Web search engine technology; adopti... more We present a system that improves on current documentcentric Web search engine technology; adopting an entity-centric perspective, we are able to integrate data from both static and live sources into a coherent, interlinked information space. Users can then search and navigate the integrated information space through relationships, both existing and newly materialised, for improved knowledge discovery and understanding. 1
Proceedings of the 10th International Conference on World Wide Web, 2001
Recently, there has been a wide interest in using ontologies on the Web. As a basis for this, RDF... more Recently, there has been a wide interest in using ontologies on the Web. As a basis for this, RDF Schema (RDFS) provides means to define vocabulary, structure and constraints for expressing metadata about Web resources. However, formal semantics are not provided, and the expressivity of it is not enough for full-fledged ontological modeling and reasoning. In this paper, we will show how RDFS can be extended in such a way that a full knowledge representation (KR) language can be expressed in it, thus enriching it with the required additional expressivity and the semantics of this language. We do this by describing the ontology language OIL as an extension of RDFS. An important advantage of our approach is a maximal backward compatability with RDFS: any meta-data in OIL format can still be partially interpreted by any RDFS-only-processor. The OIL extension of RDFS has been carefully engineered so that such a partial interpretation of OIL meta-data is still correct under the intended semantics of RDFS: simply ignoring the OIL specific portions of an OIL document yields a correct RDF(S) document whose intended RDFS semantics is precisely a subset of the semantics of the full OIL statements. In this way, our approach ensures maximal sharing of meta-data on the Web: even partial interpretation of meta-data by less semantically aware processors will yield a correct partial interpretation of the metadata. We conclude that our method of extending is equally applicable to other KR formalisms.
Web Semantics Science Services and Agents on the World Wide Web, Nov 1, 2012
In this paper, we discuss the architecture and implementation of the Semantic Web Search Engine (... more In this paper, we discuss the architecture and implementation of the Semantic Web Search Engine (SWSE). Following traditional search engine architecture, SWSE consists of crawling, data enhancing, indexing and a user interface for search, browsing and retrieval of information; unlike traditional search engines, SWSE operates over RDF Web dataloosely also known as Linked Data -which implies unique challenges for the system design, architecture, algorithms, implementation and user interface. In particular, many challenges exist in adopting Semantic Web technologies for Web data: the unique challenges of the Web -in terms of scale, unreliability, inconsistency and noise -are largely overlooked by the current Semantic Web standards. Herein, we describe the current SWSE system, initially detailing the architecture and later elaborating upon the function, design, implementation and performance of each individual component. In so doing, we also give an insight into how current Semantic Web standards can be tailored, in a besteffort manner, for use on Web data. Throughout, we offer evaluation and complementary argumentation to support our design choices, and also offer discussion on future directions and open research questions. Later, we also provide candid discussion relating to the difficulties currently faced in bringing such a search engine into the mainstream, and lessons learnt from roughly six years working on the Semantic Web Search Engine project.
Proceedings of the Seventeenth National Conference on Artificial Intelligence and Twelfth Conference on Innovative Applications of Artificial Intelligence, 2000
Community web portals serve as portals for the information needs of particular communities on the... more Community web portals serve as portals for the information needs of particular communities on the web. We here discuss how a comprehensive, ontology-based approach for building and maintaining a high-value community web portal has been conceived and implemented. The ontology serves as a semantic backbone for accessing knowledge on the portal, for contributing information, as well as for developing and maintaining the portal. In particular, the ontology allows for flexible querying and inferencing of knowledge. Actual usage of our technology is facilitated through a set of tools that are about to turn our research system into a portal for wide-spread usage right now. The development of these tools has greatly benefited from some first experiences we had with actual users of the community web portal of the knowledge acquisition community.
Several query federation engines have been proposed for accessing public Linked Open Data sources... more Several query federation engines have been proposed for accessing public Linked Open Data sources. However, in many domains, resources are sensitive and access to these resources is tightly controlled by stakeholders; consequently, privacy is a major concern when federating queries over such datasets. In this paper, we present SAFE, a SPARQL query federation engine that enables decentralised, policy-aware access to clinical information represented as RDF data cubes. We validate the performance of the system with experiments over real-world datasets provided by three clinical organisations as well as legacy Linked Datasets. In our evaluation, we show that SAFE enables granular graph-level access control over distributed clinical RDF data cubes and efficiently reduces the query execution time when compared with general-purpose SPARQL query federation engine. 1
With cloud computing as an infrastructure model maturing, more and more efforts around cloud-base... more With cloud computing as an infrastructure model maturing, more and more efforts around cloud-based software development are emerging. In this model, a cloud-based environment enables developers to edit, test and deploy Web applications through a Web browser. We consider this tool stack to be disruptive in its nature, changing the way software development is being carried out and opening up new opportunities for service providers as well as (teams of) developers. In this report, we review the state of the art of cloud-based software development environments, analyse their shortcomings and provide a roadmap for the next generation of cloud-based development tools.
Web search engines are immensly useful for locating documents online. However, with more and more... more Web search engines are immensly useful for locating documents online. However, with more and more structured data being published online, the restriction to the hyperdocument model impairs the usefulness for searching and browsing. In contrast, an object-orientated model provides means to firstly integrate data about the same object from multiple sources, and secondly enable expressive queries over the integrated information space. We present SWSE, a search engine over 1.1 billion statements published on the Semantic Web. The system provides an easy-to-use end-user interface through which users can find and navigate an object-orientated information space. In addtion, the system exposes the data via a full SPARQL REST service which is open for application developers to query and integrate data in own applications.
With respect to large-scale, static, Linked Data corpora, in this paper we discuss scalable and d... more With respect to large-scale, static, Linked Data corpora, in this paper we discuss scalable and distributed methods for: (i) entity consolidation-identifying entities which signify the same referent, aka. smushing, entity resolution, object consolidation, etc.using explicit owl:sameAs relations; (ii) extended entity consolidation based on a subset of OWL 2 RL/RDF rules-particularly over inverse-functional properties, functional-properties and (max-)cardinality restrictions with value one; (iii) deriving weighted concurrence measures between entities in the corpus based on shared inlinks/outlinks and attribute values using statistical analyses; (iv) disambiguating (initially) consolidated entities based on inconsistency detection using OWL 2 RL/RDF rules. Our methods are based upon distributed sorts and scans of the corpus, where we purposefully avoid the requirement for indexing all data. Throughout, we offer evaluation over a diverse Linked Data corpus consisting of 1.118 billion quadruples derived from a domain-agnostic, open crawl of 3.985 million RDF/XML Web documents, demonstrating the feasibility of our methods at that scale, and giving insights into the fecundity of the approach and the quality of the results.
Fair use policy allows legal owners to share products they bought with their acquaintance; it is ... more Fair use policy allows legal owners to share products they bought with their acquaintance; it is based on the assumptions that the owners pass an original product and they cannot use it at the same time.
Web services and Grid computing are technologies with a great impact these days. Both technologie... more Web services and Grid computing are technologies with a great impact these days. Both technologies are taking a syntactical based approach to describe services, and therefore, limited support is provided for service related tasks like: discovery, composition, etc. Semantic Web services try to overcome the limitations of syntactical based approaches by adding semantics to services descriptions. One of the most salient initiatives in Semantic Web services area is the Web Service Modeling Ontology(WSMO). WSMO provides a conceptual model and languages to express semantic descriptions of services. We believe that WSMO, the conceptual model, and WSML, the associated family of languages, with some extensions and/or restrictions could be the solution for semantically describe services in Grid environment. In order support this statement, we provide a modeling example of a Grid service using WSMO/WSML.
... Stefan Decker, Michael Erdmann, Dieter Fensel and Rudi Studer University of Karlsruhe, Instit... more ... Stefan Decker, Michael Erdmann, Dieter Fensel and Rudi Studer University of Karlsruhe, Institute AIFB, D-76128 Karlsruhe, Germany ((decker, erdmann, fensel, studer)@aifb.uni-karlsruhe.de) http://www.aifb.uni-karlsruhe.de/WBS/broker Abstract. ...
Proceedings of the Sigchi Conference on Human Factors in Computing Systems, Apr 10, 2010
Abstract There have been many studies of computer based text reading. However, only a few have co... more Abstract There have been many studies of computer based text reading. However, only a few have considered text integrated with video and 3D graphics. This paper presents an investigation into the effects of varying (a) text drawing style (plain, billboard, Anti-Interference, shadow),(b) image polarity (positive and negative), and (c) background style (video and 3D) on text readability. Reading speed and accuracy were measured and subjective views of participants recorded.
Ever since computer networks have become popular libraries tend to join into federations. Each fe... more Ever since computer networks have become popular libraries tend to join into federations. Each federated digital library, apart from delivering discovery and navigation features within their own database allows users to search among other digital library systems. However the variety of users introduces various types of libraries and eventually types of federations of libraries. We present the current state of communication between digital libraries. We also present how Semantic Web technologies can help to overcome the problems with creating heterogeneous networks of digital libraries. We finally exemplify possible solutions with existing tools.
We present a system that improves on current documentcentric Web search engine technology; adopti... more We present a system that improves on current documentcentric Web search engine technology; adopting an entity-centric perspective, we are able to integrate data from both static and live sources into a coherent, interlinked information space. Users can then search and navigate the integrated information space through relationships, both existing and newly materialised, for improved knowledge discovery and understanding. 1
Proceedings of the 10th International Conference on World Wide Web, 2001
Recently, there has been a wide interest in using ontologies on the Web. As a basis for this, RDF... more Recently, there has been a wide interest in using ontologies on the Web. As a basis for this, RDF Schema (RDFS) provides means to define vocabulary, structure and constraints for expressing metadata about Web resources. However, formal semantics are not provided, and the expressivity of it is not enough for full-fledged ontological modeling and reasoning. In this paper, we will show how RDFS can be extended in such a way that a full knowledge representation (KR) language can be expressed in it, thus enriching it with the required additional expressivity and the semantics of this language. We do this by describing the ontology language OIL as an extension of RDFS. An important advantage of our approach is a maximal backward compatability with RDFS: any meta-data in OIL format can still be partially interpreted by any RDFS-only-processor. The OIL extension of RDFS has been carefully engineered so that such a partial interpretation of OIL meta-data is still correct under the intended semantics of RDFS: simply ignoring the OIL specific portions of an OIL document yields a correct RDF(S) document whose intended RDFS semantics is precisely a subset of the semantics of the full OIL statements. In this way, our approach ensures maximal sharing of meta-data on the Web: even partial interpretation of meta-data by less semantically aware processors will yield a correct partial interpretation of the metadata. We conclude that our method of extending is equally applicable to other KR formalisms.
Web Semantics Science Services and Agents on the World Wide Web, Nov 1, 2012
In this paper, we discuss the architecture and implementation of the Semantic Web Search Engine (... more In this paper, we discuss the architecture and implementation of the Semantic Web Search Engine (SWSE). Following traditional search engine architecture, SWSE consists of crawling, data enhancing, indexing and a user interface for search, browsing and retrieval of information; unlike traditional search engines, SWSE operates over RDF Web dataloosely also known as Linked Data -which implies unique challenges for the system design, architecture, algorithms, implementation and user interface. In particular, many challenges exist in adopting Semantic Web technologies for Web data: the unique challenges of the Web -in terms of scale, unreliability, inconsistency and noise -are largely overlooked by the current Semantic Web standards. Herein, we describe the current SWSE system, initially detailing the architecture and later elaborating upon the function, design, implementation and performance of each individual component. In so doing, we also give an insight into how current Semantic Web standards can be tailored, in a besteffort manner, for use on Web data. Throughout, we offer evaluation and complementary argumentation to support our design choices, and also offer discussion on future directions and open research questions. Later, we also provide candid discussion relating to the difficulties currently faced in bringing such a search engine into the mainstream, and lessons learnt from roughly six years working on the Semantic Web Search Engine project.
Proceedings of the Seventeenth National Conference on Artificial Intelligence and Twelfth Conference on Innovative Applications of Artificial Intelligence, 2000
Community web portals serve as portals for the information needs of particular communities on the... more Community web portals serve as portals for the information needs of particular communities on the web. We here discuss how a comprehensive, ontology-based approach for building and maintaining a high-value community web portal has been conceived and implemented. The ontology serves as a semantic backbone for accessing knowledge on the portal, for contributing information, as well as for developing and maintaining the portal. In particular, the ontology allows for flexible querying and inferencing of knowledge. Actual usage of our technology is facilitated through a set of tools that are about to turn our research system into a portal for wide-spread usage right now. The development of these tools has greatly benefited from some first experiences we had with actual users of the community web portal of the knowledge acquisition community.
Several query federation engines have been proposed for accessing public Linked Open Data sources... more Several query federation engines have been proposed for accessing public Linked Open Data sources. However, in many domains, resources are sensitive and access to these resources is tightly controlled by stakeholders; consequently, privacy is a major concern when federating queries over such datasets. In this paper, we present SAFE, a SPARQL query federation engine that enables decentralised, policy-aware access to clinical information represented as RDF data cubes. We validate the performance of the system with experiments over real-world datasets provided by three clinical organisations as well as legacy Linked Datasets. In our evaluation, we show that SAFE enables granular graph-level access control over distributed clinical RDF data cubes and efficiently reduces the query execution time when compared with general-purpose SPARQL query federation engine. 1
With cloud computing as an infrastructure model maturing, more and more efforts around cloud-base... more With cloud computing as an infrastructure model maturing, more and more efforts around cloud-based software development are emerging. In this model, a cloud-based environment enables developers to edit, test and deploy Web applications through a Web browser. We consider this tool stack to be disruptive in its nature, changing the way software development is being carried out and opening up new opportunities for service providers as well as (teams of) developers. In this report, we review the state of the art of cloud-based software development environments, analyse their shortcomings and provide a roadmap for the next generation of cloud-based development tools.
Web search engines are immensly useful for locating documents online. However, with more and more... more Web search engines are immensly useful for locating documents online. However, with more and more structured data being published online, the restriction to the hyperdocument model impairs the usefulness for searching and browsing. In contrast, an object-orientated model provides means to firstly integrate data about the same object from multiple sources, and secondly enable expressive queries over the integrated information space. We present SWSE, a search engine over 1.1 billion statements published on the Semantic Web. The system provides an easy-to-use end-user interface through which users can find and navigate an object-orientated information space. In addtion, the system exposes the data via a full SPARQL REST service which is open for application developers to query and integrate data in own applications.
With respect to large-scale, static, Linked Data corpora, in this paper we discuss scalable and d... more With respect to large-scale, static, Linked Data corpora, in this paper we discuss scalable and distributed methods for: (i) entity consolidation-identifying entities which signify the same referent, aka. smushing, entity resolution, object consolidation, etc.using explicit owl:sameAs relations; (ii) extended entity consolidation based on a subset of OWL 2 RL/RDF rules-particularly over inverse-functional properties, functional-properties and (max-)cardinality restrictions with value one; (iii) deriving weighted concurrence measures between entities in the corpus based on shared inlinks/outlinks and attribute values using statistical analyses; (iv) disambiguating (initially) consolidated entities based on inconsistency detection using OWL 2 RL/RDF rules. Our methods are based upon distributed sorts and scans of the corpus, where we purposefully avoid the requirement for indexing all data. Throughout, we offer evaluation over a diverse Linked Data corpus consisting of 1.118 billion quadruples derived from a domain-agnostic, open crawl of 3.985 million RDF/XML Web documents, demonstrating the feasibility of our methods at that scale, and giving insights into the fecundity of the approach and the quality of the results.
Fair use policy allows legal owners to share products they bought with their acquaintance; it is ... more Fair use policy allows legal owners to share products they bought with their acquaintance; it is based on the assumptions that the owners pass an original product and they cannot use it at the same time.
Uploads
Papers by Stefan Decker