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47
SPARQ2L: Towards Supporting Subgraph Extraction Queries
- in RDF Databases. Proceedings of the WWW Conference 2007, May 7-12, 2005
, 2007
"... Many applications in analytical domains often have the need to “connect the dots ” i.e., query about the structure of data. In bioinformatics for example, it is typical to want to query about interactions between proteins. The aim of such queries is to “extract ” relationships between entities i.e. ..."
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Cited by 44 (3 self)
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Many applications in analytical domains often have the need to “connect the dots ” i.e., query about the structure of data. In bioinformatics for example, it is typical to want to query about interactions between proteins. The aim of such queries is to “extract ” relationships between entities i.e. paths from a data graph. Often, such queries will specify certain constraints that qualifying results must satisfy e.g. paths involving a set of mandatory nodes. Unfortunately, most present day Semantic Web query languages including the current draft of the anticipated recommendation SPARQL, lack the ability to express queries about arbitrary path structures in data. In addition, many systems that support some limited form of path queries rely on main memory graph algorithms limiting their applicability to very large scale graphs. In this paper, we present an approach for supporting Path Extraction queries. Our proposal comprises (i) a query language SPARQ2L which extends SPARQL with path variables and path variable constraint expressions, and (ii) a novel query evaluation framework based on efficient algebraic techniques for solving path problems which allows for path queries to be efficiently evaluated on disk resident RDF graphs. The effectiveness of our proposal is demonstrated by a performance evaluation of our approach on both real world and synthetic datasets.
Querying Ontology Based Database Using OntoQL (an Ontology Query Language
- IN: PROCEEDINGS OF ONTOLOGIES, DATABASES, AND APPLICATIONS OF SEMANTICS (ODBASE 2006
, 2006
"... Nowadays, ontologies are used in several research domains by offering the means to describe and represent concepts of information sources. Therefore, several approaches and systems storing ontologies and their instances in the same repository (database) have been proposed. As a consequence, definin ..."
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Cited by 20 (12 self)
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Nowadays, ontologies are used in several research domains by offering the means to describe and represent concepts of information sources. Therefore, several approaches and systems storing ontologies and their instances in the same repository (database) have been proposed. As a consequence, defining a query language to support ontology-based database (OBDB) becomes a challenge for the database community. In this paper, we present OntoQL, an ontology query language for OBDBs. Firstly, we present formally the OBDB data model supported by this language. Secondly, an overview of the algebra defining the semantics of operators used in OntoQL is described. Several query examples showing the interest of this language compared to traditional database query languages are given along this paper. Finally, we present a prototype of the implementation of OntoQL.
Foundations of rule-based query answering
- IN REASONING WEB, INT. SUMMER SCHOOL, LNCS
, 2007
"... This survey article introduces into the essential concepts and methods underlying rule-based query languages. It covers four complementary areas: declarative semantics based on adaptations of mathematical logic, operational semantics, complexity and expressive power, and optimisation of query evalua ..."
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Cited by 19 (10 self)
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This survey article introduces into the essential concepts and methods underlying rule-based query languages. It covers four complementary areas: declarative semantics based on adaptations of mathematical logic, operational semantics, complexity and expressive power, and optimisation of query evaluation. The treatment of these areas is foundation-oriented, the foundations having resulted from over four decades of research in the logic programming and database communities on combinations of query languages and rules. These results have later formed the basis for conceiving, improving, and implementing several Web and Semantic Web technologies, in particular query languages such as XQuery or SPARQL for querying relational, XML, and RDF data, and rule languages like the “Rule Interchange Framework (RIF) ” currently being developed in a working group of the W3C. Coverage of the article is deliberately limited to declarative languages in a classical setting: issues such as query answering in F-Logic or in description logics, or the relationship of query answering to reactive rules and events, are not addressed.
RDF querying: Language constructs and evaluation methods compared
- IN: REASONING WEB, SECOND INTERNATIONAL SUMMER SCHOOL 2006. VOLUME 4126 OF LNCS.
, 2006
"... This article is firstly an introduction into query languages for the Semantic Web, secondly an in-depth comparison of the languages introduced. Only RDF query languages are considered because, as of the writing of this paper, query languages for other Semantic Web data modeling formalisms, especial ..."
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Cited by 16 (5 self)
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This article is firstly an introduction into query languages for the Semantic Web, secondly an in-depth comparison of the languages introduced. Only RDF query languages are considered because, as of the writing of this paper, query languages for other Semantic Web data modeling formalisms, especially OWL, are still an open research issue, and only a very small number of, furthermore incomplete, proposals for querying Semantic Web data modeled after other formalisms than RDF exist. The limitation to a few RDF query languages is motivated both by the objective of an in-depth comparison of the languages addressed and by space limitations. During the three years before the writing of this article, more than three dozen proposals for RDF query languages have been published! Not only such a large number, but also the often immature nature of the proposals makes the focus on few, but representative languages a necessary condition for a non-trivial comparison. For this article, the following RDF query languages have been, admittedly subjectively, selected: Firstly, the “relational” or “pattern-based” query languages SPARQL, RQL, TRIPLE, and Xcerpt; secondly the reactive rule query language Algae; thirdly and last the “navigational access ” query language Versa. Although subjective, this choice is arguably a good coverage of the diverse language paradigms considered for querying RDF data. It is the authors ’ hope and expectation, that this comparison will motivate and trigger further similar studies, thus
Twelve theses on reactive rules for the web
- In Proc. Int. Workshop Reactivity on the Web
, 2006
"... Abstract. Reactivity, the ability to detect and react to events, is an essential functionality in many information systems. In particular, Web systems such as online marketplaces, adaptive (e.g., recommender) systems, and Web services, react to events such as Web page updates or data posted to a ser ..."
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Cited by 16 (9 self)
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Abstract. Reactivity, the ability to detect and react to events, is an essential functionality in many information systems. In particular, Web systems such as online marketplaces, adaptive (e.g., recommender) systems, and Web services, react to events such as Web page updates or data posted to a server. This article investigates issues of relevance in designing high-level programming languages dedicated to reactivity on the Web. It presents twelve theses on features desirable for a language of reactive rules tuned to programming Web and Semantic Web applications. 1
Survey over Existing Query and Transformation Languages -- Revision 2.0
, 2006
"... A widely acknowledged obstacle for realizing the vision of the Semantic Web is the inability of many current Semantic Web approaches to cope with data available in such diverging representation formalisms as XML, RDF, or Topic Maps. A common query language is the first step to allow transparent acce ..."
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Cited by 12 (5 self)
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A widely acknowledged obstacle for realizing the vision of the Semantic Web is the inability of many current Semantic Web approaches to cope with data available in such diverging representation formalisms as XML, RDF, or Topic Maps. A common query language is the first step to allow transparent access to data in any of these formats. To further the understanding of the requirements and approaches proposed for query languages in the conventional as well as the Semantic Web, this report surveys a large number of query languages for accessing XML, RDF, or Topic Maps. This is the first systematic survey to consider query languages from all these areas. From the detailed survey of these query languages, a common classification scheme is derived that is useful for understanding and differentiating languages within and among all three areas. This revision of deliverable I4-D1 extends that deliverable by a refined version of the presented material that has been published as a chapter in the LNCS tutorial volume for the REWERSE “Reasoning Web ” 2005 summer school as well as short outlooks on further refinements of the material for upcoming tutorials
Reactive rules on the web
- In Reasoning Web, Int. Summer School
, 2007
"... Abstract. Reactive rules are used for programming rule-based, reactive systems, which have the ability to detect events and respond to them au-tomatically in a timely manner. Such systems are needed on the Web for bridging the gap between the existing, passive Web, where data sources can only be acc ..."
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Cited by 11 (8 self)
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Abstract. Reactive rules are used for programming rule-based, reactive systems, which have the ability to detect events and respond to them au-tomatically in a timely manner. Such systems are needed on the Web for bridging the gap between the existing, passive Web, where data sources can only be accessed to obtain information, and the dynamic Web, where data sources are enriched with reactive behavior. This paper presents two possible approaches to programming rule-based, reactive systems. They are based on different kinds of reactive rules, namely Event-Condition-Action rules and production rules. Concrete reactive languages of both kinds are used to exemplify these programming paradigms. Finally the similarities and differences between these two paradigms are studied. 1
Flavours of XChange, a Rule-Based Reactive Language for the (Semantic) Web
, 2005
"... This article introduces XChange, a rule-based reactive language for the (Semantic) Web. Stressing application scenarios, it first argues that high-level reactive languages are needed for both Web and Semantic Web applications. Then, it discusses technologies and paradigms relevant to high-level reac ..."
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Cited by 10 (7 self)
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This article introduces XChange, a rule-based reactive language for the (Semantic) Web. Stressing application scenarios, it first argues that high-level reactive languages are needed for both Web and Semantic Web applications. Then, it discusses technologies and paradigms relevant to high-level reactive languages for the (Semantic) Web.
Integrating XQuery and Logic Programming.
- In Proceedings of the 17th International Conference on Aplications of Declarative Programming and Knowledge Management, INAP’07 and 21th Workshop on (Constraint) Logic Programming, WLP’07,
, 2009
"... Abstract. In this paper we investigate how to integrate the XQuery language and logic programming. With this aim, we represent XML documents by means of a logic program. This logic program represents the document schema by means of rules and the document itself by means of facts. Now, XQuery expres ..."
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Cited by 7 (4 self)
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Abstract. In this paper we investigate how to integrate the XQuery language and logic programming. With this aim, we represent XML documents by means of a logic program. This logic program represents the document schema by means of rules and the document itself by means of facts. Now, XQuery expressions can be integrated into logic programming by considering a translation (i.e. encoding) of for-let-where-return expressions by means of logic rules and a goal.
Flavors of KWQL, a Keyword Query Language for a Semantic Wiki
, 2010
"... This article introduces KWQL, spoken “quickel”, a rulebased query language for a semantic wiki based on the label-keyword query paradigm. KWQL allows for rich combined queries of full text, document structure, and informal to formal semantic annotations. It offers support for continuous queries, t ..."
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Cited by 7 (2 self)
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This article introduces KWQL, spoken “quickel”, a rulebased query language for a semantic wiki based on the label-keyword query paradigm. KWQL allows for rich combined queries of full text, document structure, and informal to formal semantic annotations. It offers support for continuous queries, that is, queries re-evaluated upon updates to the wiki. KWQL is not restricted to data selection, but also offers database-like views, enabling “construction”, the re-shaping of the selected (meta-)data into new (meta-)data. Such views amount to rules that provide a convenient basis for an admittedly simple, yet remarkably powerful form of reasoning. KWQL queries range from simple lists of keywords or label-keyword pairs to conjunctions, disjunctions, or negations of queries. Thus, queries range from elementary and relatively unspecific to complex and fully specified (meta-)data selections. Consequently, in keeping with the “wiki way”, KWQL has a low entry barrier, allowing casual users to easily locate and retrieve relevant data, while letting advanced users make use of its full power.
