Efficient evaluation of XML Query Languages has become a crucial issue for XML exchanges and inte... more Efficient evaluation of XML Query Languages has become a crucial issue for XML exchanges and integration. Tree Pattern (Sihem et al., 2002; Jagadish et al., 2001; Chen et al., 2003) are now well admitted for representing XML Queries and a model -called TGV (Travers, 2006; Travers et al., 2006; Travers et al., 2007c)has extended the Tree Pattern representation in order to make it more intuitive, respect full XQuery specification and got support to be manipulated, optimized and then evaluated. For optimization, a search strategy is needed. It consists in generating equivalent execution plan using extensible rules and estimate cost of plan to find the better one. We propose the specification of extensible rules that can be used in heterogeneous environment, supporting XML and manipulating Tree Patterns.
RESUME : La programmation de jeux vidéo est une motivation souvent donnée par les étudiants désir... more RESUME : La programmation de jeux vidéo est une motivation souvent donnée par les étudiants désireux de suivre une formation en sciences informatiques. Or implémenter un jeu vidéo est complexe et fait appel à beaucoup de notions dont la plus visible est l'Interface Homme-Machine (IHM). Cette dernière fait souvent obstacle à la proposition d'un sujet de projet portant sur le jeu vidéo. Pourtant, les jeux vidéo font appel aux notions fondamentales (algorithmiques, bases de données, réseaux, intelligence artificielle, etc.) des sciences informatiques. Nous montrons dans cet article que la plupart des jeux vidéo peuvent néanmoins être implémentés avec une IHM minimale qui pourra ensuite être étendue suivant la motivation des étudiants. Dans cet article, nous avons catégorisé les jeux existants suivant leur genre et les avons classés en fonction des compétences visées tout au long de la formation informatique à l'université de Cergy-Pontoise. Nous montrons comment nous avons mise en place des solutions pour encadrer les étudiants dans leur réalisation de projets de jeux vidéo. Les résultats sur 14 ans d'enseignements en projets de jeux vidéo montrent l'efficacité de cette approche dans l'apprentissage des sciences informatiques. Mots clés : jeux vidéo, apprentissage des sciences informatiques, apprentissage par projet 1
This paper proposes a generic cost framework for query optimization in an XML-based mediation sys... more This paper proposes a generic cost framework for query optimization in an XML-based mediation system called XLive, which integrates distributed, heterogeneous and autonomous data sources. Our approach relies on cost annotation on an XQuery logical representation called Tree Graph View (TGV). A generic cost communication language is used to give an XML-based uniform format for cost communication within the XLive
XQuery is a powerful language defined by the W3C to query XML documents. Its query functionalitie... more XQuery is a powerful language defined by the W3C to query XML documents. Its query functionalities and its expressiveness satisfy the major needs of both the database community and the text and documents community. As an inconvenient, the grammar used to define XQuery is thus very complex and leads to several equivalent query expressions for one same query. This complexity often discourages XQuery-based software developers and designers and leads to incomplete XQuery handling. Works have been done in [DPX04] and especially in [Che04] to reduce equivalent forms of XQuery expressions into identified "canonical forms". However, these works do not cover the whole XQuery specification. We propose in this paper to extend these works in order to canonize the whole untyped XQuery specification.
Several federated database systems have been built in the past using the relational or the object... more Several federated database systems have been built in the past using the relational or the object model as federating model. This paper gives an overview of the XMLMedia system, a federated database system mediator using XML as federating model, built in the Esprit Project MIRO-Web. The system is composed of four main components: a wrapper generator using rule-based scripting to produce XML data from various source formats, a mediator querying and integrating relational and XML sources, an XML DBMS extender supporting XML on top of relational DBMSs, and client tools including a Java API and an XML query browser. The results demonstrate the ability of XML with an associated query language (we use XML-QL) to federate various data sources on the Internet or on Intranets.
ABSTRACT XML has emerged as the leading language for representing and exchanging data not only on... more ABSTRACT XML has emerged as the leading language for representing and exchanging data not only on the Web, but also in general in the enterprise. XQuery is emerging as the standard query language for XML. Thus, tools are required to mediate between XML queries and heterogeneous data sources to integrate data in XML. This paper presents the XMedia mediator, a unique tool for integrating and querying disparate heterogeneous information as unified XML views. It describes the mediator architecture and focuses on the unique distributed query processing technology implemented in this component. Query evaluation is based on an original XML algebra simply extending classical operators to process tuples of tree elements. Further, we present a set of performance evaluation on a relational benchmark, which leads to discuss possible performance enhancements.
Providing services by integrating information available in web resources is one of the main goals... more Providing services by integrating information available in web resources is one of the main goals of a mediation architecture. In this paper, we consider the standard wrapper-mediator architecture under the following hypothesis: (i) the information exchanged between wrappers and the mediator consists in XML documents, (ii) wrappers have limited resources, and (iii) to answer queries even if sources are not available, materialized XML views are stored at the mediator level. In this setting, we focus on the problem of maintaining materialized XML views, when the sources change. In our context, wrappers send the updated document without providing any information about the type and the localization of the update in the document. Then, the problems we address are, first, identifying the updates, and, second, updating the view in such a way that accesses to the sources are restricted. Our approach is based on the XAlgebra, which allows to consider XQuery requests on XML documents as relational tables. Moreover, our solution uses identifier annotations for XAlgebra and a diff function.
XML has emerged as the leading language for representing and exchanging data not only on the Web,... more XML has emerged as the leading language for representing and exchanging data not only on the Web, but also in general in the enterprise. XQuery is emerging as the standard query language for XML. Thus, tools are required to mediate between XML queries and heterogeneous data sources to integrate data in XML. This paper presents the XMedia mediator, a unique tool for integrating and querying disparate heterogeneous information as unified XML views. It describes the mediator architecture and focuses on the unique distributed query processing technology implemented in this component. Query evaluation is based on an original XML algebra simply extending classical operators to process tuples of tree elements. Further, we present a set of performance evaluation on a relational benchmark, which leads to discuss possible performance enhancements.
XQuery is the emerging standard for querying XML data sources. XLive is a light XML/XQuery mediat... more XQuery is the emerging standard for querying XML data sources. XLive is a light XML/XQuery mediator developed at University of Versailles whose engine processes an XML algebra derived from the relational one extended to process in dataflow XML trees. The query optimizer translates a subset of XQuery in this algebra. To extend the optimizer's coverage of XQuery and better optimize
The MIROWeb Esprit project has developed aunique technology to integrate multiple datasources thr... more The MIROWeb Esprit project has developed aunique technology to integrate multiple datasources through an object-relational model withsemistructured data types. It addresses theproblem of integrating irregular Web sourcesand regular relational databases through amediated architecture based on a hybrid model, supporting relational, object and semistructuredfeatures. The project data exchange format isXML, the new standard of the Web, and the pivotlanguage is XMLQL, a query language based onXML templates from ...
Efficient evaluation of XML Query Languages has become a crucial issue for XML exchanges and inte... more Efficient evaluation of XML Query Languages has become a crucial issue for XML exchanges and integration. Tree Pattern (Sihem et al., 2002; Jagadish et al., 2001; Chen et al., 2003) are now well admitted for representing XML Queries and a model -called TGV (Travers, 2006; Travers et al., 2006; Travers et al., 2007c)has extended the Tree Pattern representation in order to make it more intuitive, respect full XQuery specification and got support to be manipulated, optimized and then evaluated. For optimization, a search strategy is needed. It consists in generating equivalent execution plan using extensible rules and estimate cost of plan to find the better one. We propose the specification of extensible rules that can be used in heterogeneous environment, supporting XML and manipulating Tree Patterns.
RESUME : La programmation de jeux vidéo est une motivation souvent donnée par les étudiants désir... more RESUME : La programmation de jeux vidéo est une motivation souvent donnée par les étudiants désireux de suivre une formation en sciences informatiques. Or implémenter un jeu vidéo est complexe et fait appel à beaucoup de notions dont la plus visible est l'Interface Homme-Machine (IHM). Cette dernière fait souvent obstacle à la proposition d'un sujet de projet portant sur le jeu vidéo. Pourtant, les jeux vidéo font appel aux notions fondamentales (algorithmiques, bases de données, réseaux, intelligence artificielle, etc.) des sciences informatiques. Nous montrons dans cet article que la plupart des jeux vidéo peuvent néanmoins être implémentés avec une IHM minimale qui pourra ensuite être étendue suivant la motivation des étudiants. Dans cet article, nous avons catégorisé les jeux existants suivant leur genre et les avons classés en fonction des compétences visées tout au long de la formation informatique à l'université de Cergy-Pontoise. Nous montrons comment nous avons mise en place des solutions pour encadrer les étudiants dans leur réalisation de projets de jeux vidéo. Les résultats sur 14 ans d'enseignements en projets de jeux vidéo montrent l'efficacité de cette approche dans l'apprentissage des sciences informatiques. Mots clés : jeux vidéo, apprentissage des sciences informatiques, apprentissage par projet 1
This paper proposes a generic cost framework for query optimization in an XML-based mediation sys... more This paper proposes a generic cost framework for query optimization in an XML-based mediation system called XLive, which integrates distributed, heterogeneous and autonomous data sources. Our approach relies on cost annotation on an XQuery logical representation called Tree Graph View (TGV). A generic cost communication language is used to give an XML-based uniform format for cost communication within the XLive
XQuery is a powerful language defined by the W3C to query XML documents. Its query functionalitie... more XQuery is a powerful language defined by the W3C to query XML documents. Its query functionalities and its expressiveness satisfy the major needs of both the database community and the text and documents community. As an inconvenient, the grammar used to define XQuery is thus very complex and leads to several equivalent query expressions for one same query. This complexity often discourages XQuery-based software developers and designers and leads to incomplete XQuery handling. Works have been done in [DPX04] and especially in [Che04] to reduce equivalent forms of XQuery expressions into identified "canonical forms". However, these works do not cover the whole XQuery specification. We propose in this paper to extend these works in order to canonize the whole untyped XQuery specification.
Several federated database systems have been built in the past using the relational or the object... more Several federated database systems have been built in the past using the relational or the object model as federating model. This paper gives an overview of the XMLMedia system, a federated database system mediator using XML as federating model, built in the Esprit Project MIRO-Web. The system is composed of four main components: a wrapper generator using rule-based scripting to produce XML data from various source formats, a mediator querying and integrating relational and XML sources, an XML DBMS extender supporting XML on top of relational DBMSs, and client tools including a Java API and an XML query browser. The results demonstrate the ability of XML with an associated query language (we use XML-QL) to federate various data sources on the Internet or on Intranets.
ABSTRACT XML has emerged as the leading language for representing and exchanging data not only on... more ABSTRACT XML has emerged as the leading language for representing and exchanging data not only on the Web, but also in general in the enterprise. XQuery is emerging as the standard query language for XML. Thus, tools are required to mediate between XML queries and heterogeneous data sources to integrate data in XML. This paper presents the XMedia mediator, a unique tool for integrating and querying disparate heterogeneous information as unified XML views. It describes the mediator architecture and focuses on the unique distributed query processing technology implemented in this component. Query evaluation is based on an original XML algebra simply extending classical operators to process tuples of tree elements. Further, we present a set of performance evaluation on a relational benchmark, which leads to discuss possible performance enhancements.
Providing services by integrating information available in web resources is one of the main goals... more Providing services by integrating information available in web resources is one of the main goals of a mediation architecture. In this paper, we consider the standard wrapper-mediator architecture under the following hypothesis: (i) the information exchanged between wrappers and the mediator consists in XML documents, (ii) wrappers have limited resources, and (iii) to answer queries even if sources are not available, materialized XML views are stored at the mediator level. In this setting, we focus on the problem of maintaining materialized XML views, when the sources change. In our context, wrappers send the updated document without providing any information about the type and the localization of the update in the document. Then, the problems we address are, first, identifying the updates, and, second, updating the view in such a way that accesses to the sources are restricted. Our approach is based on the XAlgebra, which allows to consider XQuery requests on XML documents as relational tables. Moreover, our solution uses identifier annotations for XAlgebra and a diff function.
XML has emerged as the leading language for representing and exchanging data not only on the Web,... more XML has emerged as the leading language for representing and exchanging data not only on the Web, but also in general in the enterprise. XQuery is emerging as the standard query language for XML. Thus, tools are required to mediate between XML queries and heterogeneous data sources to integrate data in XML. This paper presents the XMedia mediator, a unique tool for integrating and querying disparate heterogeneous information as unified XML views. It describes the mediator architecture and focuses on the unique distributed query processing technology implemented in this component. Query evaluation is based on an original XML algebra simply extending classical operators to process tuples of tree elements. Further, we present a set of performance evaluation on a relational benchmark, which leads to discuss possible performance enhancements.
XQuery is the emerging standard for querying XML data sources. XLive is a light XML/XQuery mediat... more XQuery is the emerging standard for querying XML data sources. XLive is a light XML/XQuery mediator developed at University of Versailles whose engine processes an XML algebra derived from the relational one extended to process in dataflow XML trees. The query optimizer translates a subset of XQuery in this algebra. To extend the optimizer's coverage of XQuery and better optimize
The MIROWeb Esprit project has developed aunique technology to integrate multiple datasources thr... more The MIROWeb Esprit project has developed aunique technology to integrate multiple datasources through an object-relational model withsemistructured data types. It addresses theproblem of integrating irregular Web sourcesand regular relational databases through amediated architecture based on a hybrid model, supporting relational, object and semistructuredfeatures. The project data exchange format isXML, the new standard of the Web, and the pivotlanguage is XMLQL, a query language based onXML templates from ...
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