State-of-the-art on evolution and reactivity

This report starts by, in Chapter 1, outlining aspects of querying and updating resources on the Web and on the Semantic Web, including the development of query and update languages to be carried out within the Rewerse project. From this outline, it becomes clear that several existing research areas and topics are of interest for this work in Rewerse. In the remainder of this report we further present state of the art surveys in a selection of such areas and topics. More precisely: in Chapter 2 we give an overview of logics for reasoning about state change and updates; Chapter 3 is devoted to briefly describing existing update languages for the Web, and also for updating logic programs; in Chapter 4 event-condition-action rules, both in the context of active database systems and in the context of semistructured data, are surveyed; in Chapter 5 we give an overview of some relevant rule-based agents frameworks

Lazy Services: A Service Oriented Architecture based on Incremental Computations and Commitments

A service oriented architecture (SOA) aims to structure complex distributed systems in terms of re-usable components, called services. To guarantee a good service interoperability these services must be weakly coupled and their description must be separated from their implementations. The interface of a service provides information on how it can be invoked: the logical location where it can be invoked, the supported communication protocol and the types of its input (parameters) and output (result). Traditionally, a service can only be invoked when its parameters are fully defined and, symmetrically, these services only return their results after they have been totally processed. In this paper, we promote a more liberal view of services by allowing them to consume their data lazily (i.e., as they need it) and produce their results incrementally (i.e., as they are produced). We develop this notion as 'lazy services' by building up from the model of guarded attributed grammars that was recently introduced in the context of distributed collaborative systems. We abstract from this model and limit somewhat its expressiveness so that it can comply more broadly to SOA principles. We introduce an improvement on subscription management to optimize the distributed implementation of lazy services

State-of-the-art on evolution and reactivity

This report starts by, in Chapter 1, outlining aspects of querying and updating resources on the Web and on the Semantic Web, including the development of query and update languages to be carried out within the Rewerse project. From this outline, it becomes clear that several existing research areas and topics are of interest for this work in Rewerse. In the remainder of this report we further present state of the art surveys in a selection of such areas and topics. More precisely: in Chapter 2 we give an overview of logics for reasoning about state change and updates; Chapter 3 is devoted to briefly describing existing update languages for the Web, and also for updating logic programs; in Chapter 4 event-condition-action rules, both in the context of active database systems and in the context of semistructured data, are surveyed; in Chapter 5 we give an overview of some relevant rule-based agents frameworks

Gestion des données distribuées avec le langage de règles Webdamlog

Notre but est de permettre à un utilisateur du Web d organiser la gestionde ses données distribuées en place, c est à dire sans l obliger à centraliserses données chez un unique hôte. Par conséquent, notre système diffèrede Facebook et des autres systèmes centralisés, et propose une alternativepermettant aux utilisateurs de lancer leurs propres pairs sur leurs machinesgérant localement leurs données personnelles et collaborant éventuellementavec des services Web externes.Dans ma thèse, je présente Webdamlog, un langage dérivé de datalogpour la gestion de données et de connaissances distribuées. Le langage étenddatalog de plusieurs manières, principalement avec une nouvelle propriété ladélégation, autorisant les pairs à échanger non seulement des faits (les données)mais aussi des règles (la connaissance). J ai ensuite mené une étude utilisateurpour démontrer l utilisation du langage. Enfin je décris le moteur d évaluationde Webdamlog qui étend un moteur d évaluation de datalog distribué nomméBud, en ajoutant le support de la délégation et d autres innovations tellesque la possibilité d avoir des variables pour les noms de pairs et des relations.J aborde de nouvelles techniques d optimisation, notamment basées sur laprovenance des faits et des règles. Je présente des expérimentations quidémontrent que le coût du support des nouvelles propriétés de Webdamlogreste raisonnable même pour de gros volumes de données. Finalement, jeprésente l implémentation d un pair Webdamlog qui fournit l environnementpour le moteur. En particulier, certains adaptateurs permettant aux pairsWebdamlog d échanger des données avec d autres pairs sur Internet. Pourillustrer l utilisation de ces pairs, j ai implémenté une application de partagede photos dans un réseau social en Webdamlog.Our goal is to enable aWeb user to easily specify distributed data managementtasks in place, i.e. without centralizing the data to a single provider. Oursystem is therefore not a replacement for Facebook, or any centralized system,but an alternative that allows users to launch their own peers on their machinesprocessing their own local personal data, and possibly collaborating with Webservices.We introduce Webdamlog, a datalog-style language for managing distributeddata and knowledge. The language extends datalog in a numberof ways, notably with a novel feature, namely delegation, allowing peersto exchange not only facts but also rules. We present a user study thatdemonstrates the usability of the language. We describe a Webdamlog enginethat extends a distributed datalog engine, namely Bud, with the supportof delegation and of a number of other novelties of Webdamlog such as thepossibility to have variables denoting peers or relations. We mention noveloptimization techniques, notably one based on the provenance of facts andrules. We exhibit experiments that demonstrate that the rich features ofWebdamlog can be supported at reasonable cost and that the engine scales tolarge volumes of data. Finally, we discuss the implementation of a Webdamlogpeer system that provides an environment for the engine. In particular, a peersupports wrappers to exchange Webdamlog data with non-Webdamlog peers.We illustrate these peers by presenting a picture management applicationthat we used for demonstration purposes.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Context-free games on strings and nested words

Kontextfreie Spiele sind ein formales Modell, welches in seiner einfachsten Form den Ableitungsmechanismus kontextfreier Grammatiken zu einem Spiel für zwei Spieler (genannt Juliet und Romeo) verallgemeinert; dabei wählt in einer gegebenen Satzform (d.h. einer Zeichenkette aus Terminal- und Nichtterminalsymbolen) jeweils Juliet ein zu ersetzendes Nichtterminalsymbol aus, worauf Romeo jeweils entsprechend den Ableitungsregeln entscheidet, wodurch dieses Nichtterminalsymbol ersetzt werden soll. Die Gewinnbedingung für Juliet in einem solchen Spiel ist das Erreichen einer Satzform aus einer gegebenen Zielsprache, wohingegen Romeo die Aufgabe hat, dies zu verhindern. Das zentrale algorithmische Problem in kontextfreien Spielen stellt die Frage, gegeben ein Spiel und eine initiale Satzform, ob Juliet in dem gegebenen Spiel auf der Satzform eine Gewinnstrategie hat. Die zentrale praktische Anwendung kontextfreier Spiele liegt in der Modellierung von Active XML-Dokumenten, d.h. XML-Dokumenten, die Referenzen auf externe Quellen enthalten, welche zur Laufzeit aufgerufen werden können um aktuelle Daten in das Dokument einzufügen. Vor diesem Hintergrund ist es sinnvoll, Erweiterungen der oben genannten kontextfreien Spiele auf verschachtelte Wörter zu betrachten, also auf XML-artige Linearisierungen von Bäumen in Zeichenketten. Weitere praktisch motivierte Verallgemeinerungen beinhalten unter anderem die Modellierung von syntaktischer oder semantischer Behandlung von Aufrufparametern beim Aufruf externer Referenzen. Ziel dieser Dissertation ist, einen weitgehend vollständigen Überblick über den aktuellen Stand der Forschung zu kontextfreien Spielen auf Zeichenketten und verschachtelten Wörtern zu liefern. Dazu liefert sie jeweils komplexitätstheoretische Klassifizierungen des Gewinnproblems (und verwandter Probleme) für diverse Varianten kontextfreie Spiele auf Zeichenketten und verschachtelten Wörtern und gibt einen Überblick über Beweismethoden und algorithmische Techniken zur Behandlung dieses Gewinnproblems. Als Teil dieser Betrachtung stellt sie darüber hinaus grundlegende Ergebnisse zu relevanten Automatenmodellen auf verschachtelten Wörtern dar, darunter Varianten von alternierenden Automaten und Transducern

From Relations to XML: Cleaning, Integrating and Securing Data

While relational databases are still the preferred approach for storing data, XML is emerging as the primary standard for representing and exchanging data. Consequently, it has been increasingly important to provide a uniform XML interface to various data sources— integration; and critical to protect sensitive and confidential information in XML data — access control. Moreover, it is preferable to first detect and repair the inconsistencies in the data to avoid the propagation of errors to other data processing steps. In response to these challenges, this thesis presents an integrated framework for cleaning, integrating and securing data. The framework contains three parts. First, the data cleaning sub-framework makes use of a new class of constraints specially designed for improving data quality, referred to as conditional functional dependencies (CFDs), to detect and remove inconsistencies in relational data. Both batch and incremental techniques are developed for detecting CFD violations by SQL efficiently and repairing them based on a cost model. The cleaned relational data, together with other non-XML data, is then converted to XML format by using widely deployed XML publishing facilities. Second, the data integration sub-framework uses a novel formalism, XML integration grammars (XIGs), to integrate multi-source XML data which is either native or published from traditional databases. XIGs automatically support conformance to a target DTD, and allow one to build a large, complex integration via composition of component XIGs. To efficiently materialize the integrated data, algorithms are developed for merging XML queries in XIGs and for scheduling them. Third, to protect sensitive information in the integrated XML data, the data security sub-framework allows users to access the data only through authorized views. User queries posed on these views need to be rewritten into equivalent queries on the underlying document to avoid the prohibitive cost of materializing and maintaining large number of views. Two algorithms are proposed to support virtual XML views: a rewriting algorithm that characterizes the rewritten queries as a new form of automata and an evaluation algorithm to execute the automata-represented queries. They allow the security sub-framework to answer queries on views in linear time. Using both relational and XML technologies, this framework provides a uniform approach to clean, integrate and secure data. The algorithms and techniques in the framework have been implemented and the experimental study verifies their effectiveness and efficiency

Active XML (une approche des services Web centrée sur les données)

Cette thèse introduit Active XML (AXML, en abrégé), un modèle déclaratif mettant à profit la technologie des services Web pour la gestion de données distribuées et mis en oeuvre dans une architecture pair-à-pair. Un document AXML est un document XML pouvant contenir des appels de services Web, dont l'invocation enrichit le document. Un service AXML est un service Web échangeant des document AXML. Un "pair" AXML est un entrepôt de documents AXML, jouant d'une part le rôle de client, en invoquant les appels de services inclus dans ses documents, et d'autre part celui de serveur, en fournissant des services AXML pouvant être définis comme des requêtes ou mises-à-jour sur ses documents. L'approche AXML permet de combiner harmonieusement données extensionnelles (en XML) et intensionnelles (les appels de services). La capacité des pairs AXML à échanger de tels documents conduit à un paradigme puissant de gestion de données distribuées. L'approche AXML génère des questions importantes également étudiées dans cette thèse. Nous nous intéressons d'abord au contrôle de l'échange de documents AXML, en proposant l'utilisation de schémas déclaratifs et en fournissant des algorithmes pour leur vérification statique. Puis, nous envisageons l'évaluation "paresseuse" de requêtes sur des documents AXML, en introduisant des techniques analysant la pertinence pour les requêtes des appels de services inclus dans les documents. Notre implantation des pairs AXML, conforme aux standards du W3C est également présentée dans la thèse.This thesis introduces Active XML (AXML, for short), a declarative framework that harnesses Web services for distributed data management, and is put to work in a peer-to-peer architecture. An AXML document is an XML document that may contain embedded calls to Web services, whose invocation enriches the document. An AXML service is a Web service that exchanges AXML documents. An AXML "peer" is a repository of AXML documents. On the one hand, it acts as a client, by invoking the service calls embedded in its documents. On the other hand, a peer acts as a server, by providing AXML services that can be declaratively specified as queries or updates over the AXML documents of its repository. The AXML approach allows for gracefully combining stored information with data defined in an intensional manner (as service calls). The fact that AXML peers can exchange a mix of materialized and intensional data (via AXML documents) leads to a very powerful distributed data management paradigm. The AXML approach leads to a number of important problems that are studied in the thesis. First, we address the issue of controlling the exchange of AXML data. We propose to use declarative schema specifications, and provide algorithms to statically enforce them. Second, we propose techniques for the "lazy evaluation" of queries on AXML documents, that detect which embedded service calls may contribute to query answers. An implementation of AXML peers compliant with W3C standards is also described in the thesis.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Regular rewriting of active XML and unambiguity

We consider here the exchange of Active XML (AXML) data, i.e., XML documents where some of the data is given explicitly while other parts are given only intensionally as calls to Web services. Peers exchanging AXML data agree on a data exchange schema that species in particular which parts of the data are allowed to be intensional. Before send-ing a document, a peer may need to rewrite it to match the agreed data exchange schema, by calling some of the services and materializing their data. Previous works showed that the rewriting problem is undecidable in the general case and of high complexity in some restricted cases. We argue here that this diculty is somewhat articial. Indeed, we study what we believe to be a more adequate, from a practical view point, rewriting problem that is (1) in the spirit of standard 1-unambiguity constraints imposed on XML schema and (2) can be solved by a single pass over the document with a computational device not stronger than a nite state au-tomaton. Following previous works, we focus on the core of the problem, i.e., on the problem on words. The results may be extended to (A)XML trees in a straightforward manner. 1