Ensuring Query Compatibility with Evolving XML Schemas

During the life cycle of an XML application, both schemas and queries may change from one version to another. Schema evolutions may affect query results and potentially the validity of produced data. Nowadays, a challenge is to assess and accommodate the impact of theses changes in rapidly evolving XML applications. This article proposes a logical framework and tool for verifying forward/backward compatibility issues involving schemas and queries. First, it allows analyzing relations between schemas. Second, it allows XML designers to identify queries that must be reformulated in order to produce the expected results across successive schema versions. Third, it allows examining more precisely the impact of schema changes over queries, therefore facilitating their reformulation

Semantic adaptation of multimedia documents

laborie2011aInternational audienceMultimedia documents have to be played on multiple device types. Hence, usage and platform diversity requires document adaptation according to execution contexts, not generally predictable at design time. In an earlier work, a semantic framework for multimedia document adaptation was proposed. In this framework, a multimedia document is interpreted as a set of potential executions corresponding to the author specification. To each target device corresponds a set of possible executions complying with the device constraints. In this context, adapting requires to select an execution that satisfies the target device constraints and which is as close as possible from the initial composition. This theoretical adaptation framework does not specifically consider the main multimedia document dimensions, i.e., temporal, spatial and hypermedia. In this paper, we propose a concrete application of this framework on standard multimedia documents. For that purpose, we first define an abstract structure that captures the spatio-temporal and hypermedia dimensions of multimedia documents, and we develop an adaptation algorithm which transforms in a minimal way such a structure according to device constraints. Then, we show how this can be used for adapting concrete multimedia documents in SMIL through converting the documents in the abstract structure, using the adaptation algorithm, and converting it back in SMIL. This can be used for other document formats without modifying the adaptation algorithm

A Logical Approach To Deciding Semantic Subtyping

International audienceWe consider a type algebra equipped with recursive, product, function, intersection, union, and complement types together with type variables and implicit universal quantification over them. We consider the subtyping relation recently defined by Castagna and Xu over such type expressions and show how this relation can be decided in EXPTIME, answering an open question. The novelty, originality and strength of our solution reside in introducing a logical modeling for the semantic subtyping framework. We model semantic subtyping in a tree logic and use a satisfiability-testing algorithm in order to decide subtyping. We report on practical experiments made with a full implementation of the system. This provides a powerful polymorphic type system aiming at maintaining full static type-safety of functional programs that manipulate trees, even with higher-order functions, which is particularly useful in the context of XML

Semantic multimedia document adaptation with functional annotations

laborie2009aInternational audienceThe diversity of presentation contexts (such as mobile phones, PDAs) for multimedia documents requires the adaptation of document specifications. In an earlier work, we have proposed a semantic adaptation framework for multimedia documents. This framework captures the semantics of the document composition and transforms the relations between multimedia objects according to adaptation constraints. In this paper, we show that capturing only the document composition for adaptation is unsatisfactory because it leads to a limited form of adapted solutions. Hence, we propose to guide adaptation with functional annotations, i.e., annotations related to multimedia objects which express a function in the document. In order to validate this framework, we propose to use RDF descriptions from SMIL documents and adapt such documents with our interactive adaptation prototype

Smart Trip Alternatives for the Curious

International audienceWhen searching for flights, current systems often suggest routesinvolving waiting times at stopovers. There might exist alternative routes which aremore attractive from a touristic perspective because their duration isnot necessarily much longer while offering enough time in anappropriate place. Choosing among suchalternatives requires additional planning efforts to make sure thate.g. points of interest can conveniently be reached in theallowed time frame. We present a system that automatically computes smart tripalternatives between any two cities. To do so, it searchespoints of interest in large semantic datasets considering theset of accessible areas around each possible layover. It then elects feasible alternatives and displays theirdifferences with respect to the default trip

Encoding Multimedia Presentation for User Preferences and Limited Environments

International audienceThis paper discusses a new approach of generating TV-like multimedia presentations that are adapted to the target user preferences and to limited devices. Three main points are discussed: 1) The encoding of video presentations from a SMIL specification 2) The adaptation of the video content based on the user preferences, and 3) The delivery of adapted multimedia presentations. The used architecture includes a content server, an adaptation proxy and a set of small devices in the form of personal device assistants (PDA). These devices request the content through a wireless network. In order to show how the system behaves regarding the user preferences and capabilities, two negotiation dimensions are considered: the user language and the memory capability of the device. The first dimension is used to generate a content that can be understood by the target user, e.g. a video with subtitles written in the preferred language. The second dimension is chosen to solve the problem of the system blocking that usually happens when limited devices access rich multimedia presentations over the network

Mobile Augmented Reality Applications for Smart Cities

International audienceToday, one of the main challenges in mobile augmented reality applications design is understanding how our perception of reality can be profitably augmented and how this augmentation can be made to fit seamlessly with the user’s interaction with the world. The European VENTURI project which began in 2011 is aiming to develop the first generation of ubiquitous augmented reality (AR) tools that meet real user needs and fit within the context they operate in

SPARQLGX in Action: Efficient Distributed Evaluation of SPARQL with Apache Spark

International audienceWe demonstrate SPARQLGX: our implementation of a distributed sparql evaluator. We show that sparqlgx makes it possible to evaluate SPARQL queries on billions of triples distributed across multiple nodes, while providing attractive performance figures

Mu-Calculus Based Resolution of XPath Decision Problems

XPath is the standard declarative notation for navigating XML data and returning a set of matching nodes. In the context of XSLT/XQuery analysis, query optimization, and XML type checking, XPath decision problems arise naturally. They notably include XPath containment (whether or not for any tree the result of a particular query is included in the result of a second one), and XPath satisfiability (whether or not an expression yields a non-empty result), in the presence (or the absence) of XML DTDs. In this paper, we propose a unifying logic for XML, namely the alternation-free modal mu-calculus with converse. We show how to translate major XML concepts such as XPath and DTDs into this logic. Based on these embeddings, we show how XPath decision problems can be solved using a state-of-the-art EXPTIME decision procedure for mu-calculus satisfiability. We provide preliminary experiments which shed light, for the first time, on the cost of solving XPath decision problems in practice

Mobile Augmented Reality Applications for Smart Cities

International audienceToday, one of the main challenges in mobile augmented reality applications design is understanding how our perception of reality can be profitably augmented and how this augmentation can be made to fit seamlessly with the user’s interaction with the world. The European VENTURI project which began in 2011 is aiming to develop the first generation of ubiquitous augmented reality (AR) tools that meet real user needs and fit within the context they operate in