RDF - Semantic Web Standards Overview RDF is a standard model for data interchange on the Web. RDF has features that facilitate data merging even if the underlying schemas differ, and it specifically supports the evolution of schemas over time without requiring all the data consumers to be changed. RDF extends the linking structure of the Web to use URIs to name the relationship between things as well as the two ends of the link (this is usually referred to as a “triple”). Using this simple model, it allows structured and semi-structured data to be mixed, exposed, and shared across different applications. This linking structure forms a directed, labeled graph, where the edges represent the named link between two resources, represented by the graph nodes. Recommended Reading The RDF 1.1 specification consists of a suite of W3C Recommendations and Working Group Notes, published in 2014. A number of textbooks have been published on RDF and on Semantic Web in general. Discussions on a possible next version of RDF
Le web sémantique ou le futur du Web « un blog, des blogs L’expression « Web sémantique » a été utilisée la première fois en 1994 par Tim Berners-Lee, l’inventeur du World Wide Web et directeur du World Wide Web Consortium (« W3C »), qui supervise le développement des technologies communes du Web sémantique. En 1999, Tim Berners-Lee a exprimé la vision du Web sémantique comme suit : « J’ai fait un rêve pour le Web [dans lequel les ordinateurs] deviennent capables d’analyser toutes les données sur le Web — le contenu, liens, et les transactions entre les personnes et les ordinateurs. Il montre alors en quoi les liens hypertextes ou, plus précisément, la façon dont on met en relation les documents sur le Web est trop limitée pour permettre aux machines de relier automatiquement les données contenues sur le Web à la réalité. Le « Layer cake » de Tim Berners-Lee D’un web orienté « document », nous évoluons donc vers un web qui a du « sens ». (Source : L’E-Réputation à l’heure de la surcharge informationnelle, par Eglantine Schimtt) (Source : BnF)
Langage d'interrogation SPARQL pour RDF Résumé RDF est un format de données de graphe orienté et étiqueté pour représenter des informations dans le Web. Cette spécification définit la syntaxe et la sémantique du langage d'interrogation SPARQL pour RDF. Statut de ce document Cette section décrit le statut de ce document au moment de sa publication. Ceci est une recommandation du W3C. Ce document a été examiné par des membres du W3C, par des développeurs de logiciels, et par d'autres groupes du W3C et des tiers intéressés, et a été approuvé par le Directeur comme recommandation du W3C. Les commentaires à propos de ce document sont à envoyer à public-rdf-dawg-comments@w3.org, une liste de diffusion avec des archives publiques. Ce document a été produit par le groupe de travail RDF Data Access, sous l'égide de l'activité Semantic Web du W3C. Le groupe de travail Data Access a ajourné 12 questions, dont les fonctions agrégées et un langage de mise à jour. Annexes 1 Introduction 1.1 Plan du document 1.2 Conventions du document Données :
Microformats vs RDFa vs Microdata « Philip Jägenstedt Warning: The microdata syntax has changed (e.g. item="foo" is now itemscope itemtype="foo") since this blog post was written. Don’t copy the examples. I spent last weekend with my good friend Emil sketching a REST-style interface for his graph database Neo4j. The three candidates were microformats, microdata and RDFa. <p> I'm Philip Jägenstedt at <a href=" The simple task at hand is to make my name and homepage machine-readable using each of these formats. Microformats <p class="vcard"> I'm <span class="fn">Philip Jägenstedt</span> at <a class="url" href=" Microformats are “a set of simple, open data formats”, i.e. predefined vocabularies under centralized control. The only thing that distinguishes microformats from random CSS classes is the tree structure. Microformats. Still, I have great respect for some of the people behind microformats and the down-to-earth philosophy. RDFa Back to RDFa. I don’t hate RDF(a).
Mark Watson, Ruby and Java Consultant and Author From Enterprise Search to Unified Information Access Semantic web tutorial: RDF, RDFS and SPARQL using CORESE These pages are deprecated ; please go to the pages of our new team Edelweiss updated 17/04/2007 For remarks or questions on this tutorial contact Fabien Gandon This semantic web tutorial gives a quick tour of RDF, RDFS, SPARQL and Rules. TOC: RDFS intro, RDF/XML intro, SPARQL intro, Rules intro, OWL intro. This tutorial uses four files: a small ontology in RDFS: human_2007_04_17.rdfs a small set of annotations in RDF: human_2007_04_17.rdf a small set of rules : human_2007_04_17.rul a standalone version (2.3.0 or above) of the search engine Corese distributed as one executable ".jar" file. A previous version of this tutorial (Corese V2.2.2) is available. Rapid reminder of the basics RDF is a triple model where every assertion is decomposed in three parts: (subject, predicate, object) for instance (tutorial.php, author, "Fabien"). The serialization of RDF in its XML syntax is not unique i.e. the same RDF graph may be represented in different XML forms. example 1: example 2: example 3: or Examples:
★ Le Web Sémantique ou l'importance des données liées , dans con Ce billet n'est pas un transcript de ma conférence sur l'identité numérique et le Web Sémantique à Paris Web mais un document permettant de résumer ce qui a été dit (pour les absents), de lier les ressources citées (pour les fainéants) et de proposer des pistes pour aller plus loin (pour les curieux). Web Sémantique ? Le premier problème du Web Sémantique est probablement son nom. Il est difficile de comprendre ce qui se cache derrière ce terme qui manque de sens (un comble !) au premier abord. Il a donc été supplanté par Web des Données pendant un moment, terme qui se retrouve d'ailleurs dans l'introduction sur le site du W3C : The Semantic Web is a web of data. Mais je ne suis pas vraiment d'accord avec ce nom qui est réducteur et je lui préfère de loin celui de Données Liées qui permet de visualiser d'un seul coup les deux fondements du Web : la donnée et le lien. l'ajout de sens afin d'augmenter la pertinence des contenus ;la constitution d'une base de données à l'échelle du web. Bilan
AllegroGraph RDFStore Web 3.0's Database Geospatial and Temporal Reasoning AllegroGraph stores geospatial and temporal data types as native data structures. Combined with its indexing and range query mechanisms, AllegroGraph lets you perform geospatial and temporal reasoning efficiently. Social Networking Analysis AllegroGraph includes an SNA library that treats a triple-store as a graph of relations, with functions for measuring importance and centrality as well as several families of search functions.
NLGbAse: semantic resource and tagin tools for the semantic web Build Your Own NYT Linked Data Application Now that we’ve published nearly 10,000 of our tags as Linked Open Data, you’re probably wondering what kind of cool applications you can build with this data. To help you get started (and since linked data applications are a little different from your average Web application), we thought we’d provide a sample application and detailed information about how we built it. Our sample application, “Who Went Where,” lets you explore recent Times coverage of the alumni of a specified college or university. The Who Went Where application (click for larger image) You can find the application here and beautified source code here. Before we dive into the source, let’s take a high-level look at the application’s control (which is fairly straightforward). Wait! Linked Data: The idea behind linked data is super simple. DBpedia: Have you ever noticed those handy little info boxes on certain Wikipedia articles? Step-by-Step to Your Own NYT Linked Data Application Step 1: Initializing the Auto-Complete Field
The Web of Data: Creating Machine-Accessible Information In the coming years, we will see a revolution in the ability of machines to access, process, and apply information. This revolution will emerge from three distinct areas of activity connected to the Semantic Web: the Web of Data, the Web of Services, and the Web of Identity providers. These webs aim to make semantic knowledge of data accessible, semantic services available and connectable, and semantic knowledge of individuals processable, respectively. In this post, we will look at the first of these Webs (of Data) and see how making information accessible to machines will transform how we find information. The amount of information and services available is growing exponentially. Every day, it is getting harder to find the information we are actually looking for. Because it can't. It is critical that machines gain a new level of understanding. The Web of Data The idea of the Web of Data originated with the Semantic Web. Linking Open Data (Photo by zorro-art.
Semantic Web I have an idea that I think is very important but I haven’t yet polished to the point where I’m comfortable sharing it. I’m going to share it anyway, unpolished, because I think it’s that useful. So here I am, handing you a dull, gray stone, and I’m saying there’s a diamond inside. Maybe even a dilithium crystal. My hope is that a few experts will see what I see and help me safely extract it. The problem I’m trying to solve is at the core of decentralized (or loosely-coupled) systems. RDF offers a solution to this, but it turns out to be pretty hard to put into practice. Consider two on-the-web temperature sensors: The careful human reader will immediately wonder whether these temperatures are in Celcius or Fahrenheit, or if maybe the first is in Celcius and the second Fahrenheit. Here’s the first sketch of my solution: I know it looks ugly, but now it’s clear that both readings are in Fahrenheit. This way, if a third sensor came on line: That’s the essence of the idea. I’m not sure yet.