Semantic web Guideline Semantic web guideline This Guideline is part of the cooperation project between São Paulo State Government and the UK Government SPUK Improving business environment through transparency in São Paulo State Melhoria do ambiente de negócios por meio da transparência no Estado de São Paulo Partners Secretaria de Governo Year 2015 This content is licensed under Creative Commons. Attribution-NonCommercial-NoDerivs BY NC ND CC BY-NC-ND SPUK Improving business environment through transparency in São Paulo State Melhoria do ambiente de negócios por meio da transparência no Estado de São Paulo EXECUTION GOVERNMENT OF THE STATE OF SÃO PAULO Secretariat of Government • Sub-secretariat for Partnerships and Innovation Chief of Staff • Special Advisor for Foreign Affairs Foundation for Administrative Development - Fundap State System for Data Analysis Foundation - Seade Public Adminsitration Transparency Board THE UK GOVERNMENT British Embassy in Brasília THE BRAZILIAN NETWORK INFORMATION CENTER - NIC.br Web Technologies Study Center - CeWeb.br AUTHOR Carlos Laufer COORDINATION General: Roberto Agune - iGovSP Vagner Diniz – CeWeb.br Executive and Editorial: Caroline Burle dos Santos Guimarães - CeWeb.br Helena Pchevuzinske - iGovSP Sergio Pinto Bolliger - iGovSP IDEALIZATION Alvaro Gregório - iGovSP DESIGN Alcione de Godoy - iGovSP - e-books Deblyn Pereira Prado - NIC.br - HTML Ricardo Hurmus - Bulerías Arte & Design - ilustrações summary 1. Introduction...................................................................................................6 2. WWW and Semantics.........................................................................................9 2.1 Web of Documents...........................................................................10 2.2 Programmable Web..........................................................................12 2.3 Web of Data.....................................................................................14 2.4 Semantics.........................................................................................16 2.5 Metadata..........................................................................................19 3. Data Ecosystem on the Web............................................................................22 3.1 Actors and Roles...............................................................................23 3.2 Life cycle..........................................................................................24 3.3 Architecture......................................................................................25 4. Semantic Web...............................................................................................31 4.1 RDF.................................................................................................32 4.1.1 Data Model...................................................................................33 4.1.2 URIs.............................................................................................37 4.1.3 Serializations..................................................................................39 4.2 RDFS..............................................................................................44 4.3 OWL...............................................................................................46 4.4 SPARQL..........................................................................................53 4.5 Metadata Embedded in Pages...........................................................59 4.5.1 Microformat..................................................................................59 4.5.2 RDFa............................................................................................61 4.5.3 Microdata.....................................................................................64 5. Linked Data..................................................................................................66 5.1 The Four Principles...........................................................................68 5.2 The 5 Stars........................................................................................69 5.3 Linked Data API..............................................................................74 5.4 Examples.........................................................................................76 4 SUMMARY 5.4.1 DBpedia ......................................................................................76 5.4.2 Linked Data from the National Library of Spain...........................80 5.4.3 BBC Things..................................................................................83 5.4.4 Federal Budget of the Brazilian Government.................................84 5.4.5 Bio2RDF.......................................................................................85 6. Vocabularies and Ontologies........................................................................ 87 6.1 Dublin Core.....................................................................................89 6.2 FOAF..............................................................................................90 6.3 SKOS..............................................................................................92 6.4 Schema.org.....................................................................................95 6.5 PROV.............................................................................................97 6.6 DCAT.............................................................................................99 7. Conclusion.................................................................................................102 Appendix – Application Development Environments............................................104 A.1 D2RQ..........................................................................................105 A.2 Virtuoso........................................................................................107 A.3 Sesame..........................................................................................108 A.4 Jena-Fuseki....................................................................................110 A.5 PublishMyData.............................................................................110 A.6 Epimorphics Linked Data Publishing Platform.............................112 A.7 Triple Stores..................................................................................116 A.8 Libraries ....................................................................................117 References...................................................................................................119 5 Semantic Web Guideline Introduction Chapter 1 6 INTRODUCTION The Semantic Web is a web of information designed to be easily processable by machines on a global scale. The general idea is to create an efficient way to represent data on the World Wide Web and build a global linked database. The intent of this guide is to introduce the basic concepts of the Semantic Web, as well as some examples of development environments and the implementation of applications for manipulating data published on the Web. It was written to help readers understand this new universe that is emerging from the vast amount of data published daily on the Web, and to explain how to describe this information so that both people and machines can comprehend it. Readers with less technical knowledge can focus on sections 2 and 3, which give an overview and expound on the current state of the Web. Subsequent sections go into more detail in terms of the proposed technical infrastructure to describe published data. Section 2 presents the concepts that define the World Wide Web, showing how the Web has evolved since its invention, starting as a Web of Documents, and then expanding in the direction of a universal platform to run applications, until reaching its current extension as a Web of Data. This section also introduces the concepts of semantics and metadata. The next section discusses the ecosystem that encompasses data on the Web, where the roles played by different types of participants in this environment are presented, in addition to the data life cycle and the architecture underlying this ecosystem. In Section 4, the guide moves into a more technical description, presenting the technologies and standards that define the Semantic Web, followed by a section that presents the basis of the concept of Linked Data, with its principles, classification scheme and some examples. Section 6 deals with an essential aspect for achieving the goal that the meaning intended by the data publisher is the same as the meaning understood by the data consumer: the use of vocabularies that have well-defined semantics. This section addresses some of the most-used reference vocabularies for the semantic definition of data and definition of domain-specific ontologies. Last comes the conclusion to the guide, followed by an appendix that gives some examples of software currently used in development environments to generate applications that manipulate Linked Data. 7 Semantic Web Guideline The purpose of this guide is not to delve deeply into the technical side of the subjects presented, but rather to introduce the reader to this new universe of data. Those interested in further technical details have at their disposal a set of more than 100 links to related specifications and documents. All the references in this guide are available on the Web. Bon Voyage! 8 WWW AND SEMANTICS