Linked Open Data Martin Nečaský Faculty of Mathematics and Physics, Charles University in Prague

Web Applications Eco-system  Linked Data helps to create an eco-system of web applications which publish, enrich and consume data about things in one shared global data space Shared Global Data Space on the Web (Web of Data) App 1 App 2 App 3 App 4 App 5 App 4

Web of Documents Current Web (of Documents) provides lot of data about Prague. Problems Data about Prague encoded in documents (HTML, XLS, CSV, XML, PDF,...) distributed across the Web Most documents intended for humans not computers Data about Prague and related things not linked Therefore, automated processing of data about Prague published on the Web is hard Prague budget Basic info about Prague Prague public contracts Demography of Prague EU funded projects in Prague

Web of Documents Try to search for this information on the current Web Top 100 suppliers of Prague with headquarters outside of Prague region. Money spent in Prague for new children playgrounds in the last 5 years per one child. Organizations in Prague funded by EU structural funds and their top 100 suppliers. Prague budget Basic info about Prague Prague public contracts Demography of Prague EU funded projects in Prague

Linked Data  data published on the Web according to four simple principles (introduced by sir T. B. Lee) 1.Use URIs as names for things 2.Use HTTP URIs so that people can look up those names. 3.When someone looks up a URI, provide useful information encoded in RDF, SPARQL 4.Include links to other URIs so that they can discover more things.

Things as first-class citizens Project CZ.2.16/2.1.00/22189 Prague City Prague Council Prague Demography Prague Budget Contract DIL/23/07/007302/2010

HTTP URIs for Things Project CZ.2.16/2.1.00/22189 praha.eu (Prague) contract/ council city mfcr.cz (Ministry of Finance) prague/budget prague risy.cz (Regional Information Service) location/prague tract/ project/22189 czso.cz (Czech Statistical Office) czso.cz/prague prague ague/demogstat

Data about Things in RDF Client Playground Revitalization Authority: Prague Delivery date: Price: CZK... Playground Revitalization CZK dcterms:title pc:contracting Authority pc:agreedPrice gr:hasCurrency Value pc:estimated EndDate contract/ contract/7302/price council

dcterms:title "Playground Revitalization" ; pc:estimatedEndDate " " ; pc:agreedPrice ; pc:contractingAuthority. gr:hasCurrency "CZK" ; gr:hasCurrencyValue " ". Data about Things in RDF Client Playground Revitalization Authority: Prague Delivery date: Price: CZK... contract/7302

Vocabularies  published RDF data would be hardly interpretable when each publisher would use proprietary predicates  therefore, standardized (or at least widely used) predicates should have priority before proprietary ones  e.g. Dublin Core, Good Relations, FOAF, schema.org,...  or more specific ones for public procurement e.g., Public Contracts Ontology ( )  predicates are defined in so called vocabularies (or ontologies)  note: ontology is a special case of vocabulary, it contains more detailed reasoning rules which is out of scope of this lecture  note: not only predicates but also classes (= types of things) are defined in vocabularies/ontologies

Linking URIs of Related Things praha.eu (Prague) contract/ city mfcr.cz (Ministry of Finance) prague/budget prague risy.cz (Regional Information Service) location/prague tract/ project/22189 czso.cz (Czech Statistical Office) czso.cz/prague prague ague/demogstat c: hasBeneficiary a:fundedBy b:hasBudget council d:hasDemography

Linking URIs of Related Things praha.eu (Prague) contract/7302 mfcr.cz (Ministry of Finance) prague/budget prague risy.cz (Regional Information Service) tract/ project/22189 czso.cz (Czech Statistical Office) ague/demogstat c:hasBeneficiary a:fundedBy city location/prague czso.cz/prague prague council owl:sameAs b:hasBudget

Other examples  linked.opendata.cz  lekovaencyklopedie.cz

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