OVERCOMING THE CATCH-22 DILEMMAUNLOCKING THE FULL POTENTIAL OF LOCATION-BASED SERVICES AS LINKED OPEN DATA IN REAL-TIME ECOSYSTEMS.

Raf Buyle, Ziggy Vanlishout Cristian Vasquez Paulus and Pieter ColpaertINSPIRE – 2017 - Strasbourg France

Flanders Information Agency

The cost for re-using public sector information is too high.

Scalable services are expensivefor public administrations

The 5-star Flemish Address Registrylessons learned

The Address Base Registry contains well over 4 million addresses and their geographical coordinates.

http://data.vlaanderen.be/id/adres/2584882

Persistent Identifiers

URIs1

Dereferenceable HTTP

URIs

Human readable

Links to other

information1

Machine friendly

5-STAR Linked Open Data The Web as a Blueprint

information in line with

standards (RDF) 1

1 Tim Berners-Lee, https://www.w3.org/DesignIssues/LinkedData.html

Linked Data Address Products

A data dump• all triples in an entire dataset• http://data.vlaanderen.be/dumps

A subject page • triples about a specific subject in a dataset• http://data.vlaanderen.be/id/adres/2584882

A SPARQL endpoint• triples that correspond to a SPARQL query• http://data.vlaanderen.be/sparql

CPU-cost raises linearly with amount of queries

Resources on the web, identified by urls through the uniform interface offered by HTTP can be cached easily

SPARQL endpoints implement a protocol on top of HTTP, therefore regular HTTP caching can not be applied2

2 Verborgh R. et al. http://linkeddatafragments.org/publications/ldow2014.pdf

Verborgh R. et al. http://linkeddatafragments.org

Can we balance the CPU-cost between the client and the server?

A comparison of required processing (filledbars) and datatransfer (dottedlines) shows why ldf scales significantly better.Verborgh R. et al

Addresses LDF• > 4 Mio addresses are published as Linked Data Fragments • RDF documents can be compared to ‘tiles’• Documents contain links to other documents, which allow machines to

browse the dataset• The document-fragments are visualized on a map,

and cached using the standard HTTP infrastructure

TAKE AWAY

@info_vlaanderen @rafke @ziggyvanlishout @pietercolpaert

Scaling Linked Data SPARQL endpoints is expensive

Overcome catch 22 by reassessing client server trade-offs.

Linked Data Fragments, offer a hybrid solution.

New querying paradigm

Demo: https://bit.ly/geo_ldf API: https://bit.ly/geo_ldf_api

Flemish GovernmentLDF initiatives

Geospatial LDF – Address Registry• Demo: https://bit.ly/geo_ldf • API: https://bit.ly/geo_ldf_api

Heritage Thesauri in Flanders - LDF• Online editor: loveable user interface• Open API for reading and writing• Demo: https://thesaurus.onroerenderfgoed.be• Source: https://github.com/OnroerendErfgoed/atramhasis