Representing Linked Data as Virtual File Systems

Transcription

1 Representing Linked Data as Virtual File Systems Bernhard Schandl University of Vienna Department of Distributed and Multimedia Systems Madrid, Spain, April 20th 2009

2 Motivation Linked Data are made for applications to be used. However: desktop applications have no idea about URIs, HTTP, RDF, Triples, etc. Desktop and Web environments are distinct worlds we want to build bridges. Idea: represent Linked Data as virtual file systems. 2

3 Potential Applications Unified browsing and navigation of local files and remote LOD sets. Direct data import and reuse. (Semantic) Integration with desktop resources. and probably some more things we haven t thought of. 3

4 Design Considerations Structural Mismatch: graphs and trees don t fit easily. Entry Points: where to start? Naming: URIs vs rdfs:labels vs file names Literal values: the data flesh of Linked Data Resource representations: only partially considered in LOD, but important for desktop applications. 4

5 Mapping Approach Virtual directory /!resource/ that holds all resources. Each resource is represented as virtual directory. /!resource/ / 5

6 Mapping Approach Object properties are represented as virtual directories containing symlinks to other resource directories. rdf:type dbpedia-owl:city /!resource/ / rdf:type / dbpedia-owl:city /!resource/ dbpedia-owl:city / symlink 6

7 Mapping Approach Datatype properties are represented as virtual files that store the property s value. p:area "891.82"^^xsd:double /!resource/ / p:area / value-17.txt "891.82"^^xsd:double 7

8 Mapping Approach Incoming object properties are represented as virtual directories with is... of naming: rdf:type dbpedia-owl:city /!resource/ dbpedia-owl:city / is rdf:type of / symlink symlink /!resource/ / rdf:type / dbpedia-owl:city 8

9 Mapping Approach Resource representations are mapped to virtual files for different (standard) content types. /!resource/ /!resource/ / content-application_rdf.xml / content-text_rdf.n3 /!resource/ / content-text.html /!resource/ / content-text.csv 9

10 Mapping Approach / Entry points: Virtual /!resource/ directory: for known resources. Virtual /<search>/ directory: for fulltext search results.!resource dbpedia:2raumwohnung dbpedia:wannsee content-text.html content-application_rdf.xml p:location rdfs:label value-1.txt value-2.txt... dbpedia:vienna... berlin dbpedia:wannsee... Symbols Directory File Symlink 10

11 Implementation Prototype available, based on Java and FUSE (sorry Windows users...) One SPARQL endpoint is represented as one virtual file system. Data is retrieved from the endpoint on demand. 11

12 Experience: LOD Issues (I) Resource rendering: what is the right way to display a resource? URI prefixes: how to find them? How to use them in a consistent manner? Content representation: how do I know which representations of a resource do exist? 12

13 Experience: LOD Issues (II) RDF language features: how to deal with collections, containers, reification, blank nodes? Fulltext queries: regex(), bif:contains, pf:textmatch, sail:query,??? LOD Updates: would be nice! 13

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20 Future Work Inclusion of multiple SPARQL endpoints Update (write access) and local modifications Caching 20

21 Questions?