Representing Linked Data as Virtual File Systems Bernhard Schandl - - PowerPoint PPT Presentation

Representing Linked Data as Virtual File Systems

Bernhard Schandl University of Vienna Department of Distributed and Multimedia Systems http://events.linkeddata.org/ldow2009#ldow2009 Madrid, Spain, April 20th 2009

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.

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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.

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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.

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Mapping Approach

• Virtual directory /!resource/ that holds all resources.
• Each resource is represented as virtual directory.

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dbpedia:Berlin dbpedia:Berlin /!resource/ /

Mapping Approach

• Object properties are represented as virtual directories

containing symlinks to other resource directories.

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dbpedia:Berlin dbpedia-owl:City rdf:type dbpedia:Berlin /!resource/ / rdf:type / dbpedia-owl:City /!resource/ / dbpedia-owl:City symlink

Mapping Approach

• Datatype properties are represented as virtual files that store

the property’s value.

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dbpedia:Berlin "891.82"^^xsd:double p:area dbpedia:Berlin /!resource/ / p:area / value-17.txt "891.82"^^xsd:double

Mapping Approach

• Incoming object properties are represented as virtual

directories with “is ... of” naming:

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dbpedia:Berlin dbpedia-owl:City rdf:type dbpedia:Berlin /!resource/ / is rdf:type of / dbpedia-owl:City /!resource/ / dbpedia:Berlin symlink rdf:type dbpedia-owl:City symlink /

Mapping Approach

• Resource representations are mapped to virtual files for

different (standard) content types.

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dbpedia:Berlin dbpedia:Berlin /!resource/ / content-application_rdf.xml dbpedia:Berlin /!resource/ / content-text_rdf.n3 dbpedia:Berlin /!resource/ / dbpedia:Berlin /!resource/ / content-text.csv content-text.html

Mapping Approach

• Entry points:
• Virtual /!resource/ directory:

for known resources.

• Virtual /<search>/ directory:

for fulltext search results.

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/ !resource dbpedia:2raumwohnung berlin dbpedia:Berlin p:location rdfs:label dbpedia:Wannsee dbpedia:Vienna dbpedia:Berlin ... dbpedia:Wannsee dbpedia:Berlin value-1.txt value-2.txt ... ... content-text.html content-application_rdf.xml

File Directory Symlink Symbols

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.

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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
• f a resource do exist?

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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!

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Future Work

• Inclusion of multiple SPARQL endpoints
• Update (write access) and local modifications
• Caching

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Questions?

bernhard.schandl@univie.ac.at http://www.cs.univie.ac.at/bernhard.schandl http://lodfs.sourceforge.net

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