Command Line Semantic Web with Redland

Dave Beckett — @dajobe

Redland RDF C Libraries

Raptor RDF Parser Toolkit (libraptor) RDF Input and Output to / from syntax. (parsing, serialising, URIs, WWW, Unicode, XML, ...) Rasqal RDF Query Library (librasqal) Query engine for SPARQL and RDQL. Redland (librdf) RDF API and triple stores (Memory, File, URI, Sleepycat / BDB, MySQL, PostgreSQL, SQLite, Trees, Virtuoso). Redland Bindings Language bindings to Redland librdf C#, Java, Obj-C, Perl, PHP, Python, Ruby, Tcl

Command Line Redland

Every library has a utility and a manpage:

rapper — syntax command line

Raptor http://librdf.org/raptor/ via rapper(1):

# count triples
$ rapper -c http://librdf.org/redland.rdf

# or the unix way
$ rapper -q http://librdf.org/redland.rdf | wc -l

# get triples from home page
$ rapper -g -q -o turtle http://www.dajobe.org/

# What was it doing?
$ rapper -g -q -c --trace http://www.dajobe.org/

# parse the slides
$ rapper -g -q -o turtle index.html

# what just happened?
rapper -g -c --trace index.html

rapper parsing — What just happened?

RDF Graph Query

SPARQL Protocol and RDF Query Language

Query: Find names and websites of people on PlanetRDF:

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?website
FROM   <http://planetrdf.com/bloggers.rdf>
WHERE { ?person foaf:weblog ?website ;
                foaf:name ?name .
        ?website a foaf:Document
      }

Protocol:

http://.../qps?
query-lang=http://www.w3.org/TR/rdf-sparql-query/
&graph-id=http://planetrdf.com/bloggers.rdf
&query=PREFIX foaf: <http://xmlns.com/foaf/0.1/...

roqet — querying command line

Rasqal http://librdf.org/rasqal/ via roqet(1):

# use planetrdf query
$ roqet example.rq

# I'd like json please
$ roqet -r json example.rq

# or CSV
$ roqet -r csv example.rq

# just the names in column 2
$ roqet -r csv example.rq | awk -F, '{print $2}'

roqet querying — What just happened?

$ rdfproc
Redland RDF processor utility 1.0.10
Copyright 2000-2008 David Beckett. Copyright 2000-2005 University of Bristol
Try `rdfproc --help' for more information.

# Guess - aka GRDDL parse
$ rdfproc test parse http://www.dajobe.org/ guess

# debug print
$ rdfproc test print

# Ntriples please
$ rdfproc test serialize ntriples

# query
$ rdfproc test query sparql - 'select ?o where { ?s <http://xmlns.com/foaf/0.1/name> ?o} '

$ python
Python 2.5.5 (r255:77872, Feb  1 2010, 19:53:42) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
<<< import RDF
<<< 

$ perl -MRDF::Redland '...'

Thanks

Slides: http://bit.ly/semweb-sxsw

Redland: http://librdf.org/

• Source tarballs, GIT
• debs for libraries and supported bindings
• Linux: Debian, Ubuntu, Fedora, SUSE, ... and several others
• BSD ports
• Gentoo Linux emerge ports
• Win32: not available yet (in progress slows)
• Perl CPAN: old versions. Use newer versions from source/packages

Emergency Command Line Results

$ rapper -c http://librdf.org/redland.rdf
rapper: Parsing URI http://librdf.org/redland.rdf with parser rdfxml
rapper: Serializing with serializer ntriples
rapper: Parsing returned 40 triples

$ rapper -g -q -o turtle http://www.dajobe.org/

results: home.ttl

$ rapper -g -q -c --trace http://www.dajobe.org/
rapper: Processing URI http://www.dajobe.org/
rapper: Processing URI http://www.dajobe.org/foaf.rdf
rapper: Processing URI http://journal.dajobe.org/journal/comments.rdf
rapper: Processing URI http://www.dajobe.org/xslt/grokXFN.xsl

$ rapper -g -c --trace index.html 
rapper: Parsing URI file:///Users/dajobe/websites/www.dajobe.org/talks/201003-semweb-sxsw/index.html with parser guess
rapper: Processing URI file:///Users/dajobe/websites/www.dajobe.org/talks/201003-semweb-sxsw/slides.xslt
rapper: Guessed parser name 'grddl'
rapper: Parsing returned 58 triples