RDF::Query - A SPARQL/RDQL implementation for RDF::Redland and RDF::Core

RDF::Query allows RDQL and SPARQL queries to be run against an RDF model, returning rows of matching results.

Requirements

To install RDF::Query you'll need the following perl modules installed:

• RDF::Core or RDF::Redland
• Parse::RecDescent
• DateTime::Format::W3CDTF
• JSON
• Error
• Storable

The following additional modules are recommended for some functionality:

• LWP::Simple

Installing RDF::Query

To install, run:

Version History

Version 1.037 (2006-07-06)

• execute() method now takes optional 'bind' parameter for pre-binding query variables.
• Updated code to support basic FILTERs in SQL compilation.
• Fixed bug in SQL compilation where no WHERE clause was needed.
• Fixed bug in SQL compilation when using model-specific Statements tables.
• Added Storable to the list of required modules (was missing in the list).
• Fixed typos in metadata about past versions in DOAP Changes.ttl.

Version 1.036 (2006-06-26)

• Fixed memory leak in RDF::Query::Stream that resulted in too many database handles.
• Initial support for OPTIONALs in SQL compiler.
• Removed LWP requirement for systems without libwww.
• Added support for class variable to hold parsing errors. (Beware under threads.)
• RDF::Query now sets error variable upon parsing error. (Access with error().)
• Fixed POD errors, and added tests for POD coverage.
• Added model API methods to SQL model class.
• Added close() method to RDF::Query::Stream.

Version 1.035 (2006-06-04)

• Added DAWG tests and harness.
• Rewrote core logic in OPTIONAL handling code.
• Comparisons on literals now respect numeric datatypes.
• Fixed outdated calling conventions in casting functions.
• Added custom functions:
  • jena:sha1sum
  • jena:now
  • jena:langeq
  • jena:listMember
  • ldodds:Distance
• Added new model methods: equals, subject, predicate, object.
• Relocated external http-based test data to .Mac URLs.

Version 1.034 (2006-05-01)

• Added JSON serialization for bindings and boolean queries.
• Initial support for compiling RDF queries to SQL queries using the Redland schema.
• Added to_string method to query results Stream class.
• Model objects now store the query parse tree for access to data needed in serialization.
• Unquoted number and boolean literals in SPARQL are now datatyped appropriately.
• Fixed crashing bug when RDF::Query::Model::Redland::as_string was called with an undefined value.
• Fixed bug parsing queries with predicate starting with 'a' (confused with { ?subj a ?type}).
• Fixed bug parsing queries whose triple pattern ended with the optional dot.

Version 1.033 (2006-03-08)

• Updated test suite to work if one of the model classes is missing.
• Data-typed literals are now cast appropriately when used in a FILTER.
• Added support for xsd:dateTime datatypes using the DateTime module.
• Added support for LANG(), LANGMATCHES() and DATATYPE() built-in functions.
• Updated TODO list.
• Added more exception types to RDF::Query::Error.
• Added POD coverage.
• Fixed SPARQL parsing bug for logical operators <= and >=.

Version 1.032 (2006-03-03)

• Replaced the Parse::RecDescent SPARQL parser with a much faster hand-written one.
• Updated SPARQL parsing rules to be better about URI and QName character sets.
• FILTER equality operator now '=', not '==' (to match SPARQL spec).
• Initial support for FILTER constraints as part of the triple pattern structure (Will allow for nested FILTERs).
• Implemented support for ordering query results by an expression.
• Fixed bug in expresion handling of unary minus.
• Fixed bug in Redland NAMED GRAPH parsing.
• Fixed bug in RDF::Core parsing code where blank nodes would be accidentally smushed.

Version 1.031 (2006-02-08)

• Added support for NAMED graphs.

Version 1.030 (2006-01-13)

• Added support for SELECT * in SPARQL queries.
• Added support for default namespaces in SPARQL queries.
• Added tests for querying RDF collections in SPARQL (1 ?x 3)
• Added tests for triple patterns of the form { ?a ?a ?b . }
• Added tests for default namespaces in SPARQL.
• Added tests for SELECT * SPARQL queries.
• Bugfix where one of two identical triple variables would be ignored ({ ?a ?a ?b }).

Version 1.028 (2005-11-18)

• Added SPARQL functions: BOUND, isURI, isBLANK, isLITERAL.
• Updated SPARQL REGEX syntax.
• Updated SPARQL FILTER syntax.
• Added SPARQL RDF Collections syntactic forms.
• Fixed FILTER support in OPTIONAL queries.
• Added binding_value_by_name method to Query results stream class.
• Added isa_blank methods to RDF::Redland and RDF::Core model classes.
• Fixed RDF literal datatyping when using Redland versions >= 1.00_02.
• Updated SPARQL grammar to make 'WHERE' token optional.
• Added directives to SPARQL grammar.
• Updated SPARQL 'ORDER BY' syntax to use parenthesis.
• Fixed SPARQL FILTER logical-and support for more than two operands.
• Fixed SPARQL FILTER equality operator syntax to use '=' instead of '=='.
• Now requires Test::More 0.52 because of changes to is_deeply().

Version 1.027 (2005-07-28)

Version 1.026 (2005-06-05)

• Added new DBI model bridge (accesses Redland's mysql storage directly).
• Added built-in SPARQL functions and operators (not connected to grammar yet).
• Added bridge methods for accessing typed literal information.

Version 1.024 (2005-06-02)

• Added missing SPARQL OFFSET grammar rules.
• Added XML Results support for graph and boolean queries (DESCRIBE, CONSTRUCT, ASK).
• Fixed major bugs in RDF::Core bridge:
  • - Bridge wasn't using passed model.
  • - Literal construction was broken.
  • - Blank node construction was broken when no identifier was specified.
• Stream::bindings_count now returns the right number even if there is no data.
• XML Result format now works with RDF::Core models.
• The Model bridge object is now passed to the Stream constructor.
• Internal code now uses the variables method.
• Removed redundant code from ORDER BY/LIMIT/OFFSET handling.
• Removed unused count method.
• Removed unused delegating AUTOLOAD.
• Removed unused parse_files method.
• Removed usused add_file method.
• Removed duplicate net test file.
• Added test file for local file-based SPARQL 'FROM' queries.
• Added test file for SPARQL Result Forms (LIMIT, ORDER BY, OFFSET, DISTINCT).
• Added test file for SPARQL Protocol for RDF (XML Results).
• Added new tests based on Devel::Cover results.
• Some test files now run against both Redland and RDF::Core:
  • - 00-simple.t
  • - 03-coverage.t
  • - 10-sparql_protocol.t
• All debugging is now centrally located in the _debug method.
• Moved Stream class to lib/RDF/Query/Stream.pm.
• Fixed tests that broke with previous fix to CONSTRUCT queries.
• Fixed tests that broke with previous change to ASK query results.

Version 1.021 (2005-06-01)

• Added SPARQL UNION support.
• Broke OPTIONAL handling code off into a seperate method.
• Added new debugging code to trace errors in the twisty web of closures.

Version 1.020 (2005-05-18)

• Added support for SPARQL OPTIONAL graph patterns.
• Calling bindings_count on a stream now returns 0 with no data.
• Added Stream methods:
  • is_bindings
  • binding_name
  • binding_values
  • binding_names
• Added as_xml method to Stream class for XML Binding Results format.

Version 1.016 (2005-05-08)

• Added initial support for SPARQL ASK, DESCRIBE and CONSTRUCT queries.
  • Added new test files for new query types.
• Added methods to bridge classes for creating statements and blank nodes.
• Added as_string method to bridge classes for getting string versions of nodes.
• Broke out triple fixup code into fixup_triple_bridge_variables().
• Updated FILTER test to use new Geo::Distance API.

Version 1.015 (2005-05-03)

• Fixes to the arguments passed to FILTERs.
• Filter tests now show example of two custom filters:
  • Transitive subClassOf testing.
  • Logical comparison operators (range testing lat/lon values).
• Added literal_value, uri_value, and blank_identifier methods to bridges.
• Redland bridge now calls sources/arcs/targets when only one field is missing.
• Fixes to stream code. Iterators are now destroyed in a timely manner.
  • Complex queries no longer max out mysql connections under Redland.
• Cleaned up node sorting code.
  • Removed dependency on Sort::Naturally.
  • Added new node sorting function ncmp().
• check_constraints now calls ncmp() for logical comparisons.
• Added get_value method to make bridge calls and return a scalar value.
• Fixed node creation in Redland bridge.
• Moved DISTINCT handling code to occur before LIMITing.
• Added variables method to retrieve bound variable names.
• Added binding_count and get_all methods to streams.
• get_statments bridge methods now return RDF::Query::Stream objects.

Version 1.014 (2005-04-26)

• Made FILTERs work in SPARQL.
• Added initial SPARQL support for custom function constraints.
• SPARQL variables may now begin with the '$' sigil.
• Added direction support for ORDER BY (ascending/descending).
• Added 'next', 'current', and 'end' to Stream API.

Version 1.012 (2005-04-24)

• Stream objects now handle being constructed with an undef coderef.
• Streams are now objects usinig the Redland QueryResult API.
• RDF namespace is now always available in queries.
• row() now uses a stream when calling execute().
• Added ORDER BY support to RDQL parser.
• SPARQL constraints now properly use the 'FILTER' keyword.
• SPARQL constraints can now use '&&' as an operator.
• SPARQL namespace declaration is now optional.
• Updated tests.

Version 1.010 (2005-04-21)

• execute now returns an iterator
• Added core support for DISTINCT, LIMIT, OFFSET
• Added initial core support for ORDER BY (only works on one column right now)
• Broke out the query parser into it's own RDQL class
• Added initial support for a SPARQL parser
  • Added support for blank nodes
  • Added lots of syntactic sugar (with blank nodes, multiple predicates and objects)
  • Added SPARQL support for DISTINCT and ORDER BY
• Moved model-specific code into RDF::Query::Model::*
• Moving over to redland's query API (pass in the model when query is executed)

Copyright

Copyright © 2005–2006 Gregory Williams. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.