kasei / perlrdf

RDF::Query - An RDF query implementation of SPARQL/RDQL in Perl for use with RDF::Trine, 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:

     * DateTime
     * DateTime::Format::W3CDTF
     * Digest::SHA1
     * Error
     * I18N::LangTags
     * JSON
     * List::Util
     * LWP
     * Parse::RecDescent
     * RDF::Trine
     * Scalar::Util
     * Set::Scalar
     * Storable
     * URI

  The following additional modules are recommended for some functionality:

     * RDF::Core
     * RDF::Redland
     * JavaScript
     * Geo::Distance

INSTALLATION

   To install, run:

   perl Makefile.PL
   make
   make test
   make install

VERSION HISTORY

  Version 2.200 (2009-08-06)

     * Federation / Service Descriptions:

         * Rewrote the optimistic plan generator in RDF::Query::Federate::Plan.
         * Added threshold timeout argument to RDF::Query::Plan::ThresholdUnion and support for it in 
         RDF::Query::Federate::Plan.
         * Simplified logging in RDF::Query::Federate::Plan (now only logs to category 'rdf.query.federate.plan').
         * RDF::Query::ServiceDescription now adds an 'origin' label annotations to RDF::Query::Algebra::Triple objects.

                  * Removed check of the sd:definitive property in RDF::Query::ServiceDescription (was based on wrong 
         assumptions).
         * Updated RDF::Query::ServiceDescription::answers_triple_pattern() to recognize wildcard capabilities, 
         constructor now adds wildcard by default.
         * Added new RDF::Query::ServiceDescription::new_with_model constructor.
         * RDF::Query::ServiceDescription::computed_statement_generator now returns empty iterators when passed triple 
         patterns with bound blank nodes.
         * Added test data in data/federation_data/.
         * RDF::Query::Plan::Service now adds an 'origin' label annotation to the RDF::Query::VariableBindings object.
         * Added 'optimistic_threshold_time' query flag to RDF::Query::ExecutionContext and RDF::Query constructor.
         * RDF::Query::Federate::add_service() now adds the appropriate computed statement generators to the query 
         object.
         * Removed optimistic query rewriting test from t/34-servicedescription.t (now covered by t/federate.t).
         * Added t/federate.t with tests for optimistic federated query optimization using ::Plan::ThresholdUnion and 
         RDF::Endpoint::Server.

     * Aggregates:

         * Fixed serialization quoting issue in RDF::Query::Algebra::Aggregate::sse().
         * RDF::Query::Plan::Aggregate now attempts plain string comparisons for MIN,MAX when strict_errors is not set.
         * Added support for average aggregates, and fixed datatype support in aggregates.

     * Command Line Inferface:

         * Added bin/query.pl, a fork of examples/query.pl, to support simple query execution.
         * Added RDF::Query::Util as home to helper functions (added CLI args parsing functions to create queries and 
         models).
         * Simplified CLI argument parsing in bin/ and examples/ programs.

     * Refactoring, Code Cleanup, and Documentation:

         * Added and updated POD to RDF::Query::Util, RDF::Query::Node and RDF::Query::Plan and 
         RDF::Query::Federate::Plan.
         * Added check for RDFQUERY_THROW_ON_SERVICE environment variable in RDF::Query::Plan::Service.
         * Cleaned up code in RDF::Query::Model::get_computed_statements().
         * Updated SSE formatting and uninitialized warning in RDF::Query::Plan, RDF::Query::Algebra::Filter, 
         RDF::Query::Algebra::Distinct and RDF::Query::Algebra::Sort.
         * Moved shared RDF::Trine-related model methods into RDF::Query::Model from subclasses.
         * Raised required RDF::Trine version to 0.111 which brings RDF::Trine::Graph support.
         * RDF::Query::Model::RDFTrine::BasicGraphPattern::execute now returns $self.
         * Removed dependency on Test::JSON, List::MoreUtils, and XML::Parser.
         * Removed TODO on test in t/29-serialize.t.
         * Removed unnecessary code in RDF::Query::Plan subclasses, bin/query.pl, bin/graph-bgp.pl and 
         bin/graph-query.pl.

     * Logging:

         * Added logging in RDF::Query::Plan::ThresholdUnion, and RDF::Query::Model.
         * Changed logging level from debug to trace in RDF::Query::Plan::Triple, RDF::Query::Plan::Project, 
         RDF::Query::Plan::Filter, RDF::Query::Plan::Join::NestedLoop, RDF::Query::Plan::PushDownNestedLoop, and 
         RDF::Query::Model::RDFTrine.
         * Added calls to Log::Log4perl::is_debug to eliminate unnecessary serialization of logging when not in use.
         * Made error message more useful when SERVICE calls fail in RDF::Query::Plan::Service.

     * Bugfixes:

         * Fixed bug in RDF::Query::Plan::Offset in cases where the offset was beyond the end of the result set.
         * Fixed testing for Bloom::Filter in t/31-service.t.
         * Fixed test expectations when making remote DBPedia query in t/34-servicedescription.t.
         * Fixed check of $ENV{RDFQUERY_NETWORK_TESTS} to test boolean value, not just existence.
         * Fixed (bad) expected serializations in t/29-serialize.t.
         * Fixed bug in RDF::Query::Plan::ThresholdUnion attempting to close an iterator twice.
         * Fixed sse serialization issues in RDF::Query::Algebra::BasicGraphPattern and RDF::Query::Algebra::Project.
         * Fixed bug in RDF::Query::Node::from_trine() that up-cast blank nodes to variables.
         * Fixed quoting issue in RDF::Query::Algebra::Service::sse().
         * Fixed parameter handling in bin/graph-qeps.pl:prune_plans().
         * Fixed handling of 'GRAPH ?g {}' (empty GraphGraphPatterns) to return all graph names.
         * Added check for ref($node) in RDF::Query::VariableBindings::new (broke code after previous removal of 
         blessed() check).
         * Added use of defined() in code that had been testing boolean value of objects (and causing expensive string 
         overloading).

     * Miscellaneous Changes:

         * Added examples of queries and service descriptions in examples/.
         * Updated dawg-eval.t to actually test graph equivalence.
         * Clarified graph labels in RDF::Query::Model::RDFTrine::BasicGraphPattern::graph().
         * Added the ability to add label annotations to RDF::Query::VariableBindings, RDF::Query::Algebra::Triple and 
         RDF::Query::Algebra::Quad objects.
         * RDF::Query::Plan::Quad and RDF::Query::Plan::Triple now add an 'origin' label annotation to the 
         RDF::Query::VariableBindings object if the underlying statement has one.
         * RDF::Query::Plan::prune_plans now uses a stable sort when comparing plan costs.
         * RDF::Query::Algebra::Triple::new now up-casts to RDF::Query node objects, if necessary.
         * RDF::Query::Model::RDFTrine::generate_plans now respects the force_no_optimization query flag.
         * RDF::Query::Algebra::BasicGraphPattern::sse() now sorts triples for output.
         * Added distinguish_bnode_variables method to RDF::Query::Algebra::Quad and RDF::Query::Algebra::Triple.
         * Added RDF::Query::Node::Blank::make_distinguished_variable method.
         * Added caching of sparql serializations to RDF::Query::Algebra::BasicGraphPattern and 
         RDF::Query::Algebra::Triple.
         * Added code to RDF::Query::VariableBindings::new to up-cast any RDF::Trine::Node objects to their RDF::Query 
         equivalents.
         * RDF::Query::new() now looks for $args{ defines }, and adds them to the internal %options HASH.
         * Added hook in RDF::Query::execute_plan() to print the query plan to STDERR if $options{plan} is set (can be 
         set if defines).
         * Updated RDF::Query::Plan to only consider model-specific plans (if there are any).

  Version 2.100 (2009-03-18)

     * API:
     
         * Added ::Algebra::BasicGraphPattern::connected method.
         * Added 'node_counts' as a recognized key to ::Model::RDFTrine::suports().
         * Added ::Model::node_count method.
         * Added ::Model::RDFTrine::count_statements() and ::Model::RDFTrine::node_count() methods.
         * Added 'store' field to the data returned by the meta() method in the ::Model::* classes.
         * Added a peek method to ::Iterator to support execution deferment like in ::Algebra::Service.
         * Added ability to force SERVICE calls to abort using $ENV{RDFQUERY_THROW_ON_SERVICE} and 
         RequestedInterruptError.
         * Added bf methods to ::Triple and ::BasicGraphPattern to describe the BGP in terms of bound/free.
         * Added bind_variables method to RDF::Query::Algebra.
         * Added caching to ::Algebra::Service::_names_for_node.
         * Added code to count (and warn) the rate of false positives from a bloomjoin.
         * Added cost model hooks in RDF::Query and ::Algebra::BasicGraphPattern.
         * Added FeDeRate BINDINGS to the list of supported extensions.
         * Added get_basic_graph_pattern to ::Model::RDFTrine (not used yet).
         * Added is_solution_modifier() methods to ::Algebra classes.
         * Added labels and common patterns to service description template.
         * Added more logic and debugging to aggregating triples into BGPs for SERVICE calls.
         * Added optional restriction argument to ::Algebra::subpatterns_of_type.
         * Added RDF::Query::Model::RDFTrine::BasicGraphPattner::graph() method.
         * Added RDF::Query::Node::compare for sorting (either Trine or Query) node objects.
         * Added RDF::Query::plan_class so that ::Federate can overload calls to ::Plan methods.
         * Added support for computed statement generators (like ARQ's computed property support [e.g. list:member]).
         * Added trial subsumes() methods to ::Algebra::BasicGraphPattern and ::Algebra::Triple.
         * Algebra classes now call RDF::Query::algebra_fixup for optimization before falling back on normal fixup code.

                  * Allow equality test and disjunction filters in patterns that can be compiled to SQL.
         * Fixed ::Algebra::GroupGraphPattern to use join_bnode_streams in cases where the bloom filter wasn't 
         automatically created but instead provided by the user.
         * Fixed ::Model::RDFTrine::as_string use with Quads.
         * Fixed argument list for RDF::Query::Algebra::Service::_names_for_node called from bloom function.
         * Fixed bug so ::Model::RDFTrine::meta may be called as a class method.
         * Fixed RDF::Query::algebra_fixup to ignore service capabilities that would result in empty BGPs.
         * Modified code for aggregate queries (though they are currently broken).
         * Moved construction of bloom-filter-optimized patterns to 
         RDF::Query::Algebra::GroupGraphPattern::_bloom_optimized_pattern().
         * Moved initial federated service code into RDF::Query::fixup and ::algebra_fixup.
         * Moved QEP generation code to RDF::Query::query_plan so it can be overloaded.
         * Moved RDF::Query::add_service() to RDF::Query::Federate::add_service().
         * Parsing service descriptions now more forgiving in the face of missing values.
         * RDF::Query::Algebra::Triple::new now adds RDF::Query::Node::Variable objects for undefined nodes.
         * RDF::Query::fixup() now only returns a construct pattern (the query pattern now being returned by 
         RDF::Query::query_plan()).
         * RDF::Query::Model::get_computed_statements now doesn't die if there's no query object present.
         * RDF::Query::new() now accepts two-argument form with just $query and \%options.
         * RDF::Query::Node::Literal objects now can compare as equal when they're of numeric type but the lexical 
         values aren't numeric.
         * RDF::Query::prune_plans now takes ExecutionContext as an argument, and in turn calls ::Plan::prune_plans.
         * RDF::Query::query_plan() now returns all possible query plans when called in list context.
         * RDF::Query::query_plans now calls RDF::Query::prune_plans to select from the list of possible QEPs.
         * RDF::Trine::Node::Resource now escapes unicode in base URIs (now just relative URI part) before calling 
         URI->new_abs.
         * Removed now unused RDF::Query::construct() and RDF::Query::fixup().
         * Removed old execute() code from ::Algebra classes.
         * Removed unused redland fallback code from RDF::Query::Model::RDFTrine.
         * Split RDF::Query::execute into prepare() and execute_plan() methods.
         * Converted RDF::Query::execute() to use ::Plan classes.
         * Updated ::Compiler::SQL to recognize ::Algebra::Project objects.
         * Updates to RDF::Query::execute() to support explicit pre-binding lists (instead of just scalar values).
         * ::Algebra::GroupGraphPattern now throws an exception if passed unblessed values as patterns.
         * ::Federate now labels nodes in the QEP tree with applicable services.
         * ::Model::debug() now shows data from the named graph model.
         * ::Model::RDFTrine::add_uri now decodes resulting content as utf8 before proceeding.
         * ::Model::RDFTrine::meta() probes the underlying store object to declare the proper 'store' class.
         * ::Service::_names_for_node updated to use ::Plan classes for query execution (fixes use of the k:bloom 
         filter).

     * CLASSES:
     
         * Added algebra classes for solution modifiers and query forms (construct, project).
         * Added code and tests for Query Execution Plan classes RDF::Query::Plan::*.
         * Added RDF::Query::Federate::Plan for federation-specific code.
         * Added RDF::Query::BGPOptimizer implementing a basic optimizer for basic selectivity-based join ordering.
         * Added RDF::Query::CostModel classes for computing/estimating the cost of executing a specific pattern.
         * Added RDF::Query::ExecutionContext to hold all necessary information for query execution (query, model, bound 
         variables).
         * Added RDF::Query::ServiceDescription for parsing DARQ-style service descriptions.
         * Added RDF::Query::VariableBindings to wrap existing HASH-based variable binding structure.
         * Added stub ::Plan::ThresholdUnion class for running optimistic queries.
         * Added workaround to RDFCore bridge so that RDF::Core doesn't die if getStmts is called with a Literal in the 
         subj or pred position.
         * Added a RequestedInterruptError exception class.
         * Added code for RDF-Trine specific BGP query plans.
         * Changed debugging in RDF::Query modules to use Log::Log4perl.
         * Made SERVICE work again by rolling back streaming socket work (now commented out).
         * Moved federation code to new RDF::Query::Federate class.
         * Plan generation now includes any plans the model object can provide.
         * RDF::Query now always uses a cost model (defaulting to ::Naive).
         * RDF::Query::Federate now defaults to SPARQLP parser.
         * Removed logging/warn calls from forked process in ::Service (was screwing up the parent-child IO pipe).
         * Removed use of "DISTINCT" queries in SERVICE calls (for pipelining).
         * ServiceDescription now only runs sofilter if ?subject/?object are bound.
         * Started work on a more holistic approach to supporting service descriptions (instead of using 
         add_computed_statement_generator()).
         * Updated ::Algebra::Service to fork and use LWP's callback mechanism for concurrency.
         * ::Algebra::Service now defers loading of content until the first result is requested.
         * ::Model::RDFTrine now only produces BGP plans if there is no get_computed_statement_generators in the query 
         object.
         * Code now materializes all node identities before creating the Bloom filter (so capacity arg is accurate).
         * Bloom filter use is now only attempted on SERVICE blocks that don't immediately contain a FILTER.
         * Re-ordered conditionals so that the service-bloom-filter try block is called less frequently.
         * SERVICE execution now uses non-identity reasoning Bloom filter function.

     * SYNTAX and SERIALIZATION:
     
         * Added from_sse method to ::Statement, ::Node.
         * Added initial code for ARQ-style property paths.
         * Added initial parser code for SPARQL Update (SPARUL) extension.
         * Added new 'UNSAID' syntax for SPARQLP, implementing negation.
         * Added parse_expr method to RDF::Query::Parser::SPARQL.
         * Added RDF::Query::Algebra::Quad::bf() method.
         * Fixed RDQL parser to qualify URIs before returning from parse().
         * Fixed SSE serialization of Aggregates using '*' instead of a variable as the column.
         * Removed (now unused) parser generator script.
         * SPARQL parser now always adds a ::Algebra::Project (even when the query selects '*').
         * SPARQL parser now creates ::Algebra::Construct objects for CONSTRUCT queries.
         * SPARQL parser now puts ::Distinct above ::Sort algebras in the parse tree.
         * SPARQLP parser now creates ::Project object as parent of any ::Aggregate.
         * Turtle parser now doesn't modify the lexical value of numeric typed literals.
         * Turtle parser now makes universal IDs for all blank node (even those with given IDs like _:xyz).
         * Updated ::Algebra SSE serializations to conform to Jena's serialization syntax.
         * Updated ::Algebra::Limit::sse to emit 'slice' serialization if its child is a ::Algebra::Offset.
         * Updated as_sparql() methods to support the new ::Construct classes.
         * Updated RDF::Query::sse to emit base and prefix serializations.
         * Updated SPARQL parser and serializer tests to always assume an ::Algebra::Project on SELECT queries.
         * Updated SSE serialization of ::Join::PushDownNestedLoop to use 'bind-join' terminology.
         * Updates to SPARQLP parser to support FeDeRate BINDINGS keyword.
         * ::Algebra::Distinct now does proper serialization in as_sparql().
         * ::GroupGraphPattern::sse() updated to output the '(join ...)' only if the GGP has more than one pattern.

     * OPTIMIZER:
     
         * Added benchmark/plans.pl to show the runtimes of the available QEPs for a query.
         * Added benchmark/costmodel.pl for testing the RDF::Query::CostModel.
         * Added logging for execution time (time to construct iterator) of Triples, BGPs, GGPs and sorting.
         * Added logging of cardinalities in ::Algebra::Triple, ::Algebra::BasicGraphPattern and ::Algebra::Service.
         * Added logging to plan classes ::NestedLoop, ::Service, ::Triple.
         * Naive plan is used in ::Federate::Plan::generate_plans only if no optimistic plans are available.
         * Updated cost model code to work with ::Plan classes instead of ::Algebra classes.
         * Logging code now uses sse serialization as log keys (because of expressions that can't be serialized as 
         SPARQL).
         * Logging object can now be passed to RDF::Query constructor.
         * Updated logging of algebra execution to use SPARQL serialization as logging key.

     * MISC:
     
         * SPARQL parser now constructs ::Algebra::Project objects (had been in RDF::Query::execute).
         * Updated RDF::Query to require version 0.108 of RDF::Trine.
         * Added new bloom:filter function variant that doesn't use identity reasoning.
         * Added debugging information when RDFQUERY_THROW_ON_SERVICE is in effect.
         * Fixed test plan for t/optimizer.t in cases where no appropriate model is available.
         * Updated plan generation code to use ::BGPOptimizer when the model supports node_counts.
         * Fixed SSE serialization bug in ::Algebra::Sort.
         * Fixed bugs in RDF::Query and RDF::Query::Expression classes that insisted variables be RDF::Query objects 
         (and not simply RDF::Trine objects).
         * Fixed propogation of iterator binding_names when pre-bound values are used in ::Algebra execution.
         * Fixed RDF::Query::Algebra::Triple to correctly set binding_names when pre-binding is used.
         * Fixed use of pre-binding in execution of RDF::Trine optimized BasicGraphPatterns.
         * Fixed bug in SQL compilation when restricting left-joins to specific node types (based on functions like 
         isIRI).
         * Fixed node identity computation based on owl:sameAs.
         * Fixed bitrotted livejournal example script to work with new 2.000 API.

     * TESTS:
     
         * Added expected result count test in t/34-servicedescription.t.
         * Added initial tests for algebra subsumes method.
         * Added logging and costmodel tests.
         * Added more example capabilities and patterns to the test service descriptions.
         * Added RDF::Trine::Store::Hexastore to test model construction list in t/models.pl.
         * Added sparql:pattern data to test service descriptions.
         * Added sse re-serialization test to t/29-serialize.t.
         * Added support for sparql:pattern in service description parsing.
         * Added t/plan-rdftrine.t to test QEP generation optimized for RDF::Trine BGPs.
         * Added test data for repeat patterns (e.g. { ?a ?a ?b}).
         * Added tests to t/plan.t for QEP sse serialization.
         * Cleaned up federation tests.
         * Commented out in-progress service description tests.
         * Fixed bug in t/23-model_bridge.t to allow two models from the same model class to be used in testing.
         * Fixed error handling in t/plan.t.
         * Fixed t/costmodel-naive.t to provide a serialized query to ::Plan::Service constructor.
         * Fixed test count in algebra-bgp.t.
         * Fixed test in t/31-service.t that relied on identity-reasoning support in bloom filters (which is now off by 
         default).
         * Fixed use of RDFQUERY_NETWORK_TESTS in 31-service.t.
         * Improved use of temporary RDF::Trine stores in RDF::Query tests.
         * Marked tests TODO for federated query serialization.
         * Removed what looks like an accidentally pasted test in t/plan.t.
         * SERVICE tests involving bloom filter handling marked as TODO.
         * ServiceDescription parsing now gets entire sparql:patterns and not just arcs to depth one.
         * Silenced unfinished test debugging in t/logging.t.
         * Updated args to roqet call in failing_earl_tests.sh.
         * Updated costmodel and logging test expected results that changed due to changes to ::Plan::Join code.
         * Updated dawg-eval.t regex to recognize RDFTrine blank nodes.
         * Updated DBPedia test query in t/34-servicedescription.t to reflect new source data.
         * Updated expected cardinalities in t/logging.t for current plan choice.
         * Updated logging tests to use the new sparql serialization keys.
         * Updated SERVICE test in t/plan.t (still broken, but only runs when dev env var RDFQUERY_NETWORK_TESTS in 
         effect).
         * Updated t/plan.t to be less dependent on the specific state of the kasei.us service endpoint.
         * Updated test service description RDF for new tests.
         * Updates to improve logging and test coverage.

     * EXAMPLES and DOCS:
     
         * Added examples/query.pl to show a simple example of loading data and executing a query.
         * Added examples/create_query_api.pl for generating queries programatically (based on request from KjetilK).
         * Added bin/graph-bgp.pl to produce a png of a query's BGP variable connectivity graph.
         * Added bin/graph-query.pl to graph the (one chosen) QEP tree.
         * Added bin/graph-qeps.pl to vizualize all QEPs of a query with GraphViz.
         * Updated bin/parse.pl to emit the SSE serialization of the query algebra tree.
         * Updated bin/rdf_parse_turtle.pl to warn on any parser error.

  Version 2.002 (2008-04-25)

     * Updated Bloom::Filter required version in RDF-Query's Makefile.PL.
     * Fixed bug in get_function() when called as a class method.
     * Updated sparql:logical-* functions to accept more than two operands.
     * Added code to make loading of Bloom::Filter optional.
     * Added Bloom::Filter to list of recommended modules.

  Version 2.001 (2008-04-19)

     * Fixed use of "DESCRIBE <resource>" (instead of "DESCRIBE ?var").
     * Fixed SPARQL serialization of queries with DISTINCT.
     * Added ::Algebra::subpatterns_of_type method for retrieving all subpatterns of a particular type.
     * Moved sort_rows() into new ::Algebra classes Sort, Limit, Offset and Distinct.
     * Updated SQL compiler to handle new ::Algebra classes.
     * Bumped required RDF::Trine version to 0.106.
     * Added methods to RDF::Query for retrieving lists of supported SPARQL extensions and extension functions.
     * RDF::Trine pattern optimization now holds onto the original BGP object for forwarding of calls to as_sparql().
     * Removed use of Storable module. Query execution no longer clones parse tree before running.
     * Simplified project operation on query stream in RDF::Query::execute().
     * fixup() method in ::Algebra and ::Expression now passed the query object as an argument.
     * Replaced ::RDFTrine::unify_bgp with more general fixup() implementation.
     * ::Algebra classes now defer to the bridge during fixup() to allow model-specific optimizations.
     * RDF::Trine::Iterator::smap now allows overriding default construct_args (e.g. binding names).
     * sparql:str now throws a TypeError if argument isn't bound.
     * Fixed referenced_variables in RDF::Query::Expression.
     * Fixed COUNT function to only count bound variables.
     * Fixed aggregation to work with expressions.
     * Added support for GROUP BY clauses to aggregation queries.
     * Removed now unused ::Algebra::OldFilter class.
     * Added serialization tests for aggregate and union patterns.
     * Moved as_sparql methods from RDF::Trine:: to RDF::Query:: classes.
     * Removed context- (quad-) specific code from RDF::Query::Algebra::Triple.
     * Fixed serialization of BOUND filter functions.
     * Fixed serialization of unary expressions.
     * Fixed call to join_streams to use ::Iterator::Bindings instead of ::Iterator.
     * var_or_expr_value now takes bridge object as an argument.
     * var_or_expr_value will now accept any RDF::Query::Expression object as an argument.
     * Added test for using AS syntax for variable renaming: "(?var AS ?newvar)".
     * Added support for MIN, MAX, COUNT and COUNT-DISTINCT aggregate operators to the SPARQLP parser.
     * Added COUNT DISTINCT variant aggregate operator.
     * Aggregates (MIN, MAX, COUNT, COUNT-DISTINCT) now return xsd:decimal values (this shouldn't really happen for 
     non-numeric operands to MIN and MAX...)
     * Added as_sparql submethod to RDF::Query::Node::Literal to serialize numeric types unquoted.
     * Added var_or_expr_value method in RDF::Query.
     * Removed unused _true and _false methods in RDF::Query.
     * Fixed existing aggregates code and tests.
     * Removed unused (and bitrotted) t/05-stress.t test.
     * Made all tests that access the network opt-in with the RDFQUERY_NETWORK_TESTS environment variable.
     * Updated POD for ::Expression::Alias.
     * Added tests for select expressions.
     * Added initial support for selecting expression values.

  Version 2.000 (2008-03-19)

     * RDF::Query now uses RDF::Trine package for common classes (nodes, statements, iterators).
     * Moved RDF::Query::Stream into RDF::Trine::Iterator namespace.
     * Reshuffled SPARQL parsers tests.
     * Added support for RDF::Trine::Model.
     * RDF::Trine::Iterator can serialize to XML and JSON natively; Updated tests accordingly.
     * rdf namespace is only added by default for RDQL.
     * Fixed bug where the wrong bridge object would be returned for queries with FROM clauses.
     * Moved query_more code to Algebra classes.
     * Added RDF::Query::pattern method to return the GGP algebra pattern for the query.
     * Added RDF::Query::as_sparql method to serialize query as SPARQL string.
     * Removed unused RDF::Query::set_named_graph_query method.
     * Fixed bug where triples from a FROM clause were loaded into the underlying persistent store.
     * Added POD to RDF::Query::Node classes.
     * Added equal method to RDF::Query::Node classes.
     * RDF::Query::Node::Blank constructor now optionally produces identifiers.
     * Merged tSPARQL parsing code into new SPARQLP parser.
     * Added definite_variables method to RDF::Query::Algebra classes.
     * Triple class now serializes rdf:type shortcut 'a' appropriately.
     * Removed 'VAR' type from ::Node::Variable object structure.
     * Updated code to always expect a HASH reference from ::Bindings iterator.
     * Added more (sparql and see) serialization tests.
     * Removed old fixup code, replaced by ::Algebra fixup methods.
     * Moved FROM clause data loading to its own method.
     * Started removing old code (RDF::Base, direct DBI use, AUTOLOAD, profiling).
     * Moved general count_statements() method into bridge superclass.
     * Fixed SQL compiler to work with ::Algebra and ::Node classes.
     * Added as_native method to bridge superclass for converting ::Node objects to bridge-native objects.
     * Updated document namespace declaration for SPARQL XML Results.
     * Added support for SERVICE queries (ala ARQ) with Bloom filter semijoins.
     * Moved Expression classes out of the Algebra hierarchy and into their own space (RDF::Query::Expression).

  Version 1.501 (2007-11-15)

     * Fixed CONSTRUCT+OPTIONAL bug.
     * Added as_sparql methods to Algebra and Node classes to serialize patterns in SPARQL syntax.
     * Added deparse script.
     * Fixed jena:sha1sum tests when Digest::SHA1 isn't available.

  Version 1.500 (2007-11-13)

     * Query Engine:
       * URIs are now properly qualified with a BASE when present.
       * Base URI passed to constructor is now used if no BASE clause exists in the query.
       * Fixed BASE qualification when an IRI contains Unicode characters (Emulating IRI support with the URI module).
       * NAMED graph data is now seperated from the default model into new (temporary) models.
       * NAMED graphs now work with RDF::Core.
       * Added new RDF::Query::Algebra:: classes that are used to represent query ASTs.
       * Added new RDF::Query::Node:: classes that are used to represent RDF Nodes and Variables.
       * Major refactoring to RDF::Query::query_more() to enhance extensibility.
       * Added RDF::Query::query_more_triple() and RDF::Query::query_more_bgp() for triple and bgp matching.
       * Improved support of GGP pattern matching.
       * Added sgrep, smap, swatch and concat methods to RDF::Query::Stream class.
       * Refactored query_more() variants and sort_rows() to use new stream methods sgrep, smap, and concat.
       * Continued to fix bugs to more closely align with DAWG tests.
       * Updated DAWG tests to run with the RDF::Core backend.
       * Any DAWG tests with mf:requires are now automatically marked TODO.
       * DAWG tests graph equality is now punted to user verification.
       * Fixed bNode merging code in DAWG tests.
       * query_more() variants and sort_rows() now all return RDF::Query::Stream objects.
       * query_more() (and everything it calls) now expects bridge object as a method argument (to ensure NAMED graph 
       querying works).
       * Added join_streams() to perform netsted-loop natural joins on two Stream objects.
     * Filters:
       * Added call_function() method to abstract the generation of ['FUNCTION',...] blocks.
       * FILTER operator != is now negative for unknown datatypes.
       * Fixed exception handling in check_constraints().
       * Fixed type-promotion in arithmetic operations and added recognized xsd numeric types.
       * API Chnage: extension functions now take a bridge object as their second argument (after the query object).
       * Fixed equals() method in RDF::Core bridge to properly use the RDF::Core API.
       * Javascript function makeTerm now accepts language and datatype parameters.
       * toString() javascript funtion now returns just the literal value (not including language or datatype).
       * sop:str now will stringify blank nodes properly.
       * sparql:langmatches now properly differentiates between no language tag and an empty language tag.
     * Parsers:
       * Parsers now generate ASTs using the Algebra and Node classes.
       * Fixed bugs in SPARQL tokenizer for some Unicode strings (with combining accents).
       * RDF::Query::Parser::new_literal() now canonicalizes language tags (to lowercase).
       * Fixed GGP verification in RDF::Query::Parser::SPARQL::fixup().
       * Merged GGPAtom changes from tSPARQL to SPARQL grammar.
     * Backends:
       * Fixed bug in RDF::Query::Model::RDFCore::equals() when comparing two blank nodes.
       * Changed RDF::Query::Model::RDFCore::as_string to return strings where node type is identifiable (like Redland, 
       URIs as [...], literal \"...\", bnodes (...)).
       * Model methods literal_value, literal_datatype and literal_value_langauge now return undef if argument isn't a 
       literal.
       * Model methods uri_value and blank_identifier now return undef unless argument is of correct type.
       * Model add_string methods now normalize Unicode input.
       * Blank node prefix is now scoped to bridge, not lexically in RDF::Query::Model::RDFCore.
       * RDF::Query::Model::Redland::new_literal now forces argument to a string (XS code breaks on non-PVOK scalars).
       * RDF::Query::Model::Redland::add_uri now uses LWP instead of relying on Redland to fetch content.
       * Redland model class now recognizes DateTime objects as literals.
       * Updated add_uri() method in RDF::Core bridge to support named graphs (only one name per model for now).
     * Miscellaneous:
       * Added rudimentary profiling code (Devel::DProf seems to crash on RDF::Query)
       * Added initial code for supporting property functions (using time:inside as an example).
       * Removed multi_get code.
       * Removed code for MULTI patterns. Will replace with algebra-based optimization in the future.
       * RDF::Query::Stream constructor now accepts an ARRAY reference.
       * Stopped using the peephole optimizers. Will replace with an algebra-based optimizer in the future.

  Version 1.044 (2007-09-13)

     * DAWG tests now emit EARL reports.
     * Added test harness and temporal data importing scripts to new bin/ directory.
     * Added support for temporal queries in RDF::Query and optimizers.
     * Added support for CONSTRUCT queries in new YAPP-based SPARQL parsers.
     * Added TIMED graph tests for new SPARQL temporal extensions.
     * Added tests to SPARQL parser for bugs that were discovered with temporal extensions.
     * Added POD to new SPARQL parsers.
     * Added new Parse::Yapp-based SPARQL parser in preparation for temporal SPARQL extensions.
     * Added stub functions for temporal extension support.
     * Added model_as_stream() method to Redland bridge class.
     * Addded debug() method to RDF::Query::Model.
     * Added UNION tests.
     * Added a javascript debugging flag to RDF::Query.
     * Added RDF::Query::groupgraphpattern() for handling GGPs.
     * Added xsd:integer casting function.
     * Added <http://kasei.us/2007/09/functions/warn> as a FILTER tee that warns to STDERR.
     * Added Eyapp SPARQL grammer file and replaced parser with auto-generated code from eyapp.
     * Marked some SPARQL parser tests as TODO (due to incompatability with new YAPP-based parser).
     * Network tests are now run against all available models.
     * Stream tests are now run against all available models.
     * Query parser initialization code cleaned up (and now supports beta tSPARQL parser).
     * net_filter_function() now properly accesses nodes with bridge methods.
     * RDF::Query::Parser::new_blank now assigns default names if none is supplied.
     * Updated error messages in SPARQL parser to align with new YAPP-based parser.
     * SPARQL parse_predicate_object() fixed to support tripleNodes.
     * SPARQL parse_object() and parse_predicate() fixed for whitespace insensitivity.
     * Moved old hand-written SPARQL parser to now unused SPARQL-RD.pm.
     * Moved new YAPP-based SPARQL parser to SPARQL.pm.
     * Copied YAPP-based SPARQL parser for new temporal extension tSPARQL.pm.
     * Moved existing tests for hand-written SPARQL parser to 01-sparql_parser.t.rd-old.
     * Moved new YAPP-based SPARQL tests to t/01-sparql_parser.t.
     * Removed bad-syntax queries from optimizer and SQL compiler tests.
     * Fixed bad-syntax queries in stream and hook tests.
     * Made output of coverage tests easier to read by adding test names.
     * Fixed SPARQL parsers to allow keywords as variable names.
     * Fixed SPARQL parsers to allow dashes and underscores in variable names.
     * Fixed bad parser constructor call in SQL compiler tests.
     * Suppressed RDF::Base loading (again) during RDF::Query startup.
     * RDF::Query::Model::Redland::debug now shows contexts during iterator debugging.
     * Moved the old (hand written) SPARQL parser out of the way to make test harnesses happy.
     * SPARQL parser now respects spec regarding the reuse of blank node labels across BGPs.
     * SPARQL parser now does the right thing with NIL (the empty list).
     * SPARQL parser now handles embedded GGPs correctly.
     * Updated SPARQL parser and tests to pass (almost all) DAWG tests.
     * Fixed bug where results couldn't be sorted by a non-selected variable.
     * Removed the unused RDF::Query::timed_graph() method.
     * RDF::Query::qualify_uri is now more liberal in what it accepts.
     * Fixed xsd:boolean casting of integer values.
     * RDF::Query::Parser::new_variable can now generate private variable names.
     * Fixed test suite to work properly on systems without Redland.
     * Disabled loading of tSPARQL parser for release.
     * Removed function prototype definitions in Model base class (was causing loading problems when models are 
     missing).

  Version 1.043 (2007-06-14)

     * Fixed broken MANIFEST causing MakeMaker code to break.

  Version 1.042 (2007-06-13)

     * Added support for Javascript URL-based extension functions.
     * Added GPG signing support for Javascript functions.
     * Added meta methods to model classes.
     * Added count_statements methods to model classes.
     * Added default format for stringifying query result streams.
     * Added SPARQL syntax coverage tests.
     * Added stream tests.
     * ISIRI() now returns a sop:isIRI function IRI.
     * Redland bridge add_uri strips off URI fragment from parser base URI.
     * Underlying models aren't loaded if turned off by environment variables.
     * Stopped using the (currently broken) multi-get code.
     * Model classes aren't used if turned off by environment variable.
     * Standardized node testing to is_node (replacing older isa_node).
     * GPG verification failure now throws exceptions.
     * GPG fingerprint handling is now whitespace insensitive.
     * Removed (currently) unused multiget tests.
     * Redland bridge uri_value returns undef if not called with a node.

  Version 1.041 (2006-11-26)

     * Removed unwanted '+' signs on stringified bigints when running under perl 5.6.x.
     * Fixed unicode errors when running under perl 5.6.x.
     * Added tests for model bridge classes.
     * Fixed bugs in SQL bridge class.
     * RDFCore and Redland bridge classes now throw error when passed a bad model object.
     * Bridge class support() method now responds to feature requests for 'temp_model'.
     * Fixed bug in RDF::Query::Model::RDFCore::isa_resource returning true for blank nodes.
     * Fixed code in RDF::Query::Model::::SQL::equals().
     * Added partial support for new RDF::Storage::DBI storage class.
     * Added support for RDF::Query:::Model::SQL models in RDF::Query bridge code.
     * Removed RDF::Query::Model::SQL::* code that's now in RDF::Storage::DBI.
     * Added tests for backend bridge classes (RDF::Query::Model::*).
     * Added checks for which backends support XML serialization.
     * Fixed naive peephole tests in cases where model supports cost-based analysis.
     * Fixed bugs in tests that were relying on C<as_string> to act like C<literal_value>.
     * Added RDF::Base support.
     * Fixed bug in C<fixup> that prevented running queries against multiple models.
     * Added SimpleQueryPatternError exception class for future work on multi-get optimizations.
     * Removed forced dependence on Digest::SHA1.
     * Makefile.PL now recommends Digest::SHA1 (for jena function) and Geo::Distance (for 07-filters.t).

  Version 1.040 (2006-07-21)

     * Added support for BOUND() fiters in SQL compilation.
     * SQL compiler now produces valid SQL when query variable names are SQL reserved keywords.
     * Moved SPARQL parser test data into YAML.
     * Added YAML as a build-time prerequisite.
     * Fixed SPARQL parsing bug for blank nodes as statement objects.
     * Added peephole optimizer code with naive and cost-analysis strategies.
     * Added add_string method to RDF::Query::Model::Redland.
     * Added node_count method to RDF::Query::Model::Redland (only used for testing at this point).
     * RDF::Query::execute() now uses the peephole optimizer.
     * Removed punting code in RDF::Query::execute that tried to do JIT optimization.
     * Removed calls to getLabel() on model objects in test files.
     * Fixed dawg tests (was dying because of multiple plans being printed).
     * Fixed cost-based peephole optimizer tests (by forcing Redland to do node counting).

  Version 1.039 (2006-07-14)

     * Removed dawg tests from distribution. Only used as developer tests now.
     * Updated package to use Module::Install instead of ExtUtils::MakeMaker.
     * Fixed a spurious uninitialized warning in RDF::Query::get_bridge.

  Version 1.038 (2006-07-09)

     * Fixed DBI case-sensitivity for PostgreSQL support.
     * Cleaned up SQL syntax for easier debugging.
     * Removed extra parens in SQL that were causing postgresql to break.
     * Reference test foaf file using File::Spec->catfile() instead of directly.
     * Fixed SPARQL parsing bug for anonymous nodes in FILTER expressions.
     * Fixed major SQL compilation bugs for testing equality in FILTER expressions.
     * Fixed bug in hashing code for blank nodes in SQL compiler.

  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 C<error()>.)
     * Fixed POD errors, and added tests for POD coverage.
     * Added model API methods to SQL model class.
     * Added C<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 <commit> 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)

     * Updated to follow SPARQL Draft 2005.07.21:
        + ORDER BY arguments now use parenthesis.
        + SPARQL parser now supports ORDER BY operands:
          variable, expression, or function call.
     * Added binding_value_by_name() method to query result streams.

  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 (C) 2005-2009 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.

AUTHOR

  Gregory Todd Williams <gwilliams@cpan.org>