/ 
RDF-Query-Client-0.03
River stage one • 5 direct dependents • 5 total dependents
/ RDF::Query::Client

NAME

RDF::Query::Client - Get data from W3C SPARQL Protocol 1.0 servers

VERSION

0.03

SYNOPSIS

use RDF::Query::Client;

my $query = new RDF::Query::Client ("SELECT * WHERE {?s ?p ?o. ?o ?p ?s.}");
my $iterator = $query->execute('http://example.com/sparql');
while (my $row = $iterator->next) {
  print $row->{'s'}->as_string;
}

METHODS

new ( $query, \%opts )

Returns a new RDF::Query::Client object for the specified $query. The object's interface is designed to be roughly compatible with RDF::Query objects. The query language is always 'sparql'.

Options include:

* UserAgent - an LWP::UserAgent to handle HTTP requests.
execute ( $endpoint, \%opts )

$endpoint is a URI object or string containing the endpoint URI to be queried.

Options include:

* UserAgent - an LWP::UserAgent to handle HTTP requests.
* QueryMethod - 'GET', 'POST' or undef (automatic).
* QueryParameter - defaults to 'query'.
* AuthUsername - HTTP Basic authorization.
* AuthPassword - HTTP Basic authorization.
* Headers - additional headers to include (hashref).
* Parameters - additional GET/POST fields to include (hashref).

Returns undef on error; an RDF::Trine::Iterator if called in a scalar context; an array obtained by calling get_all on the iterator if called in list context.

get ( $endpoint, \%opts )

Executes the query using the specified endpoint, and returns the first matching row as a LIST of values. Takes the same arguments as execute().

as_sparql ()

Returns the query as a string in the SPARQL syntax.

useragent ()

Returns the LWP::UserAgent object used for retrieving web content.

http_response ()

Returns the last HTTP Response the client experienced.

error ()

Returns the last error the client experienced.

SECURITY

The <execute()> and <get()> methods allow AuthUsername and AuthPassword options to be passed to them for HTTP Basic authentication. For more complicated Authentication (Digest, OAuth, Windows, etc), it is also possible to pass these methods a customised LWP::UserAgent.

If you have the Crypt::SSLeay package installed, requests to HTTPS endpoints should work. It's possible to specify a client X.509 certificate (e.g. for FOAF+SSL authentication) by setting particular environment variables. See Crypt::SSLeay documentation for details.

BUGS

Probably.

SEE ALSO

AUTHOR

Toby Inkster, <tobyink@cpan.org>

COPYRIGHT AND LICENSE

Copyright (C) 2009 by Toby Inkster

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.6.0 or, at your option, any later version of Perl 5 you may have available.