ARC2 is a complete rewrite of ARC1. We tried to incorporate all the feedback we received, especially requests by people used to PHP frameworks, and new to RDF. Here we go:
Setup
ARC2 introduces a static class which is all that needs to be included. Any other component can then be loaded via ARC2, without the need to know the exact path to the class file.include_once("path/to/arc/ARC2.php");
Accessing and using ARC components
Once the static ARC2 class is made available, you can load the components with simple method calls and start using them:$parser = ARC2::getRDFParser();
$parser->parse('http://example.com/foaf.ttl');
$triples = $parser->getTriples();
Configuration options
Configuration options can be provided during any class instantiation. Dynamically loaded sub-components will inherit their caller's configuration. This allows you to specify certain settings once, without having to worry about them later:$config = array( /* db */ 'db_name' => 'my_db', 'db_user' => 'user', 'db_pwd' => 'secret', /* store */ 'store_name' => 'arc_tests', /* network */ 'proxy_host' => '192.168.1.1', 'proxy_port' => 8080, /* parsers */ 'bnode_prefix' => 'bn', /* sem html extraction */ 'sem_html_formats' => 'rdfa xfn', ); $store = ARC2::getStore($config);
Error collection
Similar to the configuration settings that are passed to sub-components, any processing error that occurs will be logged and forwarded to the calling component:$rs = $store->query('...');
if ($errs = $store->getErrors()) {
/* $errs contains errors from the store and any called
sub-component such as the query processor, parsers, or
the web reader */
...
}A complete example
Detailed component descriptions are available in the other documentation sections. Here is a quick example that hopefully illustrates how ARC2 works:include_once("path/to/arc/ARC2.php");
$config = array(
/* db */
'db_name' => 'my_db',
'db_user' => 'user',
'db_pwd' => 'secret',
/* store */
'store_name' => 'arc_tests',
);
$store = ARC2::getStore($config);
if (!$store->isSetUp()) {
$store->setUp();
}
/* LOAD will call the Web reader, which will call the
format detector, which in turn triggers the inclusion of an
appropriate parser, etc. until the triples end up in the store. */
$store->query('LOAD <http://example.com/home.html>');
/* list names */
$q = '
PREFIX foaf: <http://xmlns.com/foaf/0.1/> .
SELECT ?person ?name WHERE {
?person a foaf:Person ; foaf:name ?name .
}
';
$r = '';
if ($rows = $store->query($q, 'rows')) {
foreach ($rows as $row) {
$r .= '<li>' . $row['name'] . '</li>';
}
}
echo $r ? '<ul>' . $r . '</ul>' : 'no named persons found';