any23-core/src/site/apt/extraction.apt

Notes on the extraction process

 This page describes some extractions corner-cases and their relative RDF representations. Main aim of this section is to describe how
 some specific cases are processed with <<Any23>> showing the correspondences between the extracted RDF triples.

* Nesting different Microformats

 This section describes how <<Any23>> represents, with RDF, the content of an HTML fragments containing different nested
 Microformats.
 <<Any23>> performs the extraction executing different extractors for every supported Microformat on a input HTML page.
 There are two different possibilities to write extractors able to produce a set of RDF triples that coherently
 represents this nesting.

 More specifically:

  * Embedding explicitly the logic within the {{{xref/org/deri/any23/extractor/html/package-summary.html}Microformats Extractors}}

  * Using the default <<Any23>> nesting feature.

 In the first case, the logic for representing the nested values, is directly embedded in the upper-level Extractor.
 For example, the following HTML fragment shows an hCard that contains an hAddress Microformat.

+----------------------------------------------------------------------------------------------
<span class="vcard">
    <span class="fn">L'Amourita Pizza</span>
     Located at
    <span class="adr">
        <span class="street-address">123 Main St</span>,
        <span class="locality">Albequerque</span>,
        <span class="region">NM</span>.
    </span>
    <a href="http://pizza.example.com" class="url">http://pizza.example.com</a>
</span>
+----------------------------------------------------------------------------------------------

 Since, as shown below, the {{{xref/org/deri/any23/extractor/html/HCardExtractor.html}HCardExtractor}}
 contains the code to handle nested hAddress,

+------------------------------

foundSomething |= addSubMicroformat("adr", card, VCARD.adr);

...

private boolean addSubMicroformat(String className, Resource resource, URI property) {
    List<Node> nodes = fragment.findAllByClassName(className);
    if (nodes.isEmpty()) return false;
    for (Node node : nodes) {
        addBNodeProperty(
            getDescription().getExtractorName(),
            node,
            resource, property, getBlankNodeFor(node)
        );
    }
    return true;
}

+------------------------------

 it explicitly produces the triples claiming the native nesting relationship:

+----------------------------------------------------------------------------------------------------
<rdf:Description rdf:nodeID="nodee2296b803cbf5c7953614ce9998c4083">
	<vcard:url rdf:resource="http://pizza.example.com"/>
	<vcard:adr rdf:nodeID="nodea8badeafb65268ab3269455dd5377a5e"/>
	<rdf:type rdf:resource="http://www.w3.org/2006/vcard/ns#VCard"/>

	<rdf:Description rdf:nodeID="nodea8badeafb65268ab3269455dd5377a5e">
	<rdf:type rdf:resource="http://www.w3.org/2006/vcard/ns#Address"/>
	<vcard:street-address>123 Main St</vcard:street-address>
	<vcard:locality>Albequerque</vcard:locality>
	<vcard:region>NM</vcard:region>
</rdf:Description>
+-----------------------------------------------------------------------------------------------------

 Instead, the second manner is to leave to <<Any23>> the responsibility of identifying nested Microformats and produce
 a set of descriptive RDF triples.
 More specifically, the following HTML fragment, provided as a reference example on
 the {{{http://www.google.com/support/webmasters/bin/answer.py?answer=146862}Google Webmaster tools blog}},
 shows a vEvent Microformat with a nested vCard.

+----------------------------------------------------------------------------------------------
<p class="schedule vevent">
    <span class="summary">
        <span style="font-weight:bold; color: #3E4876;">
           This event is organized by
            <span class="vcard">
                <a class="url fn" href="http://tantek.com/">Tantek Celik</a>
                <span class="org">Technorati</span>
            </span>
        </span>
        <a href="/cs/web2005/view/e_spkr/1852">Tantek Celik</a>
    </span>
</p>
+----------------------------------------------------------------------------------------------

 Due to the fact that the <<Any23>> provided extractors don't explicitly foresee the possibility of nesting such two
 Microformats, it automatically identifies the nesting relationship and represents it with the following triples:

+---------------------------------------------------------
<rdf:Description rdf:nodeID="node755b2b367973b6854ec68c77bec9b3">
	<nesting_original xmlns="http://vocab.sindice.net/" rdf:resource="http://www.w3.org/2002/12/cal/icaltzd#summary"/>
	<nesting_structured xmlns="http://vocab.sindice.net/" rdf:nodeID="node985d8f2b9afb02eeddf2e72b5eeb74"/>
</rdf:Description>

<rdf:Description rdf:nodeID="node150ldsavbx29">
	<nesting xmlns="http://vocab.sindice.net/" rdf:nodeID="node755b2b367973b6854ec68c77bec9b3"/>
</rdf:Description>
+---------------------------------------------------------

 That informally means that the vEvent Microformat has a nested hCard through the property
 http://www.w3.org/2002/12/cal/icaltzd#summary providing for them two blank nodes.